3rd Annual Connference EHA Aug. 23, 2008 1 EVALUATION AND DEVELOPMENT OF GROUND WATER RESOURCES OF ADA'A–BECHO PLAINS FOR IRRIGATION PROJECT Engida ZA

3rd Annual Connference EHA Aug. 23, 2008

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EVALUATION AND DEVELOPMENT OF GROUND WATER RESOURCES OF ADA'A–BECHO PLAINS

FOR IRRIGATION PROJECT

Engida ZA*, Tilahun A*, Dr. Seifu K* and Dr. Yilma*

Client: Ministry of Water Resources

* - Consultant: Water Works Design Enterprise (WWDSE)

WATER WORKS DESIGN AND SUPERVISION ENTERPRISE

P.O.BOX 2561: Tel: 011- 6614501

Fax: 011-6615373 email: [email protected]


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TABLE OF CONTENT

1. Location2. Objective and scope of the study3. Methodology

Geology and structures, Hydrology, Geophysics, Drilling of mapping wells

Isotope and water quality, Water quality monitoring, Hydrogeology

4. Main study output of the project Developing conceptual models (Inception

phase) Preparing hydrogeological map Preparing groundwater flow system of AB

Plains


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TABLE OF CONTENT…

Evaluation of groundwater potential of Ada'a and Becho plains

Interaction of Debre Zeit Lakes with the groundwater system

Interaction of Awash river with the groundwater system


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1. LOCATION OF THE PROJECT AREA • Central Ethiopia, in Oromia Regional State

in Upper Awash river Basin• Ada’a plain is found between elevation

1600 and 1900 masl and approximately between Co-ordinates 38050’E - 39015’E and 8030’N - 8053’N (T area-1641 km2 ,223km2M Net area of the plain1418 km2

• Becho plain is found between elevation 2040 and 2120 masl and approximately between coordinates 38008’E - 38036’E and 8038’N - 9000’N (T area 1414km2 seasonally inundated area117km2 net area 1297 km2)

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Upper Awash

Abbay Plateau

ADAA PLAIN

Becho Plain

Lemi

Mulo

GolaGoja

Ambo

Mojo

Koka

Bu-i

Muger DuberDebra

Gorfo

Chobi ShenoShino

Bicho

Tefki

Dukem Ejere

BantuLemen

Degem FicheBiriti Deneba

Weberi

DaletiMinare

ChachaMekoda

Ketket

Wenoda

Aleltu

HolotaGinchi

SebetaGodino

Boneya

Dilela

Weliso

Ombole

Dinbaro

Mendida

Kachisi

AsagirtShikute

Inchini Chancho

Koremas

Sendafa

Adulala

Tarmaber

Ali Doro

Jemo Lefo

Muke TuriKembolcha

Adis Alem

Alem Gena

Tulu Bolo

Anchekorer Godo Beret

Welenkombi

Debre Zeyt

Kondaltiti

Debre Tsige

Addis AbebaChefe Donsa

Debre Genet

Debre Birhan

Shola Gebeya

Akaki Beseka

Gebre Guracha

Melka Kunture

Debre Libanos

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LOCATION MAP OF ADAA-BECHO PLAINS

8000 0 8000 16000 Meters

Fig1 LOCATION MAP OF THE PROJECT AREA


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2. OBJECTIVE AND SCOPE OF THE STUDY

• Previous studies have indicated that there is a possible high groundwater potential, currently agriculture consists mainly of rain fed annual cropping. Crop yields are generally good in the project area, the high population growth has made the available land decreasing from year to year.

• Unless remedial measures are taken, the standard of living of the farmers will further decline, especially in view of the current rapid population growth rate of about 2.9 % per year. Since the rural population is expected to double in about 25 years, it is increasingly important to deal with these issues as soon as possible by implementing irrigation in the area.


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2. OBJECTIVE AND SCOPE …

• Determine the hydrogeological condition of the Ada'a-Becho plains groundwater system

• Qualitative and quantitative evaluation of the groundwater resources of the plain and select potential well fields

• Carry out analytical and/or numerical model of the main aquifer of the area to recommended appropriate groundwater management

• Develop strategy of groundwater resources development together with cost estimates


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3. METHODOLOGY• Data collection & review of previous works.• Geological & geomorphologic mapping• Hydrological survey and analysis • Hydrogeological investigation (water point

inventory, water quality survey, water quality monitoring, mapping well drilling & testing)

• Geophysical investigation (Resistivity and TEM)

• Isotope hydrogeology• Detail qualitative & quantitative groundwater

potential evaluation• Prioritization of potential prospective area for

Pilot well field development• Analytical Modelling SN


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3. MAIN OUTPUTS OF THE PROJECTA. Developing conceptual models (In. phase):

The hydrogeological and isotope data from Akaki catchment shows the following conditions• Most of the deep wells drilled in Addis Ababa

and adjacent areas are highly confined. Confining acidic volcanic and the aquifer basic rocks (basalt of different comp. and ages)

• The upper part of Akaki catchment is steep and composed of dominantly acidic volcanic rocks (which are practically impervious) it is difficult to assume that a recharge that occurred at the upper part of the catchment has formed a confined aquifer in the basalts at the central, eastern and western AA. The upper part of Akaki river catchment is merely runoff generator.

Fig 2


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3. MAIN OUTPUTS OF THE PROJECT…A. Developing conceptual models (In. phase): The

hydrogeological and isotope data from Akaki catchment shows the following conditions• The tritium value from different sources Yves M.

Travi, Kebede S. (2000) shows Except few wells (probably shallow wells) the other wells both cold and thermal wells are depleted in tritium value in general

• Reconnaissance surveys at Muger and Abbay rivers gorges showed that the Mesozoic sedimentary formation is most likely dipping in SSE direction, which highly favors the Abay plateau groundwater flow to SSE direction into Awash River basin

• These observations led to conceptualize that the groundwater of Addis Ababa and in general Becho and Ada'a plains groundwater is recharged mainly from outside their surface catchments. The basalt plateau of Abay river basin that is found adjacent to Akaki and Awash rivers catchments could be the main recharge zone of Ada'a plain (as shown the figs 3and 4 below)


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ABBAY RIVER BASIN BASALT

PLATEAU

Mt. Erer

Mt. Intoto

PROJECT AREA (APGW B)

Abay basalt plateau basin ,possiblymain recharge area of APGW B

Upper Awash river sub-catchments

Scale 1 : 700,000

Date:- January 2006

Fig.4.3Addis Ababa, Ethiopia P.O.Box 2561 Tel. 614501 610105

Fax:- 251- 1-615371 251-1-610898

e-mail w.w.d.s.e @ telecom.net. et


EVALUATION OF GROUNDWATER RESOURCES OF ADA'A PLAIN FOR IRRIGATION PROJ ECT

REGIONAL HYDROGEOLOGICAL SETUP OFADA'A PLAIN GROUNDWATER BASIN

10 0 10 20 KM

N

Legend

MINISTRY OF WATER RESOURCES

FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA

Roads

Towns

Lakes / Reservoirs

Schematic hydrogeological x-section lines(Conceptual)

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Main output


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FIG 4.5 CONCEPTUAL HYDROGEOLOGICAL X-SECTION ALONG ADDIS ABABA -ADAA LINE

ABBAY RIVER BASIN AWASH RIVER BASIN

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FIG 3 CONCEPTUAL X-SECTION AP-AA-ADAA


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§Springs

FIG 4.6 CONCEPTUAL HYDROGEOLOGICAL SECTION ALONG BECHO - ADAA LINE

ABAY RIVER BASIN

AWASH RIVER BASIN

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FIG 4 CONCEPTUAL X-SECTION AP-BECHO-ADAA


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3. MAIN OUTPUTS OF THE PROJECT…B.Preparation of Hydrogeological map and cross-

section: Phase I: Inv. and analysis:• Hydrogeological conditions of the area is a function of

geomorphology and tectonics, on the Plateau older Tertiary volcanic outcrops to the south the younger geological formation over lies the older volcanic unit

• The recharge condition, groundwater flow and aquifer parameters in the Adaa-Becho plains is highly governed by the general bedding of the sedimentary formation underlying the volcanic unit, the tectonic condition and the hydraulic properties of the different volcanic units that outcrops in the basin

• There are two basaltic aquifers in the Becho plain and along west-east direction from Becho-Legedadi section which are separated by ignimbrites and welded tuffs

HG-Map

BECHO


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section: Phase I: Inv. and analysis:• Upper Basalt Aquifer

• composed of Quaternary of Weliso-Ambo basalts, Akaki basalts: scoria and spatter cones, and Tertiary-Neogene’s basalt of Addis Ababa basalts and Tulu ries basalts.

• one aquifer system in Ada’a plain (south of Dukem)• distributed in Upper Awash, where it outcrops at Central

Addis Ababa, Weliso and Akaki and it also overlain by ignimbrites and tuffs at Becho plaains, Legedadi area, in general where the ignimbrites and tuff outcrops

• Varies from more than 200 to 50 m thickness: TDS 400-700 mg/l

• by water balance method and chloride balance method the recharge of this aquifer is estimated to be 390 Mm3/year


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section: Phase I: Inv. and analysis:• Lower Basalt Aquifer

• composed of tertiary Tarmaber basalt composed of dominantly scoraceous basalt and Amba Aiba basalt. These tertiary basalt formations occupy more than 75% of Abay plateau about 7,000 km2. .

• mapping wells drilling at Becho Plain, Holota, Melka Kunture, Legedadi areas penetrated at different depth this aquifer. The total confining head more than 220 meters

• The yield of the well was progressively increasing when the depth of penetration is increased in this aquifer. Water level varies from artesian condition to a depth of 67.5 meters

• The total annually recharge of the lower aquifer is estimated by different method is about 700Mm3/year.

Sn 24


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Goja

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Koka

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Muger DuberDebra

Gorfo

Chobi ShenoShino

Bicho

Tefki

DukemEjere

BantuLemen

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Biriti Deneba

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DaletiMinare

ChachaMekoda

Ketket

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Ginchi

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Adis Alem

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Debre Zeyt

Kondaltiti

Debre Tsige

Addis Abeba

Chefe Donsa

Debre Genet

Debre Birhan

Shola Gebeya

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Gebre Guracha

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Segno Gebeya _Legedadi se

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HYDROGEOLOGICAL MAP OF ADAA-BECHO PLAINS GROUNDWATER BASIN

Scale 1:700,000Date: April -07

Drawn by EZA


Preliminary Hydrogeological map of Ada'a - Bechoplains and their recharge areasTITLE:

PROJECT: Evaluation of the groundwater potential of Ada'a -Becho Plains

FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIAMINISTRY OF WATER RESOURCES

Scale 1:700,000

Meters8000400004000

N

Faults/lineaments

upper awash

Abbay Plateau

Adaa-Becho plains Groundwater basin and its recharge area

Groundwater divides

Groundwater flow-directions

HYDROGEOLOGICAL X-SECTIONS

Ñ VES POINTS

#YMAPPING WELLS DRILLED BY THE PROJECTAND WOBERI WELL BY OROMIA IRRIGATIONDEV. AUTHORITY

#Y EXISTING WELLS DEPTH > 150 METERS

II. MISCELLANEOUS

Out crops in the gorges, there may be a possibility to pentrate this formation at a great depth more than 450 meters At Abay Plateau

D. Mesozoic Sedimentary aquifers

Tertiary and Quaternary Rhyolitic and trachytic volcanic r idges and volcanic centers (QbgPr+QZqTy+NebRy +NCvTy) of Bede gebaba, Ziquala, Wechecha, Furu, Yerer,etc. localized aquicludes

C3. Localized aquiclude

C2. EXtensive and regional upper aquicludeRegional to Sub-regional lower aquiclude of Asahngi Basalt (PaaB), Blue Nile Columnar Basalts (PntbB) and Alaji Ryholites acts as regonal aquiclude between the lower basalt aquifer and Mesozoic sedimentary formations

Regional to Sub-regional aquiclude of Nazaret groups (NnuRI) welded ingnimbrites, Chefe donsa pyroclastics (NQcdPc) and Addis Ababa Ignimbrites (NadB), have low groundwater potent along fractrues andweathered zone. Separates the upper and lower basaltic aquifers

C1. EXtensive and regional upper aquiclude

C. Regional and local Volcanic aquitards

B2. Lower basalt AquiferLower Tertiary Volcanic aquifer : Tarmaber scoraceous basalt (PntbB) and Amba Aiba basalt (PaaB) high productive aquifer. Outcrops in Abay plateau and underlain by acidic volcanic rocks in upper Awash

Quaternary and Tertiary basalts, Bishoftu saptter cones and lava flows (QbiB), Weliso-Ambo basalt (QabB), Akaki Basalts and Scoria (NakB) and Addis Ababa basalts (NadB) moderate to high sub-regional aquifers

B1. Upper Basalt Aquifer

B. Fractured and Scoraceous basalt Aquifers

Alluvium of Abay plateau (Qal) and Debre Zeit area allluvium and lascustrine (Qal+Qld) aquifer of modertae to high productivity

A. Extensive aquifers with primary porosity

I. Aquifers Properties

LEGEND

Fig 6

Fig 7

Fig 5 Hydrogeological Map of ADAA-BECHO PLAINS

Fig 8Fig 9 Fig 10

Fig11


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Fig 6 HYDROGEOLOGICAL X-SECTION ALONG BECHO PLAIN


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Fig 7 Hydrogeological x-section along Kachise –Becho-Ada’a line


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Fig 8 Muger-Holota-Becho


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Fig 9 SEGNO GEBYA-LEGEDADI

Well log


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Fig 10 Hydrogeological x-section along Plateau -Legedadi - Akaki section line


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Fig 11 Hydrogeological x-section in Ada’a Plain (Southwest – Northeast direction)


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3. MAIN OUTPUTS OF THE PROJECT…

B.Preparation of Groundwater flow system of AB Plains: Phase I: Inv. and analysis:

• Groundwater level elevation contour map was constructed for the regional basalt aquifer (lower aquifer) applying the data generated from drilling of mapping wells and existing bore holes identified to be representing the regional aquifer water level

• On the groundwater elevation contour map the following understanding is obtained• Entoto and Wechecha –furi and Bedegebaba ridges acts as

local barrier• The recharge at Abay plateau flows to Upper Awash through

two main direction i.e. through Becho plain and along Legedadi areas

• Almost 100% of Abay plateau is the recharge area of the lower basalt aquifer in Upper Awash basin

• Bore holes drilled along flow paths have yield and artesian if drilled at lower places

Fig12

Fig 12 sn30


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Lake Ziway

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Mt . We ch ech a

Mt . Yerer

Mt . Z iq ua la

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Mt . F ur i

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Lemi

Mulo

Gola

Goja

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Mojo

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Bu-i

Muger Duber

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Tefki

DukemEjere

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Weberi

Daleti

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Ketket

Wenoda

Aleltu

Holota

Ginchi

Sebeta

Godino

Boneya

Di lela

Weliso

Ombole

Dinbaro

Mendida

AsagirtShikute

Inchini Chancho

Koremas

Sendafa

Adulala

Ali Doro

Muke Turi

Kembolcha

Adis Alem

Alem Gena

Tulu Bolo

Welenkombi

Debre Zeyt

Kondaltiti

Debre Tsige

Addis Abeba

Chefe Donsa

Debre Genet

Debre Birhan

Shola Gebeya

Akaki Beseka

Melka Kunture

Fig 12 SIMPLIFIED GROUNDWATER FLOW PATHS IN AB


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Fig 13 Drilling at Holeta area


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Fig 14 DRILLING AT

ASGORI


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Fig 15 Melka Kunture Pumping test Q=36 l/s


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Fig 16 Artesian flow well drilled south of legedadi


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C.Evaluation of groundwater potential of Ada’a plains (ECGPAP):

• AQUIFER CHARACTERISTICS• aquifer composed of scoria, scoraceous

Basalt and fractured basalt unconfined extensive with high transmissivity

• groundwater recharge to Ada’a plain groundwater system is from three direction i.e.i) between Mountains Yerer and Guji, ii) between Bede Gebaba and Ziquala (Qgz) and from Mojo, Wedecha and Belebela catchment (Qmw).


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Lake Hado

Lake Bishoftu Guda

Lake Kurif tu

1864

1884

1856

1870

Koka reservoir

Belbela reservoir

1590

1930

Mt. Ziquala

Mt. Guji

Mt. Bede GebabaAMW5

AMW21

AMW25

AMW12A

AMW12B AMW22A

AMW22B

AMW24A

AMW24BMojo

Koka

Dukem

Ombole

Adulala

Alem Tena

Debre Zeyt

Akaki Beseka

Tede

Dire Well

Gafat well

Dukem MBI

Shimbira MedaWell

Air force well

Awash River at

155

0

190 0

1800

1650

1800

1650

1950

1900

1600

1750

1650

1850

1700

2100

1800

1600

2000

1750

1800

1950

1850

1700

1800

1750

480000

480000

490000

490000

500000

500000

510000

510000

9200

00

920000

9300

00

930000

9400

00

940000

9500

00

950000

9600

00

960000

9700

00

970000

9800

00

980000

GROUND WATER LEVEL ELEVATION CONTOUR MAP OF ADAA PLAIN GROUNDWATER BASIN

Groundwater Level elevation contour

Mapping wellsð

Groundwater flowdirections

Water Quality monitoring Bore Hole#Y

All-weather roads (asphalt)

All-weather roads (gravel)

Railway

LEGEND

A B Hydrogeological x-section

3000 0 3000 6000Meters

N

Scale 1:250,000

A

B


32

Fig 11 Hydrogeological x-section in Ada’a Plain (Southwest – Northeast direction)


33


C. ECGPAP: ESTIMATED RECHARGE APRecharge Direction

Weighted transmissivity (Tav), m2/day

Width of flow (L), m

Average flow gradient (I)

Recharge estimated in MCM/year

Remark

Yerer –Guji Zone

1200 10,800 0.02 94.6

Bede Gebaba – Ziqual

10,200 13,460 0.01 532.0

Modjo+Wedecha +Belebela

153.0 Vol. II chap 7.3

Total 779.6 MCM/Year


34

3. MAIN OUTPUTS OF THE PROJECT… ESTIMATED EXPLOITABLE GWR OF AP Analytical

method

• Excluding the recharge from Becho plain due to the maximum exploitation of the groundwater resource in the plain the net available exploitable ground water potential is estimated about 1,046MCM/year or 2.9MCM/day or 33 500 l/s


35

3. MAIN OUTPUTS OF THE PROJECT… PRIORITIZING GROUNDWATER PROSPECTING SITES IN AP

Prospective site

Prioritizing Criteria Ranking

Area, ha

GWD range, m

T,Range, m2/day

EC,range, μS/cm

A 23,425

Dominantly from 60-120

5,000-10,000 in some part >10,000

Dominantly 500-750

2

B 19,760

< 30 5,000-10,000

Dominantly 500-750

1

C 5,540 60-120 5,000-10,000

500-750 3

D 3,316 30-90 200-1,000 500-750 4

Fig 17


36

jj

j

j

j

j

j

j

Mojo

Koka

Dukem

Godino

Ombole

Adulala

Debre Zeyt

Akaki BesekaMt. Yerer

Mt. Ziquala

Mt. Guji

Mt. Bede Gebaba

A

BC

D

Koka reservoir

Belbela reservoir

Lake chelelka

Lake Bishoftu

Lake Hado

Lake Bishoftu Guda

River Awash

480000

480000

490000

490000

500000

500000

510000

510000

9200

00

920000

9300

00

930000

9400

00

940000

9500

00

950000

9600

00

960000

9700

00

970000

9800

00

980000

GROUNDWATER PROSPECTIVE SITES IN ADAA PLAIN

GROUNDWATERPROSPECTIVE SITES

Debrezeit lakes

Rivers

Townsj

LEGEND

Reservoirs

Main Roads (Asphalt)

Rail Way

N

4000 0 4000 Meters

Scale 1:250,000

Table

3. MAIN OUTPUTS OF THE PROJECT… C. ECGPAP: Fig 17 Prospective groundwater potential sites


37


C. ECGPAP: Parameters considered• The groundwater system as extensive

unconfined aquifer.• Average transmissivity of the confined

aquifer Tavg = 5000m2/day • The specific yield of the aquifer is

estimated to be about 0.25.• Thickness of Aquifer 300 m• 100 wells 1km apart in grid


38

#Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y#Y #Y #Y #Y

#Y#Y #Y

#Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y #Y

#Y #Y #Y #Y #Y #Y #Y #Y

#Y#Y

((

496000

496000

498000

498000

500000

500000

502000

502000

504000

504000

506000

506000

508000

508000

510000

510000

512000

512000

514000

514000

9620

00

962000

9640

00

964000

9660

00

966000

9680

00

968000

9700

00

970000

9720

00

972000

FIGURE 18 PROPOSED PRODUCTION WELLS DISTRIBUTION IN THE MOST PROSPECTIVE SITE OF ADAA PLAIN

N

200 0 200 400 Meters

Scale 1:50,000

CENTRAL WELL

Productionwells (proposed)#Y

Legend

C. ECGPAP: Fig 18 Proposed PW in prioritized sites


39

C. ECGPAP: Calculated Max DD in the WF for different scenario of Abstraction rate and duration of pumping

Scenari

o

Well discharge

No. wells

Total discharge

Calculated maximum drawdown at the center of the well field for

different period of exploitation

l/sm3/ day l/s

m3/day

500 days

1000 days

2000 days

5000 days

8000 days

10000 days

1.4

2.7 5.513.

7 21.927.4

1 20 1728 120 240020736

0 2.3 4.6 6.9 9.9 11.4 12.2

2 40 3456 120 480041472

0 4.6 9.113.

719.

8 22.9 24.4

3 50 4320 120 600051840

0 5.711.

417.

224.

7 28.6 30.4

4 70 6048 120 840072576

0 8 16 2434.

6 40 42.6

5 100 8640 1201200

010368

00 11.422.

934.

349.

4 57.2 60.9


40

C. ECGPAP: Estimated EGWP of prioritized area

• The estimated exploitable groundwater resource (safe yield) is about 378MCM /Year or 1,036,800 m3/day or 8, 640 l/s by 100 wells each discharging 100 l/s.

Calculated Drawdown for Diffrent Scenario Abstraction Rate and duration T = 5000 m2/day

0.0

20.0

40.0

60.0

80.0

100.0

120.0

0 2000 4000 6000 8000 10000 12000

Exploitation Period in days

Calcu

lated

Dra

wdow

n, m

Q=207,360 m3/dayQ=414,270 m3/dayQ=518,400 m3/dayQ=725,760 m3/dayQ=1,036800 m3/dayPermissible DD


41

C. ECGPAP: IMPACT ON THE LAKES

Lake Name

Distance from

the well field, m

Discharge of the wells in m3/day and drawdown after 5000 days

207360

414720

518400

725760

1036800

LakeBishoftu Guda 3025 2.68 5.36 6.69 9.37 13.39

Lake Hora 2663 0.89 1.79 2.23 3.12 4.46

Lake Bishoftu 3650 0.89 1.79 2.23 3.12 4.46


42

C. ECGPAP: IMPACT ON THE LAKES

• The result of analysis shows that the maximum drawdown created on the lakes is less than 14 meters on the nearest lake Bishoftu Guda. Here it is found possible to shift further to the east the well field by two kilometers and the draw down on Lake Bishoftu Guda decrease similar to the other lakes.

• Further Numerical modeling shall be conducted to verify this analytical calculation in the final report. The estimated exploitable resources is estimated about 378 MCM/year on site B.


43

C. ECGPAP: NEXT STAGE

• Drilling of 5 pilot wells each well discharge 100 l/s

• Detail design of 500 ha Pressurized irrigation

• Ground water modelling• Feasibility design of 10, 000 ha

pressurized irrigation


44

MAIN OUTPUTS OF THE PROJECT…

D. Interaction of Debre Zeit Lakes with the groundwater

• Hydrogeological method of analysis• Water quality monitoring• Monthly water balance of DZ lakes

(hydrologic method


45



• Hydrogeological method of analysis• Constructing a groundwater level elevation

contour: two groundwater flow regimes within Ada’a plain caused by Debre Zeit lakes and Mountain Bede Gababa which they act as a groundwater divide and Barrier to the ground water system (fig 19)

• Water Quality monitoring (fig 20)• Lake Water balance of DZ lakes (fig21)

F1


46

Fig 19 Groundwater flow paths at DZ lakes area

ÊÚ

ÊÚ

#Y

#Y

#Y

#Y

Lake chelelka

Lake Hora

Lake Kilole

Lake Bishoftu

Lake Hado

Lake Bishoftu Guda

Lake Kuriftu

1864

1884

1856

1870

1930

Mt. Guji

Mt. Bede Gebaba

Mojo

Dukem

Debre Zeyt

190 0

1800

1900

1750

1850

2000

1950

1850

1700

1750

Dire Well

Gafat well

Shimbira MedaWell

Air force well

485000

485000

490000

490000

495000

495000

500000

500000

505000

505000

510000

510000

515000

515000

520000

520000

9550

00

955000

9600

00

960000

9650

00

965000

9700

00

970000

9750

00

975000

Water Quality monitoring Bore holes#YGroundwater level elevation contour

All-weather roads (asphalt)

Motorable tracks (status uncertain)

Railway

LEGEND

1800

Groundwater f low directions

GROUNDWATER FLOW DIRECTIONS AT DEBEREZEIT LAKES AREAAND MONITORING WELLS

N

2000 0 2000 4000 Meters

Scale 1:150,000


47

Fig 20 EC versus time monitored BH (WQM)

TREND OF ELECTRICAL CONDUCTIVITY OF BORE HOLES AROUND DEBRE ZEIT LAKES FROM JANUARY 2006 TO DECEMBER 2007

0

200

400

600

800

1000

1200

1400

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

Time, months 2006-2007

EC

, mic

roS

/cm

MBI well-AdBh0038 Air force well AdBh0068

Tede Well -AdBh0040 Gafat well-AdBh0081

Dire Well-AdBh0296 DZ-Shimbra Meda Well-AdBH0064


48

Fig 21 Time series of groundwater Inflow-outflow (1000 m3)


49



• All the methods (Hydrogeological, water quality monitoring and Water balance of DZ lakes showed method the lakes except Kurftu lake acts as groundwater divide (recharge boundary) and Bede gebaba ridge as a barrier.


50

MAIN OUTPUTS OF THE PROJECT…E. Interaction of Awash river

with the groundwater• Awash river monitored two stations

(upstream at Melkakunture and down stream at Ombole river gauging stations) far apart more than 50kms. From July- September, the EC at the two stations are nearly similar (about 100µS/cm). During dry season the electrical conductivity value measured at the two stations shows larger gap (400µS/cm at Melka Kunture and 600-650µS/cm at Ombole respectively). The conductivity of the regional groundwater of the area between Melka Kunture and Ombole vary from 600 to 650 µS/cm. The higher EC value measured at Ombole site verifies the fact that the river is being recharged by regional groundwater and the base flow from November to June at this station is from the regional groundwater

Trend of Electrical Conductivity and Bicarbonates of Awash river at two Stations

0

100

200

300

400

500

600

700

800

900

1000

Jan

Feb

Mar

Apr

May Ju

n

Jul

Aug

Sep Oct

Nov

Dec Ja

n

Feb

Mar

Apr

May Ju

n

Jul

Aug

Sep Oct

Nov

Dec

Time,month- Jan 2006 -2007

Par

amet

ers

EC

in m

icro

S/c

m a

nd

HC

O3

in m

g/l

HCO3- R. Awash @ Ombole

HCO3- R. Awash @ Melka Kunture

R. Awash @t Ombole - Downstream

R. Awash @ Melka Kunture-Upstream

SN19


51

Fig 22 Interaction of Awash with the groundwater

ÊÚ

ÊÚ

ÊÚ

ÊÚ

ÊÚ

ÊÚ

ÊÚ

#·

#·

#·#·

#·

#·

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y#Y

#Y#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y

#Y#Y

#Y #Y

#Y#Y

#Y

#Y#Y

#Y

#Y

§

§

§§§

§

Aba Samuel2047

Mt. Ziquala

Mt. Guji

AMW4

AMW5

AMW12A

AMW12B

AMW24A

AMW24B

Dukem

Lemen

Boneya

Ombole

Adulala

Kondaltiti

Melka Kunture

1800

2100

1850

1650

1950

1900

1900

1750

2050

1650

1850

1700

1800

2050

2100

2000

1750

2000

1800

1950

2100

1700

1800

455000

455000

460000

460000

465000

465000

470000

470000

475000

475000

480000

480000

485000

485000

490000

4900009250

00

925000

9300

00

930000

9350

00

935000

9400

00

940000

9450

00

945000

9500

00

950000

9550

00

955000

9600

00

960000

9650

00

965000

9700

00

970000

9750

00

975000

Contours of elevation of groundwater level, masl

MAIN RIVER

RIVER

Reservoirs

LEGEND

Reservoirs

Zone grounwater dicharge to Awash river

N

4000 0 4000 8000 Meters

1:200000


52

TEM Interpretation at Inchini


53

Segno Gebeya


54

Sululta


55

Chancho


56

THANK YOUFOR YOUR ATTENTION!!

Documents

3rd Annual Connference EHA Aug. 23, 2008 1 EVALUATION AND DEVELOPMENT OF GROUND WATER RESOURCES OF ADA'A–BECHO PLAINS FOR IRRIGATION PROJECT Engida ZA