غزة–الجامعة اإلسالميـة

عمادة الدراسـات العليـا

قسم الهندسة المدنية-ةكليـة الهندسـ

مياهإدارة مصادر ال

The Islamic University – Gaza

High Studies Deanery Faculty of Engineering Civil Engineering Department

Water Resources Management

Assessment of Rainwater Losses due to Urban Expansion of Gaza Strip

Atef Rushdi Khalaf

Supervised by

Dr. Jihad Hamed Dr. Husam Al-Najar

A Thesis Submitted in Partial Fulfillment of the Requirement for the Degree of Master of Science in Civil / Water Resources Management

May 2005

بسم الله الرحمن الرحيم

سورة البقرة

صدق اهللا العظيم

Dedication

I would like to dedicate this work to:

My parents for their endless and generous support.

My wife for her unlimited support, patience, and

perseverance to reach this accomplishment, and

To all my kids.

Atef Rushdi Khalaf

Acknowledgment

I would like to take this chance to thank all the people who were an indispensable part of my

knowledge and to the people who encouraged me to pursue my higher education. But first of all I

would like to thank Allah and then my advisors Dr. Jihad Hamed and Dr. Husam Al-Najar, for their

knowledge, continuing assistances, and helpful remarks. I would like to thank them for their guidance

throughout this research, for their inspiration, and for their deep understanding for water resources

engineering.

Special thanks to Dr. Hassan Sha'ban, the head of Palestinian Land Reclamation, who sparked my

interest in the field of water resources.

I'm grateful for deputy of the Ministry of Housing and Public Works Eng. Diaf-Allah Al-Akhrass for

his encouragement and support.

I'm in deep appreciation to the following people who offered helpful data and valuable advices: Mr.

Basheer Abu-Elaish from the Environmental Quality Authority, Mr. Mansour Abu-kwaik, and Eng.

Nabeel Aiad from Ministry of Planning, Dr. Hassn Ashour, Eng. Mustafa Al-baba, and Eng. Mohamed

Abu-Jabal from Al-Azhar University-Gaza, Dr. Mohamed Al-kahlout, from the Islamic University-

Gaza, Eng. Sobhi Skaik from Ministry of Local Governorate, Eng. Sami Hamdan, and Eng. Jamal Al-

dadah from Palestinian Water Authority.

I would like to thank all Water Resources Management Program staff, especially Professor Hamed El-

Nakhal, Dr. Nahd Ghbn, and Dr. Mohamed Sager.

I would like to express my deepest thanks and gratitude to my teachers Dr. Mohamed Al-Agha,

Professor Mohmed Ashour, Dr. Salah Bahar, and Dr. Sameer Yaseen.

Also, I wish to express my ultimate gratitude to my colleagues in the Ministry of Housing and Public

Works, especially Eng. Rushdi El-Shaltoni and Eng. Foad Ouda.

Many thanks are also extended to those entire not mentioned in person who contributed in any way at

the entire project stages.

I would like to dedicate this work to the memory of Dr. Bassam Al-Ashi.

I

Abstract

Water is a vital source supporting all forms of developments in Gaza Strip. Unfortunately, water

scarcity is the main characteristic of the Gaza Strip. Throughout the years, the Gaza Strip has been

experiencing an increasing shortage of water, due to growing demands and its location in a semi-arid

region with a small average rainfall of 300 mm/yr. The main source of water in the Gaza Strip is the

groundwater aquifer that is naturally recharged from rainfall. Over the time, continuous increase of

population resulted in dramatic urban expansion, which has a direct influence in reducing groundwater

recharge and increasing the surface run-off.

To quantify the losses due to run-off, Geographical Information Systems (GIS) as a measurement tool,

in addition to the soil conditions and metrological data for more than 20 years is used. The

comparison between various scenarios like the Gaza Strip without urban areas, agricultural land, the

existing land use and the future expansion has led to the following findings; the amount of delivered

rainwater to the groundwater accounts for 125 Mm3 and 55 Mm3 a year assuming that the Gaza Strip

is an open and fully cultivated areas, respectively.

The urbanized area represents around 16% in the year of 1998 and 21% in the year of 2005, and is

expected to increase in the next years due to the rapid increase in population to represent 33% and

45% for the years of 2015 and 2025 respectively. In the meantime, the water demand will increase due

to the expansion of water supply systems. The total amount of rainwater losses due to urbanization as

surface run-off is estimated 14.5 Mm3 in the year of 1998 and expected to increase to about 20 Mm3,

35Mm3, and 52 Mm3 for the years of 2005, 2015 and 2025 respectively. These will results in an

increasing pressure on underground water resources, which has lead to an irreversible depletion of the

aquifer.

II

الخالصـة

على الرغم من أن الماء يعتبر مصدر حيوي لدعم جميع مجاالت التطور في الحياة، إال أن قطـاع غزة يعاني على مر السنين من نقص حاد في مصادر المياه و ذلك لزيادة الطلب على المياه و النمو

.السكاني و قلة األمطار غزة، كما وتعتبر مياه األمطار المـصدر يعتبر الخزان الجوفي المصدر الرئيسي للمياه في قطاع

. لتغذيتهالطبيعي الوحيد إن الزيادة المطردة لعدد السكان قابله زيادة في التوسع العمراني، و الذي أدى بدوره إلـي زيـادة

نقص معدل كميات مياه األمطار التـي يمعدل فاقد مياه األمطار كمياه جارية على السطح و بالتال .فيتغذي الخزان الجو

: نتيجة التمدد العمراني األمطار لتقدير حجم فاقد مياه ةضمن اإلجراءات التي اتبعت في هذه الدراس تم استخدام برامج نظم المعلومات الجغرافية كأداة قياس، إضافة إلي دراسة المعلومـات المناخيـة

يائية ألنواع للقطاع خصوصا كميات الهطول في عشرين سنة سابقة، و أيضا دراسة الخصائص الفيز .التربة المختلفة مع التركيز على درجة الرشح

األراضي في قطاع غـزة مـن تاشتملت هذه الدراسة على المقارنة بين عدة فرضيات الستخداما قطاع غزة منطقة فضاء بدون وجود مناطق زراعية أو عمرانية، قطاع غزة منطقة زراعية، : أهمها

قطاع غزة، تأثير االستخدام المستقبلي لألراضي فـي قطـاع تأثير االستخدام الحالي لألراضي في .غزة

:من أهم النتائج التي توصلت إليها الدراسة مليون متر مكعب سـنوبأ فـي 125أن كمية مياه األمطار التي تصل إلى الخزان الجوفي تبلغ §

رضـية مليون متر مكعب في حالة الف 55حالة الفرضية األولى، في حين أن هذه الكمية تبلغ .الثانية

سوف 1998من مساحة القطاع في سنة % 16إن المناطق العمرانية التي كانت تمثل ما نسبته §، كما ويتوقع أن تـزداد 2005من المساحة اإلجمالية للقطاع في سنة % 21تزداد لتمثل حوالي و ذلك لمواجهة النمو المطرد 2025في سنة % 45 و 2015في سنة % 33هذه النسبة لتمثل

لسكان القطاع، و الذي سوف يقابله زيادة في الطلب على المياه كنتيجة للزيادة في تمديد شبكات .و أنظمة تزويد المياه لهذه المناطق العمرانية

النتيجة المباشرة للتوسع العمراني في قطاع غزة هو زيادة إلجمالي فاقد كميات مياه األمطـار § مليون متـر 14.5 بحوالي 1998يه في سنة على شكل جريان سطحي، حيث قدرت هذه الكم

مليون متر مكعب 52، 35، 20مكعب، و من المتوقع أن تزداد هذه الكمية المهدرة لتصل إلى . على الترتيب2025، 2015، 2005في سنوات

III

Table of Contents

Page Item

iii

Abstract……………………………………………………………………………..…….. viii List of Tables………………………………………………………………….………….. x List of Figures…………………………………………………..……………………........ xv List of Acronyms and Abbreviations……………………………..…………………......... 1 Chapter (1) Introduction……………………………………………..………………….1 Background………………………………………………………….. 1.1 2 Statement of the Problem……………………………………………... 1.2 4 Research Objectives…………………………………………………... 1.3 4 Research Methodology……………………………………………...... 1.4 4 Thesis Layout…………………………………………………………. 1.5 5 Chapter (2) Literature Review……………………………………….…………………. 5 Introduction………………………………………………………….... 2.1 6 Soils Water Movement ……………………………………………….. 2.2 7 Percolation…………………………………………………………….. 2.2.1 7 Infiltration……………………………………………………………... 2.2.2 7 Infiltration Terminology………………………………………………. 2.2.2.1 8 Measurement of Soil Infiltration Rate……………………………….... 2.2.2.2 8 Infiltrometers………………………………………………………….. 2.2.2.3 9 Factors Influence Infiltration Rate…………………………………….. 2.3 9 Crust ………………………………………………………………….. 2.3.1 9 Compaction……………………………………………………………. 2.3.2 9 Soil Texture……………………………………………………………. 2.3.3 10 Organic Matter………………………………………………………… 2.3.4 10 Pores…………………………………………………………………... 2.3.5 10 Aggregation and Structure…………………………………………….. 2.3.6 11 Water Content…………………………………………………………. 2.3.7 12 Computation Methods of Infiltration………………………………….. 2.4 12 Empirical Methods……………………………………………………. 2.4.1 12 Horton's Equation……………………………………………………... 2.4.1.1 13 Interception - Effective Rainfall - Direct Run-off…………………….. 2.5 13 Interception……………………………………………………………. 2.5.1 14 Effective Rainfall…………………………………………………….... 2.5.2 15 Direct Run-off…………………………………………………........... 2.5.3 15 Types of Run-off………………………………………………………. 2.5.3.1 16 Computation Methods of Surface Run-off……………………………. 2.5.3.2 20 Rainfall Harvesting……………………………………………………. 2.6 21 Rainwater Harvesting Techniques………………………….…………. 2.6.1 21 Rainwater Harvesting System Components…………………………… 2.6.2 21 The Catchment Surface………………………………………………… 2.6.2.1 21 Storage Facilities………………………………………………………. 2.6.2.2 22 Filtration Mechanisms…………………………………………………. 2.6.2.3

IV

22 Parameters Effecting Rainwater Harvesting…………………………... 2.6.3 24 Chapter (3) The Study Area…………………………………………………………….. 24 Location……………………………………………………………….. 3.1 24 Topography…………………………………………………………… 3.2 26 Meteorological Conditions……………………………………............. 3.3 26 Air Temperature………………………………………………………. 3.3.1 27 Wind Speed……………………………………………………............. 3.3.2 27 Solar Radiation…………………………………………………........... 3.3.3 27 Air Humidity………………………………………………………….. 3.3.4 27 Evaporation……………………………………………………............ 3.3.5 27 Rainfall…………………………………………………………........... 2.3.6 28 Demography……………………………………………………........... 3.4 28 Geology of the Gaza Strip…………………………………………….. 3.5 30 Tertiary formation………………………..……………….................... 3.5.1 30 Quaternary formation…………………………………………............. 3.5.2 30 Marine Kurkar Formation…………………………………………….. 3.5.2.1 30 Continental Kurkar Formation…………………………………........... 3.5.2.2 31 Quaternary Deposits…………………………………………............... 3.5.2.3 31 Subsoil Formation……………………………………………………... 3.6 31 Kurkar…………………………………………………………………. 3.6.1 32 Hamra…………………………………………………………………. 3.6.2 32 Soil Condition…………………………………………………………. 3.7 35 Hydrology of the Gaza strip…………………………………………… 3.8 35 Wadis Run-off…………………………………………………………. 3.8.1 35 Stormwater Run-off……………...……………………………………. 3.8.2 36 Existing Stormwater Management……………………………………... 3.8.2.1 38 Hydrogeology of the Gaza strip………………………………………. 3.9 40 Groundwater Level……………………………………………………. 3.9.1 41 Groundwater Flow……………………………………………………. 3.9.2 42 Groundwater Balance………………………………………………….. 3.9.3 42 Land Use………………………………………………………………. 3.10 44 Rural and Urban Development in Gaza Strip…………………………. 3.11 45 Before 1948 War and Establishment of Israel…………………............3.11.1 45 The Egyptian Period from 1948 to 1967………………………………. 3.11.2 45 The Occupation Period from 1967 to 1994…………………………… 3.11.3 46 From 1994 until Present Time …………………………………...........3.11.4 47 Chapter (4) Methodology …………………………………………………………........ 47 Literature Review…………………………………………….……….. 4.1 47 Geographical information System (GIS)………………………............ 4.2 47 Calculation of Urbanized Areas……………………………….……..... 4.2.1 48 Calculation of Agricultural Areas……………………………..………. 4.2.2 48 Calculation the Areas of Various Soil Types…………………………. 4.2.3 48 Three Dimensional Topographical View Map………………………..… 4.2.4 48 Deriving the Slope………………………………………….…………. 4.2.5 48 AutoCAD Program……………………………………………………. 4.3

V

50 Effective Rainfall………………………………………………............ 4.4 51 Evaporation…………………………………………………………… 4.5 51 Run-off Coefficient……………………………………………............ 4.6 52 Infiltration in Situ……………………………………………………... 4.7 52 Infiltration Rate for Various Soil Types…………………………........ 4.8 52 Rainfall Amount Infiltrated in the Various Soil Types………………. 4.9 53 Amount of Surface Run-off……………………………………............ 4.10 53 Total Amount of Rainfall Losses………………………………... …… 4.11 53 Net Amount Infiltrated into the Soil…………………………………… 4.12 54 Chapter (5) Results and Discussions…………………………………………………… 54 Introduction…………………………………………………………… 5.1 54 Infiltration Rate of the Varies Soil Types…………………………….. 5.2 57 Topography and Run- off Directions of Gaza Strip…………………... 5.3 61 Estimated Amount of Rainfall Infiltrated into the Soil……………….. 5.4 61 Scenario (1): Gaza Strip as an Open Space Area………………........... 5.4.1 63 Scenario (2): Gaza Strip as an Agricultural Area………….………….. 5.4.2 65 Scenario (3): The Influence of Existing Land Use……………………. 5.4.3 65 The Influence of the Different Land Use before September/ 2000…… 5.4.3.1

80 The Influence of the Israeli Incursion from September / 2000 until August

/2004……………………………………………………….. 5.4.3.2

83 Scenario (4): The Influence of Proposed Land Use………………….... 5.4.4 83 Future land Use Demand for Agriculture……………………………… 5.4.4.1 83 Gaza Airport and Gaza Sea Port Land Demand………………………. 5.4.4.2 83 Future land Use Demand for Industrial and Commerce………………. 5.4.4.3 84 Future Urbanized Land Demand………………………………………. 5.4.4.4 85 Future Urban Run-off for Gaza Strip…………………………………. 5.4.4.5 98 The Conflict between Urban Expansion and Groundwater Protection.. 5.5 100 Stormwater Mitigation Measures………………………………….….. 5.6 101 Stormwater Harvesting………………………………………………... 5.6.1 101 Small Scale Stormwater Harvesting…………………………………... 5.6.1.1 103 Large Scale Stormwater Harvesting…………………………………... 5.6.1.2 104 A further Stormwater Harvesting…………………………………….… 5.6.1.3 105 Chapter (6) Conclusions and Recommendations………………………………………. 105 Conclusions………………………………………………………….......... 6.1 107 Recommendations………………………………………………………… 6.2 108 References ……………………………………………………………………………….. 115 Useful Websites……………………………………………………………………….….. 117 Appendices…………………………………………………………………………..........

VI

List of Tables

Page Title Table

8 Infiltration Terminology (Adapted from Goris and Samain (2001) and Wilson, (1990))............................................................................................

Table 2.1:

9 Dimensions of Three Used Infiltrometers by Goris and Samain (2001)….. Table 2.2:

10 Texture of the Different Soil Types in the Gaza Strip (Adapted from Goris and Samain

(2001), and Hamdan (1999)………………………... Table 2.3:

13 The Infiltration Parameters for the Different Soil Type in Gaza Strip (Adapted from

Goris and Samain, 2001)…………………………........ Table 2.4:

18 Run-off Coefficient for Different Surface Types in Gaza Strip (Sogreah, et. al.,

1999)…………………………………..……………………….. Table 2.5:

19 The Intensity Duration Relationship for Various Return Periods in Gaza (Sogreah, et. al., (1999)…………………………………………………...

Table 2.6:

27 The Daily Average Variation in the Evaporation Rate in Gaza Strip

(mm/day) (Mortaja, 1998)……………………………………………... Table 3.1:

29 Geology and Geological History of the Gaza Strip. (Palestinian Environmental

Protection Authority, 1994) and (Hamdan, 1999)……. Table 3.2:

34 Classification and Characteristics of Different Soil Types in Gaza Strip (Mopic, 1997;

Goris and Samain, 2001, and the Author Work)………. Table 3.3:

42 Estimated Water Balance of the Gaza Strip (Metcalf and Eddy, 2000)…. Table 3.4:

43 Land Use Distribution in Gaza Strip (MOPIC, 1998)…………………… Table 3.5: 43 The Proposed Land Use Distribution in Gaza Strip (MOLG, 2004)…….. Table 3.6: 51 Shows Example Calculation of Effective Rainfall in Beit Hanoun Station. Table 4.1:

55 Infiltration Rate of Various Soil Types in Gaza Strip Based on Infiltrometer Reading

and Horton's Equation………………………..... Table 5.1:

62 Scenario (1): Gaza Strip as an Open Space Area………………………… Table 5.2: 64 Scenario (2): Gaza Strip as an Agricultural Area………………………… Table 5.3:

66 The Amount of Rainfall Infiltrated in the Various Surfaces of Northern

Governorate…………………………………………………………… Table 5.4:

67 Amount of Surface Run-off Destination in Northern Governorate……… Table 5.5: 68 Sub-Scenario (3.1): The Influence of Existing Land Use Before Sep/2000 Table 5.6:

70 Summarizes the Influence of the Existing Land Use in the Northern Governorate on

Infiltration and Run-off Amounts before Sep./ 2000… Table 5.7:

72 Summarizes the Influence of the Existing Land Use in Gaza Governorate on Infiltration

and Run-off Amounts before Sep./ 2000………………. Table 5.8:

74 Summarizes the Influence of the Existing Land Use in the Middle Governorate on

Infiltration and Run-off Amounts before Sep./ 2000.... Table 5.9:

76

Summarizes the Influence of the Existing Land Use in Khanyounis Governorate on Infiltration and Run-off Amounts before Sep./ 2000…

Table 5.10:

78

Summarizes the Influence of the Existing Land Use in Rafah Governorate on Infiltration and Run-off Amounts before Sep./ 2000…………………..

Table 5.11:

80 Number of Dunums Razed in Gaza Strip until Aug./2004 (MOP,2004)…. Table 5.12: 82

Scenario (3.2): The Influence of the Israeli Incursion from September /2000 until

August2004…………………………………………………

Table 5.13:

84 Land Demand for Industrial, Trade and Commercial Use (MOPIC, 1998) Table 5.14: 84 The Urbanized Land demand per Governorates (MOPIC, 1998)………… Table 5.15:

VII

85 Housing Units in 1997 and the Expected Urban Development Represent by Housing

Units and Build up Area in 17 years (MOPIC, 1998)……. Table 5.16:

87 Scenario (4): The Influence of Proposed Land Use for the Year 2015 ….. Table 5.17:

95 The Changes in Urbanized Area and Surface Run-off per Governorate for the years

1998, 2005, 2015, 2025……………………………………… Table 5.18:

99 Areas Controlled by Israel in Gaza Strip (P.W.A., 2004)………………… Table 5.19:

X

List of Acronyms and Abbreviations

Item

Symbol

Run-off Coefficient C United States Environmental Protection Agency EPA Environmental systems research Institute ESRI Basic infiltration rate fb

Infiltration capacity f c Initial infiltration rate f o Food and Agriculture Organization of the United Nation FAO Geographical Information Systems GIS Rainfall Intensity i Joule per square centimeter per day J.cm2 day -1 Meter per second m s-1 Ministry of Environmental Affairs MENA Millimeter per year mm/yr Million cubic meter per year Mm3/yr Ministry of Local Governorates MOLG Ministry of Planning MOP Ministry of Planning and International Corporation MOPIC Ministry of Transportation MOT Mean Sea Level MSL Northern Virginia Planning District Commission NVPDC Palestinian Water Authority PWA Palestinian Central Bureau of Statistics PCBs Effective Rainfall Pe. Palestinian Economic Council for Development and Reconstruction PECDAR Palestinian Hydrology Group PHG Palestinian National Authority PNA Part per million ppm United Kingdom Environment Agency UKEA U.S.A Agricultural Research Service USDA

1

Chapter (1)

Introduction

1.1 Background

Today, nearly half of the world’s population lives in cities. In developing countries,

people are leaving rural areas towards urban areas while population is rising rapidly.

Urban population growth and rapid urbanization have profound impact on the

hydrological cycle, including major changes in groundwater recharge (Lawrence,

et.al, 1998).

Urbanization, from a hydrologic perspective refers to the addition of impervious area

to a watershed. Impervious area includes, but is not limited to, structures such as

roads, houses, parking lots and industrial buildings. Commonly, cities are referred to

as ‘urban’ and towns have the distinction of being ‘rural’; however, in this context

urbanization refers to the addition of impervious areas to a watershed regardless of

scale (Zeckoski, 2002).

Urbanization of watersheds causes drastic effects on hydrology (Zeckoski, 2002).

Increasing run-off is a result of the increase in impervious area and that resulting in a

decrease in infiltration rate into deep soil layers (Schueler, 1987). Impervious area

includes any surface through which water cannot infiltrate. The effective impervious

area is the area that will have the most impact on the hydrology of the watershed

(Booth and Jackson, 1997).

The filtering effect of vegetation is lost when run-off from impervious areas is

transported directly to streams via the storm water conveyance system (NVPDC,

et.al., 1992).

In the Gaza Strip physical planning and planning policy for the Palestinian areas has

been for a long time under the control of the Israeli civil administration. The

important element for the overall policy of the Israeli occupation was security.

Therefore, security issues were the important criteria for planning rather than

resources protection.

After the Oslo agreement, the Palestinian planning institutions have not only been

faced with limited natural resources but also with a rapidly growing population. The

density of population in the Gaza strip is considered to be the highest population

2

density in the world especially in the refugee camps, which represent 70 % of Gaza

Strip residents.

According to the Palestinian central Bureau of statistics (PCBs) in 1997, the

population of the Gaza Strip is characterized by three distinct sectors: an urban

population, a rural population, and a refugee camp population.

Most of the urban expansion falls outside formal planning domain. In addition,

absence of adequate legal and administrative framework for planning, control and

enforcement of land use leads to destroy natural resources especially the

groundwater.

Considering the existing situation and the Israeli aggression to the Palestinian cities,

the planning takes the emergency manner. However, these were far below the

technical and administrative requirements of modern planning institutions needed to

cope with the enormous tasks of planning for the rebuilding and development of

Palestine (Shaat, 2002). Gaza Strip is a very poor area of natural resources.

Groundwater is one of the main resources to consider in the future urban expansion.

The scarcity of the land is the largest constraint with regard to the environmental

management of the Gaza Strip. Nowadays, the build up area represents around 20%

while it expected to reach 26% of the total Gaza Strip area by year 2010 (Al-Najar,

2003).

Water consumption is increasing due to population increase while groundwater

suffering of high depletion due to the lack of recharge from rainwater because of

urbanization, this leads to seawater intrusion. Consequently, groundwater quality is

deteriorating, salts concentrations are above the limits for drinking water (PHG,

2002).

1.2 Statement of the Problem

Water in Gaza Strip like many arid and semi arid areas is becoming an increasingly

scarce and planners are forced to consider any sources of water which might be used

economically and effectively to promote future development.

The main aquifer in the Gaza Strip is part of what is known as the coastal plain

aquifer. This aquifer covers the whole area of Gaza and extends over a distance of

120 km. It has a width of 7 to 20 km (PNA, 2002). The thickness of this aquifer

ranges from 100 to 180 meters with average thickness is 150 meters (PWA, 2002).

3

One of the major problems in Gaza Strip aquifer is the overexploitation of

groundwater resources and the absence of regulations, which control water

abstraction. More than 4000 wells penetrate the only main aquifer in the area with a

total estimated annual production of about 150 Mm3/yr., and the natural recharge of

the aquifer is estimated to be about 70 Mm3/yr., (PWA, 2002). The aquifer is

replenished mainly from the infiltration of rainwater. It is estimated that almost 40%

of the total annual rainfall infiltrates into the ground and recharges the groundwater

system (Abu-Mayla, et.al., 1998); the remaining rainwater evaporates or dissipates as

run-off during the short periods of the heavy rainstorms. The infiltration rate is

gradually decreasing due to the random urbanization that leads to reduce the

agricultural lands and increase the run-off towards the sea, leaving the groundwater

without considerable recharge. Water shortage in the Gaza Strip accounts for 25

Mm3/yr., (El-Kharouby, et.al, 2003). This value will be doubled within 10 years if

another marginal resource is not used (Al-Najar, 2003).

Gaza is essentially a foreshore plain gradually sloping westward toward the sea.

Thus, the total run-off of the rainwater ended in the sea, without giving enough time

for infiltration to the groundwater.

Nowadays, storm water may be conveyed in pipes, conduits and in paved streets

between curbs in densely developed areas, but few of these systems are seen in the

urban areas of the Gaza Strip. When an intense rainfall occurs, the water quickly

flows from flat or pit chides roofs to the streets often mixing with silage flow or

untreated sewage. Such flows soon become a nuisance with potential health

hazardous or a major flooding problem (LYSA, 1995). In more arid regions of the

Negev desert, run-off water has been used extensively in the past for both drinking

water and agricultural production (Bruins, et.al., 1991). In Gaza Strip, rainwater may

be collected from house roof, greenhouses and as overland flow from paved streets.

The current research concerns about the amount of the rainfall, which mostly

consider as losses due to the random expansion of the cities and refugee camps.

Moreover, some new housing projects are established over the best groundwater

quality locations. That leads to disturb the sustainability of water resources.

4

1.3 Research Objectives

The main objective of the research is the assessment of rainwater losses due to urban

expansion.

The research work is intended to achieve the following objectives:

§ Assessment of the existing build up area and the future urban expansion, and its

effect on groundwater recharge.

§ Evaluation of rainwater losses due to urban expansion as a result of surface run-off.

§ To propose some mitigation measures in small and large-scale approaches to

maintain sustainable water resource.

1.4 Research Methodology

The methodology of this research will be relied on:

§ Collecting data from relevant institution, ministries, libraries and internet.

§ Revision of accessible studies similar to the topic of this study.

§ Collecting statistical data about the number of houses, roofs, paved streets and

squares and compared with the numerical data form the municipalities and village

councils for stormwater collection and to assess the losses by run-off.

§ Utilization of GIS (Geographical Information Systems) to protect the groundwater

as a valuable natural and scarce resource in Gaza Strip within the frame of urban

planning.

§ Using Microsoft Excel, AutoCAD programs to quantify the rainfall losses.

§ Asses the infiltration rate for different soil texture in Gaza Strip.

§ Using the available data to predict the future urban areas and future run-off from

these areas.

§ Interpreting data according to the main aim and objectives.

1.5 Thesis Layout

The thesis layout consists of the introductory work, background information about

water shortage in Gaza strip. In addition to the main source of groundwater, recharge.

As soon as the problem is identified, various options and scenarios were discussed. The

results of these scenarios are listed, analyzed, and based on that conclusion and

recommendations are followed on the light of results.

5

Chapter (2)

Literature Review

2.1 Introduction

Most of the water or precipitation that comes to earth runs-off the land because of

gravity, the remaining usually infiltrates or seeps into the ground becoming

groundwater that can replenish aquifers, and increase the level of the water table.

Many factors affect run-off, such as type of precipitation, precipitation intensity,

amount of precipitation, and other meteorological factors such as wind, humidity,

temperature and season. As well as, many physical characteristics affect run-off: land

use, vegetation, elevation, soil type, and topography.

Dry soils allow for high infiltration rates, while it reduced in wet or moist soil and

eventually prohibits permeation of any more moisture, in some instances when

flooding occurs.

Water, which enters the soil, can be used by plants, evaporated, percolate to

groundwater aquifers, or become stream flow by means of lateral subsurface flow

and/or groundwater discharge. Water that does not infiltrate will pond on the soil

surface and run-off as overland flow.

Urban soils generally have less porosity, which significantly reduces water

movement rates as compared to similar forest or agricultural soils. Layering of soil

material during construction creates hydraulic discontinuities in the profile that

reduce water movement (Kays and Patterson, 1982).

Naturally, rainwater considered as the main source to recharge the groundwater

aquifer. However, the increase of urbanization leads to increase run-off, which

causes flooding, and depletion of groundwater.

Growth of urban and suburban communities is rapid in most urbanized watersheds

and has affected many watersheds that historically supported only resource-based

activities. Urbanization is assumed to have important impacts on both the availability

and quality of water resources.

Gaza Strip like most of the communities in the world urban area increased causing

increase in run-off. Collected data from MOP and MOLG shows the need for

expansion areas in the future. For a given rainfall, increased volume of run-off and

6

increased peak discharge are two effects attributable to urban development

(Pouraghniaei, 2002).

Urbanization results in impermeable land-surface; which reduces direct infiltration of

excess rainfall, but also tends to lower evaporation and thus increase and accelerate

surface run-off. Surface impermeabilisation processes include the construction of

roofs, and of paved areas, such as major highways, minor roads, parking lots,

industrial patios, airport aprons, etc. While the proportion of the land area covered is

a key factor, it should be noted that some types of urban pavement, such as tile, brick

and porous asphalt, are, in fact, quite permeable and, conversely, that some unpaved

surfaces become highly compacted with reduced infiltration capacity (Bouvier,

1990). Urbanization causes radical changes in the frequency and rate of groundwater

recharge, with a general tendency for volume to increase significantly and for quality

to deteriorate significantly (Foster, et.al., 1993). The changes in recharge caused by

urbanization in turn influence groundwater levels and flow regimes in underlying

aquifers (Van de Ven, 1990).

Infiltration rates are dependent upon texture of the soil material, but more important

is the structural condition of the soil material. Soil in an undisturbed forest condition

will have a high infiltration rate, compared to the same soil in an agricultural field.

The infiltration rate is reduced under the highly disturbed urban condition where

structure may be nearly destroyed. Consequently, significant decline in infiltration

rates is attributed to urban disturbances. Many studies were conducted in this

concern; in this research, the outcome of these studies will be reviewed.

2.2 Soils Water Movement

The main components of water movement in the soil are percolation, infiltration and

preferential flow especially in agricultural lands. The infiltration rate of a soil is the

sum of percolation and water entering storage above the groundwater table (Wilson,

1990). The movement of water into the soil by infiltration may be limited by any

restriction to the flow of water through the soil profile. The flow path may be

vertically downward, horizontal, or upward. The most important items influencing

the movement of water in the soil have to do with the physical characteristics of the

soil and the cover on the soil surface, but such other factors as soil water,

temperature, and rainfall intensity are also involved, (Schwab, et. al., 1993).

7

2.2.1 Percolation

Percolation refers to the ability of water to go through the subsoil, which can reach a

constant value after the entrapped air is removed. Percolation rate depends on the

hydraulic conductivity in the vertical direction and groundwater flow pattern

(Hamdan, 1999). Percolation is occurring much more quickly than infiltration (Perry

and Vanderklein, 1996). When percolation rate is less than infiltration rate, infiltrated

water spreads horizontally. Percolation could be constrained by substrata having less

permeability than the upper most layers. Consequently, water goes horizontally over

those non-permeable layers to find its way downward through the disconnection of

these layers (Bouwer, 1996). Direct percolation is most effective in recharging

groundwater where the soil is highly permeable or the water table is close to the

surface (Linsley, et.al., 1988).

2.2.2 Infiltration

According to Sharma (1983), infiltration refers to the entrance of water into soil or

porous material through the interstices or pores of a soil or other porous medium.

Infiltration is the sole source of soil water to sustain the growth of vegetation and of

the groundwater supply of wells, springs, and streams. (Schwab, et.al., 1993). The

capacity of any soil to absorb the rainwater falling continuously at an excessive rate

goes on decreasing with time until a minimum rate of infiltration reached. The

infiltration rate is a function of time, and has the dimensions of volume per unit of

time per unit of area. These units reduce to depth per unit time; it is expressed in

(mm/min) (Suresh, 1993).

2.2.2.1 Infiltration Terminology

The infiltration rate f is the actual rate at which water enters the soil at a given time.

The infiltration capacity fc is the maximum rate at which water can enter the soil

under given soil conditions and at a given time. If the rainfall rate exceeds fc, then f equal fc whereas, if the rainfall rate drops below fc then f equal the rate of rainfall

(Wilson, 1990). Relevant parameters symbols, units and definitions for infiltration

process are listed in table (2.1).

8

Table (2.1): Infiltration Terminology (Adapted from Goris and Samain (2001), and Wilson, (1990))

Parameter Symbol Definition Unit

Infiltration rate f The rate at which water is absorbed by the soil mm/min

Initial infiltration rate fo

The rate at which water is absorbed by the soil at time equal zero ( at the beginning of the rainfall )

mm/min

Basic infiltration rate fb

The relatively steady infiltration rate which is approached over the time

mm/min

Cumulative infiltration fp

The total accumulated depth of infiltrated water in a given time period.

mm

Infiltration index fi The average rate of water loss through infiltration mm

2.2.2.2 Measurement of Soil Infiltration Rate.

There are numerous techniques available for estimation of water infiltration rate

through the soil. These methods may be classified in a various ways according to the

way in which water is added, and the measurements are made. In this study, the

measured of infiltration rate for different soil types by Hamdan (1999) and Goris and

Samain (2001) are considered.

2.2.2.3 Infiltrometers

There are various devices for measuring the infiltration rate of water through soils,

the most common being the ring infiltrometer. This may be either a single or a

double ring. It consists of two open-ended metal cylinders that are driven

concentrically into the ground and then partially filled with water. As water seeps

into the soils, water is added to the cylinders to keep the liquid level constant. By

measuring the amounts of water added to each cylinder, the operator is able to

calculate the infiltration rate of the soil. From the infiltration rate, hydraulic

conductivity can be calculated. The dimensions of the double ring infiltrometer are

distinguished according to the purposes of the study needed and the physical

properties of the soil. Hamdan's (1999) study for surface infiltration was carried out

using double ring infiltrometer of different sizes of 4.6, 7.2, 10.4 and 15.3 cm and

height of 20 cm. in which the rings were inserted into the soil about 10 cm. Three

9

infiltrometers were used on each soil type in a study by Goris and Samain (2001) as

indicated in table (2.2).

Table (2.2): Dimensions of Three Used Infiltrometers by Goris and Samain (2001).

Infiltrometer No. Diameter inner ring d1 (cm)

Diameter outer ring d2 (cm) d2 / d1

1 28 53 1.89 2 30 55 1.83 3 32 57 1.78

In their study three-time interval were measured for each infiltration depth and the

mean infiltration rate is calculated.

Not all soil types in the Gaza Strip are tested by Goris and Samain (2001), therefore,

both results shall be taken into account in this study. However, both studies indicate

that the infiltration rates and the hydraulic conductivities of all soil type in the Gaza

Strip are very high.

2.3 Factors Influence Infiltration Rate.

The National Soil Survey Center in cooperation with (NRCS) and the U.S

Agricultural Research Service (USDA) suggested in (1998) that a number of factors,

which affect soil infiltration, some of these factors, are follow:

2.3.1 Crust

Soils that have many large surface connected pores have higher intake rates than

soils that have few such pores. A crust on the soil surface can seal the pores and

restrict the entry of water into the soil.

2.3.2 Compaction

A compacted zone or an impervious layer close to the surface restricts the entry of

water into the soil and tends to result in pounding on the surface.

2.3.3 Soil Texture

The type of soil (sandy, silty, and clayey) can control the rate of infiltration. For

example, a sandy surface soil normally has a higher infiltration rate than a clayey

surface soil. Hamdan (1999) suggested that soil texture is important to identify the

vulnerability of the artificial recharge basin to surface sealing, where a thin lamina of

fine particles covers the surface of spread basin will decrease the infiltration much

more clogging. Heil, et.al, (1997), tested different soils in Sahel region in Africa. The

findings of that program indicate that all sites with more than 5% clay content at 0–

10

50 mm depth were sealed, while sites with less than 5% clay were unsealed. Goris

and Samain (2001) described the texture of five different soils in Gaza strip, while

Hamdan (1999) added another sixth one as shown in table (2.3).

Table (2.3): Texture of the Different Soil Types in the Gaza Strip. (Adapted from Goris and Samain (2001), and Hamdan (1999)).

Soil type Clay % Silt% Sand % Soil texture Sandy regosol 08.5 01.8 89.8 Sandy Sandy loess soil over loess 17.5 16.3 66.2 Sandy loam Loessial sandy soil 18.0 25.0 57.0 Sandy loam Dark brown/reddish brown 25.3 12.8 61.9 Sandy clay loam Sandy loess soil 23.2 20.3 56.5 Sandy clay loam Loess soil 06.0 34.0 58.0 sandy loam

2.3.4 Organic Matter

An increased amount of plant material, dead or alive, generally assists the process of

infiltration. Organic matter increases the entry of water by protecting the soil

aggregates from breaking down during the impact of raindrops. Particles broken from

aggregates can clog pores, seal the surface, and decrease infiltration during a rainfall

event.

2.3.5 Pores

Continuous pores that are connected to the surface are excellent conduits for the

entry of water into the soil. Discontinuous pores may retard the flow of water

because of the entrapment of air bubbles.

Organisms such as earthworms increase the amount of pores and assist the process of

aggregation that enhances water infiltration.

2.3.6 Aggregation and Structure

Soils refer to the arrangements of the soil particles (aggregates) separated by pores

and cracks as represented in Figure (2.1). The basic types of aggregate arrangements

and its flow rate are shown in Figure (2.2). Soils that have stable strong aggregates as

granular or blocky soil structure have a higher infiltration rate than soils that have

weak, massive, or plate like structure. Soils that have a smaller structural size have

higher infiltration rates than soils that have a larger structural size.

11

Figure (2.1): The Soil Structure.( FAO,1993).

1. GRANULAR 2. BLOCKY

3. PRISMATIC 4. MASSIVE

Figure (2.2): The Basic Types of Soil Structures. ( FAO,1993).

2.3.7 Water Content

The content or amount of water in the soil affects the infiltration rate of the soil. The

infiltration rate is generally higher when the soil is initially dry and decreases, as the

soil becomes wet. Pores and cracks are open in a dry soil, and many of them are

filled in by water or swelled when the soil becomes wet. As they become wet, the

Moderate Flow Slow Flow

Rapid Flow Moderate Flow

12

infiltration rate slows to the rate of permeability for most restrictive layer. Water is

stored in the soil within the pore space between the soil particle by forces of

attraction acting between the water molecules and the particles of the soil matrix. The

forces holding the water to the soil matrix are called matrix forces (Raes, 1999). The

amount of water retained and stored in soil after watering and following drainage is

important in both plant growth and hydrological studies (Goris and Samain, 2001)

2.4 Computation Methods of Infiltration.

2.4.1 Empirical Methods

Empirical methods are usually in the form of simple equations. These equations only

provide estimates of cumulative infiltration and infiltration rates, and do not provide

information regarding water content distribution. Most are derived based on a

constant water content being available at the surface. (Parlange and Haverkamp,

1989). The study of all methods is not the scope of this study; the most familiar

methods, which can be applicable to the soils type of Gaza Strip, will be introduced

such that:

2.4.1.1 Horton's Equation

Horton's Equation (1939) is an empirical relation that assumes infiltration begins at

some rate fo and exponentially decreases until it reaches a constant rate fb (Chow,

et. al.,1988).

The infiltration rate is expressed as:

f = fb + ( fo - fb ) e – k t (2.1)

While the cumulative infiltration capacity is expressed as:

fp = fb t + [ ( fo - fb )/ K ] e – k t (2.2)

Where; f is the infiltration rate (mm/min), fb is the final constant infiltration rate

(Basic) at large times (mm/min), fo is the initial infiltration rate (mm/min), fp is the

cumulative infiltration capacity (mm), and K is the soil parameter representing the

rate of decrease of infiltration (min -1)

Horton's Equation can be used to describe the concepts of infiltration rate and basic

infiltration, it requires evolution of fo , fb and k ( these parameters are derived based

on infiltration tests ( Linsley, et. al., 1988 ). The infiltration parameters for the

13

different soil type in Gaza Strip are evaluated from the experimental infiltration data

done by Goris, and Samain (2001) as shown in table (2.4).

Table (2.4): The Infiltration Parameters for the Different Soils Type in Gaza Strip (Adapted from Goris and Samain, 2001).

Soil type Texture

Initial infiltration rate ( f o )

mm/hr

Basic infiltration rate ( f b )

mm/hr

soil parameter

( k )

Sandy regosol sandy 1263.0 401.4 0.24 Sandy loess soil over loess Sandy loam 0357.6 097.2 0.08

Loessial sandy soil Sandy loam 0498.6 145.8 0.08 Dark/reddish brown Sandy clay loam 1051.2 208.8 0.11 Sandy loess soil Sandy clay loam 0270.6 066.0 0.06 Loess soil Sandy loam 0428.1 121.5 0.08

In spite of different equations like, Kostiakov's; Holton's Equation, Boughton's, and

Philips equation used to find the infiltration rate, Horton's Equation is used. Where,

other equations require specific parameters that are not available in the case of Gaza

Strip. For more detail, information about these equations and the parameters see

Appendix (A).

2.5 Interception - Effective Rainfall- Direct Run-off

2.5.1 Interception

Interception, that is, the depth of rainwater retained on a forest or litter canopy for

subsequent evaporation, constitutes a significant portion of the incident precipitation

in certain watersheds (Calder, 1992), and has a significant influence on the energy

and water budgets at the land surface. Interception capacity (generally expressed in units of volume per unit area) refers to

the maximum volume of water that can be stored on the projected storage area of the

vegetation—that is, on the area of leaves, twigs, and branches that can retain water

against gravity—under still air conditions (Ramirez and Senarath, 2000).

Several factors such as leaf area; leaf area index, precipitation intensity, and surface

tension forces resulting from leaf surface pattern, liquid viscosity, and mechanical

activity (Aston, 1979) influence interception capacity. Massman (1983) observed a

clear dependence of interception on rainfall intensity, identified it as one of the main

contributors toward the drip of intercepted rainwater, and indicated that interception

14

and rainfall intensity are inversely related to each other. Where, Suresh (1993)

emphasized that the amount and intensity of precipitation reaching a soil surface is

influenced by the amount and type of vegetation cover on a site.

The capacity of vegetated surfaces to intercept and store water is of great practical

importance. To hydrologists, the most important aspect of interception relates to its

effect on site and catchments water balances (Van Dijk, 2002). It is well documented

that the rate of evaporation from a wet canopy is higher than that under dry canopy

conditions (Calder, 1992).

As such, rainfall interception and its subsequent evaporation constitute a net loss to

the system, which may assume considerable values under certain conditions

(Ramirez and Senarath, 2000).

Zinke (1967) found that 15% to 40% of annual gross precipitation can be lost by

interception in conifer-dominated forests and 10% to 20% in hardwood-dominated

forests. Interception may exceed 59% of annual gross precipitation for old growth

forest trees (Van Dijk, 2002).

Several studies have simulated urban forest impacts on storm water run-off. Sanders

(1986) assert that’s; tree canopy cover 22% lowering potential run-off from a 6-hour,

one year storm by about 7%, and by increasing tree cover to 50% over all pervious

surfaces, run-off reduction was increased to 12%. Lormand (1988) proposed that

increasing tree canopy cover from 21 % to 35% was projected to reduce mean annual

run-off by 2% and 4%, respectively. A healthy urban forest can mitigate storm water

impacts of urban development (Sanders, 1986). Trees intercept and store rainfall on

leaves and branch surfaces, thereby reducing run-off volumes and delaying the onset

of peak flows.

2.5.2 Effective Rainfall

According to FAO (1997), the term effective rainfall has been interpreted differently

not only by specialists in different fields but also by different workers in the same

field.

According to water engineers interested in providing a drinking water supply from

storage tank or lake, effective rainfall will be that amount of rainfall, which enters the

reservoir.

15

According to Geohydrologists point of view; effective rainfall that part of rainfall

which contributes to groundwater storage, in which the extent of the rise in the water

table or well levels would be the effective rainfall. Assessments of effective rainfall

provide an indication of how much of the rainfall over an aquifer outcrop actually

contribute to the recharge of groundwater (UKEA, 2001).This study will be relied on

the later concept to calculate the effective rainfall in Gaza Strip.

Ouda, (1999) calculated the effective rainfall in Gaza Strip in the period from 1981

until 1994. In this study, the calculation of effective rainfall will be from 1982 until

2004 based on the FAO general formula for effective rainfall (Pe) which is as

follows:

Pe = 0.8 * P - 25 for average rainfall (P) > 75 mm / month (2.3)

Pe = 0.6 * P - 10 for average rainfall (P) < 75 mm / month (2.4)

The detailed computation of effective rainfall is shown in Appendix (B).

2.5.3 Direct Run-off

Run-off refers to that part of the precipitation or effective rainfall moved by gravity

in surface channels or depressions. It is a residual quantity, representing excess of

precipitation over Evapotranspiration (Perry, and Vanderklein, 1996). Run-off occurs

only when the rate of precipitation exceeds the rate at which water may infiltrate into

the soil (Sharma, 1983). Run-Off is generated by the soil surface when the rainfall

intensity is higher than the infiltration rate of the rainwater into the soil. The type of

soil, therefore, is an important aspect to assess the run-off generating capacity of a

certain area (Bruins, et. al., 1991).

Approximately 47,000 km3 of water per year (35 % of all precipitation) is returned to

oceans through run-Off (Perry and Vanderklein, 1996).

2.5.3.1 Types of Run-off

Based on the time delay between rainfall and run-off, Suresh (1993) classified the

run-off into the following three types:

§ Surface Run-off

It is that portion of rainfall, which enters the stream immediately after the rainfall.

The amount of surface run-off may be quite small, however, since surface flows over

a permeable soil surface occur only when the rainfall rate exceeds the local

16

infiltration capacity. Hence, surface run-off may occur only from impermeable and

saturated areas. (Linsley, et. al., 1988).

§ Sub-Surface Run-off (Inter Flow)

It is that part of rainfall, which first leaches into the soil and moves laterally without

joining the water table, to the streams, rivers or oceans. It moves more slowly than

the surface run-off and reaches the stream later. Interflow may be much larger in

quantity, especially in storms of moderate intensity, and hence may be principal

factor in the smaller rises of stream flow (Linsley, et. al., 1988).

§ Base Flow (Groundwater Flow)

It is defined as that part of rainfall, which after falling on the ground surface,

infiltrated into the soil and meets to the water table. Sometimes base flow is also

known as groundwater flow. In this research, the main concern is given to the surface

run-off.

2.5.3.2 Computation Methods of Surface Run-off.

There are numerous methods available for rainfall-run-off computations on which the

design of storm water drainage and flood control plans may be based. Accurate

computation of run-off amount is difficult, as it depends up on several factors

concerned with atmospheric and watershed characteristics (Suresh, 1993). The

following methods are frequently used in soil and water conservation for estimating

the maximum or peak run-off of a particular watershed, in which this study will be

relied up on the rational method.

I. Rational Method

It is the simplest and the widely used method to predict the peak run-off rate. The

Rational Method is perfectly acceptable for calculating storm drain and inlet peak

discharges as well as calculating street surface flow peak discharges (Chow, et.al.,

1988). It depends on calculating the flow as the product of rainfall intensity; drainage

area, and a coefficient, which reflects the combined effects of surface storage,

infiltration, and evaporation. (McGhee, 1991). The Rational Method is based on the

following assumptions for the determination of peak discharge:

A. The storm duration is equal to the time of concentration.

17

B. The return period, or frequency, of the calculated peak discharge is the same as

the return period for the design storm.

C. The run-off coefficient does not vary during a storm and the necessary basin

characteristics can be identified.

D. The rainfall intensity is constant during the storm duration, and is uniform over

the entire drainage area under consideration.

E. The calculated peak discharge at the design point is a function of the average

rainfall rate during the time of concentration to that point. With these underlying

assumptions, the peak discharge can be calculated as:

Q = C i A (2.5)

Where; Q is the Peak discharge in cubic meter per second, C is the Run-off

coefficient which represents the ratio of run-off to rainfall for the drainage area

considered, i is the average rainfall intensity in mm per hour for a period of time

equal to the time of concentration (Tc) for the drainage area under consideration, and

A is the drainage area in square meter, contributing run-off to the point of

consideration.

I-1 Run-off Coefficient (C )

It is defined as the ratio of the peak rate of direct run-off to the average intensity of

rainfall in a storm (Chow, et. al., 1988).The proportion of the total rainfall that will

reach the design point depends on the imperviousness of the surface, the surface

slope, the ponding characteristics of the area and the design storm event (Sharma,

1983). The run-off coefficient (C ) in the Rational Formula is also dependent on the

character of the soil. The type and condition of the soil determines its ability to

absorb precipitation. The rate at which a soil absorbs precipitation generally

decreases as the rainfall continues for an extended period. The soil infiltration rate is

influenced by the presence of soil moisture (antecedent precipitation), the rainfall

intensity, the proximity of the groundwater table, the degree of soil compaction, the

porosity of the subsoil, and ground slopes (USDA,1998). Sogreah, et al., (1999)

calculated the run-off coefficients for different surface types in Gaza Strip as it given

in table (2.5).

18

Table (2.5): Run-off Coefficient for Different Surface Types in Gaza Strip (Sogreah, et. al., 1999).

Development Coefficient Pavement, Road/Parking 0.90 Commercial / Public lots 0.70 Residential Communities 0.60 Parks / Unimproved Areas 0.30 Irrigation Areas 0.20 Natural Zones 0.05

I.2. Rainfall Intensity ( i )

Rainfall intensity ( i ) is the average rainfall rate in mm per hour, and is selected on

the basis of design rainfall duration and design frequency of occurrence. The design

duration is equal to the time of concentration for the drainage area under

consideration. The design frequency of occurrence is a statistical variable, which is

established by design criteria.

Two main studies modified the intensity duration relationship (PECDAR, 2000),

which are:

1. USAID wastewater master plane for Gaza city. Where a modified figure for the

intensity duration relationship for 2, 5, 20, and 100 year return periods is shown in

table (2.6). The derived intensity duration equation for 5 years return period was

given as:

I (mm/min) = 6.20 T0.65 (2.6)

Resulting in 26 mm rain in one hour. This equation is more applicable to the rainfall

intensity in Gaza Strip and it will be used in the calculation of this study.

2. JICA wastewater master plan for Khanyunis. This project used date from Dorot

metrological station (near to Khanyunis). The derived intensity duration equation for

5-year return period was given as:

I (mm/min) = 4.28 T0.60 (2.7)

Resulting in 22 mm rain in one hour

Sogreah, et al., (1999) used the general formula:

I = a T b (2.8)

Where; I is the rainfall intensity (mm/min), T is the duration time (min), and a, b are

constants and related to the number of return years. For 5years return period, the

rainfall intensity equals to 26mm/hr, for another return periods see table (2.6).

19

Table (2.6): The Intensity Duration Relationship for Various Return Periods in Gaza. (Sogreah, et. al., (1999).

Return Period: 2 years – a: 4.06 – b:-0.636

Duration 5

min

15

min

30

min 1 h 2 h 3 h 6 h 12 h 18 h 24 h Pj= p24h X 0.875

Rainfall

(mm) 7.3 10.9 14 18 23.2 26.9 34.6 44.5 51.6 57.3 50

Return Period: 5 years – a: 6.18 – b: 0.649

Duration 5

min

15

min

30

min 1 h 2 h 3 h 6 h 12 h 18 h 24 h Pj= p24h X 0.875

Rainfall

(mm) 10.9 16 20.4 26 33.2 38.2 48.8 62.2 71.7 79.4 69

Return Period: 10 years – a: 7.95 – b: 0.660

Duration 5

min

15

min

30

min 1 h 2 h 3 h 6 h 12 h 18 h 24 h Pj= p24h X 0.875

Rainfall

(mm) 13.7 20 25.3 32 40.5 46.5 58.8 74.4 85.5 94.2 82

Return Period: 20 years – a: 9.39 – b: 0.665

Duration 5

min

15

min

30

min 1 h 2 h 3 h 6 h 12 h 18 h 24 h Pj= p24h X 0.875

Rainfall

(mm) 16.1 23.3 29.3 37 46.7 53.5 67.5 85.1 97.5 107 94

Return Period: 50 years – a: 11.89 – b: 0.675

Duration 5

min

15

min

30

min 1 h 2 h 3 h 6 h 12 h 18 h 24 h Pj= p24h X 0.875

Rainfall

(mm) 20.1 28.7 35.9 45 56.4 56.4 64.3 80.5 100.9 155.1 111

Return Period: 100 years – a: 13.60 – b: 0.682

Duration 5

min

15

min

30

min 1 h 2 h 3 h 6 h 12 h 18 h 24 h Pj= p24h X 0.875

Rainfall

(mm) 22.7 32.2 40.1 50 62.3 70.9 88.4 110.2 125.4 137.4 120

20

I.3 Time of Concentration (Tc)

The time of concentration is the time associated with the travel of run-off from an

outer point that best represents the shape of the contributing areas. Run-off from a

drainage area usually reaches a peak at the time when the entire area is contributing,

in which case the time of concentration is the time for a drop of water to flow from

the most remote point in the watershed to the point of interest. Sogreah, et al., (1999)

recorded that the Kirpich formula will be suitable to be used in determining the

concentration time for over land run-off flows in Gaza Strip, which is:

Tc = (L) 1.15 / ( 52 (H) 0.38 ) (2.9)

Where; Tc is the Concentration time in minutes, L is the Longest path of the drainage

area in meter, and H is the Difference in elevation between the most remote point and

the outlet in meters.

I.4 Drainage Area (A)

The size in square kilometer of the watershed needs to be determined for application

of the Rational Method. The drainage divide lines are determined by street layout, lot

grading, structure configuration and orientation, and many other features that are

created by the urbanization process. The Gaza Strip is divided into 24 main

catchments areas based on the topography of the area (Sogreah, et al., 1999). The

coastal part of the Gaza Strip drains directly into the Mediterranean Sea.

2.6 Rainfall Harvesting

Rainwater harvesting is defined as a method for inducing collecting, storing and

conserving local surface run-off for agriculture and urban areas in arid and semi-arid

regions. Rainwater Harvesting as a method of utilizing Rainwater for domestic and

agricultural use is already widely used throughout the world (Stuart, 2001), and even

here in Palestine. Botswana and Israel show that is between 80 to 85 percent of all

measurable rain can be collected and stored from outside catchments areas (Dixit,

and Patil, 1996). In remote areas where ground and surface water supplies are of

inadequate quantity or quality, rainwater harvesting has provided an economical and

reliable alternative water source. It has wide application also in urban and pre-urban

areas, where the reliability and quality of piped water is increasingly being

questioned (Stuart, 2001). This technology, which has been used for thousands of

21

years, has recently seen increasing usage in both modern and developing countries.

The increase is attributing to both governmental support and advances in technology.

2.6.1 Rainwater Harvesting Techniques Several classification of modern rainfall harvesting techniques has been proposed in

the past decade. According to Bazza and Tayaa (1993), the following techniques can

be used for urban Rainwater harvesting: 1. Storage in artificial above or underground tanks.

2. Recharging aquifer directly through existing dug up wells. 3. Recharging aquifer by percolation / soakage into the ground.

4. Pumping (putting under pressure) rainwater into the soil to prevent seawater

intrusion.

2.6.2 Rainwater Harvesting System Components System Components Regardless of the goal of a rainwater collection system, all have

the same primary components: a catchment surface, storage facility, and filtration

mechanism (Stuart, 2001). Depending on the goals of the design of a system, each

of these components can vary dramatically. The designs may vary depending on the

intended use of the system, required reliability, cost, available materials, local

climate and other parameters. 2.6.2.1 The Catchment Surface

The catchment surface is typically the rooftop area of the residence and gutters to

transport it. Any impervious surface near a residence could be used with a rainwater

collection system but contaminant hazards must be considered. A system configured

for potable water use should not collect run-off from on-grade surfaces due to the

higher risk of pollutants. Systems configured to infiltrate water to the sub surface

must also consider the risk of polluting the subsurface by infiltrating surface

pollutants. (Woods and Choudhury, 1992)

2.6.2.2 Storage Facilities

Storage facilities are typically the most expensive component of a collection system

and can vary greatly in size, cost and material. A system designed only to detain run-

off from single large storm events could be small, but a system used for summer

irrigation would need to be as large as possible to store the maximum amount of

22

winter rainfall. (Prinz and Singh, 2004). The size and type of a storage tank are

dependent on the area available at the site and on aesthetic requirements.

2.6.2.3 Filtration Mechanisms

Filtration mechanisms vary depending on water use. All systems should have a

debris filter to remove solids before water enters the storage tank. Users collecting

water only for irrigation do not require post tank filtration or purification as indoor

water users do ( Bucheli, et. al., 1998). Depending on the location of the catchment

and surrounding land use, the quality of collected rainfall and therefore the necessary

level of purification can vary dramatically.

2.6.3 Parameters Effecting Rainwater Harvesting.

The most important parameters that effecting rainwater harvesting process are as

follows:

I. Rainfall

The knowledge of rainfall characteristics (intensity and distribution) for a given area

is one of the pre-requisites for designing a water harvesting system (Prinz and Singh,

2004). The availability of rainfall data series in space and time and rainfall

distribution is important for rainfall-run-off process. A threshold rainfall events (e.g.

of 5 mm/event) is used in many rainfall run-off. The intensity of rainfall is a good

indicator of which rainfall is likely to produce run-off.

II. Land Use or Vegetation Cover.

Vegetation density can be characterized by the size of the area covered under

vegetation. From the studies in West Africa, and Syria (Prinz, et. al., 1998) proved

that an increase in the vegetation density results in a corresponding increase in

interception losses, retention and infiltration rates which consequently decrease the

volume of run-off.

III. Topography and Terrain Profile.

The terrain analysis can be used for determination of the length of slope, a parameter

regarded of very high importance for the suitability of an area for macro-catchment

water harvesting. With a given inclination, the run-off volume increases with the

length of slope. The slope length can be used to determine the suitability for macro or

micro- or mixed water harvesting systems decision-making (Prinz, et. al., 1998).

23

IV. Soil Type and Soil Depth.

The suitability of a certain catchment area in water harvesting depend strongly on its

soils characteristics and surface structure; the infiltration and percolation rate, and the

soil depth including soil texture which determine water movement into the soil (Prinz

and Singh, 2004).

V. Hydrology and Water Resources.

The hydrological processes relevant to rainwater harvesting practices are those

involved in the production, flow and storage of run-off from rainfall within a

particular project area. The rain falling on a particular catchment area can be

effective (as direct run-off) or ineffective (as evaporation, deep percolation). The

quantity of rainfall that produces run-off is a good indicator of the suitability of the

area for water harvesting.

VI. Socio-economic and Infrastructure Conditions.

For any water harvesting planning, designing and implementation, the chances for

success are much greater if resource users and community groups are involved from

early planning stage onwards. The financial capabilities of the average people, the

cultural behavior together with religious belief of the people, property rights and the

role of women and minorities in the communities are crucial issues. (Tauer and

Humborg, 1992).

24

Chapter (3)

The Study Area

3.1 Location

The Gaza strip is a coastal area along the eastern Mediterranean Sea; 45km long and

between (6-12) km wide, with total area of about 365 km2.

Gaza strip is located between longitudes 330-2" east and latitudes 310-16" north’s, as

shown in Figure (3.1). The area forms a transitional zone between the semi-humid

coastal zone in the north and the semi-arid loess plains of the northern Negev in the

east, and the arid Sinai desert of Egypt in the south.

The total amount of rainfall over the area of the strip is about 120 Mm3/yr., (Al-

Agha, 1997).

Administratively, Gaza Strip is divided into five governorates: North, Gaza, Middle,

Khan Younis and Rafah governorate in the south bordering with Egypt.

3.2 Topography

Topography refers to the altitude of the land surface. Gaza strip is a coastal foreshore

plain gradually sloping westward toward the sea allowing for surface run-off to

reinfiltrates the soil.

A sandy beach stretches all along the coast, bound in the east by a ridge of sand

dunes known as Kurkar ridges (Bruins, et. al., 1991).This alternating sequence of

permeable and impermeable layers serves as a natural catchment area for rainfall and

renders the sand favorable for growing crops.

The topography in the Gaza Strip is influenced by the ancient kurkar ridges, which

run parallel to the present coastal line (Hamdan, 1999). The altitude of the Gaza Strip

land surface ranges between zero meters at the shore line to about 90 meters above

mean sea level in some places, as shown in Figure (3.2). The height increases

towards the east from 20 to 90 meter above the sea level.

25

Figure (3.1): Gaza Strip Base Map Showing Weather Stations Distributions (PWA,

2003).

26

Figure (3.2): Topographical Map of Gaza Strip. (MOPC, 1997) 3.3 Meteorological Conditions

3.3.1 Air Temperature

The area has a Mediterranean dry summer sub-topical climate with mild winter; this

is because of its locations as transitional zone between semi-humid Mediterranean

climate and arid desert climate. The mean monthly lowest temperature in January is

13.5 C0 and the highest in August is 25.9 C0, with the mean annual temperature of

19.9 C0

27

3.3.2 Wind Speed

The wind velocity with northwest direction at 2 meter above the surface in the

summer is about 1.5 m s-1 , which is less than that’s during winter months where

velocity reaches values of 2.8 m s-1 ( D, Haeyer, 2000).

3.3.3 Solar Radiation

The mean annual solar radiation is about 2200 J.cm2 day -1 ( D, Haeyer, 2000). The

mean monthly values in winter are about one third of the mean monthly values in

summer. These values are applicable for the whole area since Gaza strip is too small

to have a distinct climate.

3.3.4 Air Humidity

The daily relative humidity varies between 66% in the night to 86% at the daytime in

summer and between 53% to 81% respectively in winter (Goris and Samain, 2001)

3.3.5 Evaporation

Table (3.1) shows the variation in the evaporation rate in Gaza strip. There is a clear

annual variation in the evaporation rate due to solar radiation. Mortaja (1998)

recorded that is the annual evaporation in the area ranges between 1300 to 1500 mm.

Table (3.1): The Daily Average Variation of the Evaporation Rate in Gaza Strip (Mortaja, 1998).

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Average (mm/day) 2.05 2.85 3.95 4.7 5.4 6.7 7.25 6.35 6.45 4.6 3.4 2.15

2.3.6 Rainfall

Most of Rainfall is measured in about 15 stations distributed through out Gaza Strip,

as shown in Figure (3.1). The records are taken every day to give a daily rainfall. The

average rainfall increases from south to north; it is about 242 mm/yr., in Rafah in the

south, to about 473 mm/yr., in Beit Lahia in the north. The average rainfall from

nine-weather station distributed along Gaza Strip for the period from 1982 to 2004 is

given in appendix (B). Because of variation in the rainfall intensity, the effective

rainfall differs from the south to the north. The effective rainfall mm/month for all

weather stations is given in appendix (B). Rainfall occurs only in the winter months

(October –March), most of the Rainfall occurs during December to January. The

28

number of rainy days as recorded in different weather stations along Gaza strip is 41

days. Rainfall is the main renewable resource that feeds the groundwater aquifer in

the Gaza Strip. About 40% (46 Mm3/yr.) of the total rainfall is recharging the

groundwater aquifer (Abu-Mayla, et.al., 1998). The distribution and the availability

of rainfall in space and time are important for rainfall-run-off process. Figure (3.3)

showing the number of rainy days according to the quantity for nine weather stations

in Gaza Strip for the year 2004.

0

5

1 0

1 5

2 0

2 5

GA

ZA

B.H

anou

n

B.La

hia

Elsh

atia

Elm

oghr

aqa

Elnu

siera

t

D.B

alah

Kha

nyuo

nis

Rafa

h

S ta tio n s L o c a tio n

Num

ber o

f Day

s

R ain y D a ys >

5m m

10 m m

20 m m

30 m m

40 m m

50 m m

Figure (3.3): Number of Rainy Days According to the Quantity in (mm) for Nine Weather Stations in Gaza strip for the Year 2004 (MOT, 2004).

3.4 Demography

The population of the Gaza Strip is characterized by three distinct sectors: urban

population is about 64%, rural population is about 5%, and a refugee camps

population is about 31%. The Palestinian central Bureau of statistics estimated the

population of the Gaza strip in 2003 to be 1,364,733 inhabitants with an annual

growth rate of 3.2% (PCBs, 1997). The population density within the eight refugee

camps is nearly 38,600 inhabitant/km2; even the urban areas have population

densities of approximately 15,400 inhabitant/km2.

3.5 Geology of the Gaza Strip

The Gaza strip is a shore plain gradually sloping to the west. It is underlain by a

series of geological formations from the Mesozoic to the Quaternary. The main

formations known were composed in the last two system periods, Tertiary formation

called “Saqiya formation” of about 1200-meter thickness, and the Quaternary

29

deposits in the Gaza Strip are of about 160 meters thickness and cover Saqiya

formation (Mortaja, 1998). Table (3.2) summarizes the geological history of the area,

where Figure (3.4) illustrates a geological cross-section in the Gaza Strip. The

geological formations deposited in the area are described as follows:

Table (3.2): Geology and Geological History of the Gaza Strip (Palestinian Environmental Protection Authority, 1994) and (Hamdan, 1999).

Era

Syst

em

Perio

d

Serie

s

Age

mill

ion

year

s

Form

atio

n

Envi

ronm

ent o

f D

epos

ition

Lith

olog

y

Max

. Thi

ckne

ss (m

)

Wat

er B

earin

g C

hara

cter

Hol

ocen

e

0.01 Alluvial Terrestrial Sand, loess,

calcareous silt and gravel

25 Locally phreatic aquifer

Continental Kurkar

Aeolian Fluvial 100 Main

aquifer Qua

tern

ary

Plei

stoc

ene

1.8 Marine Kurkar Near Shore 100 Main

aquifer

5 Conglomerate Near Shore Conglomerate 20 Base of the

coastal Zone aquifer

Plio

cene

12 Saqiya Shallow marine

Clay , Marl, Shale 1000 Aquiclude

Cen

ozoi

c

Terti

ary

Neo

gene

Mio

cene

22.5 Marine

Marl, Limestone,

Sandstone and Chalk

500

Aquiclude alternating permeable layers with saline water

Mesozoic Paleozoic Precambrian

30

Figure (3.4): A geological Cross-Section in the Gaza Strip. (Metcalf and Eddy, 2000).

3.5.1 Tertiary Formation

The tertiary formations are composed mainly of Saqiya formation, which consist of

clay, Marl and Shale, and overlies the limestone layer beneath. (Hamdan, 1999).The

thickness of this formation is about 1200 m at the shoreline, and it descends down

rapidly at the east. According to oil exploitation logs, it is found that there are other

Tertiary formations such as Chalks, limestone, and sandstone at depths of 2000 m.

3.5.2 Quaternary Formation

The quaternary deposits in the area have a thickness of about 160 m and covering the

Pliocene Saqiya formation. The overlying Pleistocene deposits “Lower Quaternary “,

consists of: -

3.5.2.1 Marine Kurkar Formation

It is composed of shell fragments and quartz sands with calcareous cement. The

thickness varies between 10 to 100 meters on the coast.

3.5.2.2 Continental Kurkar Formation

It is composed of red loamy sand beds (Hamra). The maximum thickness is about

100 meters with often-calcareous cement (Palestinian Environmental protection

Authority, 1994).

31

3.5.2.3 Quaternary Deposits

These deposits are found at the top of the Pleistocene formation with a thickness up

to 25 m. It can be divided into the following different types:

I. Sand Dunes

Sandy soil is found in the dunes area along the southern seashore, in a width of 2-3

km. The total area of the sandy covers about 70 km2. The sand dunes are 30-50 m

above sea level. Lucite soil is widely spread in the middle of Gaza. This soil is a

mixture of sand and loam (Palestinian Environmental protection Authority, 1994).

The thickness of these dunes is about 15 m. These dunes originate partly from Nile

river sediments. It extends along the shoreline, with small width in the south,

increasing northward up to 3 km.

II. Sand Loess and Gravel Beds.

It has a small thickness of about 10 m, and it is considered as the main formation of

Wadi Gaza.

III. Alluvial Deposits.

These formations have a thickness of 25 m and spreading around the Wadi Gaza.

IV. Beach Formation

It composed of relatively thin layer of sand with shell fragments. It is mainly

unconsolidated, however; in some places, it is cemented due to deposition of calcium

carbonate.

3.6 Subsoil Formation

The deposits formed in the Pleistocene and Holocene ages are classified as subsoil

formations and soil respectively. The subsoil formations from the Pleistocene age are

distinguished in two categories that are:

3.6.1 Kurkar

Hamdan (1999) suggested that these formations results from the continuous

deposition of sand through the Pleistocene age in a sedimentary basin, which extends

beyond the border of the coastal region. The sand was deposited as Aeolian dunes

that consolidated later by litho static pressure and precipitation. Cemented sandstone

are present near the surface, they form distinctive topographic ridges with vertical

relief up to 60 meter. These Kurkar ridges, from which the coastal aquifer has

32

obtained its name, typically extend in NE-SW direction. Hamdan (1999) emphasized

that this formation is the water-bearing layer that allows significant amounts of water

to go through. The hydraulic conductivity (the rate at which the formation allows

water to go through) of Kurkar depends on the type of the cement (clay mineral,

calcium carbonate).

3.6.2 Hamra

Hamra and Kurkar are found in consecutive stratification and formed in the

Pleistocene and Holocene series of the Quaternary system. Hamra and Kurkar

interchange each other on the outcrops at the ground surface of the Gaza Strip.

Hamra formation is a mix of clay, silt and fine grains that are covered by iron oxides

with red colour. The formation is free of lime and founded in beds at different depths

of about one meter thickness. Besides, it can be found in fragmented small layers.

3.7 Soil Condition

Soil is the surface layer that covers the rock formation; it is affected by the parent

rock and the local climate. It contains a mixture of organic and inorganic

constituents, water and air.

As shown in Figure (3.5) soils classification based on soil texture (MOPIC, 1997).

Another classification considered the outward properties and soil physical properties

in various depths (30 cm, 60 cm, 90 cm, 100 cm) ( Goris and Samain, 2001). The

classification and the characteristics of different soil types of Gaza Strip are

summarized in table (3.3). The infiltration rate differs from one type of soil to

another However, since the increasing urban development, the natural soil was

disturbed and covered by impermeable layers such as paved roads or occupied by

buildings. This, of course reduced drastically the amount of infiltrated rainfall that

replenishes the groundwater. The decrease in infiltrated rainwater appeared as a

surface run-off, is lost by either evaporation or diverted to the sea. The infiltrated

water in Gaza Strip goes through the soil in a rate of one to two metes per day in the

areas where fine sand is found, and this rate increases in the coarser formation e.g.

kurkar. However, the percolation rate decreases, if it encounters a clayey layer in the

subsurface. Water goes horizontally above the non-permeable layer until it

encounters a disconnection in this layer and travels vertically downward to

groundwater reservoir (PWA, 2003).

33

Figure (3.5): Soil Classifications in Gaza Strip. (Adapted from MOPIC, 1997)

10 11

1

2

4 3

5

6

10

7

5

7

9

8

34

Local Classification Location Area

( m2 ) Description Texture Infiltration rate ( mm / hr)

Loess soil Between the

Gaza city and the Wadi Gaza

23920170

Loess soils sedimented in Pleistocene until Holocene Series. The grain size of loess fluctuates from 0.002 to 0.068 mm. Loess has been transported by winds and sedimented in loose form in the upper part, and in hard form in the lower part of the layers. They are brownish yellow-colored often with accumulation of lime concretions in the subsoil and containing 8 – 12 % calcium carbonate.

Sandy loam (6% clay, silt 34% , sand 58%) 404.5

Dark brown /reddish brown

Beit Hanoun and Wadi

Gaza 20355450

These alluvial soils are Usually dark brown to reddish in colour, with a well-developed structure. At some depth, lime concretions can be found. The calcium carbonate content can be around 15–20%

Sandy clay loam (25% clay, 13% silt,

62% sand) 963.42

Sandy loess soil

Deir el Balah and Abssan 32517819

This is a transitional soil, characterized by a rather uniform, lighter texture. Apparently, windblown sands have been mixed with loessial deposits.

Sandy clay loam (23% clay, 21% silt,

56% sand) 258.66

Loessial sandy soil

It is found in the central and southern part of the strip

82937834 Forms a transitional zone between the sandy soil and the loess soil, usually with a calcareous loamy sandy texture and a deep uniform pale brown soil profile.

The top layer is sandy loam (14% clay, 20% silt, 66% sand). The lower profile is loam (21% clay, 30% silt,

49% sand)

471.48

Sandy loess soil over loess

It is found east of Rafah and Khan Younis

58324040 It is loess or loessial soils which have been covered by a 20 to 50 cm thick layer of sand dune

Sandy loam (17.5% clay, 16.5% silt, 66%

sand) 337.6

Sandy regosol It is found a

long the coast of Gaza Strip

113848480

Soil without a marked profile. Texture in the top meters is usually uniform and consists of medium to coarse quartz sand with a very low water holding capacity. The soils are moderately calcareous, very low matter and chemically poor, but physically suitable for intensive horticulture in greenhouses. In the deeper subsurface occasionally loam or clay loam layers of alluvial origin can be found

Top layer is loamy sand (9% clay, 4% silt, 87% sand). Deeper profile is

sand (7.5% clay, 0% silt, 92.5% sand)

1079

Table (3.3): Classification & Characteristics of Different Soil Types in Gaza Strip. (Mopic, 1997; Goris and Samain, 2001, and the Author Work).

35

3.8 Hydrology of the Gaza strip

There are no permanent surface water resources in the Gaza Strip, like rivers or

lakes. Temporary flow of surface run-off owing to rainfall is the only source of

ephemeral surface water, which may be used through so-called rainwater harvesting

techniques. (Bruins, et. al., 1991).

3.8.1 Wadis Run-off

The Surface water system in Gaza Strip consists of Wadis, which only flow during

short period. Wadis are characterized by short duration flash floods that occur after

heavy rainfall. During most of the time, the Wadis are completely dry. The major

Wadis are Wadis Gaza that originates in the Negev desert. Its Catchment area is a

large of 3500 km2. In addition, there are two small and insignificant Wadis in Gaza

Strip, Wadi El-Salqa in the South Without outflow to the sea and Wadi Beit Hanoun

in the north which Flows into Israel. The estimated average annual flow volume of

Wadi Gaza is 20 to 30 Mm3 (PECDAR, 2000). In 1994 the run-off was estimated at a

bout 40 Mm3, Where the rainfall in Gaza Strip in that year was a bout 1000 mm. Dry

periods, lasting a couple of years without any significant run-off are experienced.

When surface run-off occurs, it occurs during a limited number of days (Abu-Maila

and Aish, 1997).

A major problems associated with Wadis in Gaza Strip include, urbanization with

increased building near those natural areas, discharge of untreated sewage, disposal

of solid waste in the Wadis coarse , and loss of flow due to Israeli interception.

Sogreah, et al., (1999) reported that the surface water (Wadis) infiltration is

estimated to be between (1 – 4) Mm3/yr.

3.8.2 Stormwater Run-off

Storm run-off in the Gaza Strip is a function of rainfall intensity and duration

coupled with the ability of soil to absorb the water at a rate sufficient to prevent

collection of water on the surface. When the rainfall intensity is greater than the

infiltration rate into the soil, then run-off occurs. (Bruins, et.al., 1991). The type of

soil is very important, especially its capability to receive water, while the slope of the

terrain also becomes a factor, with flatter surfaces usually possessing higher

infiltration rates.

36

3.8.2.1 Existing Stormwater Management

The capture and infiltration of storm water is a necessity component of any

management plan. Besides there are some storming water catchment areas as shown

in Figure (3.6). Most of Gaza Strip municipalities suffering from storm water run-off

in the streets during the winter season. According to Sogreah, et.al, (1999);

PECDAR (2000), and Metcalf and Eddy (2000) the existing storm water systems in

Gaza Strip will be as following:

I. Beit Hanoun

Storm drainage takes normally place in the streets. While all new roads are being

built with storm drains. No particular problem for storm water drainage has been

reported.

II. Beit Lahia

Storm drainage takes normally place in the streets. No particular problem for storm

water drainage has been reported.

III. Jabalia

Storm water run-off in Jabalia town is lesser problem than that of Jabalia Camp. In

the case of Jabalia Camp storm water run-off takes place in the streets, the storm

water converges towards local depressions. The most one is Abu Rashid pond, which

located in the middle of the camp and having volume capacity of 47,000 m3. In the

case of Jabalia Town there are some local storm water run-off problems reported in

areas in the southeast part of Jabalia. Storm water run-off takes place on the streets.

Two catchment areas in the south part drains towards Sheikh Radwan pond in Gaza.

IV. Gaza

Storm water in the Coastal zone is not a major problem, as the area slopes to the sea.

Most storm water runs-off in the streets, a few drains exist in the lower areas. The

Gaza City having two Storm water reservoirs, which are:

IV.1 Sheikh Radwan Reservoir

It serves its own catchment of about 9000 dunums and it receives over flow from

Waqf reservoir, which serves a catchment of 9500 dunums. The storage capacity of

Sheikh Radwan reservoir is about 560,000 m3.

37

IV.2 Waqf Reservoir

It is located at a low point in the Asqoula area of the city and receives storm water

flows from the adjacent streets and developed areas. Waqf reservoir, serves a

catchment of 9500 dunums. The storage capacity of this reservoir is about 34,000 m3.

V. Middle Area

Currently there are no facilities for storm water drainage in the urban areas of the

middle area. No particular problem for storm water drainage has been reported.

Rainfall was retained on the vegetation or infiltrated and run-off was intercepted by

streams and Wadis. Recent urban development has increased the run-off ratios and

blocked the natural drains.

VI. Khanyounis and Surrounding Villages.

Generally, storm water is drained by surface run-off in the streets or in ditches. A

part of Khanyounis is drained towards a depression in the town center near the

municipal office, another to the EL-Katiba depression. This depression is flooded

during rain. Several smaller depressions in the town center are pumping the water to

nearby streets.

VII. Rafah

The main storm water problem in Rafah is in the area near the Rafah Camp, where

the storm water is mixed with sewage. Rafah is divided into 15 catchment areas; each

catchment has a depression in to which the storm water drains.

VII. Rural Locations

Storm water control in rural areas is varied and sporadic, with emphasis on storage

for use in irrigation rather that any flooding problems. Some rainfall collection

systems do exist, which are privately controlled and sometimes water is sold on local

consumers.

38

Figure (3.6): Stormwater Facilities in Gaza Strip. (Metcalf and Eddy, 2000).

3.9 Hydrogeology of the Gaza strip

Groundwater is considered the only dependable and regular source of water in the

Gaza Strip. It is a source of drinking, domestic, irrigation and industrial water

supplies. The aquifer depth varies from 10 meter in the east to 120 meter in the west

(Abu-Mayla, et.al., 1998). According to Environmental planning Directorate (1996),

it is believed from studies done by Israeli researchers that the deep aquifer under the

Negev Desert contains brackish water at depth of about in some areas of 1500 to

3200 meters below the sea level.

39

Groundwater in the Gaza Strip occurs in a system of shallow sub-aquifers, which is

made up mainly of quaternary sands; calcareous sandstone and pebbles with inter

beds of impervious semi-pervious clay. Approximately 90% of the Gaza Strip water

comes from this shallow coastal aquifer (Al-agha, 1995).

The top of the system consists of recent sand dunes in the western part of the strip

and finer deposits (sands and loess) in the eastern part and beyond, inter bedded with

paleo-soils. Assessing to Figure (3.7) a hydrological cross section that passes through

the Gaza Strip shows the depth and sub-aquifers. Groundwater is found in three

aquifers composed mainly of sand, sandstone and pebbles. The three aquifers are

divided into sub-aquifers that overlay each other in certain places separated by

impervious and semi-impervious clayey layers (Mogheir, 1997), where these aquifers

described as follows:

1. The upper aquifer lies closest to the sea and extends to two kilometers inland

at a depth mainly below sea level.

2. The middle sub-aquifer is situated below the upper aquifer near the coastline.

They rise in an eastward direction according to the general slope of the

geological layers.

3. The lower sub-aquifers extend further inland.

Figure (3.7): Hydrological Cross section along Gaza Strip. (Environmental Planning Directorate, 1996)

40

3.9.1 Groundwater level

Groundwater heads in the aquifer fall from about 15 meters above mean sea level

along the strip's eastern borders to mean sea level in the west along the shoreline.

The depth of groundwater in the aquifer ranges between 60 meter along the eastern

border drops to about 8 meter near the shore (Environmental Planning Directorate,

1996). Mortaja, (1998) reported that, the continuous over pumping from the aquifer

has resulted in a drop of the water table at rate of (15 – 20) centimeter per year.

Figures (3.8, 3.9) illustrated the present groundwater levels in the north and in the

south are -4 meters and -7 meters below mean sea level respectively (PWA, 2003).

Figure (3.8): Groundwater Level in Gaza Strip for the year 1998 (PWA, 2003).

41

3.9.2 Groundwater Flow

Under normal hydrological conditions, water will flow from regions of high

hydraulic head to regions of lower head. The natural flow of groundwater in Gaza

Strip is from east to West toward the Mediterranean Sea as presented in Figure (3.9).

There are two sources for the underground flow, the fresh water from the Judian

group aquifer in the West Bank, and the brackish water from the aquifer under the

Negev and Sinai (Environmental Planning Directorate, 1996). However, over-

exploitation of the aquifer has lowered the head in the aquifer and developed an

inverse flow pattern, represented by the phenomenon of seawater intrusion. (Abu-

Mayla, et. al., 1998).

Figure (3.9): Groundwater Flow and Level in Gaza Strip for the year 2002 (PWA, 2003).

42

3.9.3 Groundwater Balance

In order to analyze the water balance in the Gaza Strip, it is necessary to compare

water supply with water demand (Assaf, 2001). It should be noted that, the Gaza

coastal aquifer is a dynamic system with continuously change inflow and outflow.

The present net aquifer balance is negative, that is a water deficit. Under defined

average climate condition and total abstraction and return flows; the net deficit range

between 18-26 Mm3/yr., as shown in table (3.4). In the year 2020, there will be 2

Million inhabitants, double the current population, and the water demand could

easily double from the current 154 Mm3/yr. to 216 Mm3/yr., which makes it

necessary to generate and obtain additional water supplies in order to cover these

alarming shortages. Table (3.4): Estimated Water Balance of the Gaza Strip (Metcalf and Eddy, 2000).

Inflows (Mm3/yr.) Outflows (Mm3/yr.) Min. Max. Min. Max.

Rainfall recharge 40.0 45.0 Municipal abstraction 47.0 47.0 Lateral inflow from Israel 18.0

30.0 Agriculture abstraction

80.0

100.0

Lateral inflow from Egypt 2.0 5.0 Mekorot abstraction

5.0 8.0

Saltwater intrusion 10.0 15.0 Discharge to the sea 10.0 15.0 Water system leaks 10.0 15.0 Wastewater return flow 10.5 10.5 Irrigation return flow 20.0 25.0 Loss of aquifer storage 2.1 3.2 Other recharge 3.5 3.5 Total 116.1 152.2 142.0 170.0 Net balance -25.9 -17.8

3.10 Land Use

Land is one of the primary natural resources in the Gaza Strip. Land is scarce in the

Gaza Strip. Because of human activity, few areas remain a pristine natural state. The

pressure on land is increasing rapidly for all sectors. Urban and Horticulture

expansion is concentrated in the western coastal zones of Gaza. The expansion of

buildings and other urban dwelling is estimated to be (1000 – 1500) dunums per year

43

(MENA, 1999). Based on a study of MOPIC, 1998 the distribution of the land use

within the Gaza Strip per type of use is illustrated in table (3.5). The breakdown of

land use by sectors is provided in Figure (3.10). Agricultural lands occupies about

45.7 % of the land surface and is the dominant economic sector in Gaza Strip, on the

other hand the build up area represented 15.8%, where about 15.6% of the total area

is occupied by the Israeli settlement. The unused land is about 23%, distributed all

over the Gaza Strip governorates.

Table (3.5): Land Use Distribution in Gaza Strip (MOPIC, 1998)

Type of Use Area (Km2) Area in % Build up area 057.5 15.8 Israeli settlement & yellow area 057.0 15.6 Agriculture area 167.0 45.7 Unused Land 083.5 22.9 Total 365 100

The distribution of the proposed land use within the Gaza Strip per type of use for

the year 2004 is illustrated in table (3.6) derived from the study carried out by

(MOLG). Agriculture and assisting agriculture lands occupies about 47.5% of the

land surface and the residential area represented 24%, public building 2.1%, where

the main and secondary roads represented about 7.64% of the land surface.

Table (3.6): Proposed Land Use Distribution in Gaza Strip for the Year 2004 (MOLG, 2004)

Type of Use Area ((Km2) Area in % Main and Secondary Roads 027.875 07.64 % Public Building 007.675 02.10 % Residential Areas 087.745 24.04 % Industrial Area 012.445 03.41 % Gaza Airport 015.000 00.41 % Agricultural Area 167.675 45.94 % Assisting Agricultural Area 005.595 01.81 % Open and Green Areas 008.100 02.22 % Reserved Areas for Future Plans 025.450 06.97 % Others Area 019.940 05.46 % Total Area 365 100 %

44

Figure (3.10): Land Use in Gaza Strip. (MOPIC, 1998).

3.11 Rural and Urban Development in Gaza Strip

The urban development characteristics of Gaza Strip are strongly influenced by

political role. Because of the unique political situation of Gaza Strip, there has been

four phases of urban expansion from 1948 up to now.

#

#

#

#

#

#

#

#

Sea

Agricultural Land UseAlmondsCitrusCitrus/HorticultureDatesGrapesGreenhousesHorticultureOlivesRainfed Crops

Built-up areas

RoadsRegionalMain

WadiDelimiting LineInternational Border

# Entry Point

Scale 1:200,000

Sources:Cairo Agreement Map, 1994Aerial Photos, 1996MOPIC

Legend

0 1 2 3 4 5 km

N

MEDITERRANEAN SEA

45

3.11.1 Before 1948 War and Establishment of Israel

The rural population of Gaza Strip represents 32% of the total population, and most

of the residents are the original Gaza Strip population. The area, which is presently

called Gaza Strip, was formerly part of the sub-district of Palestine; during the

British mandate period. It was one of 18 sub-districts with a total area of 1111.5 km2

(El-Dabag, 1987). The Gaza coastal strip covers only 27% of the territory of the old

mandatory Gaza sub-district, yet in 1948 this narrow piece of land had to house not

only the entire population of the district but also tens of thousands of refugees from

the central coastal towns of Jaffa and Haifa and much of southwest Palestine. The

indigenous population of 70,000 was swamped by some 250,000 who fled (Roy,

1995). The agricultural area estimated of 10000 dunums, and most of the area

considered as an open space area.

3.11.2 The Egyptian Period from 1948 to 1967

Most of the Gaza Strip area are occupied and declared as part of Israel; only 360 km2

is left for Palestinians under the Egyptian rules. This period is characterised by

movements of Palestinian refugees toward Gaza Strip, and settled in refugee camps

attached to original urban areas. Therefore, the urban population increased rapidly,

while the rural population grow naturally. The rural population represents only 10% of

the total population (Al-Najar, 2003).

3.11.3 The Occupation Period from 1967 to 1994

Gaza Strip falls completely under the Israeli occupation. At this period, the

percentage kept constant with some expansion of the urban areas. Around 14% of

Gaza Strip area declared as military zones. These areas are the best of groundwater

quality (Al-Najar, 2003). Urban planning and housing projects are enrolled by the

Israeli military administration. The main criteria were the security issues and the use

of all available resources of Gaza. "Sara Roy quotes Yitzhak Rabin, who in 1985,

while defense minister, said: `There will be no development in the occupied

territories initiated by the Israeli government, and no permits given for expanding

agriculture and industry which may compete with the state of Israel.'" (Roy, 1995).

Although Gaza had, a population of over half a million at the time of the Israeli

occupation, the Israelis was not deterred from planting settlements in the Strip and

46

appropriating of its land and of its water. Dams were built to change the flow

direction of Wadi Gaza to be used for the Israelis purposes. Israel pacified the

resistant populace and then set about Gaza's deconstruction by expropriating the land

and water. Gaza's schools, hospitals and welfare services were not expanded to meet

the demands of the growing population.

3.11.4 From 1994 until Present Time

Roy (1995) argues convincingly that the peace process, the signing of the Oslo

Accords and the establishment of the Palestine National Authority, has not changed

Israel's intentions and policies and that Israel can be expected to restrict and obstruct

the development of the Palestinian self-rule enclaves. The reason Israel continues to

follow such policies, Roy asserts, is that it has not yet renounced its claims on or

sovereignty over Gaza and the West Bank. Until (and if) Israel takes this drastic step,

she believes `de-development will continue' because the Oslo Accords have not

altered the basic relationship between occupier and occupied (Roy, 1995).

Al-Najar (2003) emphasised that; rural population represents only 8% of the total

population. Rapid expansion of urban areas could happen due to the Palestinian

returnees from neighbour Arab countries. Most of the returnees preferred to settle in

the urban areas due to the culture they gained. The build up area will be doubled

within 10 years. Nowadays, the build up area represents around 20% while it

expected to reach 26% of the total Gaza Strip area by year 2010.

47

Chapter (4)

Methodology

This chapter discussed the methodology that used in this research. Many techniques

and approaches were used to achieve the objective of this research.

4.1 Literature Review

A literature review was conducted to examine the impacts of urbanizations on

groundwater recharge. Information regarding case studies was compiled through

literature reviews, and discussions with developers. Data related collected from, web

site, libraries, ministries, and institutions.

4.2 Geographical information System (GIS)

GIS is a computerized information system. It is designed to store, manipulate,

retrieve, analyze, and display spatially referenced data.

Geographic Information Systems (GIS) play an important role in managing the daily

operations and planning activities of Storm Water Services (EPA, 1994). GIS is a

technology that involves converting data and other information into computer-

generated maps that can identify creeks, flood plain boundaries, building locations

and project components.

4.2. 1 Calculation of Urbanized Areas

A. Two themes were used; one as an urbanization Layer and the other one as

topographic layer that both consider Shape file (*.shp) for each governorate.

When a data boundary between layers matches, as a result a new layer is creating

containing the characteristics of the both layers as showed in Figure (4.1).

Figure: (4.1) Show the Combination of Two Layers in GIS.

Urban +

Topographic

Combined Layers

48

Two software developed by Environmental systems research Institute (ESRI) which

are, Arc View 3.2 and ArcMap8.3 , are used to display and query maps.

Arc Map Software, part of the suite of integrated applications in the Arc GIS

desktop, also Arc Map work with versioned spatial databases as well as a coverage

and shape files.

B. Area Calculation

There are many ways to calculate the area by using GIS.

Calculation of the urban areas is formed by using two-shape file that are built-up area

and topology. After determination; the aspect of slope, the built-up area in each slope

and aspect were determined and have made selection by the selection tools in

ArcView3.2 software. The total built-up areas in each aspect of slope are calculated

by statistical tools in the attribute tables.

4.2.2 Calculation of Agricultural Areas

Two themes were used; one as agricultural Layer and the other one as soil layer that

both consider Shape file for each governorate. Then the same steps used in the

calculation of the urbanized area were used.

4.2.3 Calculation of the Areas of Various Soil Types

a. Activate the soil layer theme.

b. The area of each soil type taken code number according to its location.

c. The area of each code is calculated by using ArcMap8.3 software.

4.2.4 Three Dimensional (3D) View Map

To create 3D view map in the GIS, the contour shape file should be converted to

TIN’s model.

4.2.5 Deriving the Slope

The slope can be derived from the surface menu after activated the topographic

theme.

4.3 AutoCAD Program

AutoCAD program is one of the most developed programs, which serve all different

engineering specializations and other various scientific fields. Moreover, it is used to

present two and three-dimensional engineering drawings. In this study, the AutoCAD

49

program is used to locate the intersection points between the topographical elevations

from the sea level and the proposed parallel lines as follows:

1. Taken scale 1 : 100

2. Dividing Gaza Strip into 23 equal zones parallel to its northern borders.

3. Determining intersection points between zones parallel to the northern borders and

contour lines as presented in Figure (4.2).

Figure (4.2): Intersection Points between Zones Parallel Northern Borders and

Contour Lines.

50

4. Calculating the distance between the intersection points and the shoreline.

5. Determining the elevation of each intersection point from the sea level.

6. A drawing plots to show the relations between the distance and the elevation of

the intersection points for each line as presented in Figure (4.3).

7. The result is 23 topographical profiles in the direction from east to west parallel to

the northern border of Gaza Strip as indicated in Appendix (C).

0

10

20

30

40

50

60

70

80

0.2

0.6

1.0

1.4

1.8

2.2

2.6

3.0

3.4

3.8

4.2

4.6

5.0

5.4

5.8

6.2

6.6

Distance from the shore line (K m ).

Elev

atio

n fr

om th

e se

a le

vel (

m)

4.4 Effective Rainfall

According to Geohydrologists point of view; effective rainfall that part of rainfall

which delivered to groundwater storage, in which the extent of the rise in the water

table or well levels would be the effective rainfall.

The calculation of effective rainfall based on the FAO general formula for effective

rainfall (Pe) as presented in equations (2.3, 2.4).

The effective rainfall for nine weather stations in Gaza Strip for the period from 1982

to 2004 was calculated. Table (4.1) shows example calculation of the city of Beit

Hanoun. For more detailed see Appendix (B).

Figure (4.3): The Relations between the Distance and the Elevation of the Intersection Points

51

Table (4.1) Shows Example Calculation of Effective Rainfall in Beit Hanoun Station.

SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL82-83 0.0 0.0 128.0 89.0 212.0 147.5 89.5 1.5 0.0 667.583-84 0.0 1.5 31.0 12.5 174.5 5.0 41.0 8.0 0.0 273.584-85 0.0 6.0 31.5 41.0 5.0 149.5 20.5 10.0 0.0 263.585-86 0.0 7.5 3.5 64.5 41.0 64.0 1.0 27.0 8.0 216.586-87 0.0 84.5 335.5 75.5 107.5 37.4 24.7 0.0 0.0 665.187-88 0.0 73.5 5.0 46.9 114.8 219.0 19.5 4.0 0.0 482.788-89 0.0 30.0 42.5 0.0 169.0 71.3 26.0 0.0 0.0 338.889-90 0.0 40.0 82.2 33.5 142.4 103.5 67.0 27.0 0.0 495.690-91 0.0 0.0 21.0 3.2 199.9 62.4 176.5 0.0 0.0 463.091-92 0.0 3.0 120.2 309.0 141.0 172.6 12.0 0.0 9.0 766.892-93 0.0 0.0 55.4 179.9 93.9 153.5 17.5 0.0 5.0 505.293-94 0.0 49.0 93.1 2.4 99.8 35.5 42.5 0.0 0.0 322.394-95 0.0 39.0 247.5 167.0 10.0 78.3 18.0 22.0 0.0 581.895-96 0.0 0.0 66.3 106.8 162.0 38.0 108.1 11.5 0.0 492.796-97 0.0 33.2 6.6 40.0 106.5 64.0 67.4 0.0 16.5 334.297-98 0.0 13.3 3.7 154.5 107.8 27.7 109.5 0.0 5.0 421.598-99 0.0 2.6 19.7 16.3 89.8 25.5 1.6 13.0 0.0 168.599-00 0.0 15.0 17.1 34.5 243.1 58.1 27.9 0.0 0.0 395.700-01 0.0 107.9 22.2 141.3 124.1 77.5 7.0 5.0 0.0 485.001-02 0.0 47.5 24.8 193.5 211.7 24.4 32.0 7.0 7.5 548.402-03 0.0 51.7 1.5 247.9 193.9 243.5 51.0 12.0 0.0 801.503-04 0.0 0.0 6.0 92.0 167.9 67.0 21.5 1.0 1.5 356.9AVR. 0.0 27.5 62.0 93.2 132.6 87.5 44.6 6.8 2.4 456.7

Pe 0 6.5 27.2 49.6 81.1 45 16.8 0 0 226.2

4.5 Evaporation

The area has a Mediterranean dry summer sub-topical climate with mild winter; the

mean annual temperature of about 19.9 C0. As indicated before the annual

evaporation in the area ranges between 1300 to 1500 mm. MOT, (2004) recorded

that the average maximum temperature in the winter season for twenty years is about

13.5 Co , the rate of evaporation in this study will be considered of about 10 %, as the

infiltration rate is high ,and there is no stagnant surface water.

4.6 Run-off Coefficient

Sogreah, et al., (1999) assert typical runoff coefficients for the different surface types

in Gaza Strip as presented in table (2.5). The Run-off Coefficients of Pavement,

Road/Parking; Residential Communities, and Commercial / Public lots are 0.9, 0.6,

and 0.7 respectively. Based on the representative ratio of these different types of

impervious surfaces from the total build up area which are (11.42, 47.55, and 40.95)

correspondingly (MOLG, 2004), and by using interpolation, the existing run-off

52

coefficient for the different types of build up area in Gaza Strip will be considered to

be equal 0.67.

C = 11.42 × 0.9 + 47.55 × 0.6 + 40.95 × 0.7 = 67%

While that is for the proposed urban expansions for the years 2015, 2025, will be

0.78 and 0.87 respectively, in case of the expansion of the different impervious

surfaces will be increased in a constant ratio.

4.7 Infiltration in Situ

As mentioned above the evaporation rate is considered 10% and the run-off

coefficient 67%, therefore by simple calculation, the rate of infiltration in situ will be

considered 23%.

4.8 Infiltration Rate for Various Soil Types

For all sites, the estimated infiltration rate of soils based on Horton’s equation (2.1).

The infiltration parameters for the different soil type in Gaza Strip are evaluated from

the experimental infiltration data carried out by Goris and Samain (2001) as

presented in table (2.4).

Example:

For Sandy regosols: from table (2.4)

f o = 21.05 mm/min , and f b = 6.69 mm/min, K = 0.24 min -1

By applying Horton’s equation (2.1)

f = 18 mm/min

The detailed calculations of infiltration rate for the various soil types in Gaza Strip

can be seen in table (5.1).

4.9 Rainfall Amount Infiltrated in the Various Soil Types

Because of that, the infiltration rate of the different soil types are exceeding the

rainfall intensity for five years duration as a worsen case. So, the amount of rainfall

reaches soil surface will be infiltrated in.

The amount of rainfall reaches soil surface can be calculated by:

q = I × A (4.1)

Where; q is the amount of rainfall reaches the soil surface (m3/yr.), I is the average

rainfall intensity measured at the nearest metrological station to the considered area

(mm/yr). In case of there are two or more metrological stations founded in the

53

considered area, the median of measurements of the stations is taken, and A is the

considered area (m2 ).

Example:

Loess soil type covering an area of 18837495.74m2 from the whole area of Gaza

City, the average rainfall intensity measured at the nearest metrological station to the

considered area equal 0.4422 m/yr.

By applying the previous equation:

q = 18837495.74 X 0.4422 = 8329940 m3 = 8.3 Mm3

Detailed calculation could be found in Appendix (D).

4.10 Amount of Surface Run-off

Accurate computation of run-off amount is difficult, as it depends up on several

factors concerned with atmospheric and watershed characteristics (Suresh, R., 1993).

Because of that, the rational method is widely used and perfectly acceptable for

calculating surface run-off. This study will be relied on the calculation of rain surface

run-off according to rational method equation (2.5).

Example:

The build up area in Rafah Governorate is assumed to be 5680319 m2. The average

rainfall intensity at the nearest metrological station is considered to be 242 mm/yr,

and C = 0.67

By applying the rational method:

Q = 5680319 × 242 × 0.67 = 0.92 M m3/yr.

The detailed calculations of the rainwater run-off in Gaza Strip Governorates can be

seen in Appendix (D).

4.11 Total Amount of Rainfall Losses

It refers to that amount of rainfall which are not infiltrated into the soil, it included

that amount evaporated, intercepted by the plants, stagnant in impervious areas,

conducting by sewage or stormwater collection systems, and that’s run to the sea and

crossing the border to Israel.

4.12 Net Amount Infiltrated into the Soil

It refers to the sum of that amount of rainfall infiltrated in situ, and that portion of

rainfall run-off infiltrated in agriculture and open areas.

54

Chapter (5)

Results and Discussions

5.1 Introduction

Arid and semi-arid regions typically suffer from severe water shortages. This general

phenomenon is even more acute in Gaza Strip, due to its high rate of population

growth and urbanization, which has resulted in serious gaps between the available

water supply and the demands for the water.

Over the years rising populations, growing urbanizations, and expanding intensive

agriculture due to the lack of lands have pushed up the demand for water. Water

scarcity in Gaza Strip demands the use of every raindrop in optimal way. Amount of

rainfall varies both spatially and temporally. Urbanized areas and areas in which

development has altered the natural hydrology and infiltration characteristics of the

land typically experience increased surface runoff (EPA, 1994). Land development

alters the natural balance between runoff and natural absorption areas by replacing

them with greater amounts of impervious surface.

In addition, urban growth increases the land area, which has impermeable surfaces

for infiltration and therefore increase surface run-off.

In this chapter, the amount of surface run-off will be estimated considering different

soils infiltration rate, intensity of urban areas, effective rainfall in agricultural lands

and the direction of run-off.

5.2 Infiltration Rate of the Varies Soil Types

Different types of soil allow water to infiltrate at different rate based on soil structure

and texture. Each soil type has a different infiltration capacity measured in mm/min

(Wilson, 1990). Texture of Gaza Strip soil types throughout profiles in different

depths (30 cm, 60 cm, 90 cm, and 100 cm), initial infiltration rate and basic

infiltration rate by using infiltrometer is measured by Goris and Samain (2001). The

computations of the infiltration rate of the different soil types in Gaza Strip derived

from infiltrometer reading and Horton's equation as explaining in section (4.8) is

illustrated in table (5.1).

Based on the Gaza Strip soils classification made by Ministry of Agriculture (MOA)

and MOPIC in 1997 as shown in Figure (3.5), the area of these different soils

according to its location is calculated by using GIS measurements.

55

Table (5.1): Infiltration Rate of Various Soil Types in Gaza Strip Based on Infiltrometer Reading and Horton's Equation *

**Codes, Locations, area of different soil types % from the total area

Initial infiltration fo(mm/min)

Basic infiltration

fb(mm/min) K

Infiltration Rate

f(mm/min) Soil Type

Code Location Area ( m2 ) 1 Gaza City 18837495 4 Wadi Gaza 5082675 Loess Soil

Total area = 23920170.75

06.6 07.14 2.03 0.08 07.0

2 Gaza, Wadi Gaza 15805892 6 Wadi Alslqa +Al-Qarara 4549557

11 Beit Hanoun 29290185 Dark brown / Reddish brown

Total area = 49645634.95

13.7 17.52 3.48 0.11 16.0

3 Deir Albalah + Zaweda+ Maqhazi 26035828

8 Abssan 4615097 9 Rafah 1866893

Sandy Loess Soil

Total area = 32517819.55

09.0 4.51 1.10 0.06 04.3

Deir Albalah+ Al-Qarara Khanyounis + Rafah 82937834 Loessial Sandy

Soil 5

Total area = 82937834.35

23.0 8.31 2.43 0.08 07.9

7 Khanyounis + Rafah 58324040 Sandy Loess over Loess Total area = 58324040.84

16.2 5.96 1.62 0.08 06.0

10 It is founded along the Coastal plain of Gaza Strip 113848480 Sandy regosols

Total area = 113848480.34

31.5 21.05 6.69 0.24 18.0

Total soil Types Area 361193981 m 2 %100 *Horton equation: f = fc + ( fo - fc ) e – k t

** Code according to the location of the soil

56

Loess soil cover about 6.6% of the Gaza strip area and it distributed in Gaza City and

Wadi Gaza. The infiltration rate of this type of soil is predictable according to

Horton's equation to be 7 mm/min.

The second type of Gaza strip soil is the dark brown/reddish brown soil with an area

of about 13.7% of the total area of Gaza Strip, this type of soil is distributed in Gaza

City, Wadi Gaza , Wadi Alslqa, Al-Qarara and in Beit Hanoun. In spite of its reddish

brown appearance, the infiltration rate is estimated to be about 16 mm/min, and this

is due to many reason which are; this type of soil is used as an agricultural soil in

Gaza Strip as consequently root growth and decomposition increase the capacity and

rate of soils to infiltrate rainfall and reduce overland flow, At some depth, lime

concretions can be found. The infiltration rate increases due to calcium carbonate

content, which can be around 15 – 20%. In addition, the soil texture is classified as

sandy clay loam (25% clay, 13% silt, 62% sand). Therefore, the high amount of sand

62% makes the soil more permeable and that is reflecting the relatively high

infiltration rate.

Third type of Gaza strip soil is a Sandy Loess soil, which represents about 9%, with

infiltration rate of about 4 mm/min. This type of soil is found in Deir Albalah,

Zaweda, Maqhazi, Abssan, and Rafah.

The fourth type of soil is the Loessial Sandy soil with an area of about, 23% from the

total area of Gaza Strip, the infiltration rate of this type of soil is about 8 mm/min.

This type of soil is located in Deir Albalah, Al-Qarara, Khanyounis, and Rafah.

The fifth one is the Sandy Loess over Loess Soil which cover an area of about 16.2%

from the total area of the Gaza Strip, with infiltration rate of about 6 mm/min. this

type of soil is located in two districts in the south of Gaza Strip, which are

Khanyounis and Rafah.

The sixth one is the Sandy Regosols soil, which founded along the Coastal plain of

Gaza Strip. This type of soil represents about 31.5% of the whole area of Gaza Strip.

The infiltration rate of this type of soil is the highest among the different soils types,

which estimated to be of about 18 mm/min.

Generally, the whole Gaza Strip soil types have a relative high infiltration rate. Goris

and Samain (2001) and Hamdan (1999) reported the same results.

57

5.3 Topography and Run-off Directions

The directions and magnitudes of Gaza Strip topographical slope, which are

indicated in Figures (5.1) and (5.2), are derived from GIS measurements. Most of

Gaza Strip topographical area is described as flat area and gradually sloping with a

range from (0 – 5) %, westward toward the sea allowing for surface runoff. The other

sloping directions of Gaza strip are North East (22o.5 -67o.5), East (67o.5 – 112o.5),

South East (112o.5 – 157o.5), South (157o.5 – 202o.5), South West (202o.5 – 27o.5),

West (247o.5 – 292o.5), and North West (292o.5 – 337o.5). The direction of the slope

is of a great importance in which it affects the evaporation and transpiration losses

due to its influence on the amount of heat received from the sun (Suresh, 1993).

Figure (5.1): Topographic Slope Magnitude

58

6 0 6 Kilometers

Aspect of Slope of topologyFlat (-1)North (0-22.5,337.5-360)Northeast (22.5-67.5)East (67.5-112.5)Southeast (112.5-157.5)South (157.5-202.5)Southwest (202.5-247.5)West (247.5-292.5)Northwest (292.5-337.5)No Data

Sea

N

Med

iterra

nean

Sea

Legend

Figure (5.2): Topographical Slope Directions

Figure (5.3) shows topographical profiles taken parallel to the northern border of the

Gaza Strip; 23 profiles can be seen in Appendix (c), where these profiles illustrate

the westward decline to the sea and a number of depressions area. In addition these

depressions can be seen clearly in the three dimensional view of Gaza Strip as

identify in Figure (5.4). These depressions areas detained water during the run-off

events. This water will subsequently evaporate or infiltrate into the soil according to

the type of the soil surface. Depression area is like interception, has the effect of

reducing run-off at the beginning of a rainfall event (McGhee, 1991). From the

59

Figures, it is apparent that’s the depressions founded at elevations ranging from 20 to

60 meter, wherein the Surfaces type is impervious due to the urbanizations, as

consequently the amount of water detained will be losses due to evaporation or run

through the stormwater collection system, which finally pumped, to the sea.

Figure (5.3): Topographical Profiles Parallel to the Northern Border Line of Gaza Strip Showing Number of Depression Zones (Red Cycle) a long the East West Slope. Directions.

A. T opographic Profile 4 K m from the N orthe rn B orde r of G aza Strip

0

10

20

30

40

50

60

70

80

90

0.1

0.5

0.9

1.3

1.7

2.1

2.5

2.9

3.3

3.7

4.1

4.5

4.9

5.3

5.7

6.1

6.5

6.9

7.3

7.7

8.1

8.5

8.9

9.3

D is tance fro m the Sho re Line ( K m )

Elv

atio

n fr

om t

heSe

a L

evel

( m

)

B. TopographicProfile 13.6 Km. from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

0.1

0.4

0.7

1.0

1.3

1.6

1.9

2.2

2.5

2.8

3.1

3.4

3.7

4.0

4.3

4.6

4.9

5.2

5.5

5.8

6.1

6.4

Distance from the shore line. ( Km )

Elev

atio

n fr

om

the

sea

leve

l ( m

)

C. Topographic Profile 42.7 Km from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

80

90

0.4

0.9

1.4

1.9

2.4

2.9

3.4

3.9

4.4

4.9

5.4

5.9

6.4

6.9

7.4

7.9

8.4

8.9

9.4

9.9

10.4

10.9

11.4

11.9

Distance from the Shore Line ( Km).

Ele

vatio

n fr

om

the

sea

Leve

l (m

)

60

Le g e n d

E le v a t io n R a n g e9 0 - 1 0 08 0 - 9 07 0 - 8 06 0 - 7 05 0 - 6 04 0 - 5 03 0 - 4 02 0 - 3 01 0 - 2 0

B u il t -u p a re a

N

Figure (5.4): Three-dimensional View of the Gaza Strip Topography.

61

5.4 Estimated Amount of Rainfall Infiltrated into the Soil

Four scenarios were proposed to estimate the amount of rainfall that can be

infiltrated to the groundwater. These scenarios are as follows:

5.4.1 Scenario (1): Gaza Strip as an Open Space Area

This scenario is assumed to estimate the amount of rainfall infiltrate to the aquifer

when Gaza Strip free of urbanization and agriculture. Even it is not logic, but it is

considered for comparison purposes. The amount of rainfall infiltrate the ground into

the aquifer is estimated in table (5.2). As the infiltration rate of all kinds of soils is

more than the rainfall intensity that occurs in five years. Therefore, all amounts of

rainfall fallen in Gaza Strip will be infiltrated into deep soil layers. On other hands

the amount of rainfall, which is infiltrated in the same soil type, differed according to

its location, area, and the variation of rainfall intensity from the south to the north.

Example:

As the sandy loess soil is located with different areas within three locations with

code numbers (3, 8, 9), and the average rainfall in these locations are (324, 306, 242)

mm/yr., respectively as indicated in table (5.2) and Figure (3.5). The infiltration rates

of all soil types in Gaza Strip are higher than the rainfall intensity that occurs in five

years. The amount of rainfall infiltrated in this soil type at the different locations is

calculated according to the explanation in section (4.9), and it is estimated to be (8.4,

1.4, 0.5) Mm3/yr., respectively.

As presented in table (5.2), the calculations shows that, the total amount of rainfall

infiltrated in the different kinds of soils are; loess soil of about 10.2 Mm3/yr., dark

brown/ reddish brown of about 21.3 Mm3/yr., sandy loess of about 10.2 Mm3/yr.,

loessial sandy soil of about 24 Mm3/yr., sandy loess over loess of about 15.9

Mm3/yr., and sandy regosols of about 43.4 Mm3/yr. Therefore, the total amount of

rainfall infiltrated in case of Gaza Strip is considered as an open space area will be

about 125 Mm3/yr. Al-Agha, (1997) estimated the total rainfall amount over the area

of about 120 Mm3/yr.

62

Soil Type Code a location Area (m 2) Average Rainfall (mm/yr.)

Metrological Station

b Rainfall Intensity for

5 yr. ( I5 ) mm/hr.

Infiltration Rate.

( f ) mm/hr. check Amount of Rainfall

Infiltrated (Mm 3)

1 Gaza City 18837495 442 Gaza 26 f > I5 8.3 4 Wadi Gaza 5082675 389 Al-Moghraqa 26 404.5 f > I5 1.98 Loess Soil

Total area = 23920170.75 Total = 10.2

2 Gaza City + Wadi Gaza 15805892 416 Gaza+ Al-Moghraqa 26 f > I5 6.57

6 Wadi Alslqa + Al- Qarara 4549557 306 Khanyounis 22 f > I5 1.39

11 Beit Hanoun 29290185 457 Beit Hanoun 26

963.42

f > I5 13.37

Dark/ Brown/ reddish brown

Total area = 49645634.95 Total = 21.3

3 Deir Albalah+ Zaweda

+ Maqhazi

26035828 324 Deir Albalah 26 f > I5 8.43

8 Abssan 4615097 306 Khanyounis 22 f > I5 1.41 9 Rafah 1866893 242 Rafah 22

258.68

f > I5 0.45

Sandy Loess Soil

Total area = 32517819.55 Total = 10..2

5 Deir Albala+Al-Qarara +Khanyounis + Rafah 82937834 291 Deir Albalah +

Khanyounis 22 471.48 f > I5 24.00 Loessial Sandy Soil

Total area = 82937834.35 Total = 24.00

7 Rafah+ AlFokhary+ AlShoha+ Khozaa 58324040 273 Khanyounis +

Rafah 22 337.6 f > I5 15.8 Sandy Loess over Loess Total area = 58324040.84 Total = 15.8

10 It is founded along the Coastal plain of Gaza

Strip 113848480 382

Metrological Stations in Gaza Strip

26 1079 f > I5 43.28 Sandy regosols

Total area = 113848480.34 Total = 43.3 Total 361193981 m 2 = 125 Mm 3

Table (5.2): Scenario (1) Gaza Strip as an Open Space Area.

a The Classification is Based on the Soil Type and not the District Borders. b Rainfall Intensity is Based on Sogreha, et al, 1999.

63

5.4.2 Scenario (2): Gaza Strip as an Agricultural Area

The amount and intensity of precipitation reaching a soil surface is influenced by the

amount and type of vegetation on a site. The capacity of vegetated surfaces to

intercept and store water is of a great practical importance. Massman, (1983)

observed a clear dependence of interception on rainfall intensity and identified it as

one of the main contributors toward the drip of intercepted rainwater.

Root growth and decomposition increase the capacity and rate of rainfall infiltration

through soil layers and reduce overland flow. Removal or changing in vegetation

affects the natural balance of ecosystems, including water flows. Vegetation reduces

storm water runoff and promotes absorption and infiltration. Massman (1983)

conducted that's naturally vegetated areas produce only about 10% runoff, where in

dense urban areas, up to 90% of rainfall ends up in storm water runoff.

The purpose of this scenario is to estimates both the amount of rainfall intercepted

and that infiltrated to the soils, in other words the effective rainfall that is hitting the

surface in case of Gaza Strip is cultivated with horticultural plants.

The calculation in table (5.3) show that the effective rainfall in a different location,

which calculated based up on section (4.4) is exceeding the rainfall intensity occurs

in five years. Therefore the amount of rainfall infiltrated to the soils is almost equal

to that amount of effective rainfall which hitting the surface.

A comparison of the amount of rainfall that’s infiltrated into different soil types in

the two scenarios was conducted, its obvious that’s the amount of rainfall infiltrated

in scenario number (1) is exceeding that’s in scenario number (2) of about 56%,

where the total amount in the first scenario is estimated to be 125 Mm3/yr., the total

amount in second scenario is about 55 Mm3/yr. That means the rainfall interception

and its subsequent evaporation constitute a net loss of about 56%, which may assume

considerable values under certain conditions. The result of these scenarios is build

upon assumption that the average rainfall is the same under open space and Gaza

Strip as agricultural area. While it is naturally, have more rain in case of forest or

horticulture locations. According to Van Dijk (2002), the interception may exceed

59% of annual gross precipitation for old growth trees.

64

Soil Type Code location Area ( m 2 )

a Effective Rainfall (mm/yr.)

Metrological Station

Rainfall Intensity for

5yr ( I5 ) mm/hr.

Infiltration Rate. ( f ) mm/hr.

check Amount of Rainfall Infiltrated (Mm 3)

1 Gaza City 18837495.74 216 Gaza 26 f > I5 4.06 4 Wadi Gaza 5082675.01 178 Al-Moghraqa 26 404.5 f > I5 0.90 Loess Soil

Total area = 23920170.75 Total = 5.00

2 Gaza City + Wadi Gaza 15805892.29 197 Gaza+ Al-

Moghraqa 26 f > I5 3.11

6 Wadi Alslqa + Al- Qarara 4549557.91 120 Khanyounis 22 f > I5 0.55

11 Beit Hanoun 29290185.75 226 Beit Hanoun 26

963.42

f > I5 6.63

Dark/ Brown/ reddish brown

Total area = 49645634.95 Total = 10.3

3 Deir Albalah +Zaweda

+ Maqhazi

26035828.75 144 Deir Albalah 26 f > I5 3.74

8 Abssan 4615097.62 120 Khanyounis 22 f > I5 0.55 9 Rafah 1866893.18 55 Rafah 22

258.68

f > I5 1.0

Sandy Loess Soil

Total area = 32517819.55 Total = 5.3

5 Deir Albala+Al-Qarara +Khanyounis + Rafah 82937834.35 110 Deir Albalah +

Khanyounis 22 471.48 f > I5 9.12 Loessial Sandy Soil

Total area = 82937834.35 Total = 9.1

7 Rafah+ AlFokhary+ AlShoha+ Khozaa 58324040.84 87 Khanyounis +

Rafah 22 337.6 f > I5 5.1 Sandy Loess over Loess Total area = 58324040.84 Total = 5.1

10 It is founded along the Coastal plain of Gaza

Strip 113848480.34 176

Metrological Stations in Gaza Strip

26 1079 f > I5 20.00 Sandy regosols

Total area = 113848480.34 Total = 20.00

Total 361193981.7 m 2 54.8 Mm 3

Table (5.3): Scenario (2), Gaza Strip as an Agricultural Area.

a Effective Rainfall is calculated based on FAO formula as presented in section (4.4).

65

5.4.3 Scenario (3): The Influence of Existing Land Use

Due to the special political situation in Gaza Strip, the latest land use map did not

update from the year 1998. Hence, the scenario is relied on the year (1998) land use

map. To estimates the quantity of rainfall run-off, this scenario consider Gaza Strip

as build up, open, and agricultural areas. In addition, because of the Israeli incursion,

which began in the fourth quarter of the year 2000, this scenario will be divided into

two sub scenarios to see the effects of this incursion on the hydrological system.

5.4.3.1 The Influence of the Different Land Use before September/ 2000

By use of GIS measurements, the build up area which included residential, industrial,

commercial, and a paved and unpaved road represents about 16%, where an

agricultural area represents about 57%, in which it included agricultural, assisting

agriculture areas, and Israeli settlements area. An open area, which includes sand

dunes and unused land, represent an area of about 27% from the area of Gaza Strip.

The calculations in this sub scenario will be according to the administrative

classification, in which Gaza Strip is divided into five governorates which are:

Northern, Gaza, Middle, Khanyounis, and Rafah, with an area of (60.7, 73.4, 56.2,

110, and 60.5) km2 respectively. The detailed calculation is indicated in Appendix

(D), where table (5.6) summarizes it.

Example:

Northern Governorate with a total area of about (60,682,708 m2) is assumed to be

classified into three land use sectors, which are build up, open, and agriculture areas.

These areas are (10474960, 23835750, 26371998) m2, respectively. The build up

areas is classified according to both its topographical elevation from the sea level,

and its slope direction that has estimated by using GIS techniques as shown in Figure

(5.5) and table (5.4). According to (MOT, 2004) the average rainfall in this

Governorate is about 465 mm/yr., where the effective rainfall in agriculture area is

calculated referring to FAO formula, and estimated to be about 231mm/yr as

mentioned in section (4.4). To estimate the amount of rainfall, which may contribute

to the groundwater, both the amount of rainfall either infiltrated or run over the

surface area, must be calculated as follows:

1. Due to that’s the different soil types having a high infiltration rate exceeding the

rainfall intensity occurs in a five years. As a result, the amount of rainfall infiltrated

66

into the soil is equal to that amount hitting the surface in both the open and the

agriculture areas.

The amount of rainfall infiltrated in both open and agriculture areas is calculated

referring to equation (4.1).

a. Amount infiltrated in the open area = 465 X 23835750 = 11.08 Mm3 (1)

b. Amount infiltrated in agriculture area = 231 X 26371998 = 6.08 Mm3 (2)

Table (5.4): The Amount of Rainfall Infiltrated in the Various Surfaces of Northern Governorate.

Gov

erno

rate

Item

Cod

e

Slop

e D

irec

tion

Elev

atio

n fr

om

the

Sea

Leve

l (m

)

Are

a (m

2 )

Ave

rage

Rai

nfal

l (m

m/y

r)

Rai

nfal

l Am

ount

H

ittin

g th

e Su

rfac

e (M

m3 )

Evap

orat

ion

10%

(M

m3 )

Infil

trat

ion

in si

tu

(Mm

3 )

Run

-off

Am

ount

(M

m3 )

A S - N 80 -90 115418 465 0.05 0.01 0.01 0.04 B NW - SE 40 - 70 829348 465 0.39 0.04 0.09 0.26 C NW - SE 40 - 50 214364 465 0.10 0.01 0.02 0.07 D NW - SE 30 - 40 36093 465 0.02 0.00 0.00 0.01 E S - N 60 - 70 469813 465 0.22 0.02 0.05 0.15

F NW - SE SE - NW 30 - 50 8644784 465 4.02 0.40 0.92 2.69

G E - W 10 - 20 165140 465 0.08 0.01 0.02 0.05 Tota

l Bui

ld u

p A

reas

10474960 465 4.87 0.49 1.12 3.26

Ope

n A

rea

23835750 465 11.08 11.08

Agr

ic. A

rea

26371998 231 6.08 6.08

Nor

ther

n

Tota

l

60682708 22.02 0.49 18.27 3.26

2. Referring to section (4.6), the run-off coefficient is estimated to be about 67%, the

evaporation rate about 10%, and as a consequence the infiltrated amount about 23%

from the total rainfall amount. Both the amounts of rainfall infiltrated and that’s run-

off in the build up areas is calculated according to rational method equation (2.5).

a. Amount of rainfall infiltrated in build up area in situ

= 465 X 10474960 X 0.23 = 1.12 Mm3 (3)

From 1, 2, 3, it is obvious that’s:

The total amount of rainfall infiltrated in situ = 18.27 Mm3 (4)

b. Amount of surface run-off = 465 X 10474960 X 0.67 = 3.26 Mm3

67

According to the slope direction of the different build up locations as shown in Figure

(5.5), this run-off amount could be reach to a various locations as illustrated in table

(5.5), and amount of about 3 Mm3 could be infiltrated and delivered to the

groundwater. Therefore, the net amount infiltrated will be increased to become equal

to 21.3 Mm3.

To confirm this assumption, for example time of concentration Tc for the run-off

amount release from build up area A1 and predestined in an open space area A2 as

shown in Figure (5.5) could be calculated based on equation (2.9) as follows:

1. Run-off amount release from A1 , Q1 = C I A1

Let I equal the peak stormwater intensity occurred within five years,

I = I5 = 26mm/hr., A1 from table (5.4) = 115418 m2 , C = 0.67

Q1 = 0.67 X 115418 m2 X 0.026 m/hr = 2011 m3 / hr.

2. Rooted to topographical profile number (C) in Appendix (C ), such parameter

measured; H= 30 m, and L= 0.3 X 103 m.

From equation (2.9): Tc = (0.3 X 103 )1.15 / 52 (30)0.38 = 50 min, Which is the

time required for Q1 to reaches the open area.

3. Referring to the equation (4.1), Q2 in the open area, with sandy regosols soil that’s

infiltration rate = 18 mm/min., is calculated as: Q2 = I5 X A2

A2 is calculated based on GIS measurement = 122453 m2 , I = I5 = 26mm/hr.

Q2=122453 m2 X 0.026 m/hr = 3184 m3 / hr.

3. The total amount Q reaches the open area = 2011 + 3184 = 5195 m3 / hr.

4. The required area needed to infiltrate the heaviest storm = 5195/ 1080= 481 m2 ,

which is more smaller than A2 . Therefore no flooding will occurs.

Table (5.5): Amount of Surface Run-off Destination in Northern Governorate.

Run-off Amount Destination (Mm3) Code

Run-off Amount (Mm3)

To the Sea

Agric.Area

Open Area Imper.Area To

Israel

Infiltrated Amount (Mm3)

A 0.04 0.04 B 0.26 0.26 C 0.07 0.07 D 0.01 0.01 E 0.15 0.15 F 2.69 2.69 G 0.05 0.05

Total 3.26 0.05 2.69 0.26 0.07 0.19 2.95

68

Table (5.6): Scenario (3.1): The Influence of the Existing Land Use before September 2000.

Run-off Amount Destination (Mm3 )

Gov

erno

rate

Item

Are

a C

alcu

late

d b

y G

IS (m

2 )

Ave

rage

Rai

nfal

l (m

m/y

r)

Rai

nfal

l Am

ount

H

ittin

g th

e Su

rfac

e (M

m3 )

Evap

orat

ion

10%

(Mm

3 )

Infil

tratio

n in

si

tu (M

m3 )

Run

-off

Am

ount

(M

m3 )

Dire

ct to

the

Sea

Agr

icul

ture

A

rea

Ope

n A

rea

Impe

rvio

us

Are

a

Dire

ct to

Is

rael

Tota

l Los

ses

(Mm

3 )

Net

Infil

tratio

n (M

m3 )

Build up Area 10474960 465 4.9 0.5 1.1 3.3 0.05 2.7 0.26 0.07 0.2 0.8 4.1 Open Area 23835750 465 11.1 11.1 11.1

Agriculture Area 26371998 231 6.1 6.1 6.1 Nor

ther

n

Total Area 60682708 22.0 0.5 18.3 3.3 0.05 2.7 0.26 0.07 0.2 0.8 21.2 Build up Area 21972379 436 9.6 1.0 2.2 6.4 0.06 0.02 0.03 6.3 0.02 7.3 2.3

Open Area 20370046 436 8.9 8.9 8.9 Agriculture Area 31016425 210 6.5 6.5 6.5 G

aza

Total Area 73358851 25.0 1.0 17.6 6.4 0.06 0.02 0.03 6.3 0.02 7.3 17.7 Build up Area 7501893 363 2.7 0.3 0.6 1.8 0.7 0.5 0.06 0.6 2 1.1

Open Area 12368555 363 4.5 4.5 4.5 Agriculture Area 36353273 177 6.4 6.4 6.4 M

iddl

e

Total Area 56223721 13.6 0.3 11.5 1.8 0.7 0.5 0.06 0.6 2 12 Build up Area 10388624 306 3.2 0.3 0.7 2.1 0.07 0.9 0.1 1.10 1.6 1.6

Open Area 26340802 306 8.1 8.1 8.1 Agriculture Area 73339147 120 8.8 8.8 8.8

Kha

nyou

nis

Total Area 110068574 20.0 0.3 17.6 2.1 0.07 0.9 0.1 1.10 1.6 18.5 Build up Area 5680319 242 1.4 0.14 0.32 0.92 0.18 0.6 0.05 0.1 0.42 1.0

Open Area 15688921 242 3.8 3.79 3.8 Agriculture Area 39118444 55 2.1 2.1 2.1 R

afah

Total Area 60487683 07.3 0.14 06.2 0.92 0.18 0.6 0.05 0.1 0.42 6.9 Total 360821537 88 2.2 71 14.5 1.1 4.6 0.4 7.1 1.3 12 76

69

In Northern governorate, the total build up area represents about 17.3 % from the

total area and it is located at different elevations from the sea level with varies slope

directions as shown in Figure (5.5), where the agricultural area represents an area of

about 43.4% and distributed into different soil types as shown in Figure (5.6). The

open area represents an area of 39.3% from the total governorate area. From table

(5.6), the amount of rainfall hitting the surface area is estimated to be 22 Mm3. While

18.3 Mm3/yr., infiltrated in situ; the residue is classified as 0.8 Mm3/yr., losses and

3.3 Mm3/yr., as run-off. The destination of the amount of run-off indicates that’s

about 2.95 Mm3/yr., infiltrated in agricultural and open areas and the rest reach the

sea, therefore the net amount infiltrated is 21.2 Mm3/yr. Table (5.7) summarizes the

influence of the existing land use in the northern governorate on the infiltration and

run-off amounts before September 2000.

Figure (5.5): Build up Area over Topographical Layer in Northern Governorate.

2 0 2 Kilometers

Legend

Run-off directionDepression Zone

Sea

Topography1011 - 2021 - 3031 - 4041 - 5051 - 6061 - 7071 - 8081 - 9091 - 110

Built-up area

N

Med

iterra

nean

Sea

Area (A)

Open Area (Sandy Regosol)

70

Sea

Agricultural Land UseAlmondsCitrusCitrus/HorticultureDatesGrapesGreenhousesHorticultureOlivesRainfed Crops

Soil TypesDark brown / reddish brownLoess soilsLoessal sandy soilSandy loess soilSandy loess soil over loessSandy regosols

Wadi

MEDIT

ERRANEAN

SEA

N

0 2 4 Kilometers

Legend

Figure (5.6): Agricultural Area over Soil Layer in Northern Governorate.

Table (5.7): Summarizes the Influence of the Existing Land Use in the Northern Governorate on Infiltration and Run-off Amounts before September 2000.

Without Stormwater Collection

System

With Stormwater Collection

System

Gov

erno

rate

Item

Perc

enta

ge fr

om th

e To

tal

Gov

erno

rate

Are

a R

ainf

all A

mou

nt H

ittin

g th

e Su

rface

Are

a (M

m3 )

Infil

tratio

n in

Situ

(Mm

3 )

Run

-off

Am

ount

(Mm

3 )

Tota

l Los

ses

Am

ount

(Mm

3 )

Net

Infil

tratio

n A

mou

nt (M

m3 )

Tota

l Los

ses

Am

ount

(Mm

3

Net

Infil

tratio

n A

mou

nt (M

m3 )

Build up Area 17.3 4.9 1.1 3.3 0.8 4.1 3.8 1.1 Open Area 39.3 11.1 11.1 11.1 11.1 Agric. Area 43.4 6.1 6.1 6.1 6.1

Nor

ther

n

Total 100 22.0 18.3 3.3 0.8 21.2 3.8 18.2

71

In Gaza governorate, the build up area represents about 30% from the total area with

varies elevations and slope directions as illustrated in Figure (5.7), while the open

area represents about 28%, and the agricultural area represents 42% from the total

area of Gaza governorate as shown in Figure (5.8). The net amount infiltrated is

estimated to be of about 17.7Mm3/yr. from total amount of rainwater of about 25

Mm3/yr., that is hitting the surface area of the governorate annually. About 7.3

Mm3/yr., is the total losses, where the total amount of run-off due to large area of

impervious surface is estimated to be of about 6.4 Mm3/yr.; ultimately these amounts

is reach by either the sewer system or by the stormwater collection system to the sea.

Table (5.8) summarizes the influence of the existing land use in Gaza governorate on

infiltration and run-off amounts before September 2000.

Figure (5.7): Build up Area over Topographical Layer in Gaza Governorate.

2 0 2 Kilometers

Legend

Run-off directionDepression Zone

Sea

Topography1011 - 2021 - 3031 - 4041 - 5051 - 6061 - 7071 - 8081 - 9091 - 110

Built-up area

N

Med

iterra

nean

Sea

72

Sea

Agricultural Land UseAlmondsCitrusCitrus/HorticultureDatesGrapesGreenhousesHorticultureOlivesRainfed Crops

Soil TypesDark brown / reddish brownLoess soilsLoessal sandy soilSandy loess soilSandy loess soil over loessSandy regosols

Wadi

MEDITE

RRANEAN

SEA

N

0 2 4 Kilometers

Legend

Figure (5.8): Agricultural Area over Soil Layer in Gaza Governorate.

Table (5.8): Summarizes the Influence of the Existing Land Use in Gaza Governorate on Infiltration and Run-off Amounts before September 2000.

Without Stormwater Collection

System

With Stormwater Collection

System

Gov

erno

rate

Item

Perc

enta

ge fr

om th

e To

tal

Gov

erno

rate

Are

a R

ainf

all A

mou

nt H

ittin

g th

e Su

rface

Are

a (M

m3 )

Infil

tratio

n in

Situ

(Mm

3 )

Run

-off

Am

ount

(Mm

3 )

Tota

l Los

ses

Am

ount

(Mm

3 )

Net

Infil

tratio

n A

mou

nt (M

m3 )

Tota

l Los

ses

Am

ount

(Mm

3

Net

Infil

tratio

n A

mou

nt (M

m3 )

Build up Area 30 9.6 2.2 6.4 7.3 2.3 8.4 1.2 Open Area 28 8.9 8.9 8.9 8.9 Agric. Area 42 6.5 6.5 6.5 6.5 G

aza

Total 100 25.0 17.6 6.4 7.3 17.7 8.4 16.6

73

The build up area in the Middle governorate represents about 13.3% from the total

area and distributed at a varies elevations with different slope directions as illustrated

in Figure (5.9), where the open area represents 22% and the agriculture area of about

64.7% from the total governorate area Figure (5.10). About 13.64 Mm3/yr. is hitting

the surface area annually, in which amount of 11.55 Mm3/yr., is infiltrated in situ,

where the total losses is estimated to be 1.58 Mm3/yr., and total amount of run-off

about 1.82 Mm3/yr. The net infiltrated amount in this governorate is estimated of

about 12 Mm3/yr. Table (5.9) summarizes the influence of the existing land use in the

Middle governorate on infiltration and run-off amounts before September 2000.

2 0 2 Kilometers

Legend

Run-off directionDepression Zone

Sea

Topography1011 - 2021 - 3031 - 4041 - 5051 - 6061 - 7071 - 8081 - 9091 - 110

Built-up area

N

Medite

rrane

an S

ea

Figure (5.9): Build up Area over Topographical Layer in Middle Governorate.

74

Sea

Agricultural Land UseAlmondsCitrusCitrus/HorticultureDatesGrapesGreenhousesHorticultureOlivesRainfed Crops

Soil TypesDark brown / reddish brownLoess soilsLoessal sandy soilSandy loess soilSandy loess soil over loessSandy regosols

Wadi

MEDITERRANEAN

SEA

N

0 2 4 Kilometers

Legend

Table (5.9): Summarizes the Influence of the Existing Land Use in the Middle Governorate on Infiltration and Run-off Amounts before September 2000.

Without Stormwater Collection

System

With Stormwater Collection

System

Gov

erno

rate

Item

Perc

enta

ge fr

om th

e To

tal

Gov

erno

rate

Are

a R

ainf

all A

mou

nt H

ittin

g th

e Su

rface

Are

a (M

m3 )

Infil

tratio

n in

Situ

(Mm

3 )

Run

-off

Am

ount

(Mm

3 )

Tota

l Los

ses

Am

ount

(Mm

3 )

Net

Infil

tratio

n A

mou

nt (M

m3 )

Tota

l Los

ses

Am

ount

(Mm

3

Net

Infil

tratio

n A

mou

nt (M

m3 )

Build up Area 13.3 2.7 0.6 1.8 2 1.1 2.1 0.6 Open Area 22.0 4.5 4.5 4.5 4.5 Agric. Area 64.7 6.4 6.4 6.4 6.4 M

iddl

e

Total 100 13.6 11.5 1.8 2 12 2.1 11.5

Figure (5.10): Agricultural Area over Soil Layer in Middle Governorate.

75

In Khanyounis governorate, the build up area represents 9.4% from the

total area located at different elevation with different slope direction, Figure (5.11).

The amount of run-off resulted from these impervious surfaces is estimated to be of

about 2.13 Mm3/yr., in which about 0.55 Mm3/yr., from this amount is infiltrated in

agricultural and open areas. The agriculture area is considered the largest one among

the five Governorates with an area of about 66.6% from the total area of the

Governorate, as present in Figure (5.12). About 24% of the total Governorate is

considered as open area. The net infiltrated amount is estimated to be of about

18.47Mm3/yr., from 20.04Mm3/yr., which is the total amount of rainfall hitting the

surface area, where the total amount losses is estimated to be 1.57 Mm3/yr.

Table(5.10): Summarizes the Influence of the Existing Land Use in Khanyounis

Governorate on infiltration and run-off amounts before September 2000.

2 0 2 Kilometers

Legend

Run-off directionDepression Zone

Sea

Topography1011 - 2021 - 3031 - 4041 - 5051 - 6061 - 7071 - 8081 - 9091 - 110

Built-up area

N

Medite

rrane

an S

ea

Figure (5.11): Build up Area over Topographical Layer in Khanyounis

76

Sea

Agricultural Land UseAlmondsCitrusCitrus/HorticultureDatesGrapesGreenhousesHorticultureOlivesRainfed Crops

Soil TypesDark brown / reddish brownLoess soilsLoessal sandy soilSandy loess soilSandy loess soil over loessSandy regosols

Wadi

MEDIT

ERRANEAN S

EA

N

0 2 4 Kilometers

Legend

Figure (5.12): Agricultural Area over Soil Layer in Khanyounis Governorate.

Table (5.10): Summarizes the Influence of the Existing Land Use in Khanyounis Governorate on Infiltration and Run-off Amounts before September 2000.

Without Stormwater Collection

System

With Stormwater Collection

System

Gov

erno

rate

Item

Perc

enta

ge fr

om th

e To

tal

Gov

erno

rate

Are

a R

ainf

all A

mou

nt H

ittin

g th

e Su

rface

Are

a (M

m3 )

Infil

tratio

n in

Situ

(Mm

3 )

Run

-off

Am

ount

(Mm

3 )

Tota

l Los

ses

Am

ount

(Mm

3 )

Net

Infil

tratio

n A

mou

nt (M

m3 )

Tota

l Los

ses

Am

ount

(Mm

3

Net

Infil

tratio

n A

mou

nt (M

m3 )

Build up Area 09.4 3.2 0.7 2.1 1.6 1.6 2.5 0.7 Open Area 24.0 8.1 8.1 8.1 8.1 Agric. Area 66.6 8.8 8.8 8.8 8.8

Kha

nyou

nis

Total 100 20 17.6 2.1 1.6 18.5 2.5 17.6

77

In case of Rafah governorate, the amount of run-off is estimated to be 0.9 Mm3/yr.,

which results from build up area of about 9.4% from the total area of the governorate

as shown in Figure (5.13), while about 69% of this amount is infiltrated, the amount

of losses is estimated to be 31% from the total amount of run-off. As shown in Figure

(5.14) the agricultural area in this governorate is represents about 64.6% from the

total governorate area, where the remaining area with 26% is considered an open

area. The net amount of rainwater infiltrated in this governorate is estimated to be 6.9

Mm3/yr., from 7.3 Mm3/yr., which is the total amount of rainwater hitting the surface

area of the governorate. Table (5.11) summarizes the influence of the existing land

use in Rafah governorate on infiltration and run-off amounts before September 2000.

2 0 2 Kilometers

Legend

Run-off directionDepression Zone

Sea

Topography1011 - 2021 - 3031 - 4041 - 5051 - 6061 - 7071 - 8081 - 9091 - 110

Built-up area

N

Med

iterra

nean

Sea

Figure (5.13): Build up Area over Topographical Layer in Rafah

78

Sea

Agricultural Land UseAlmondsCitrusCitrus/HorticultureDatesGrapesGreenhousesHorticultureOlivesRainfed Crops

Soil TypesDark brown / reddish brownLoess soilsLoessal sandy soilSandy loess soilSandy loess soil over loessSandy regosols

Wadi

MEDIT

ERRANEAN SEA

N

0 2 4 Kilometers

Legend

Figure (5.12): Agricultural Area over Soil Layer in Rafah Governorate.

Table (5.11): Summarizes the Influence of the Existing Land Use in Rafah Governorate on Infiltration and Run-off Amounts before September 2000.

Without Stormwater Collection

System

With Stormwater Collection

System

Gov

erno

rate

Item

Perc

enta

ge fr

om th

e To

tal

Gov

erno

rate

Are

a R

ainf

all A

mou

nt H

ittin

g th

e Su

rfac

e A

rea

(Mm

3 )

Infil

tratio

n in

Situ

(Mm

3 )

Run

-off

Am

ount

(Mm

3 )

Tota

l Los

ses

Am

ount

(Mm

3 )

Net

Infil

tratio

n A

mou

nt (M

m3 )

Tota

l Los

ses

Am

ount

(Mm

3

Net

Infil

tratio

n A

mou

nt (M

m3 )

Build up Area 09.4 1.4 0.32 0.92 0.42 1.0 1.08 0.32 Open Area 26.0 3.8 3.79 3.8 3.79 Agric. Area 64.6 2.1 2.10 2.1 2.10 R

afah

Total 100 7.3 6.2 0.92 0.42 6.9 1.08 6.2

79

As indicated in the table (5.6), it is clear that from the amount of 88 Mm3/yr, hitting

the surface area of Gaza Strip, the net amount infiltrated in all different surface types

is estimated to be 76.3 Mm3/yr., while amount of 71.2 Mm3/yr., is infiltrated in situ,

about 5.1 Mm3/yr., from the total amount of run-off which estimated to be of about

14.54 Mm3/yr., were infiltrated in an open and agricultural areas after awhile. The

total amount of urban runoff in Gaza Strip that drains direct to the sea is 1.1Mm3/yr

as presented in Appendix (D).

The amount of rainwater losses either by evaporation or direct run-off to the sea,

from the total amount of rainfall hits the surface area is estimated to be 11.7 Mm3/yr.,

where the total amount of rain water lost by interceptions and evapotranspiration

from the total amount of rainfall incidents in Gaza Strip as the average rainfall is 300

mm/yr and total amount of rainfall is 120 Mm3/yr., is estimated to be 32 Mm3/yr.

According to a study done by Dutsche Gesellschaft feur Technische

Zusasammenarbeit (GTZ) and quoted by PWA (1999), the total amount of urban run-

off in Gaza Strip that run-off directly to the sea is 2.1 Mm3/yr. Moreover, the total

amount of runoff lost either by evaporation or drainage to the sea reaches about 7

Mm3/yr. which is expected to increase to 80% in 2010 and 150 % in 2020

(PECDAR, 2000).

In case of that the total amount of run-off which estimated to be 14.54 Mm3/yr., were

conducting by stormwater collection and sewage systems, and 37 Mm3/yr., is the

intercepted amount of rainfall by the horticulture plants before hitting the surface

area, and the evaporation amount from the surface is estimated to be 2.2 Mm3/yr.,

therefore the total losses from 125 Mm3 of rainfall incidents on Gaza Strip is

estimated to be 54Mm3/yr. Consequently the annual losses represent about 43% from

total accumulated amount of precipitations, in which this amount is not included

that’s amount lost by transpirations from the agricultural areas. And as a result in this

case the net amount of rainwater infiltrated into the different soil types is estimated

to be 57%.While Abu-Mayla, Y., et.al., 1998 reported that: about 40 % of the total

annual rainfall infiltrates into the ground and recharges the groundwater system, but

Kahan, 1987 argue that's the rate of evaporation and evapotranspiration in the Gaza

Strip are high. The total amount is estimated to be equal 60 % of the loss of total

accumulated precipitation.

80

5.4.3.2 The Influence of the Israeli Incursion from Sep./ 2000 until Aug./ 2004.

Since the outbreak of the second Intifada in September 28, 2000, Gaza Strip facing a

series of violations committed by the Israeli Occupation Forces (IOF) consequential

in a huge campaign of demolitions and confiscation of land. The Israeli occupying

forces impose systematical destruction of Palestinian agricultural sector, including

uprooting of trees, destruction of crops, denying of access to agricultural land and

equipments, as a collective punishment against Palestinians. Gaza Strip has

examined many of the Israeli aggressive measures against land and agriculture;

especially during the year 2004. According to a report issued by the Ministry of

Agriculture, and quoted by Ministry of Planning (MOP), nearly 41 thousand of

dunums were demolished by (IOF) in the Gaza Strip until August /2004, Table (5.12)

and Figure (5.15) shows the number of dunums razed in Gaza Strip from September

2000 until August 2004. This large-scale destruction of agricultural land caused by

the Israeli forces, has terrible impacts on environment, and has contributed to further

deterioration of the Palestinian economy as hundreds of Palestinian farmers have lost

their sources of income.

Table (5.12): Number of Dunums Razed in Gaza Strip from September 2000 until August 2004 (MOP, 2004).

Agriculture Area Razed (Dunums) Governorate

15142 Northern 05139 Gaza 06416 Middle 09243 Khanyounis 04733 Rafah 40673 Total

In contrast, by comparing between tables (5.6) and (5.13), it shown that’s this

behavior will be increased the amount of rainfall that’s hitting the surface area by

about 8.5 Mm3/yr., and as consequently the amount of infiltrated rainfall by about 9

Mm3/yr., as the agricultural area is converted to an open area, and the intercepted

amount of rainfall in this up rooting areas will be downgrade. Detailed computation

of this scenario is shown in Appendix (D).

On the other hand, about 20 Mm3 will decrease the agricultural water demand /yr., if

the water needed for one dunum is assumed to be in average about 500 m3/yr.

81

!.

!.

!.

!.

!.

!.

!.

!.

Gaza

Rafah

Khan Yunis

Northern

Deir al-Balah

!.

!.

!.

!.

!.

!.

!.

!.

Gaza

Rafah

Khan Yunis

Northern

Deir al-Balah

MEDITERRANEAN SEA

· 0 2 41 Kilometers

SCALE : 1 : 50,000

Gaza Governorates Razed lands

Northern 15142 Dunum

5139 Dunum6416 Dunum

9243 Dunum4733 Dunum

40673 Dunum

Agriculture Razed Lands

GazaMiddle

Khan YounisRafahTotal

Date Augest 2004

Governorate LineDelimiting lineWadi Gaza

Main RoadRegional Road

Sea

Areas Under Israeli ControlYellow Area

Built-up Area

Data from the following sources:Cairo Agreement mapAerial photos, january 1995Municipal maps

Boundaries and names are not necessarily authorative

Legend

Ministry of Planning

!. Entry Point

Israeli Military Zone

Railway Line

Air Port

Israeli Settlements

Razed Areas

Figure (5.15): The Destructive Agriculture Land in Gaza Strip from September 2000 until August 2004 (MOP, 2004).

82

Table (5.13): Scenario (3.2): The Influence of the Israeli Incursion from September 2000 until August 2004.

Run-off Amount Destination (Mm3)

Gov

erno

rate

Item

Are

a C

alcu

late

d by

GIS

(m2 )

Ave

rage

R

ainf

all

(mm

/yr)

Rai

nfal

l Am

ount

H

ittin

g th

e Su

rfac

e (M

m3 )

Evap

orat

ion

10%

(Mm

3 )

Infil

tratio

n in

situ

(Mm

3 )

Run

-off

Am

ount

(M

m3 )

Dire

ct to

the

Sea

Agr

icul

ture

A

rea

Ope

n A

rea

Impe

rvio

us

Are

a

Dire

ct to

Is

rael

Tota

l Los

ses

(Mm

3 )

Net

Infil

tratio

n (M

m3 )

Build up Area 10474960 465 5 0.5 1 3.3 0.05 2.7 0.3 0.1 0.2 0.8 4 Open Area 38977750 465 18 18 18

Agriculture Area 11229998 231 3 3 3 Nor

ther

n

Total Area 60682708 26 0.5 22 3.3 0.05 2.7 0.3 0.1 0.2 0.8 25

Build up Area 21972379 436 10 1.0 2 6.4 0.06 0.02 0.03 6.3 0.02 7.3 2

Open Area 25509046 436 11 11 11

Agriculture Area 25877425 210 5 5 5 Gaz

a

Total Area 73358851 26 1.0 19 6.4 0.06 0.02 0.03 6.3 0.02 7.3 19

Build up Area 7501893 363 3 0.3 1 2 0.7 0.5 0.06 0.6 1.6 1

Open Area 18784555 363 7 7 7

Agriculture Area 29937273 177 5 5 5 Mid

dle

Total Area 56223721 15 0.3 13 2 0.7 0.5 0.06 0.6 1.6 13

Build up Area 10388624 306 3 0.3 1 2 0.07 0.9 0.1 1.1 1.6 1.6

Open Area 35583802 306 11 11 10.9 Agriculture Area 64096147 120 8 8 7.7

Kha

nyou

nis

Total Area 110068574 22 0.3 19 2 0.07 0.9 0.1 1.1 1.6 20.2

Build up Area 5680319 242 1 0.14 0.3 0.92 0.2 0.6 0.05 0.1 0.42 1.0

Open Area 20421921 242 5 4.9 4.9

Agriculture Area 34385444 55 2 1.9 1.9 Raf

ah

Total Area 60487683 8 0.14 7.1 0.92 0.2 0.6 0.05 0.1 0.42 7.8

Total 360821537 96.5 2.2 80 14.5 1.1 4.6 0.4 7.1 1.3 11.7 85

83

5.4.4 Scenario (4): The Influence of Proposed Land Use

The scarcity of land is the largest constraint regarding the future developments of

Gaza Strip. Estimation of the future land use for different sectors according to the

visions of a number of ministries, especially MOPIC (1998) is illustrated as follow:

5.4.4.1 Future land Use Demand for Agriculture

Agriculture is the largest sector in the economy of Gaza Strip and contributes to 32%

of the economic production. Agriculture has passed through stages of expansion and

land reduction. The cultivated area increased from 170 to 198 km2 from 1966 – 1977.

In 1978, the cultivated area was reduced to 179 km2 mainly due to the increase in

urban areas; also, the forest areas and sand dunes were reduced from 32% to 22%.

Agricultural land is mostly in private ownership. 73% of the agricultural land of

parcels of less than 9 dunums. (MENA, 2001). Metcalf and Eddy (2000) suggested

that, the current land use will not expanded in the future due to that not much land in

Gaza Strip left unused, so Metcalf and Eddy (2000) claimed that the future expansion

will be for the residential use on the account of agricultural land already used.

5.4.4.2 Gaza Airport and Gaza Sea Port Land Demand

Gaza Airport currently covers an area of about 1500 dunums, and has a total reserved

area of 3000 dunums. This area will considerably increase the storm water run-off.

5.4.4.3 Future land Use Demand for Industrial and Commerce

Before 1994, the industrial sector in Gaza Strip was completely unorganized, where

the factories spread among the residential areas. PNA started to allocate and design

industrial zones after that period. Currently, Gaza Strip has four industrial areas with

a further three proposed sites or extensions. The industrial areas often have large

areas of roof space and other impervious surfaces, approaching 80–100% of the gross

land area, which will make them contribute a large peak flow storm water rate to the

local area. Table (5.14) shows the proposed industrial, trade and commercial area for

each Governorate.

84

Table (5.14): Land Demand for Industrial, Trade, and Commercial Land Use (MOPIC, 1998).

Area Industry (Km2) Trade and Commerce (Km2) Northern 1.150 0.920 Gaza 2.500 1.980 Middle 1.290 1.040 Khanyounis 2.220 1.780 Rafah 1.270 1.020 Total 8.430 6.740

5.4.4.4 Future Urbanized Land Demand

The present urban expansion is concentrated in the western coastal zones of Gaza.

The expansion of buildings and other dwellings is estimated to be 1000–1500

dunums per year (MENA, 1999). The rate of urbanization in Gaza Strip has

increased over the last 10 years of about 39%. The percentage increase is estimated

as approximately 50% over the next 10 years and over 100% over 20 years

(PECDAR, 2000). Table (5.15) illustrated the demand build up area land per

governorate for 1997, 2005, 2015, and 2025. The projected urbanized area are

included all the area needed for housing unit, roads, industry, commerce, service and

recreations. In additions, and rooted in MOPIC (1998) the housing units in 1997 and

the expected urban development for 17 years is represented in table (5.16).

Nowadays, the urbanized area represents around 20% while it expected to reach 26%

of the total Gaza Strip area by year 2010.

Table (5.15): The Urbanized Land Demand per Governorates (MOPIC, 1998). 1997 2005 2015 2025 Governorates Urban Area (km2)

Northern 13.57 16.72 21.58 25.65 Gaza 20.23 28.94 44.12 54.57 Middle 07.03 10.34 15.40 19.85 Khanyounis 10.82 15.46 34.68 44.69 Rafah 05.86 08.35 12.31 15.48 Total 57.50 79.80 128.08 160.24

85

Table (5.16): Housing Units in 1997 and the Expected Urban Development Represented by Housing Units and Build up Area in 17 Years (MOPIC, 1998).

Residential Areas Year Area (km2) Number of Houses 1997 54.25 152851 2005 68.49 203681 2015 94.65 297433

5.4.4.5 Future Urban Run-off for Gaza Strip

As mentioned before, increasing urbanization means increasing impervious surfaces,

and therefore increasing surface run-off. Due to that’s the detailed information and

maps for the future land use demand; which proposed by MPOIC (1998) is not

offered except that’s for the year 2015, a detailed computations for the influence of

land use demands on surface run-off and rainfall amount infiltrated into different

surfaces type for the year 2015, as shown in Appendix (D), and Figure (5.16), and

summarizes in table (5.17).

According to the regional plan proposed by MOPIC (1998), and the author

calculations depends on GIS measurements, the build up area for the year 2015 will

be increased to represent about 33 % from the total area of Gaza Strip, while it will

be represents about 45% in the year 2025. In additions to face the population's

growth and due to Gaza Strip limited area, these build up areas will be denser than

that is in the previous years. As a consequence and by considering the increase in the

different types of impervious surfaces from year to year is of a constant ratio, the

run-off coefficient will be increased from 0.67 for the years 1998 and 2004, to be

about 0.78 for the year 2015 and 0.87 for the year 2025. While the open area will be

decreased from 26% to be represented about 18%, the agriculture land will be

changed from the existing one of about 57% to represent about 48% for the year

2015.

86

Figure (5.16): The Proposed Land Used for the Year, 2015 (MOPIC, 1998).

87

Table (5.17): Scenario (4): The Influence of Proposed Land Use for the Year 2015 (Mm3).

Run-off Amount Destination (Mm3)

Gov

erno

rate

Item

Are

a C

alcu

late

d by

GIS

(m2 )

Ave

rage

Rai

nfal

l (m

m/y

r)

Rai

nfal

l Am

ount

H

ittin

g Su

rfac

e (M

m3 )

Evap

orat

ion

10%

(M

m3 )

Infil

tratio

n in

situ

(M

m3 )

Run

-off

Am

ount

(M

m3 )

Dire

ct to

th

e Se

a

Agr

icul

ture

A

rea

Ope

n A

rea

Impe

rvio

us

Are

a

Dire

ct to

Is

rael

Tota

l Los

ses

(Mm

} )

Net

Infil

tratio

n (M

m3 )

Build up Area 16023448 465 7 0.7 0.9 5.8 0.07 3.5 1.5 0.73 3.1 4 Open Area 19337385 465 9 9.0 9

Agriculture Area 25321875 231 6 5.8 6

Nor

ther

n

Total Area 60682708 22 0.7 15.7 5.8 0.07 3.5 1.5 0.73 3.1 19 Build up Area 42448198 436 18 1.8 2.2 14 1.5 1.6 11.0 0.04 14.3 4

Open Area 6302224 436 2.7 2.7 3 Agriculture Area 24608429 210 5.2 5.2 5 G

aza

Total Area 73358851 26 1.8 10 14 1.5 1.6 11 0.04 14 12 Build up Area 14671901 363 5.3 0.5 0.6 4.1 2 0.6 0.4 1.4 3.7 1.6

Open Area 9520017 363 3.5 3.5 3.5 Agriculture Area 32031802 177 5.7 5.7 5.7 M

iddl

e

Total Area 56223721 14 0.5 10 4 2 0.6 0.4 1.4 3.7 11 Build up Area 35154749 306 10.8 1.1 1.3 8.4 0.22 1.4 6.8 8.1 2.7

Open Area 17031015 306 5.2 5.2 5.2 Agriculture Area 57882809 120 6.9 6.9 6.9

Kha

nyou

nis

Total Area 110068574 23 1.1 13.4 8.4 0.22 1.4 6.8 8.1 15

Build up Area 11043318 242 2.7 0.27 0.3 2.1 0.55 0.1 1.4 2.2 0.4 Open Area 13767034 242 3.3 3.3 3.3

Agriculture Area 35675333 55 2.0 2.0 2.0 Raf

ah

Total Area 60485684 8 0.27 5.6 2.1 0.55 0.1 1.4 2.2 5.7

Total 360819538 94 4.5 55 35 4.1 5.4 2.1 22 0.8 31.5 62

88

As illustrated in Figure (5.17) and table (5.17), the total build up area will represents

about 26.4% from the total area of the northern governorate for the year 2015, with

an increasing rate of about 9% from that’s in scenario number (3.1), as a result the

surface run-off in this governorate will be increased from 3.3 Mm3/yr., to 5.8

Mm3/yr. Besides the net infiltration will be decreased by about 2 Mm3/yr., from

that’s in the existing situation in case of the stormwater collection system is not

founded, and by 5.5 Mm3/yr., in case of the total amount of surface run-off will be

conducting by stormwater collection system, and will not be allowed to infiltrate in

agricultural and open areas. As proposed the open area in this governorate will be

decreased by about 7.4% from that’s in present situation and it will represent 31.9%,

while the agriculture land will be decreased by about 1.7% and will represent an area

of about 41.7% from the governorate total area.

LegendPROTECTION

Built-up

Urban Development

ELEVATION10

20

30

40

50

60

70

80

90

100

1100 1 20.5 Kilometers

·

Northern Governorate

Figure (5.17): The Existing and the Proposed Build up Area for the Year 2015 in

Northern Governorate.

89

The proposed land use in Gaza governorate for the year 2015, showing an increasing

in the build up area of about 18% from that’s in present situation; and it will be

represents about 58% from the total governorate area, as illustrated in Figure (5.18)

and table (5.17), as a consequence this will be increased the amount of surface run-

off from 6.4 Mm3/yr., to 14.4 Mm3/yr.. In contrast, this increase in build up area will

be faced by a decrease in the net amount of rainfall infiltrated, while the net

infiltrated amount in present situation was estimated to be 17.65 Mm3/yr., the net

infiltrated amount in the year 2015 will be 11.77 Mm3/yr., in case of there is not

stormwater collection system, and 10.14 Mm3/yr., in case of there will be stormwater

collection system.

Legend

PROTECTIONBuilt-up

Urban Development

ELEVATION10

20

30

40

50

60

70

80

90

100

1100 1 20.5 Kilometers

·

Gaza Governorate

Figure (5.18): The Existing and the Proposed Build up Area for the Year 2015

in Gaza Governorate.

90

The build up area in the Middle governorate will be increased by 12.8% from the

existing situation, as shown in Figure (5.19) and table (5.17), while the proposed

build up area in the year 2015 will be represented about 26.1% from the total

governorate area, the build up area represents about 13.3% in the former one. The

agriculture area, which, represents about 64.7% in the present situation will be

decreased by about 7.7% to represent about 57% for the year 2015. The open area

will be less than that is in the existing situation by about 5.1%, in which it will be

estimated to be 16.9% where in present time represents about 22%. As a

consequently of increasing the impervious area in this governorate; the surface run-

off will be more than that’s in the present situation by amount of about 2.33 Mm3/yr.,

where the amount of surface run-off is estimated to be 1.82 Mm3/yr., for the present

time, the amount of surface run-off will be estimated to be 4.15 Mm3/yr., for the year

2015.

LegendPROTECTION

Built-up

Urban Development

ELEVATION10

20

30

40

50

60

70

80

90

100

1100 1 20.5 Kilometers

·

Middle Governorate

Figure (5.19): The Existing and the Proposed Build up Area for the Year 2015

in the Middle Governorate.

91

In contrast, the net infiltration amount will be decreased from 11.55 Mm3/yr., to 9.8

Mm3/yr. This will be inverse the reality in case of the stormwater collection system is

founded in the area. While in case of the stormwater collection system is not found,

most of surface run-off amount will be destine into agricultural and open areas, and

as a result the amount of surface run-off will be decreased to be 1.3 Mm3/yr., for the

present time and about 3.2 Mm3/yr., for the year 2015. Whilst the net infiltrated

amount will be increased to be about 12.1 Mm3/yr., in the existing situation, and 10.7

Mm3/yr., in the year 2015.

According to the proposed land used and GIS calculations given in table (5.12) and

Figure (5.20), the build up area in Khanyounis governorate for the year 2015 will be

increased to represent about 31.9% with an increasing rate of about 22.5% from that

in present situation, which means a considerable increase in the impervious surfaces

and as a result an increase in the surface run-off.

Figure (5.20): The Existing and the Proposed Build up Area for the Year 2015 in Khanyounis Governorate.

Legend

PROTECTIONBuilt-up

Urban Development

ELEVATION10

20

30

40

50

60

70

80

90

100

1100 1 20.5 Kilom eters

·

Khan Younis Governorate

92

On other hand, there will be a decrease in both the agriculture and open areas, where

the agriculture area will be decreased from 66.6% to be about 52.6%, while the open

area will be decreased from 24% to be 15.5% in the year 2015.

Therefore, the net infiltration amount will be decreased from 18.5 Mm3/yr., in the

existing situation to be about 14.8 Mm3/yr., in the year 2015.

In contrast the amount of surface run-off will be increased to be about 7 Mm3/yr., for

the year 2015, where this amount is estimated to be 1.3 Mm3/yr., for existing

situation, this picture will be true in case of the stormwater collection system is not

founded in the area. While in case of the stormwater collection system is founded,

the amount of surface run-off will be more and the net infiltration amount will be less

than that is in the previous case. In this case, the net infiltration amount will be about

13.5 Mm3/yr., the amount of surface run-off will be 8.4 Mm3/yr., for the year 2015,

where the net infiltration amount is estimated to be about 17.6 Mm3/yr., and the

amount of surface run-off is estimated to be 2.1 Mm3/yr., for the present time.

Rooted in both GIS calculations and MOPIC (1998), in Rafah governorate for the

year 2015 the proposed build up area will be increased to represent about 18.3%

from the total area as given in table (5.17) and Figure (5.21), where it was

represented about 9.4% in the present time. Besides the agriculture area will be

decreased to be about 59% instead of 64.7%; with decreasing rate of about 5.7%,

where the open area will be represented about 22.8% from the total governorate area

instead of 26% in existing situation. In case of the stormwater collection system is

founded in the area, the amount of surface run-off for the year 2015 will be about 2

Mm3/yr., and the net infiltrated amount will be about 5.6 Mm3/yr., while the amount

of surface run-off for the existing situation) was estimated to be about 1.2 Mm3/yr.,

and the net infiltration amount about 6.3 Mm3/yr.,. On other hand and in case of the

stormwater collection system is not founded; the amount of surface run-off will be

1.9 Mm3/yr., 0.57 Mm3/yr., and the net infiltrated amount will be about 5.7 Mm3/yr.,

6.9 Mm3/yr., for the year 2015 and the present time, respectively.

93

Legend

PROTECTIONBuilt-up

Urban Development

ELEVATION10

20

30

40

50

60

70

80

90

100

1100 0.9 1.80.45 Kilometers

·

Rafah Governorate

Figure (5.21): The Existing and the Proposed Build up Area for the Year 2015 in Rafah Governorate.

Generally, the proposed land use in Gaza governorate for the year 2015 will show an

increase in the impervious surfaces as a result of a huge urban expansion that’s will

be occurred, in contrast decreasing in both agricultural and open areas. Therefore, it

is clear that’s the total amount of rainfall lost, as a surface run-off in Gaza Strip will

be increased to be about 35 Mm3/yr., where the amount of rainfall infiltrated will

grade down to be about 55 Mm3/yr., in a case of Gaza Strip having a stormwater

collection system. Alternatively, in case of Gaza Strip does not have stormwater

collection system, the amount of surface run-off will be about 28 Mm3/yr., due to

that amount of about 7Mm3/yr., will infiltrate into agricultural and open areas,

therefore the net infiltrated amount will increase to be about 62 Mm3/yr.

94

With each passing year, Gaza Strip becomes increasingly urbanized. Agricultural and

open areas give way to new housing and business developments. These new

developments replace permeable soils with impervious surfaces like concrete,

decreasing infiltration and recharge and increasing run-off. Where water once

absorbed into the soil and recharged the groundwater system, it now runs- off roofs,

sidewalks, and parking lots that do not allow infiltration leading to increased

flooding and associated non-point-source pollution. Table (5.18) and Figures (5. 22,

A, B, C, E, F) show the changes in urbanized area and surface run-off per

governorate of Gaza Strip for the years, 1998, 2005, 2015, 2025. As indicated, the

rapid increase in the rainwater losses is due to the expansion of urban areas towards

the western side of Gaza Strip, which lead to increase of run-off leaving no chance

for infiltration in open areas. In addition, the planning criteria considered Gaza and

Khanyounis as two main core cities where Palestinian returnees will be settled.

95

Table (5.18): The Changes in Urbanized Area and Surface Run-off per Governorate for 1998, 2005, 2015, 2025

1998 2005 2015 2025 Governorates Urban Area

(km2) Urban Run-off (Mm3)

Urban Area (km2)

Urban Run-off (Mm3)

Urban Area (km2)

Urban Run-off (Mm3)

Urban Area (km2)

Urban Run-off (Mm3)

Northern 10.48 3.26 13.58 4.22 16.23 5.88 25.65 10.37 Gaza 21.97 6.41 28.94 8.44 42.45 14.42 54.57 20.68 Middle 07.50 1.82 10.34 2.51 14.67 04.15 19.85 06.26 Khanyunis 10.39 2.13 15.46 3.17 35.15 08.39 44.69 11.90 Rafah 05.68 0.92 8.35 1.35 11.04 02.64 15.48 04.12 Total 56.02 14.54 76.67 19.69 119.54 34.84 160.24 52.46 % from the Gaza Strip total area 16% 21% 33% 45%

Note:

Calculations based on rational method: Q = CIA

Where; Q is the quantity of urban run-off (Mm3), I is the average rainfall in each considered area (mm/yr.), A is the considered area (km2),

and C is the run-off coefficients, which are for the years 1998, 2005 c = 0.67, for 2015, c = 0.78 and for 2025, c = 0.87

96

Figure (5.22): Changes in Urbanized Area and Surface Run-off for the Years 1998,

2005, 2015, and 2025 in:

A. Northern Governorate

B. Gaza Governorate

C. Middle Governorate

0

5

1 0

1 5

2 0

2 5

3 0

1 998 20 05 20 15 20 25

0

10

20

30

40

50

60

1998 2005 2015 2025

0

5

10

15

20

25

1998 2005 2015 2025

( C )

U rban A rea (km 2) U rban R u n-o ff ( M m 3)

( A )

( B)

97

D. Khanyounis Governorate

E. Rafah Governorate

F. All Gaza Strip Governorates

( C )

0

10

20

30

40

50

1998 2005 2015 2025

0

5

10

15

20

25

1998 2005 2015 2025

02040

6080

100

120140160180

1998 2005 2015 2025

( D )

( E )

( F )

98

5.5 The Conflict between Urban Expansion and Groundwater Protection

Urbanization is furnished by addition of more roads, houses, commercial and

industrial buildings. As a result, an increasing in impermeable surfaces for

infiltration and therefore increase run-off. The water table may fall because of

decreased water infiltration. In contrast, the water table may rise since of decreased

evapotranspiration, e.g. following urbanization. In Gaza Strip, increasing

urbanization has brought forth change in land use thus decreasing the net area

available for natural recharge and increasing groundwater abstraction at the same

time. Abdul Hadi, (1997) indicated that’s the quantity of the rainfall recharge has

been reduced from 90 million in the 1970s to 46 Mm3/yr and is decreasing

continuously, due to Israeli wells dug all around the Gaza Strip since the 1980s, and

the increasing in impervious area as a result of urban expansion. Over the years

rising populations, growing urbanizations, have pushed up the demand for water.

Ground water as indispensable source and its increasing extraction and decreasing

natural replenishment in Gaza Strip is reflected in the drastic lowering of water levels

leading to local drawdowns. The groundwater level in some areas of Gaza Strip has

declined below sea level over a period of two decades, with half of the decline

occurring in the past 8 years as illustrated in groundwater level maps Figures (3.8,

3.9). Combined with deep water levels, the natural recharge has become less

effective, thus increasing the demand-supply gap. Consequently, some existing wells

are not deep enough to get water and might run dry. As indicated in groundwater

level maps, the water level declines are mostly apparent in the South and the Middle,

and are most likely a reflection of the lower recharge from rainfall due a high rate of

urban expansion in these areas. In the North, most wells exhibit relatively slow

declines with partial or complete recovery due to higher rainfall recharging in this

area (PWA, 2003). Increasing water scarcity in both rural and urban areas, combined

with increasing demand, degraded natural environment. The continuous groundwater

withdrawal is causing most of Gaza’s coastal aquifer to eventually become saline.

The extensive depletion of fresh groundwater with little natural recharge has led to

excessive seawater intrusion into that aquifer which, if not corrected, will become a

drastic problem that cannot be easily remediate.

99

With the above scenario, the protected areas for ground water recharge are a matter

of priority, but it is conflict mainly with the urban development. Gaza with the

borders of today and the dramatically increase in population growth can never be

sufficient for environmental sound urban expansion (Al-Najar, 2003). According to

water level, and soil classification maps the following areas are proposed for

groundwater protection:

1. All sites represents natural depression zones especially that’s closest to the shore

line, as shown in both topographical, three dimensional view maps Figures (3.2, 5.3)

and topographical profile illustrated in Appendix (C).

2. Israeli settlements in Gaza Strip.

Where, the Israeli occupation force started to build up on the Palestinian lands after

the 1967 war. Today there are 26 Colonies in the Gaza Strip and they occupied

around 7.4% of the total area of Gaza Strip. Where the total areas controlled by Israel

in the Gaza Strip is about 106.32 km2, which constitutes about 30% of Gaza total

area (PWA, 2004). According to Khan (1987) the major concentrations of these

settlements is agriculturally oriented Colonies. Table (5.19) shows the constitutions

of the Israeli controlled areas in Gaza Strip, in which includes the build up areas,

security zones, military installations, buffer zones and yellow areas.

Table (5.19): Areas Controlled by Israel in Gaza Strip (PWA, 2004).

Item Area (Km2) Percentage (%)

Israeli colony areas 026.66 07.4

Israeli security zones 052.3 14.5

Yellow & Buffer zones 027.36 07.6

Total 106.32 29.5

It is worthwhile to mention that, these settlements are located on the best ground

water locations as presented in the Basic map Figure (3.1). The land use in these

colonies reveals that the build up is relatively minor figure in comparison to the

security and yellow zones. The later ones constitute 70% of the total area (PWA,

2004). Moreover, the Israeli confiscated all water resources declaring them state

property and forbid unlicensed construction of new water infrastructure by military

law 1-98/1967, 2-158/1967 and 3-291/1968 .

100

According to last Israeli Cabinet declaration, these Colonies shall be gradually

handed to the Palestinians. Based on water resources protect point of view, the

Colonies area should be reserved for groundwater protection.

The eastern side of the Gaza Strip, which considered being hillside locations, was

used in the former time as citrus agricultural lands. The ministry of agriculture

reported that: land use for citrus reduced 60% due to limited marketing and the high

salinity of water for irrigation (Al-Najar, 2003). Therefore, the future urban

expansion should be directed to these areas reserves the sandy dunes as basins to

recharge the ground water.

Changes in hydrology and site drainage should be minimized within the drip line of

significant or designated protected areas. Sustainable planning of housing

development and structures should be according to proper planning. Buildings,

particularly in hillside locations, should be designed to minimize impact on or

alteration to natural drainage and infiltration rate patterns. To the extent possible with

other design considerations, building designs should not degrade rainwater

infiltration, inhibit groundwater natural replenishment or otherwise increase any

undirected run-off to the sea.

5.6 Stormwater Mitigation Measures

Due to urbanization, the cities are becoming overcrowded with population as a result

over exploitation of groundwater, which in future may result in depletion of

groundwater. Urbanization cleared large areas of agricultural and open land, with the

result high rainfall intensities, increased surface runoff with high velocity. The

stormwater runoff from the increased urbanization, which used to soak into the

ground, goes into stormwater collection system, streets, causing flooding. Which

then ended in the sea without giving enough time for infiltration to the ground water

due to that Gaza strip is a foreshore plain gradually sloping westward toward the sea.

Based on the author calculations as given in table (5.6), the surface run-off result

from the existing urban areas in Gaza Strip is estimated to be 14.5 Mm3/yr.

Bruins, et al., (1991) claimed that one third of the area of the Gaza Strip would yield

surface run-off. In Gaza Strip like most developing countries appropriate urban

stormwater mitigation measures has not been appropriately addressed. Funding for

stormwater run-off collections from urban areas is relatively ignored by both local

101

and donated international agency resulting in failure of both stormwater collection

system and sewage system. Nowadays, stormwater run-off may be conveyed in

pipes, conduits and in paved streets between curbs in densely developed areas, but

few of these systems are seen in the urban areas of the Gaza Strip. When an intense

rainfall occurs, the water quickly flows from flat or pit chides roofs to the streets

often mixing with silage flow or untreated sewage. Such flows soon become a

nuisance with potential health hazardous or a major flooding problem (LYSA, 1995).

By these problems the basic needs are not met, lack of infrastructure and treatment

facilities. Sustainable Stormwater management can be achieved by several

mitigations measures like stormwater harvesting for future reuse.

5.6.1 Stormwater Harvesting

Stormwater harvesting is the collection, diversion, and storage of rainwater for future

reuse. It is appropriate for large scale such as parks, streets, schools, universities,

commercial and industrial sites, parking lots, ground play, airport and public

housing, as well as small scale such as residential houses. Historically, people relied

on harvested rainwater to provide water for drinking, landscape watering, and for

agricultural uses. More recently, people have become reacted with water harvesting,

using it to provide water for home gardens, parking lot trees, and multi-housing

lawns.. Another source of surface run-off is that flowing in Wadis, which are

ephemeral streams, characterized by short flash floods, occurs after heavy rainfall.

The main one is Wadi Gaza .The run-off of Wadi Gaza reached up to 40 Mm3 in the

wet year 1994 when the rainfall was about 1000 mm (Sogereah, et. al.,

1999).Stormwater storage and use can reduce surface water run-off and assist in

reducing the peak demand. With treatment, rainwater can be used for all domestic

needs. Consequently help in combating the chronic water shortages in the Gaza Strip.

5.6.1.1 Small Scale Stormwater Harvesting

In the semi-arid zones like Gaza Strip, the annual rainfall occurs during an

approximately four-month period, with the remaining months having little or no

rainfall. Accordingly, rainwater harvesting from residential roofs top represents a

feasible alternative under certain natural and demographic conditions to satisfy

domestic water demands during the dry season and throughout the year. Small scale

rainwater harvesting is a relatively simple technique of collecting roof run-off in

102

cisterns, and using it for both landscape irrigation and indoor purposes. Successful

applications of this technique have been observed in Amman (Jordan), Edlib and

Quneitra (Syria), Israel (Negev), West Bank (Palestine), Lebanon, Yemen (Aden)

and Syria (Rasafe). The collection of rainwater from the roofs of buildings can easily

take place within our cities and towns. All that is necessary to capture this water is to

direct the flow of rainwater from roof gutters to a rainwater storage tank (cistern).

The total amount of water that is received in the form of rainfall over an area is

called the rainwater catchment of that area. Out of this, the amount that can be

effectively harvested is called the water harvesting potential. The collection

efficiency accounts for the fact that not all the rainwater falling over an area can be

effectively harvested.

In order to calculate the amount of water which can be caught by the roof area in the

Gaza Strip, Hudhud and Najar, (1993) indicated that’s the average rainfall

(300mm/yr.), the run-off coefficient are the necessary required data in addition to the

roof surface area (average of 90 m2 per house) and the number of the houses.

Example:

§ For Individual Housing Unit

Consider a building with a roof top area of 90 m2. The average annual rainfall in

Gaza Strip is approximately 300mm. In simple terms, this means that if all the rain

that falls on the roof top area is retained, then in one year there will be rainwater on

the floor to a height of 300mm.

Area of roof top 90 m2

Height of rainfall 0.30m (300 mm)

Volume of rainfall over the roof top Area x Height of Rainfall

90 m2 x 0.30 m= 27m3

To calculate the effective rainfall harvested, assume the run-off coefficient is 67%.

Volume of water harvested = 27,000 x 0.67 = 18090 liters

That means 18090/ 365 = 50 litres of water per day will be available for the

household unit.

103

§ Multi-Storied Housing Building

Take example of a multi-storied building consist of 15 flat with a roof top area of

500 m2. The effective rainwater harvested for this building per year will be as

following:

= 500 x 0.3 x 0.67 = 100.5 m3 = 100500 liters.

Therefore the per day water availability per flat will be 18.4 liters/day.

5.6.1.2 Large Scale Stormwater Harvesting

Stormwater Harvesting on large scale, using the natural surface like; asphalted streets

or conduits, tilling roads and squares to collect the rainwater and storing it in

infiltration ponds. Infiltration ponds help the recharging of ground water. The

selected locations of the infiltration ponds should be planned according to the

topography and the catchments area. It might be more effective in case of using some

measures like; site detention which includes detention basins, roof infiltration basin

and percolation basins by increasing storage volume, increase toughness, decrease

slope, increase time for infiltration, increase area for infiltration (porous pavements

and increasing vegetation in the streets). The total amount of collected rainwater

from the build up area equals the multiplication of the average amount of rainfall

(300 mm/yr) by the run off coefficient (Steel and McGhee, 1985) which, indicate the

roughness of the surface for the paved streets and curbs and multiply with the build

up area. If the existing situation is continued and infiltration ponds are not

considered, these amounts of rain will be lost of the ground water balance. In order to

minimize the land required for infiltration ponds, artificial recharge can be

technically considered for Gaza Strip situation, but it is out scope of this study.

Ultimately, each of these scenarios has unique benefits and the optimal configuration

may depend on site-specific conditions both of the users, the residence and the

location. The implementation of these scenarios, especially that is for a large-scale

one requires separate storm water collection system. Unfortunately, in Gaza Strip the

existing combined system serves for both wastewater and storm water except for

some densely populated refugee camps. Thus, the implementation should be

considered for the new expanded urban areas, or to establish new infrastructure to

separate the collection system to obtain acceptable water quality for ground water

104

recharge. The proposed mitigation measures must be involving aspects of both

environmental engineering and urban policy in the future.

5.6.1.3 A further Stormwater Harvesting

There are many water harvesting opportunities, even from very small yards can

benefit for water harvesting. Furthermore, water harvesting can easily be planned

into new urbanized areas during the design phase. Public building like, (schools,

universities), parks, parking lots, and commercial facilities all provide sites where

rainfall can be harvested.

Example:

Consider a school building with a roof top area of 3000 m2. The effective rainwater

harvested for this building per year will be as following:

Name of the public building School building

Roof top area 3000 m2 Annual rainfall 300 mm Effective rain water harvested per year 3000 x.3 x 0.67=603 M3

105

Chapter (6) Conclusion and Recommendations

6.1 Conclusion

• Groundwater is naturally, recharged when rainwater infiltrates the ground and

percolates downward. However, the paving-over of Gaza Strip has done a great

deal to prevent stormwater from natural infiltrating into the ground. This adds to

the fact that groundwater aquifer are being depleted at an unsustainable rate.

• In Gaza Strip like most developing countries appropriate urban stormwater

mitigation measures has not been appropriately addressed. Funding for

stormwater run-off collections from urban areas is relatively ignored by both

local and donated international agencies resulting in failure of both stormwater

collection system and sewage system. Current management techniques are to

move the runoff as quickly as possible away from urbanized areas into storm

water collection, sewer system, and, eventually to the sea.

• Sixth deferent soil types covering the area of Gaza Strip, which are Loess soil ,

dark brown/reddish brown soil, Sandy Loess soil, Loessial Sandy soil, Sandy

Loess over Loess, and Sandy Regosols soil, with a representative area of

(6.6%,13.7%, 9%, 23%, 16.2% , 31.5%) from the total area of Gaza Strip,

respectively. These soil types have a relative high infiltration rate, which estimated

to be (7, 16, 4, 8, 6, 18) mm/ min, correspondingly.

• The high infiltration rate of Gaza Soils which is higher than the 5 years storm

occurrence emphasis that's the groundwater naturally recharged from rainfall.

• The direction and magnitude of Gaza Strip slope is shown that’s most of Gaza

Strip area is described as flat area and gradually sloping ranging between (0-5)%

westward toward the sea allowing for surface runoff.

• Topographical profiles show that a westward decline to the sea and a number of

depressions area. This almost founded at elevations ranging from 20 to 60m, in

which the Surfaces type is impervious due to the urbanizations. As consequently,

the amount of water detained will be losses due to evaporation or run through the

stormwater collection system, which finally pumped, to the sea.

106

• The amount of rainfall infiltrated into the sandy regosol soil which represents

about 35% from the total infiltrated amount is considered to be the greatest

amount among the different soil types.

• The total amount of rainfall infiltrated in case of Gaza Strip is considered as an

open space area is about 125 Mm3/yr. The rainfall interception by vegetation and

its subsequent evaporation in agriculture areas of Gaza Strip constitute a net loss

of about 56%, where the effective rainfall contributed to the groundwater is

estimated to be equal 44% from total amount incidents over these areas, which

may assume considerable values under certain conditions.

• At the existing land use situation the net amount of rainwater infiltrated into the

different soil types is estimated to be 57% from the total accumulated amount of

precipitations which estimated to be 125Mm3/yr., where the annual losses

represent about 43%, in which this amount is not included that’s amount lost by

transpirations from the agricultural areas.

• Due to the Israel incursion, where 41 thousand of dunum from the agriculture

land razed until August 2004. Therefore, an additional amount of about 9 Mm3

will be infiltrated and contributed to the groundwater. On the other hand the

agricultural water demand will be decreased by about 20Mm3/yr.

• With each passing year, Gaza Strip becomes increasingly urbanized. Agricultural

and open areas give way to new housing and business developments. These new

developments replace permeable soils with impervious surfaces like concrete,

decreasing infiltration and recharge and increasing run-off.

• The urbanized area represents around 16% in the year of 1998 and 20% in the

year of 2004, and is expected to increase in the next years due to the rapid

increase in population to represent 33% and 45% for the years of 2015 and 2025

respectively. In the meantime, the water demand will increase due to the

expansion of water supply systems.

• The total amount of rainwater losses due to urbanization as surface run-off is

estimated 14.5Mm3 in the year of 1998 and expected to increase to about 20Mm3,

35Mm3, and 52Mm3 for the years of 2005, 2015 and 2025 respectively. These

will results in an increasing pressure on underground water resources, which has

lead to an irreversible depletion of the aquifer.

107

• If the increase of the impervious areas is of a constant rate, the run-off coefficient

will increase from 0.67 for the years 1998 and 2004, to 0.78 by year 2015 and

will reach 0.87 by the year 2025.

• The proposed land use in Gaza governorate for the year 2015 will show an

increasing in the impervious surfaces as a result of a huge urban expansion that’s

will be occurred. As a result, the amount of rainfall infiltrated will grade down to

be about 55Mm3/yr., in a case of Gaza Strip having a stormwater collection

system.

• The groundwater level in some areas of Gaza Strip has declined below sea level

over a period of two decades, half of the decline occurred in the past 8 years .The

water level declines are mostly apparent in the South and the Middle, and are most

likely a reflection of the lower recharge from rainfall due a high rate of urban

expansion in these areas.

6.2 Recommendations

• The high infiltration rate of various soil types in the area of Gaza Strip emphasizes

the need for groundwater protection from the different sources of pollutions.

• Urban surface run-off should be collected in a constructed infiltration system to

recharge the groundwater aquifer.

• Legal and bylaws steps should be taken by relevant institutions to deal with

rainwater run-off as a main source to feed the groundwater.

• Further studies are needed to determine the best locations for groundwater recharge

including the geology of deeper soil layers.

• Assessing the quality of urban surface run-off.

• Reduce impervious surface area by using permeable pavement materials where

appropriate, including: pervious concrete/asphalt; unit pavers, i.e. turf block; and

granular materials, i.e. crushed aggregates, cobbles.

• Prevention of land use planning and development resulted in degradation of

existing groundwater quality.

• Increasing public awareness is a necessity to improve the quality of stormwater.

108

References

• Abdul Hadi, A. (1997). Gaza Water Crisis Worsening. Palestine Report. vol 2. Issue49. Online: http://www.igc.org/desip/GazaWater.html., Visited at August10, 2004.

• Abu-Mayla, Y.; Abu-Jabbal, M.; and El-Baba, M. (1998). Water Resources Management and Development in Gaza Strip-Palestine. Paper Presented at the Conference of Water and Food Security in the Middle East 20-23 April 1998. Nicosia, Cyprus.

• Abu-Mayla, Y. and Aish, A. (1997). Water Resources Program in Gaza Strip. Submitted in the Regional Meeting of IHP 8-12 September, 1997 Rabat, Morocco.

• Al-Agha, M.R. (1995). Environmental Contamination of Ground Water in the Gaza strip. Environmental Geology, vol.75: pp.109-113.

• Al-Agha, M.R. (1997). Environmental Management in the Gaza strip. Environmental Impact Assessment Review, vol.17:pp. 65-76.

• Al-Najar, H. (2003). The Effect of Urban Expansion on Groundwater Recharge as Renewable Resource in Gaza Strip. (Unpublished).

• Assaf, S. A. (2001). Existing and the Future Planned Desalination Facilities in the Gaza Strip of Palestine and their Socioeconomic and Environmental Impact, Presented at the European Conference on Desalination and the Environment: Water Shortage, Lemesos, Cyprus, 28–31 May 2001.

• Aston, A. R. (1979). Rainfall Interception by Eight Small Trees. Journal of Hydrology, vol.42, pp. 383–396.

• Bazza, M. and Tayaa, M. (1993). Present Situation and Prospects for Improvement of Water Harvesting Practices in Morocco. Expert Consultation on Water Harvesting for Improved Agricultural Production, Cairo, 21-25 November 1993.

• Booth, D.B. and Jackson, C.R. (1997). Urbanization of Aquatic Systems: Degradation Thresholds, Stormwater Detection, and the Limits of Mitigation. Journal of the American Water Resources Association, vol. 33, no.5, pp.1077-1090.

• Bouvier, C. (1990). Concerning Experimental Measurements of Infiltration for Runoff Modelling of Urban Watersheds in Western Africa. IAHS Publn, vol.198, pp. 43-49.

• Bouwer, H. (1996). Issues in Artificial Recharge. Water Science and Technology, vol. 33: pp. 381-390.

109

• Bruins, H.J.; Tuinhof, A. and Keller, R. (1991). Water in the Gaza Strip Hydrology Study Find Report. Government of the Netherlands Ministry of Foreign Affairs Directorate General International Cooperation.

• Bucheli, T. D.; Heberle, S.R. and Schwarzenbach, R.P. (1998). Occurrence and Behavior of Pesticides in Rainwater, Roof Runoff, and Artificial Stormwater Infiltration, Environmental Science Technology, vol. 32, no.22, pp. 3457 – 3464.

• Calder, I. R. (1992). Hydrological Effects of Land-Use Change. Handbook of Hydrology, D R. Maidment, Ed., McGraw-Hill, 13.1–13.50.

• Chow, V. T.; Maidment, D. R.; and Mays, L. W. (1988). Applied Hydrology. International Edition. McGraw-Hill Book Company, Inc. New York, NY .

• D,Haeyer, T. (2000). Net Irrigation Requirement for the Major Field Crops in the Gaza Strip. M.Sc Thesis. Katholieke University Leuven, Belgium.

• Dixit, M. J. and Patil, S. M. (1996). Reaching the Unreached: Challenges for the 21st. Rainwater Harvesting Discussion paper. Presented at Century 22nd WEDC Conference: New Delhi, India

• Dunin, F.X. (1976). Infiltration: It's Simulation for Field Conditions, Chapter 8. In Facts of Hydrology. ed. J.C. Rodda. pp.199-227. John Wiley and Sons. New York, NY.

• El-Dabag, H. (1987). Our Country Palestine. Palestinian studies, Dar El-Talia, Beirut. Lebanon.

• El-Kharoubi, A. (2003). Risk-in Informed Strategic Planning Approach for Infrastructure: Water Sector Case Study in Gaza City: Ziara, M., et. al., (Eds), the Proceeding of the International Conference of Engineering and City Development. Gaza, 2003, p.p. I35-I46.

• Environmental Planning Directorate, (1996). Policy Direction in Groundwater Protection and Pollution Control. The Palestinian Authority Ministry of Planning and International Cooperation. Gaza .

• Food and Agriculture Organization of the United Nation (FAO), (1993). Soil Tillage in Africa: Needs and Challenges, Soil Resources, Management and Conservation Service Land and Water Development Division, FAO Soils Bulletin 69. Rome, Italy .

• Food and Agriculture Organization of the United Nation (FAO), 1997. Crop Water Requirement, Irrigation and Drainage Paper No.24 Rome, Italy.

• Foster S. S D; Morris B. L.; and Lawrence A. R. (1993). Effects of Urbanization on Groundwater Recharge. In Groundwater Problems in Urban Areas, ICE International Conference, June 1993, London.

• Goris, K. and Samain, B. (2001). Sustainable Irrigation in the Gaza Strip. M.Sc Thesis. Katholieke University Leuven, Belgium.

110

• Hamdan, S. (1999). Potential Artificial Recharge of Groundwater in the Coastal Region of Palestine. M.Sc Thesis. Department of Civil and Environmental Engineering. Royal Institute of Technology. Stockholm, Switzerland .

• Heil, J.W.; Anthony S.R.; and Mclnnes, K.J. (1997). Soil Properties Influencing Surface Sealing of some Sandy Soils in the Sahel. Soil Science, Vol.162, No. 7, pp 459-469.

• Hudhud, A. and Najar T. (1993). Rainwater Collection Systems in the West Bank, B.Sc Graduation Project. A Najah University, Palestine.

• Kahan, D. (1987). Agriculture and Water Resources in the West Bank and Gaza (1967-1987). Boulder, Colo: West View Press .

• Kays, B. L. and Patterson. J. C. (1982). Soil Drainage and Infiltration, Chapter 5, In Phillip J. Craul (Ed.). Urban Forest Soils, Syracuse, New York.

• Lawrence AR.; Morris BL.; and Foster SSD. (1998). Hazards Induced by Groundwater Under Rapid Urbanization, in Maunds JG and Eddleston M (Eds) Geohazards in Engineering Geology. Geological Society, London, Engineering Geology Special Publications. Vol.15, pp. 319-328.

• Linsley, R.K.; Kohler, M.A.; and Paulhus, J.L.H. (1988). Hydrology for Engineers. SI Metric Edition. McGraw-Hill Book Company, Inc. New York, NY .

• Lormand, J.R. (1988). The Effects of Urban Vegetation on Stormwater Runoff in an Arid Environment. M.Sc. thesis, School of Renewable National Resources, Univ. Ariz., Tucson, AZ.100 pp .

• LYSA, (1995). Assessment of Water and Sewerage Public Services in the Gaza Strip. Palestine.

• Massman, W. J. (1983). The Derivation and Validation of A new Model for the Interception of Rainfall by Forests. Agriculture Meteorology Journal, vol. 28, pp.261– 286.

• McGhee, T. J. (1991). Water Supply and Sewage. International Edition. McGraw-Hill Book Company, Inc. New York, NY .

• Metcalf and Eddy Consultant Co. (Camp Dresser and McKee Inc.), (2000). Coastal Aquifer Management Program, Integrated Aquifer Management Plan (Gaza Strip), USAID Study Task 3, Executive Summary, Vol. 1, and Appendices B-G. Gaza, Palestine.

• Ministry of Environmental Affairs (MENA), (1999). Palestinian Environmental Strategy-Main Report. Palestinian National Authority.

• Ministry of Environmental Affairs (MENA), (2001). Assessment of Land Based Pollution Sources, Palestinian National Authority.

111

• Ministry of Local Governorates (MOLG), (2004). Maps of Urban Development of Gaza Governorates in 2004. Department of Urban Planning. Gaza, Palestinian National Authority (Unpublished).

• Ministry of Planning (MOP), (2004). Map of Agricultural Areas Losses in Gaza Strip due to he Israeli Aggression Practices during period 29/ 9/2000–31/7/2004. Palestinian National Authority. (Unpublished).

• Ministry of Planning and International Corporation (MOPIC), (1997). Technical Maps Atlas for Gaza Governorate, First Version. Gaza, Palestinian National Authority.

• Ministry of Transport (MOT), (2004). Climatic Data of Gaza Strip. Report June, 2004. Department of Meteorology. Palestinian National Authority.(Unpublished).

• Mogheir, Y. (1997). Salt Water Intrusion Modeling and Monitoring in the Gaza Strip Aquifer. MSc Thesis, IHE, Delft, the Netherlands.

• MOPIC, (1998). Regional Plan for Gaza Governorates 1998-2015. Palestinian National Authority.

• Mortaja, R. S. (1998). An Investigation into Geotechnical Aspects of Land filling-A case Study of Gaza, M.Sc Thesis. Institute of Development Engineering Loughborough University, UK.

• Northern Virginia Planning District Commission (NVPDC) and Engineers and Surveyors Institute, (1992). Northern Virginia BMP Handbook: A Guide to Planning and Designing Best Management Practices in Northern Virginia .

• Ouda, O. K. (1999). The Potential Use of Treated Wastewater in the Gaza District. M.Sc Thesis. IHE Delft, The Netherlands.

• Palestinian Central Bureau of Statistics (PCBs), (1997). The First Population and Housing Census. Gaza, Palestinian National Authority.

• Palestinian Economic Council for Development and Reconstruction (PECDAR), (2000).Tatf-Water Sector Strategic Planning Study, Final Report, Vol. III: Specialist Studies , Part B: Focal Areas. Technical Assistance and Training Department (TAT), Palestinian National Authority.

• Palestinian Environmental Protection Authority, (1994). Gaza; Environmental Profile, Inventory of Resources. Part One, Gaza Strip, Palestinian National Authority.

• Palestinian Hydrology Group (PHG), (2002). Quality Uses of Home Reverse Osmosis Filter of some Areas in Gaza Strip.

• Palestinian National Authority (PNA). (2002). Water National Plan Final Report. Vol. 1, Ramallah, Palestine.

112

• Palestinian Water Authority (PWA), (2002). Water Resources and Management Issues. Water Resources and Planning Department. Gaza, Palestinian National Authority.

• Palestinian Water Authority (PWA), (2003). Groundwater Levels Decline Phenomena in Gaza Strip. Final Report. Water Resources and Planning Department-Hydrology Section. February, 2003. Gaza, Palestinian National Authority.

• Palestinian Water Authority (PWA), (2004). Palestinian Vision for Water Management in the Israeli Colonies Area in the Gaza Strip, Strategic Planning Department Water Resources Directorate, Palestinian National Authority.

• Parlange, J.Y. and Haverkamp, R. (1989). Infiltration and Ponding Time. In Unsaturated Flow in Hydrologic Modeling, Theory and Practice. Ed. H.J. Morel-Seytoux. 95-126. Kluwer Academic Publishers. Boston, MA.

• Perry, J. and Vanderklein, E. (1996). Water Quality Management of Natural Resource. Blackwell Sience, Inc.UK.

• Pouraghniaei, M. J. (2002). Effects of Urbanization on Quality and Quantity of Water in the Watershed, Natural Resources Research Center of Semnan, Semnan Province, Iran.

• Prinz, D. and Singh, A. K. (2004). Technological-Potential for Improvements of Water Harvesting, Technical Report Prepared for World Commission on Dams, Cape Town, South Africa.

• Prinz, D., T.; Oweis; and Oberle, A. (1998). Rainwater Harvesting for Dry Land Agriculture - Developing A Methodology Based on Remote Sensing and GIS. Proceedings, XIII International Congress Agricultural Engineering, 02-06.02.1998 ANAFID Rabat Morocco.

• Raes, D. (1999). Lecture Notes-Water Management in Irrigation 14-18August 1999, Al-Azhar University, Gaza, Palestine.

• Ramirez, J.A. and Senarath, S.U. (2000).Statistical–Dynamical Parameterization of Interception and Land Surface–Atmosphere Interactions, Journal of Climate. American Meteorological Society, USA, vol. 13, pp. 4050-4063.

• Ravi, V. and Williams, J. R. (1998). Estimations of Infiltration Rate in the Vadose Zone: Compilation of Simple Mathematical Models, Volume I, Contract No. 68-C4-0031, Center for Remediation Technology and Tools office of Radiation and Indoor Air Office of Air and Radiation, Washington, DC 20460 with A Cooperation of National Risk Management Research Laboratory Ada, OK 74820 and United States Environmental Protection Agency, EPA/600/R-97/128a.

• Roy, S. (1995).The Gaza Strip: The Political Economy of De-development. Institute for Palestine Studies. Washington, D.C .

113

• Sanders, R A. (1986). Urban Vegetation Impacts on the Hydrology of Dayton, Ohio. Urban Ecol. Vol.9:pp.361-376 .

• Schuler, T.R. (1987). Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs. Metropolitan Washington Council of Governments, Washington, D.C.

• Schwab, G.O.; Fangmeier, D.D.; Elliot, W.J.; and Frevert, R.K. (1993). Soil and Water Conservation Engineering. 4th edition. John Wiley and Sons, Inc., New York.

• Shaat, A. (2002). Spatial Planning Challenges in Palestine. The Proceeding of the 5th SUPS. AlSharjh, United Arab Emirate.

• Sharma, R. K. (1983). A text Book of Hydrology and Water Resources. 2nd. Eddition. J.C. Kapur for Dhanpat Rai and Sons, Delhi-Jultundur, India .

• Sogereah; BRL; and Team. (1999). Master Plan for Sewage and Stormwater Drainage in the Gaza Governorates, Final Report, Palestinian National Authority.

• Steel E. W. and McGhee T. J. (1985). Water Supply and Sewerage. 5th edition. McGraw-Hill.

• Stuart, D. (2001). On-Site Run-off Mitigation with Rooftop Rainwater Collection and Use, King County Department of Natural Resources, Water and Land Resources Division. Washington.

• Suresh, R. (1993). Soil and Water Conservation Engineering. 1st.Edition.Nerm Chand Jain Prop. Nai Sarark, Delhi, India.

• Tauer, W. and Humborg, G. (1992). Runoff Irrigation in the Sahel zone. CTA (Technical Centre for Agriculture and Rural Co-operation) Ede/ Wageningen, NL

• United States Agricultural Research Service (USDA), (1998). Soil Quality Information Sheet: Infiltration. Online http://soils.usda.gov. Visited at 12 Sep. 2004

• United States Environmental Protection Agency (EPA), (1994). First flush of Stormwater Pollutants Investigated in Texas. Watershed Protection Techniques 1: online. http://www.epa.gov/. Visited at 2 p.m. August 22, 2004 .

• United Kingdom Environment Agency, (2001).Thames Region Hydrological Summary, March 2001. Thames Region

• Van de Ven, F H M. (1990). Water Balances of Urban Areas. IAHS Publn vol.198, pp. 21-32.

• Van Dijk, A.I.J.M. (2002). Water and Sediment Dynamics in Bench-terraced Agricultural Steep Lands in West Java, Indonesia, PhD Thesis, Vrije University Amsterdam. Netherlands.

114

• Wilson, E.M. (1990). Engineering Hydrology. 4th Edition. Macmillan Education Ltd., Hampshire RG21 2XS.

• Woods, P. and Choudhury, I. (1992). Potential for Residential Use of Rainwater in the United States, Housing Science, vol. 16, no.1, pp.71-81.

• Zeckoski, R.W. (2002). Simulation of Runoff and Pollutant Loss in Urbanizing Watersheds. M.Sc. Thesis. Blacksburg, Virginia: Virginia Polytechnic Institute and State University. USA .

• Zinke, P. J. (1967). Forest Interception Studies in the United States. International Symposium on Forest Hydrology, W. E. Sopper and H. W. Hull, Eds., Pergamon Press, 823 pp. Oxford, England.

115

Useful Websites

• Arid Lands News Letter. Online: http://ag.arizona.edu/OALS/ALN/ALNHome.html. Visited at 14.30 a.m. October 12, 2004.

• Domestic Roof Water Harvesting. Online: http://www.eng.warwick.ac.uk/dtu/rwh/index.html. Visited at 11.30 a.m. October 14, 2004.

• Effect of Urbanization on Water Quality Compiled and Synthesized by Todd Doley and Jose Lopez-Collado. Supported by Virginia Tech. Online: http://www.isis.vt.edu/~jlopezco/als5984/mnpjct.htm. Visited at 10 a.m. Aug. 5, 2004.

• Environmental Protection Agency, Non-point Source Pollution Fact Sheet. Online: http://www.epa.gov/OWOW/NPS/facts/point7.html. Visited at 9 p.m. August 14, 2004.

• Ersson family Water Harvesting Website: http://users.easystreet.com/ersson/rainwatr.htm. Visited at 11 p.m. August 14, 2004.

• Florida Stormwater Association. Online: http://www.florida-stormwater.org/publications.asp. Visited at 8.30 p.m. September 12, 2004.

• Food and Agriculture Organization of the United Nations. Online: http://www.fao.org/docrep/U3160E/U3160E00.htm. Visited at 9.30 p.m. September 12, 2004.

• Introduction to Urban Stormwater Management in Australia Environment Australia, 2002. ISBN 0 642 548 323. Online: http://pandora.nla.gov.au/external.html?link=http://www.ea.gov.au/about/siteindex.html. Visited at 1.30 p.m. Sep. 15, 2004.

• Official State Web Sight of Tennessee. Online: http://www.tn.gov.in/dtp/rainwater.htm. Visited at 3.30 p.m. October 12, 2004.

• Planning and Managing Development and Urbanization to Maintain or Improve Natural Water Regimes in Aquatic Systems June 2003. Online: http://www.apegn.nf.ca/dialogue/index.htm.Visited at 8.30 p.m. October 12, 2004.

• Queensland Water Recycling Strategy; Fact Sheet Queensland Water Recycling Strategy. Online: www.epa.qld.gov.au/sustainable_industries Visited at 6.30 p.m. October 12, 2004.

• Rainwater Harvesting Techniques used in India. Online: http://www.tn.gov.in/dtp/rainwater.htm Visited at 4.30 p.m. Aug.15, 2004.

116

• Rainwaterharvest.Org. Online: http://www.rainwaterharvesting.org/Rural/whim_tradi.htm, Visited at 13.30 a.m. October 11, 2004.

• Seattle Public Utilities, Conservation & Environment Department, Urban Creeks Legacy Program Web site informational pages: http://cityofseattle.net/util.urbancreeks/background.htm, Last Updated, May 16, 2001, visited at 9 a.m. October 5, 2004.

• State Water Resources Control Board Division of Water Quality Nonpoint Source Program. California Rangeland Water Quality Management Plan Index July 1995. Online: http://www.calcattlemen.org/CRWQMP.htm. Visited at 9.30 a.m. October 7, 2004.

• Stormwater Management Planning and Design Manual 2003. Online: http://www.gov.on.ca/MBS/english/common/queens.html .Visited at 10.30 a.m. October 7, 2004.

• The publications of Trudeau Centre for Peace and Conflict Studies at the University of Toronto. Online: http://www.library.utoronto.ca/pcs/pcs.htm. Visited at 4.30 p.m. October 13, 2004.

• Tree People, T.R.E.E.S. Project Overview, Online: www.treepeople.org/trees/ Last update, August 24, 2001. Visited at 11 a.m. October 5, 2004.

• Water Balance Study for a Water-Efficient Landscape System at the Environmental Center of the Rockies Water Year 1999 , Online:www.lawfund.org/ecr/ecrstudy.htm, Last update, July 30, 2001, visited at 10 p.m. August 14, 2004.

• Texas Rain Water Collection Information: Online: www.twdb.state.tx.us/assistance/conservation/Alternative_Technologies/Rainwater_Harvesting/Rain.htm.visited at 11 p.m. August 16, 2004

• The Environmental Center of the Rockies, Urban Stormwater Control Project. Online: www.lawfund.org/ecr/ecrlandscape.htm, Last update, July 30, 2001, visited at 10 p.m. August 14, 2004.

117

Appendices

I

Appendix (A)

The Different Equations Used to Calculate the Infiltration Rate.

A.1 Kostiakov's Equation

A.2 Holton's Equation

A.3 Boughton's Equation

A.4 Philips equation

II

A.1 Kostiakov's Equation

Kostiakovs (1932) proposed the following equation for estimating infiltration, (Ravi and Williams,

1998).

i (t) = α t – β (A.1)

Where; i is the infiltration rate at time t, and Upon integration from 0 to t, equation (A.1) yields

equation (A.2), which is the expression for cumulative infiltration, I(t).

I(t) = (α / 1 – β) * t ( 1 – β ) (A.2)

The constants α (α >0), and β (0< β <1) are empirical constants, and can be determined by curve–

fitting equation (A.2), to experimental data for cumulative infiltration, I(t). Goris & Samain (2001)

calculated the parameters of the two equations for the different soil types in Gaza Strip as shown in

table (A.1). Kostiakovs equation describes the infiltration quite well at smaller times, but becomes less

accurate at larger times (Parlange and Haverkamp, 1989).

Table (A.1): Parameters of Kostiakov's Equations for Different Soil in Gaza Strip. (Adapted from Goris and Samain, 2001).

Parameters of equation (1)

Parameters of equation (2) Soil type

α β α β Sandy regosol 14.76 0.82 14.79 0.23

Sandy loess soil over loess 7.94 0.69 12.59 0.25

Loessial sandy soil 9.12 0.74 13.18 0.24

Dark/reddish brown 18.20 0.70 21.88 0.40

Sandy loess soil 7.24 0.65 12.30 0.24 Loess soil 8.53 0.72 12.9 0.25

A.2 Holtan's Equation

The empirical infiltration equation revised by Holtan (1961) is explicitly dependent on soil water

conditions in the form of available pore space for moisture storage and takes into account the effects

of vegetation (Ravi and Williams, 1998).

f = GI a Sa1.4 + fc (A.3)

Where; f is the infiltration capacity (mm/min), GI is the growth index of vegetation, fc is the

infiltration capacity after prolonged wetting (mm/min), a is the surface-connected porosity, and Sa is

the storage available in the root zone.

The surface-connected porosity depends on the infiltration capacity of the available Storage as a

function of the density of plant roots. Table (A.2) presents a surface-connected porosity for different

soil, as been estimated from infiltrometer test.

Use of this method will be satisfied, when the precipitation rate is less than the infiltration capacity.

III

Table (A.2): Vegetation Parameters. (Suresh, 1993).

Land use Poor condition Good condition Fallow / raw crop 0.027 0.0823

Small grains/legumes 0.0548 0.0823 Hay 0.1097 0.1645

Pastures 0.2194 0.1645 Wood/forest 0.2144 0.2742

A.3 Boughton's Equation

Dunin (1976) recorded that’s Boughton in (1966) modified the rainfall-run-off relationship, as

follows:

R = P – Fr tan h ( P/ Fr ) (A.3)

Where; P is the daily rainfall (mm), R is the run-off , and Fr is an empirical parameter; however,

some success has been reported when interpreted as the initial soil moisture deficit (Dunin, 1976).

A.4 Philips equation

This method simulates vertical infiltration of water into a homogeneous sandy soil profile. Soil water

content at the inflow-end (at the surface) is held constant and at saturation.

f =1/2 S t-1/2 + A (A.4)

fp = S t1/2 + At (A.5)

Where; f is the infiltration rate (mm/min), S is the sorptivity (mm/min1/2), A is the a constant

depending on the soil properties and initial water content (mm/min), fp is the cumulative infiltration

rate at time ( t ), and t is the time in minute.

Sorptivity depends on the pore configuration of the soil and the initial water content. Values of

sorptivity can be determined from infiltrometer measurements. The Philip parameter for the different

soil types in Gaza Strip is presents in table (A.3).

Table (A.3): The Philip parameters for the different soil types in Gaza Strip (Source: Adapted from

Goris and Samain (2001).

Soil type sorptivity (mm/min1/2) A (mm/min) Sandy regosol 0.04 6.69 Sandy loess soil over loess 13.51 1.62 Loessial sandy soil 0.06 2.43 Dark/reddish brown 0.04 3.48 Sandy loess soil 0.09 1.10 Loess soil 6.8 2.03

IV

Appendix (B) Average Rainfall (Avr.) Measured at Different Weather Stations, and Effective Rainfall (Pe.)

Calculating According FAO Formula, of Gaza Strip through the Period (1982 – 2004).

V

Average and Effective Rainfall for Beit-Hanoun Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 128.0 89.0 212.0 147.5 89.5 1.5 0.0 667.5 83- 84 0.0 1.5 31.0 12.5 174.5 5.0 41.0 8.0 0.0 273.5 84- 85 0.0 6.0 31.5 41.0 5.0 149.5 20.5 10.0 0.0 263.5 85- 86 0.0 7.5 3.5 64.5 41.0 64.0 1.0 27.0 8.0 216.5 86- 87 0.0 84.5 335.5 75.5 107.5 37.4 24.7 0.0 0.0 665.1 87- 88 0.0 73.5 5.0 46.9 114.8 219.0 19.5 4.0 0.0 482.7 88- 89 0.0 30.0 42.5 0.0 169.0 71.3 26.0 0.0 0.0 338.8 89- 90 0.0 40.0 82.2 33.5 142.4 103.5 67.0 27.0 0.0 495.6 90- 91 0.0 0.0 21.0 3.2 199.9 62.4 176.5 0.0 0.0 463.0 91- 92 0.0 3.0 120.2 309.0 141.0 172.6 12.0 0.0 9.0 766.8 92- 93 0.0 0.0 55.4 179.9 93.9 153.5 17.5 0.0 5.0 505.2 93- 94 0.0 49.0 93.1 2.4 99.8 35.5 42.5 0.0 0.0 322.3 94- 95 0.0 39.0 247.5 167.0 10.0 78.3 18.0 22.0 0.0 581.8 95- 96 0.0 0.0 66.3 106.8 162.0 38.0 108.1 11.5 0.0 492.7 96- 97 0.0 33.2 6.6 40.0 106.5 64.0 67.4 0.0 16.5 334.2 97- 98 0.0 13.3 3.7 154.5 107.8 27.7 109.5 0.0 5.0 421.5 98- 99 0.0 2.6 19.7 16.3 89.8 25.5 1.6 13.0 0.0 168.5 99- 00 0.0 15.0 17.1 34.5 243.1 58.1 27.9 0.0 0.0 395.7 00- 01 0.0 107.9 22.2 141.3 124.1 77.5 7.0 5.0 0.0 485.0 01- 02 0.0 47.5 24.8 193.5 211.7 24.4 32.0 7.0 7.5 548.4 02- 03 0.0 51.7 1.5 247.9 193.9 243.5 51.0 12.0 0.0 801.5 03- 04 0.0 0.0 6.0 92.0 167.9 67.0 21.5 1.0 1.5 356.9 AVR. 0.0 27.5 62.0 93.2 132.6 87.5 44.6 6.8 2.4 456.7 * Pe 0.0 6.5 27.2 49.6 81.1 45.0 16.8 0.0 0.0 226.2

Adapted from (MOT, 2004) * Pe is the effective rainfall calculated based on FAO formula.

Average and Effective Rainfall for Beit-Lahia Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 126.5 103.0 192.5 122.0 89.1 0.0 0.0 633.1 83- 84 0.0 2.0 71.5 16.0 99.0 4.0 43.5 11.0 0.0 247.0 84- 85 0.0 19.5 26.5 32.5 14.2 108.0 20.0 25.0 0.0 245.7 85- 86 0.0 9.5 10.0 64.0 60.0 82.0 4.5 15.0 16.5 261.5 86- 87 0.0 58.0 335.5 91.5 106.5 47.0 34.2 0.0 0.0 672.7 87- 88 0.0 134.5 1.5 65.0 108.5 258.0 27.5 6.0 0.0 601.0 88- 89 0.0 34.0 64.0 0.0 178.0 52.0 52.0 0.0 0.0 380.0 89- 90 0.0 8.5 61.5 54.0 169.5 109.0 67.0 46.5 0.0 516.0 90- 91 0.0 1.0 28.0 13.0 193.0 65.0 155.5 0.0 0.0 455.5 91- 92 0.0 3.0 248.0 324.5 162.6 192.0 13.7 0.0 9.0 952.8 92- 93 0.0 0.0 49.5 197.5 70.5 181.0 18.0 0.0 5.0 521.5 93- 94 0.0 63.5 100.0 4.5 80.5 47.5 57.5 0.0 0.0 353.5 94- 95 0.0 23.0 341.5 137.5 9.8 80.9 18.0 22.0 0.0 632.7 95- 96 0.0 0.0 56.2 111.0 172.0 47.0 104.5 11.5 0.0 502.2 96- 97 0.0 35.0 7.1 41.5 135.5 28.0 63.0 0.0 18.3 328.4 97- 98 0.0 14.0 6.5 139.5 93.5 19.5 90.0 0.0 4.5 367.5 98- 99 0.0 2.0 14.0 20.0 94.5 18.6 0.7 19.0 0.0 168.8 99- 00 0.0 12.0 35.5 41.5 230.2 69.0 24.2 0.0 0.0 412.4 00- 01 1.0 79.1 22.0 149.3 145.5 67.5 12.0 5.0 0.0 481.4 01- 02 0.0 50.0 45.4 171.0 220.5 24.1 21.5 4.5 5.0 542.0 02- 03 0.0 28.8 3.5 239.5 183.7 204.0 52.5 12.0 0.0 724.0 03- 04 0.0 0.0 27.5 112.5 159.5 63.5 25.3 7.8 1.0 397.1 AVR. 0.0 26.2 76.4 96.8 130.9 85.9 45.2 8.4 2.7 472.6 Pe. 0 5.7 36.1 52.4 79.7 43.7 17.1 0 0 234.7

Adapted from (MOT, 2004)

VI

Average and Effective Rainfall for ALShatie Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 100.6 69.1 213.7 104.1 72.4 4.0 0.0 563.9 83- 84 0.0 2.5 61.4 15.8 152.3 4.5 30.2 6.3 0.0 273.0 84- 85 0.0 5.5 33.9 33.1 8.0 84.3 20.1 19.0 1.0 204.9 85- 86 0.0 8.7 7.8 65.0 58.1 45.7 1.7 21.0 25.7 233.7 86- 87 0.0 57.1 334.9 84.7 94.8 41.3 32.9 0.0 0.0 645.7 87- 88 0.0 104.2 1.0 74.1 97.3 235.1 32.8 5.5 0.0 550.0 88- 89 0.0 49.7 48.5 0.0 141.8 74.4 23.6 0.0 0.0 338.0 89- 90 0.0 7.1 113.4 57.8 181.4 108.3 64.0 28.0 0.0 560.0 90- 91 0.0 0.0 13.1 12.6 221.8 68.3 145.0 0.0 0.0 460.8 91- 92 0.0 0.0 154.2 302.2 139.8 172.4 7.0 0.0 9.0 784.6 92- 93 0.0 0.0 32.0 190.7 80.0 180.0 15.8 0.0 4.5 503.0 93- 94 0.0 39.5 24.0 7.6 74.0 30.4 29.4 0.0 0.0 204.9 94- 95 0.0 8.2 244.8 185.8 11.0 80.3 18.1 22.0 0.0 570.2 95- 96 0.0 0.0 47.0 140.2 141.2 31.8 117.7 8.6 0.0 486.5 96 - 97 0.0 32.7 5.9 32.7 101.6 15.0 43.2 0.0 12.2 243.3 97- 98 0.0 23.7 3.0 96.4 68.3 33.2 56.9 0.0 2.0 283.5 98- 99 0.0 1.0 7.8 24.7 86.3 20.0 0.0 7.5 0.0 147.3 99- 00 0.0 4.7 79.8 29.1 225.3 63.2 19.3 0.0 0.0 421.4 00- 01 1.6 125.8 16.0 130.5 119.2 67.8 7.0 5.5 0.0 473.4 01- 02 0.0 62.6 22.0 211.4 173.7 15.9 18.5 7.5 10.5 522.1 02- 03 0.0 42.1 5.0 186.9 105.1 228.9 43.0 9.2 0.0 620.2 03- 04 0.0 0.0 7.0 102.2 150.4 55.1 22.9 5.5 0.3 343.4 AVR. 0.1 26.1 62 93.3 120.2 80 37.3 6.8 3 428.8 Pe. 0 5.7 27.2 49.6 71.2 39 12.4 0 0 205.1

Adapted from (MOT, 2004)

Average and Effective Rainfall for Gaza Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 101.1 50.5 280.6 105.6 61.6 5.8 0.0 605.2 83- 84 0.0 2.2 46.7 16.4 106.8 4.2 28.5 7.3 0.0 212.1 84- 85 0.0 7.4 20.6 40.4 5.3 118.7 17.9 20.8 0.0 231.1 85- 86 0.0 7.5 5.4 63.6 46.7 37.1 1.3 22.6 21.3 205.5 86- 87 0.0 56.8 347.9 71.2 87.5 35.3 29.5 0.0 0.0 628.2 87- 88 0.0 118.8 1.2 56.9 122.3 206.5 21.8 4.6 0.0 532.1 88- 89 0.5 48.1 43.6 71.3 149.2 67.8 28.2 0.0 0.0 408.7 89- 90 0.0 19.4 112.3 79.5 190.7 90.2 64.5 27.3 0.0 583.9 90- 91 0.0 0.0 15.8 7.1 207.0 88.4 116.5 0.0 0.0 434.8 91- 92 0.0 1.4 184.8 358.4 151.3 191.6 8.5 0.0 6.5 902.5 92- 93 0.0 0.0 39.6 214.5 105.4 192.5 18.3 0.0 3.8 574.1 93- 94 0.0 6.8 27.8 2.1 83.8 37.2 40.3 0.0 0.0 198.0 94- 95 0.0 13.3 273.0 160.6 10.8 80.8 18.8 21.4 0.0 578.7 95- 96 0.0 0.2 45.4 118.3 152.7 32.3 97.6 6.8 0.0 453.3 96- 97 0.0 33.2 6.4 48.2 117.1 32.9 49.1 0.0 11.6 298.5 97- 98 0.0 33.3 6.9 103.3 86.2 38.1 74.7 0.0 2.3 344.8 98- 99 0.0 9.0 6.1 24.8 98.8 17.0 0.2 8.8 0.0 164.7 99- 00 0.0 9.4 25.9 33.3 212.8 41.2 27.2 0.0 0.0 349.8 00- 01 1.2 132.3 17.6 132.5 130.4 60.6 10.5 3.2 0.0 488.3 01- 02 0.0 75.6 23.7 198.3 202.4 17.8 11.8 12.1 6.6 548.3 02- 03 0.0 38.8 6.7 163.2 98.1 239.4 67.9 9.2 0.0 623.3 03- 04 0.0 0.0 3.8 105.6 149.7 68.3 22.2 11.5 0.4 361.5 AVR. 0.1 27.9 61.9 96.4 127.1 82.0 37.1 7.3 2.4 442.2 Pe. 0 6.7 27.1 52.1 76.7 40.6 12.3 0 0 215.5

Adapted from (MOT, 2004)

VII

Average and Effective Rainfall for ALMoghraqa Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 124.5 42.5 159.0 119.5 65.5 3.5 0.0 514.5 83- 84 0.0 5.3 34.5 21.0 111.0 2.5 19.0 3.5 0.0 196.8 84- 85 0.0 8.5 29.5 47.5 5.0 85.0 17.5 21.0 0.0 214.0 85- 86 0.0 9.0 5.0 81.0 25.0 51.5 2.5 48.5 7.0 229.5 86- 87 0.0 50.5 316.7 65.5 85.5 33.0 36.5 0.0 0.0 587.7 87- 88 0.0 111.2 2.5 44.5 86.5 155.0 21.0 6.0 0.0 426.7 88- 89 0.0 32.0 22.5 0.0 135.0 53.0 21.0 0.0 0.0 263.5 89- 90 0.0 17.5 103.0 38.5 127.0 41.5 75.5 12.0 0.0 415.0 90- 91 0.0 4.0 20.0 0.5 179.5 78.5 95.1 0.0 0.0 377.6 91- 92 0.0 0.0 129.0 275.0 168.0 141.5 15.5 0.0 8.0 737.0 92- 93 0.0 0.0 32.0 148.0 97.0 157.5 25.0 0.0 0.5 460.0 93- 94 0.0 32.0 21.0 5.0 81.5 21.2 52.0 0.0 0.0 212.7 94- 95 0.0 16.1 260.4 177.8 10.8 79.0 17.2 20.0 0.0 581.3 95- 96 0.0 0.0 36.5 117.5 110.0 34.5 121.0 15.0 0.0 434.5 96- 97 0.0 31.3 5.4 37.5 131.0 51.5 52.0 0.0 10.0 318.7 97- 98 0.0 10.5 1.5 116.0 76.5 45.0 75.0 0.0 2.5 327.0 98- 99 0.0 0.0 3.0 10.0 130.5 23.0 3.0 14.0 0.0 183.5 99- 00 0.0 40.0 38.3 9.0 227.5 21.5 27.3 0.0 0.0 363.6 00- 01 0.7 67.5 18.9 160.6 153.5 127.4 8.5 17.0 0.0 554.1 01- 02 0.0 38.5 27.5 173.0 320.7 44.0 45.5 10.5 0.8 660.5 02- 03 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 03- 04 0.0 0.0 11.6 226.0 153.0 70.0 39.5 0.0 2.5 502.6 AVR. 0.0 21.5 56.5 81.7 117.0 65.3 38.0 7.8 1.4 389.1 Pe. 0 2.9 23.9 40.4 68.6 29.2 12.8 0 0 177.8

Adapted from (MOT, 2004)

Average and Effective Rainfall for AL-Nuseirat Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 129.0 54.0 188.0 100.5 49.7 0.0 0.0 521.2 83- 84 0.0 0.0 25.9 16.0 89.0 3.0 25.5 2.0 0.0 161.4 84- 85 0.0 10.5 18.9 34.5 5.0 64.0 6.0 20.5 0.0 159.4 85- 86 0.0 0.0 8.5 80.0 15.0 45.0 0.0 47.5 10.5 206.5 86- 87 0.0 55.5 319.3 56.0 74.5 33.0 55.0 0.0 0.0 593.3 87- 88 0.0 84.5 3.0 60.7 74.5 169.0 10.5 5.5 0.0 407.7 88- 89 0.0 21.0 23.5 0.0 144.0 88.5 18.0 0.0 0.0 295.0 89- 90 0.0 17.5 69.0 40.5 94.7 44.0 64.0 14.5 0.0 344.2 90- 91 0.0 6.0 23.5 8.2 152.0 86.0 95.0 0.0 0.0 370.7 91- 92 0.0 2.0 93.0 212.2 158.9 132.5 11.5 0.0 10.5 620.6 92- 93 0.0 0.0 54.0 155.5 73.5 154.5 18.0 0.0 0.0 455.5 93- 94 0.0 20.5 26.0 2.5 115.5 19.5 62.5 0.0 0.0 246.5 94- 95 0.0 7.5 289.0 180.5 11.0 73.7 16.1 17.0 0.0 594.8 95- 96 0.0 0.0 21.5 97.5 83.1 52.5 105.0 17.5 0.0 377.1 96- 97 0.0 27.6 4.4 55.0 135.0 32.5 49.0 0.0 8.0 311.5 97- 98 0.0 20.0 0.0 136.0 36.0 25.5 36.5 0.0 2.0 256.0 98- 99 0.0 0.0 15.0 13.6 91.4 19.4 1.5 10.0 0.0 150.9 99- 00 0.0 15.0 36.0 6.2 184.0 19.5 19.0 0.0 0.0 279.7 00- 01 0.0 75.2 40.0 194.7 154.5 91.1 1.0 16.3 0.0 572.8 01- 02 0.0 37.7 15.2 158.0 220.1 22.3 81.7 10.0 0.5 545.5 02- 03 0.0 19.0 12.5 167.3 45.4 142.5 50.5 9.5 0.0 446.7 03- 04 0.0 0.0 18.0 135.0 104.0 41.1 20.0 3.5 2.0 323.6 AVR. 0.0 19.1 56.6 84.7 102.2 66.3 36.2 7.9 1.5 374.6 Pe. 0 1.5 24 42.8 56.8 29.8 11.7 0 0 209.4

Adapted from (MOT, 2004)

VIII

Average and Effective Rainfall for Deir- Albalah Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 113.5 35.5 180.5 85.0 43.0 1.5 0.0 459.0 83- 84 0.0 1.0 29.0 38.0 81.0 0.0 34.0 0.0 0.0 459.0 84- 85 0.0 2.0 23.0 38.5 4.0 74.3 15.6 15.0 0.0 183.0 85- 86 0.0 0.0 2.5 106.0 14.5 49.5 1.0 57.5 12.5 172.4 86 - 87 0.0 55.0 391.1 45.4 48.7 21.8 51.6 0.0 0.0 243.5 87- 88 0.0 132.5 2.0 60.2 82.0 154.0 12.5 2.0 0.0 613.6 88- 89 0.0 16.5 11.5 0.0 121.5 79.0 16.0 0.0 0.0 445.2 89- 90 0.0 7.0 23.0 24.0 81.5 33.2 56.9 13.0 0.0 244.5 90- 91 0.0 2.0 4.8 4.0 135.8 89.5 88.5 0.0 0.0 238.6 91- 92 0.0 17.0 81.0 147.1 145.3 121.5 12.0 0.0 5.5 324.6 92- 93 5.0 0.0 37.0 97.0 55.9 113.4 9.0 0.0 0.0 529.4 93- 94 0.0 9.0 9.0 5.6 145.5 23.0 45.0 0.0 0.0 317.3 94- 95 0.0 8.5 276.0 176.5 10.0 63.6 14.6 16.0 0.0 237.1 95- 96 0.0 0.0 27.0 83.0 86.0 48.0 94.5 9.0 0.0 565.2 96- 97 0.0 20.9 3.8 31.0 148.0 53.4 65.8 0.0 7.0 347.5 97- 98 0.0 24.0 0.0 94.0 41.0 23.0 43.5 0.0 8.5 329.9 98- 99 0.0 0.0 0.0 21.0 70.5 18.0 5.0 9.0 0.0 234.0 99- 00 0.0 12.5 39.5 5.2 160.0 23.5 15.9 0.0 0.0 123.5 00- 01 0.0 59.5 27.5 239.0 143.0 73.5 1.0 7.0 0.0 256.6 01- 02 0.0 21.0 12.0 102.0 202.6 18.0 25.0 9.5 0.5 550.5 02- 03 0.0 28.7 10.0 141.4 36.5 102.5 37.0 9.5 0.0 390.6 03- 04 0.0 0.0 14.0 150.9 97.0 34.0 17.0 4.5 1.5 365.6 AVR. 0.2 19.9 53.5 71.2 94.9 60.4 32.7 7.1 1.6 341.5 Pe. 0 1.94 22.1 32.7 50.9 26.2 9.6 0 0 143.5

Adapted from (MOT, 2004)

Average and Effective Rainfall for Khanyounis Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 138.3 78.8 142.0 78.5 34.0 0.0 0.0 471.6 83- 84 0.0 5.0 4.0 12.6 53.0 0.0 35.1 5.0 0.0 114.7 84- 85 0.0 6.0 17.0 28.0 2.0 71.0 15.5 5.7 0.0 145.2 85- 86 0.0 5.0 2.9 149.4 13.5 21.9 2.7 96.5 10.2 302.1 86- 87 0.0 40.9 280.4 40.8 18.6 27.5 63.0 2.5 0.0 473.7 87- 88 0.0 103.9 14.5 60.9 104.1 97.0 19.7 4.7 0.0 404.8 88- 89 0.0 7.0 37.5 0.0 117.2 113.0 10.7 0.0 0.0 285.4 89- 90 0.0 0.0 19.0 43.0 76.2 38.0 69.0 12.5 0.0 257.7 90- 91 0.0 0.0 11.0 18.0 128.1 86.0 105.5 0.0 0.0 348.6 91- 92 0.0 3.5 77.0 187.0 129.3 171.5 18.2 0.0 2.0 588.5 92- 93 0.0 0.0 43.5 135.0 49.2 165.0 25.5 0.0 0.0 418.2 93- 94 0.0 7.5 13.0 2.0 80.5 22.5 15.0 0.0 0.0 140.5 94- 95 0.0 7.0 265.5 166.4 9.0 56.6 12.7 13.5 0.0 530.7 95- 96 0.0 0.0 26.0 68.0 49.0 34.5 66.5 9.7 0.0 253.7 96- 97 0.0 18.0 3.4 38.0 136.5 41.6 50.5 0.0 6.0 294.0 97- 98 0.0 25.5 4.0 90.7 47.8 34.9 31.4 0.0 1.3 235.6 98- 99 0.0 0.0 14.3 6.4 29.5 12.6 0.0 14.0 0.0 76.8 99- 00 0.0 11.5 3.5 0.0 164.1 6.5 9.3 0.0 0.0 194.9 00- 01 0.0 44.0 13.0 134.6 108.8 66.5 1.6 11.2 0.0 379.7 01- 02 0.0 3.9 6.1 81.0 152.5 8.7 47.5 12.0 0.0 311.7 02- 03 0.0 21.0 8.3 127.3 24.3 50.0 54.3 10.4 0.0 295.6 03- 04 0.0 0.0 4.0 50.3 89.2 41.7 19.5 1.7 2.0 208.4 AVR. 0.0 14.1 45.7 69.0 78.4 56.6 32.1 9.1 1.0 306.0 Pe. 0 0 17.4 31.4 37.7 24 9.3 0 0 120

Adapted from (MOT, 2004)

IX

Average and Effective Rainfall for Rafah Station from 1982 - 2004 SEASON SEB OCT NOV DEC JAN FEB MAR APR MAY TOTAL 82- 83 0.0 0.0 105.0 66.5 111.5 63.0 14.0 2.0 0.0 362.0 83- 84 0.0 1.5 2.0 17.0 51.0 2.5 43.5 9.5 0.0 127.0 84- 85 0.0 33.0 18.5 28.0 1.0 79.0 25.5 8.5 0.0 193.5 85- 86 0.0 0.0 3.0 72.0 16.5 12.0 0.7 37.0 9.0 150.2 86- 87 0.0 14.0 138.0 45.8 14.0 25.0 36.5 0.0 0.0 273.3 87- 88 0.0 31.0 14.0 53.0 80.7 58.5 26.0 5.0 0.0 268.2 88- 89 0.0 6.0 14.0 0.0 72.0 103.0 22.2 0.0 0.0 217.2 89- 90 0.0 4.5 19.5 34.0 61.5 46.0 64.5 45.0 3.5 278.5 90- 91 0.0 0.0 6.5 1.0 95.5 33.5 105.5 0.0 0.0 242.0 91- 92 0.0 0.0 115.0 71.5 57.5 120.5 23.0 0.0 0.0 387.5 92- 93 0.0 0.0 16.0 103.0 18.5 135.0 20.0 0.0 0.0 292.5 93- 94 0.0 8.5 6.0 19.0 43.0 29.0 7.5 0.0 0.0 113.0 94- 95 0.0 10.0 247.0 162.7 7.5 44.5 11.5 12.0 0.0 495.2 95- 96 0.0 0.0 30.5 60.5 48.5 18.5 53.5 3.5 0.0 215.0 96- 97 0.0 14.3 3.1 39.4 131.5 50.0 26.5 0.0 4.0 268.8 97- 98 0.0 31.0 0.0 68.0 39.0 38.5 45.5 0.0 1.5 223.5 98- 99 0.0 4.5 1.0 0.0 32.0 13.0 0.0 11.0 0.0 61.5 99- 00 0.0 9.0 0.0 0.0 153.5 14.0 23.6 0.0 0.0 200.1 00- 01 0.0 54.0 13.5 68.5 106.0 47.0 5.0 14.0 0.0 308.0 01- 02 0.0 12.0 13.5 37.0 139.0 10.2 22.0 8.0 0.0 241.7 02- 03 0.0 13.5 12.0 99.0 26.8 29.0 20.5 20.0 0.0 220.8 03- 04 0.0 0.0 2.5 33.5 78.0 39.0 21.0 0.0 0.0 174.0 AVR. 0.0 11.2 35.5 49.1 62.9 45.9 28.1 8.0 0.8 241.5 Pe. 0 0 3.4 14.28 25.32 11.72 0 0 0 54.7

Adapted from (MOT, 2004)

X

Appendix (C) Topographical Profiles Parallel to the Northern Border Line of Gaza Strip in the East West Direction,

Showing Number of Depression Zones a long the East West Slope Direction.

XI

XII

0

10

20

30

40

50

60

70

80

90

0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2

3.6

4.0

4.4

4.8

5.2

5.6

6.0

6.4

6.8

7.2

7.6

8.0

8.4

8.8

9.2

Dis tance from the Shore Line ( Km )

Ele

vati

on f

rom

the

se

a le

vel (

m)

A- Topographic Profile 1.94 Km. from the Northern B order of Gaza Strip

B - T opograp hic P rofile 3 .9 K m from the N orthe rn B orde r o f G az a S tr ip

0

10

20

30

40

50

60

70

80

90

0.1

0.5

0.9

1.3

1.7

2.1

2.5

2.9

3.3

3.7

4.1

4.5

4.9

5.3

5.7

6.1

6.5

6.9

7.3

7.7

8.1

8.5

8.9

9.3

D is tance fro m the Sho re L ine ( K m )

Elv

ati

on f

rom

th

eS

ea L

evel

( m

)

C- Topographic Profile 5.8 km. from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

80

0.2

0.6

1.0

1.4

1.8

2.2

2.6

3.0

3.4

3.8

4.2

4.6

5.0

5.4

5.8

6.2

6.7

7.1

7.5

7.9

8.3

Distance from the Shore Line. ( Km)

Elev

atio

n fr

om th

e Se

a L

evel

(m )

D- Topograph ic Profile 7.8 Km from the Northe rn Borde r of the Gaza Str ip.

0

10

20

30

40

50

60

70

80

0.1

0.5

0.9

1.3

1.7

2.1

2.5

2.9

3.3

3.7

4.1

4.5

4.9

5.3

5.7

6.1

6.5

6.9

7.3

Dis tance from the Shore Line . ( Km )

Ele

vatio

n fr

om th

eSe

a le

vel (

m)

L = 0.3 Km.

Run-off Direction Depression Zones

XIII

E- Topographic Profile 9.7 km from the Northern Border of Gaza Strip.

0

5

10

15

20

25

30

35

40

45

0.2

0.5

0.8

1.1

1.4

1.7

2.0

2.3

2.6

2.9

3.2

3.5

3.8

4.1

4.4

4.7

5.0

5.3

5.6

5.9

6.2

6.5

6.8

7.1

Distance from the Shore Line. ( Km)

Ele

vatio

n fr

om th

eSe

a L

evel

(m)

F- Topographic Profile 11.7 Km from the Nortern Border of Gaza Strip.

0

10

20

30

40

50

60

70

80

0.2

0.5

0.8

1.1

1.4

1.7

2.0

2.3

2.6

2.9

3.2

3.5

3.8

4.1

4.4

4.7

5.0

5.3

5.6

5.9

6.2

6.5

Distance from the shore line (K m ).

Ele

vatio

n fr

omth

e se

a le

vel (

m)

G- TopographicProfile 13.6 Km. from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

0.1

0.4

0.7

1.0

1.3

1.6

1.9

2.2

2.5

2.8

3.1

3.4

3.7

4.0

4.3

4.6

4.9

5.2

5.5

5.8

6.1

6.4

Dis tance from the s hore line . ( Km )

Ele

vatio

n fr

om

the

sea

leve

l ( m

)

H- Topographic Profile 15.5 Km from the Northern Border of GazaStrip .

0

10

20

30

40

50

60

70

0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 6.1 6.3 6.5

Distance from the ShoreLine ( Km )

Elev

atio

n fr

om

the S

ea L

evel

( m )

XIV

I- Topographic Profile 17.5 Km from the Northern Border of Gaza Strip .

0

5

10

15

20

25

30

35

40

45

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

5.2

5.4

5.6

5.8

6.0

6.2

Dis tance from the s hore line ( Km )

Ele

vatio

n fr

om

the

sea

leve

l . (

m )

J- T o p o grap h ic P ro file 19.4 K m fro m th e N o rthern B o rd er o f Gaz a S trip .

0

1 0

2 0

3 0

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

5.7

5.9

6.1

D is tanc e fro m the s ho re line ( K m )

Ele

vati

on f

rom

the

sea

leve

l ( m

).

K- Topographic Profile 21.3 Km from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

0.2

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

5.6

5.8

Distance from the Shore Line ( km )

Ele

vatio

n fr

om

the

Sea

Leve

l (m

)

L- Topographic Profile 23.3 Km. from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

80

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

Distance from the Shore line (Km).

Elev

atio

n fr

om

the

sea

leve

l ( m

)

XV

M- Topographic Profile 25.2 Km from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

80

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

5.7

Distance from the shore line ( Km )

Ele

vatio

n fr

om

the

sea

leve

l (m

)

N- Topographic Profile 27.2 Km from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

80

0.1

0.4

0.7

1.0

1.3

1.6

1.9

2.2

2.5

2.8

3.1

3.4

3.7

4.0

4.3

4.6

4.9

5.2

5.5

5.8

Distance from the Shore Line ( Km)

Ele

vatio

n fr

om

the

SeaL

evel

(m

)

O- Topographic Profile 29.1 Km from the Northern Border of Gaza Strip. Strip

0

10

20

30

40

50

60

70

80

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

5.1

5.3

5.5

5.7

5.9

6.1

6.3

6.5

Distance from the Shore Line ( Km )

Elev

atio

n fr

om

the

Sea

Leve

l ( m

)

P- Topographic Profile 31 Km from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

80

90

1.1

1.4

1.7

2.0

2.3

2.6

2.9

3.2

3.5

3.8

4.1

4.4

4.7

5.0

5.3

5.6

5.9

6.2

6.5

6.8

7.1

7.4

7.7

8.0

8.3

Distance from the shore line ( Km )

Ele

vatio

n fr

om

the

sea

leve

l ( m

)

XVI

Q- Topographic Profile 33 Km from the Northern Border of Gaza Strip.

0102030405060708090

100

0.6

1.0

1.4

1.8

2.2

2.6

3.0

3.4

3.8

4.2

4.6

5.0

5.4 5.8

6.2

6.6

7.0

7.4

7.8

8.2

8.6

9.0

9.4

9.8

10.2

10.6

Distance from the Shore Line (Km)

Elev

atio

n fr

om

the

SeaL

evel

(m)

R- Topographic Profile 34.9 Km from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

80

90

0.3

0.7

1.1

1.5

1.9

2.3

2.7

3.1

3.5

3.9

4.3

4.7

5.1

5.5

5.9

6.3

6.7

7.1

7.5

7.9

8.3

8.7

9.1

9.5

9.9

10.3

10.7

11.1

11.5

11.9

Distance from the Shore Line ( km )

Elev

atio

n fr

om

theS

ea L

evel

(m)

S- Topographic Profile 36.9 Km from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

80

90

0.6

1.0

1.4

1.8

2.2

2.6

3.0

3.4

3.8

4.2

4.6

5.0

5.4

5.8

6.2

6.6

7.0

7.4

7.8

8.2

8.6

9.0

9.4

9.8

10.2

10.6

11.0

11.4

11.8

12.2

Distance from the Shore Line ( km )

Ele

vatio

n fr

om

the

Sea

Lev

el (m

)

T- Topographic Profile 38.8 Km from the Northern Border of Gaza Strip.

0

10

20

30

40

50

60

70

80

0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2

3.6

4.0

4.4

4.8

5.2

5.6

6.0

6.4

6.8

7.2

7.6

8.0

8.4

8.8

9.2

9.6

10.0

10.4

10.8

11.2

11.6

distance from the Shore Line (Km)

Elev

atio

n fr

om th

e Sea

Lev

el (m

)

XVII

U- Topographic Profile 40.7 Km from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

80

0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 7.2 7.6 8.0 8.4 8.8 9.2 9.6 10.0

10.4

10.8

11.2

11.6

12.0

12.4

Distance from the Shore Line ( Km )

Elev

atio

n fr

om

the S

ea L

evel

(m)

V- Topographic Profile 42.7 Km from the Northern Border of Gaza Strip .

0

10

20

30

40

50

60

70

80

90

0.4

0.9

1.4

1.9

2.4

2.9

3.4

3.9

4.4

4.9

5.4

5.9

6.4

6.9

7.4

7.9

8.4

8.9

9.4

9.9

10.4

10.9

11.4

11.9

Distance from the Shore Line ( Km).

Elev

atio

n fr

om

the

sea

Leve

l (m

)

W- Topographic Profile 44.6 Km from the Northern Border of Gaza Strip

0102030405060708090

100

5 .1

5 .4

5 .7

6.0

6 .3

6.6

6 .9

7 .2

7 .5

7 .8

8 .1

8 .4

8 .7

9 .0

9 .3

9 .6

9 .9

10.2

10.5

10.8

11. 1

11.4

11. 7

12. 0

Distance from the Shore Line ( Km )

Elev

atio

n fr

om

the

Sea

Leve

l ( m

)

XVIII

Appendix (D)

Different Scenarios to Estimate the Rainfall Amount Infiltrated into

Various Surface Types.

D-I. Sub-Scenario (3.1): Rainfall Amount Infiltrated into the Different Surface Types before

September /2000.

D-II. Sub-Scenario (3.2): Rainfall Amount Infiltrated into the Different Surface Types after the Israeli

Incursion during the Period (September /2000 until August /2004) .

D-III. Scenario (4): Rainfall Amount Infiltrated into the Different Surface Types for the Proposed

Land Use of the Year 2015.

XIX

Direct to the Sea Agriculture Area Open Area Impervious Area Dire ct to Israe l

S - N 80 -90 115418.33 464.7 0.053634898 0.00536349 0.012336027 0.035935382 0.035935382

NW - SE 50 - 60 829348.4 464.7 0.385398201 0.03853982 0.088641586 0.258216795 0.258216795

NW - SE 40 - 50 214364.06 464.7 0.099614979 0.009961498 0.022911445 0.066742036 0.066742036

NW - SE 30 - 40 36092.83 464.7 0.016772338 0.001677234 0.003857638 0.011237467 0.011237467

S - N 60 - 70 469812.74 464.7 0.21832198 0.021832198 0.050214055 0.146275727 0.146275727

NW - SE & SE - Nw 30 - 50 8644783.71 464.7 4.01723099 0.401723099 0.923963128 2.691544763 2.691544763

E - W 10 - 20 165140.04 464.7 0.076740577 0.007674058 0.017650333 0.051416186 0.051416186

Total Build up Area 10474960.11 464.7 4.867713963 0.486771396 1.119574212 3.261368355 0.051416186 2.691544763 0.258216795 0.066742036 0.193448575 0.798378193 4.06933577

Open Area 23835750.18 464.7 11.07647311 11.07647311 11.07647311

Agricultural Area 26371997.6 230.5 6.078745448 6.078745448 6.078745448

Total Governorate Are a 60682707.9 22.02293252 0.486771396 18.27479277 3.261368355 0.051416186 2.691544763 0.258216795 0.066742036 0.193448575 0.798378193 21.22455433

E - W 10 -80 21333088.09 435.5 9.290559863 0.929055986 2.136828769 6.224675108 6.224675108

E - W 70 - 80 113373.07 435.5 0.049373972 0.004937397 0.011356014 0.033080561 0.033080561

NW - SE 30 - 40 185339.72 435.5 0.080715448 0.008071545 0.018564553 0.05407935 0.05407935

E - W 40 - 50 81515.22 435.5 0.035499878 0.003549988 0.008164972 0.023784918 0.023784918

E - W 30 - 40 181576.5 435.5 0.079076566 0.007907657 0.01818761 0.052981299 0.052981299

E - W 10 - 20 16155.82 435.5 0.00703586 0.000703586 0.001618248 0.004714026 0.004714026

W - E 80 - 90 61330.88 435.5 0.026709598 0.00267096 0.006143208 0.017895431 0.017895431

Total Build up Area 21972379.3 435.5 9.568971185 0.956897119 2.200863373 6.411210694 0.057695325 0.023784918 0.033080561 6.278754459 0.017895431 7.311242333 2.257728852

Open Area 20370046.19 435.5 8.871155116 8.871155116 8.871155116

Agricultural Area 31016425.34 210.3 6.522754249 6.522754249 6.522754249

Total Governorate Are a 73358850.83 24.96288055 0.956897119 17.59477274 6.411210694 0.057695325 0.023784918 0.033080561 6.278754459 0.017895431 7.311242333 17.65163822

E - W 70 - 90 148738.71 362.6 0.053932656 0.005393266 0.012404511 0.03613488 0.03613488

E - W 40 - 50 96760.88 362.6 0.035085495 0.00350855 0.008069664 0.023507282 0.023507282

N - S 40 - 50 7885.2 362.6 0.002859174 0.000285917 0.00065761 0.001915646 0.001915646

S - N 40 - 50 4774.01 362.6 0.001731056 0.000173106 0.000398143 0.001159808 0.001159808

S - N 40 - 50 22423.81 362.6 0.008130874 0.000813087 0.001870101 0.005447685 0.005447685

S - N 10 - 20 49877.08 362.6 0.018085429 0.001808543 0.004159649 0.012117238 0.012117238

NW - SE 30 - 40 1870709.5 362.6 0.678319265 0.067831926 0.156013431 0.454473907 0.454473907

NW - SE 20 - 30 2344646.13 362.6 0.850168687 0.085016869 0.195538798 0.56961302 0.56961302

NW - SE 10 - 20 2023777.67 362.6 0.733821783 0.073382178 0.16877901 0.491660595 0.491660595

E - W 0 - 10 932299.88 362.6 0.338051936 0.033805194 0.077751945 0.226494797 0.226494797

Total Build up Area 7501892.87 362.6 2.720186355 0.272018635 0.625642862 1.822524858 0.738795769 0.454473907 0.059642161 0.56961302 1.580427424 1.13975893

Open Area 12368555.14 362.6 4.484838094 4.484838094 4.484838094

Agricultural Area 36353272.6 177 6.434529249 6.434529249 6.434529249

Total Governorate Are a 56223720.61 13.6395537 0.272018635 11.5450102 1.822524858 0.738795769 0.454473907 0.059642161 0.56961302 1.580427424 12.05912627

NW - SE 70 - 90 2589795.49 306 0.79247742 0.079247742 0.182269807 0.530959871 0.530959871

E - W 70 - 80 1682800.5 306 0.514936953 0.051493695 0.118435499 0.345007759 0.345007759

E - W 30 - 70 5352081.57 306 1.63773696 0.163773696 0.376679501 1.097283763 1.097283763

E - W 10 - 30 364049.67 306 0.111399199 0.01113992 0.025621816 0.074637463 0.074637463

SW - NE 50 - 60 399897.14 306 0.122368525 0.012236852 0.028144761 0.081986912 0.081986912

Total Build up Area 10388624.37 306 3.178919057 0.317891906 0.731151383 2.129875768 0.074637463 0.87596763 0.081986912 1.097283763 1.571800044 1.607119013

Open Area 26340802.4 306 8.060285534 8.060285534 8.060285534

Agricultural Area 73339147.45 120 8.800697694 8.800697694 8.800697694

Total Governorate Are a 110068574.2 20.03990229 0.317891906 17.59213461 2.129875768 0.074637463 0.87596763 0.081986912 1.097283763 1.571800044 18.46810224

SE - NW 50 - 70 3652303.92 241.5 0.882031397 0.08820314 0.202867221 0.590961036 0.590961036

SE - NW 70 - 90 287336.84 241.5 0.069391847 0.006939185 0.015960125 0.046492537 0.046492537

SW - NE 50 - 70 628598.741 241.5 0.151806596 0.01518066 0.034915517 0.101710419 0.101710419

E - W 30 - 40 1112079.15 241.5 0.268567115 0.026856711 0.061770436 0.179939967 0.179939967

Total Build up Area 5680318.651 241.5 1.371796954 0.137179695 0.315513299 0.919103959 0.179939967 0.590961036 0.046492537 0.101710419 0.418830082 0.952966873

Open Area 15688921.2 241.5 3.78887447 3.78887447 3.78887447

Agricultural Area 39118443.59 54.7 2.139778864 2.139778864 2.139778864

Total Governorate Are a 60487683.44 7.300450288 0.137179695 6.244166634 0.919103959 0.179939967 0.590961036 0.046492537 0.101710419 0.418830082 6.881620207

Total 360821537 87.96571934 2.170758751 71.25087696 14.54408363 1.10248471 4.636732255 0.39743206 7.098806845 1.308627769 11.6806781 76.28504127

Rafah

Middle

Build up Areas

Khanyunis

Build up Areas

Build up Areas

Build up Areas

Gaza

Net Infiltration (Mm3)

Build up Areas

Northern

Infiltration in s itu ( Mm3 )

Run-off Amount (Mm3)

Total Losse s( Mm3)

D-I. Sub-Scenario (3.1): Amount of Rainfall Infiltrated into Different Surface Types before September 2000 (M m3). Where Run-off Coefficent is estimated to be Governorate Item Slope Direction

Elevation from the Sea Level (m)

Area Calculated by GIS (m2)

Average Rainfall (mm/yr)

Amount of Rainfall Hitting the Surface

Area (Mm3)

Evaporation Rate 10% (Mm3)

Run-off Amount De stination (Mm3)

XX

D-II. Sub-Scenario (3.2): Amount of Rainfall Infiltrated into Different Surface Types after the Israeli Incursion during the Period ( September 2000 until August 2004) (Mm3). Where Run-off Coeffiecint is assumed to be = 0.67

Direct to the Sea Agriculture Area Open Area Impervious Area Direct to Israel

S - N 80 -90 115418.33 464.7 0.053634898 0.00536349 0.012336027 0.035935382 0.035935382

NW - SE 50 - 60 829348.4 464.7 0.385398201 0.03853982 0.088641586 0.258216795 0.258216795

NW - SE 40 - 50 214364.06 464.7 0.099614979 0.009961498 0.022911445 0.066742036 0.066742036

NW - SE 30 - 40 36092.83 464.7 0.016772338 0.001677234 0.003857638 0.011237467 0.011237467

S - N 60 - 70 469812.74 464.7 0.21832198 0.021832198 0.050214055 0.146275727 0.146275727

NW - SE & SE - NW 30 - 50 8644783.71 464.7 4.01723099 0.401723099 0.923963128 2.691544763 2.691544763

E - W 10 - 20 165140.04 464.7 0.076740577 0.007674058 0.017650333 0.051416186 0.051416186

Total Build up Area 10474960.11 464.7 4.867713963 0.486771396 1.119574212 3.261368355 0.051416186 2.691544763 0.258216795 0.066742036 0.193448575 0.798378193 4.06933577

Open Area 38977750.18 464.7 18.11296051 18.11296051 18.11296051

Agricultural Area 11229997.6 230.5 2.588514447 2.588514447 2.588514447

Total Governorate Area 60682707.9 25.56918892 0.486771396 21.82104917 3.261368355 0.051416186 2.691544763 0.258216795 0.066742036 0.193448575 0.798378193 24.77081073

E - W 10 -80 21333088.09 435.5 9.290559863 0.929055986 2.136828769 6.224675108 6.224675108

E - W 70 - 80 113373.07 435.5 0.049373972 0.004937397 0.011356014 0.033080561 0.033080561

NW - SE 30 - 40 185339.72 435.5 0.080715448 0.008071545 0.018564553 0.05407935 0.05407935

E - W 40 - 50 81515.22 435.5 0.035499878 0.003549988 0.008164972 0.023784918 0.023784918

E - W 30 - 40 181576.5 435.5 0.079076566 0.007907657 0.01818761 0.052981299 0.052981299

E - W 10 - 20 16155.82 435.5 0.00703586 0.000703586 0.001618248 0.004714026 0.004714026

W - E 80 - 90 61330.88 435.5 0.026709598 0.00267096 0.006143208 0.017895431 0.017895431

Total Build up Area 21972379.3 435.5 9.568971185 0.956897119 2.200863373 6.411210694 0.057695325 0.023784918 0.033080561 6.278754459 0.017895431 7.311242333 2.257728852

Open Area 25509046.19 435.5 11.10918962 11.10918962 11.10918962

Agricultural Area 25877425.34 210.3 5.442022549 5.442022549 5.442022549

Total Governorate Area 73358850.83 26.12018335 0.956897119 18.75207554 6.411210694 0.057695325 0.023784918 0.033080561 6.278754459 0.017895431 7.311242333 18.80894102

E - W 70 - 90 148738.71 362.6 0.053932656 0.005393266 0.012404511 0.03613488 0.03613488

E - W 40 - 50 96760.88 362.6 0.035085495 0.00350855 0.008069664 0.023507282 0.023507282

N - S 40 - 50 7885.2 362.6 0.002859174 0.000285917 0.00065761 0.001915646 0.001915646

S - N 40 - 50 4774.01 362.6 0.001731056 0.000173106 0.000398143 0.001159808 0.001159808

S - N 40 - 50 22423.81 362.6 0.008130874 0.000813087 0.001870101 0.005447685 0.005447685

S - N 10 - 20 49877.08 362.6 0.018085429 0.001808543 0.004159649 0.012117238 0.012117238

NW - SE 30 - 40 1870709.5 362.6 0.678319265 0.067831926 0.156013431 0.454473907 0.454473907

NW - SE 20 - 30 2344646.13 362.6 0.850168687 0.085016869 0.195538798 0.56961302 0.56961302

NW - SE 10 - 20 2023777.67 362.6 0.733821783 0.073382178 0.16877901 0.491660595 0.491660595

E - W 0 - 10 932299.88 362.6 0.338051936 0.033805194 0.077751945 0.226494797 0.226494797

Total Build up Area 7501892.87 362.6 2.720186355 0.272018635 0.625642862 1.822524858 0.738795769 0.454473907 0.059642161 0.56961302 1.580427424 1.13975893

Open Area 18784555.14 362.6 6.811279694 6.811279694 6.811279694

Agricultural Area 29937272.6 177 5.29889725 5.29889725 5.29889725

Total Governorate Area 56223720.61 14.8303633 0.272018635 12.73581981 1.822524858 0.738795769 0.454473907 0.059642161 0.56961302 1.580427424 13.24993587

NW - SE 70 - 90 2589795.49 306 0.79247742 0.079247742 0.182269807 0.530959871 0.530959871

E - W 70 - 80 1682800.5 306 0.514936953 0.051493695 0.118435499 0.345007759 0.345007759

E - W 30 - 70 5352081.57 306 1.63773696 0.163773696 0.376679501 1.097283763 1.097283763

E - W 10 - 30 364049.67 306 0.111399199 0.01113992 0.025621816 0.074637463 0.074637463

SW - NE 50 - 60 399897.14 306 0.122368525 0.012236852 0.028144761 0.081986912 0.081986912Total Build up Area 10388624.37 306 3.178919057 0.317891906 0.731151383 2.129875768 0.074637463 0.87596763 0.081986912 1.097283763 1.571800044 1.607119013

Open Area 35583802.4 306 10.88864353 10.88864353 10.88864353

Agricultural Area 64096147.45 120 7.691537694 7.691537694 7.691537694

Total Governorate Area 110068574.2 21.75910029 0.317891906 19.31133261 2.129875768 0.074637463 0.87596763 0.081986912 1.097283763 1.571800044 20.18730024

SE - NW 50 - 70 3652303.92 241.5 0.882031397 0.08820314 0.202867221 0.590961036 0.590961036

SE - NW 70 - 90 287336.84 241.5 0.069391847 0.006939185 0.015960125 0.046492537 0.046492537

SW - NE 50 - 70 628598.741 241.5 0.151806596 0.01518066 0.034915517 0.101710419 0.101710419

E - W 30 - 40 1112079.15 241.5 0.268567115 0.026856711 0.061770436 0.179939967 0.179939967

Total Build up Area 5680318.651 241.5 1.371796954 0.137179695 0.315513299 0.919103959 0.179939967 0.590961036 0.046492537 0.101710419 0.418830082 0.952966873

Open Area 20421921.2 241.5 4.93189397 4.93189397 4.93189397

Agricultural Area 34385443.59 54.7 1.880883764 1.880883764 1.880883764

Total Governorate Area 60487683.44 8.184574688 0.137179695 7.128291034 0.919103959 0.179939967 0.590961036 0.046492537 0.101710419 0.418830082 7.765744607

360821537 96.46341054 2.170758751 79.74856816 14.54408363 1.10248471 4.636732255 0.39743206 7.098806845 1.308627769 11.6806781 84.78273246

Evaporation Rate 10% (Mm3)

Governorate Item Slope Direction Elevation from the Sea Level (m)

Run-off Amount Destination (Mm3 ) Net Infiltration (Mm3 )

Build up Areas

Northern

Infiltration in situ ( Mm3 )

Run-off Amount (Mm3)

Total Losses( Mm3)

Area Calculated by GIS (m2 )

Average Rainfall (mm/yr)

Amount of Rainfall Hitting the Surface Area

(Mm3)

Build up Areas

Gaza

Middle

Build up Areas

Total

Khanyunis

Build up Areas

Build up Areas

Rafah

XXI

Direct to the Sea Agriculture Area Open Area Impervious Area Direct to Israel

S - N 80 -90 173778.64 464.7 0.080754934 0.008075493 0.009690592 0.062988849 0.062988849

NW - SE 50 - 60 2407973.25 464.7 1.118985169 0.111898517 0.13427822 0.872808432 0.872808432

NW - SE 40 - 50 1864211.57 464.7 0.866299117 0.086629912 0.103955894 0.675713311 0.675713311

NW - SE 30 - 40 1023744.43 464.7 0.475734037 0.047573404 0.057088084 0.371072549 0.371072549

S - N 60 - 70 827823.97 464.7 0.384689799 0.03846898 0.046162776 0.300058043 0.300058043

NW - SE & SE - Nw 30 - 50 9531088.36 464.7 4.429096761 0.442909676 0.531491611 3.454695473 3.454695473

E - W 10 - 20 194827.38 464.7 0.090536283 0.009053628 0.010864354 0.070618301 0.070618301

Total Build up Area 16023447.6 464.7 7.4460961 0.74460961 0.893531532 5.807954958 0.070618301 3.454695473 1.548521743 0.73411944 3.097869094 4.348227005

Open Area 19337385.3 464.7 8.986082947 8.986082947 8.986082947

Agricultural Area 25321875 230.5 5.836692188 5.836692188 5.836692188

Total Governorate Area 60682707.9 22.26887123 0.74460961 15.71630667 5.807954958 0.070618301 3.454695473 1.548521743 0.73411944 3.097869094 19.17100214

E - W 10 - 80 25619220.32 435.5 11.15717045 1.115717045 1.338860454 8.702592951 8.702592951

E - W 70 - 80 1553512.88 435.5 0.676554859 0.067655486 0.081186583 0.52771279 0.52771279

NW - SE 30 - 40 4817901.38 435.5 2.098196051 0.209819605 0.251783526 1.63659292 1.63659292 1.63659292

NW - SE 20 - 30 5732014.35 435.5 2.496292249 0.249629225 0.29955507 1.947107955

E - W 40 - 50 295536.96 435.5 0.128706346 0.012870635 0.015444762 0.10039095 0.10039095

E - W 30 - 40 831895.32 435.5 0.362290412 0.036229041 0.043474849 0.282586521 0.282586521

E - W 10 - 20 3484417.27 435.5 1.517463721 0.151746372 0.182095647 1.183621702 1.183621702

W - E 80 - 90 113699.28 435.5 0.049516036 0.004951604 0.005941924 0.038622508 0.038622508

Total Build up Area 42448197.76 435.5 18.48619012 1.848619012 2.218342815 14.4192283 1.466208224 1.63659292 10.96728961 0.038622508 14.32073935 3.854935735

Open Area 6302224.44 435.5 2.744618744 2.744618744 2.744618744

Agricultural Area 24608428.63 210.3 5.175152541 5.175152541 5.175152541

Total Governorate Area 73358850.83 26.40596141 1.848619012 10.1381141 14.4192283 1.466208224 1.63659292 10.96728961 0.038622508 14.32073935 11.77470702

E - W 70 - 90 634841.01 362.6 0.23019335 0.023019335 0.027623202 0.179550813 0.179550813

E - W 40 - 50 665082.75 362.6 0.241159005 0.024115901 0.028939081 0.188104024 0.188104024

SE - NW 40 - 50 1604471.3 362.6 0.581781293 0.058178129 0.069813755 0.453789409 0.453789409

S - N 40 - 50 2192219.38 362.6 0.794898747 0.079489875 0.09538785 0.620021023 0.620021023

S - N 10 - 20 594905.08 362.6 0.215712582 0.021571258 0.02588551 0.168255814 0.168255814

NW - SE 30 - 40 2156822.08 362.6 0.782063686 0.078206369 0.093847642 0.610009675 0.610009675

NW - SE 20 - 30 2677047.73 362.6 0.970697507 0.097069751 0.116483701 0.757144055 0.757144055

NW - SE 10 - 20 2482167.21 362.6 0.90003383 0.090003383 0.10800406 0.702026388 0.702026388

E - W 0 - 10 1664344.55 362.6 0.603491334 0.060349133 0.07241896 0.47072324 0.47072324

Total Build up Area 14671901.09 362.6 5.320031335 0.532003134 0.63840376 4.149624441 1.794794851 0.610009675 0.367654837 1.377165078 3.703963063 1.616068273

Open Area 9520017.32 362.6 3.45195828 3.45195828 3.45195828

Agricultural Area 32031802.2 177 5.669628989 5.669628989 5.669628989

Total Governorate Area 56223720.61 14.4416186 0.532003134 9.759991029 4.149624441 1.794794851 0.610009675 0.367654837 1.377165078 3.703963063 10.73765554

NW - SE 70 - 90 5766244.05 306 1.764470679 0.176447068 0.211736482 1.37628713 1.37628713

E - W 70 - 80 7936178.7 306 2.428470682 0.242847068 0.291416482 1.894207132 1.894207132

E - W 30 - 70 14815325.93 306 4.533489735 0.453348973 0.544018768 3.536121993 3.536121993

E - W 10 - 30 925048.82 306 0.283064939 0.028306494 0.033967793 0.220790652 0.220790652

SW - NE 50 - 60 5711951.81 306 1.747857254 0.174785725 0.20974287 1.363328658 1.363328658

Total Build up Area 35154749.31 306 10.75735329 1.075735329 1.290882395 8.390735565 0.220790652 1.37628713 6.793657783 8.090183764 2.667169525

Open Area 17031015.4 306 5.211490712 5.211490712 5.211490712

Agricultural Area 57882809.25 120 6.94593711 6.94593711 6.94593711

Total Governorate Area 110068574 22.91478111 1.075735329 13.44831022 8.390735565 0.220790652 1.37628713 6.793657783 8.090183764 14.82459735

SE - NW 50 - 70 6298065.92 241.5 1.52098292 0.152098292 0.18251795 1.186366677 1.186366677

SE - NW 70 - 90 534250.18 241.5 0.129021418 0.012902142 0.01548257 0.100636706 0.100636706

SW - NE 50 - 70 1274885.741 241.5 0.307884906 0.030788491 0.036946189 0.240150227 0.240150227

E - W 30 - 40 2936116.15 241.5 0.70907205 0.070907205 0.085088646 0.553076199 0.553076199

Total Build up Area 11043317.99 241.5 2.666961295 0.266696129 0.320035355 2.08022981 0.553076199 0.100636706 1.426516904 2.246289233 0.420672062

Open Area 13767033.88 241.5 3.324738682 3.324738682 3.324738682

Agricultural Area 35675332.59 54.7 1.951440693 1.951440693 1.951440693

Total Governorate Area 60485684.46 7.94314067 0.266696129 5.59621473 2.08022981 0.553076199 0.100636706 1.426516904 2.246289233 5.696851436

360819537.8 93.97437303 4.467663214 54.65893674 34.84777307 4.105488227 5.440992279 2.104884463 22.11315112 0.772741949 31.45904451 62.20481348

Rafah

Middle

Build up Areas

Khanyunis

Build up Areas

Build up Areas

Gaza

Build up Areas

Run-off amount Destination (Mm3 ) Net Infiltration (Mm3 )

Build up Areas

Northern

Infiltration in situ ( Mm3 )

Run-off Amount (Mm3)

Total Losses( Mm3)

Total

D-III. Scenario (4): Amount of Rainfall Infiltrated into Different Surface Types for the Proposed Land Use in 2015 (Mm3) . Where Run-off Coefficent is estimated to be

Governorate Item Slope DirectionElevation from the Sea Level

(m)

Area Calculated by GIS (m2 )

Average Rainfall (mm/yr)

Amount of Rainfall Hitting

the Surface Area

Evaporation Rate10% (Mm3)