Land and Water Development

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Syllabus

September, 2006 iii

Land and Water Development

Introduction to the Specialisation Land and Water Development. Availability of land and

water resources on a global and regional scale to meet the present and future food

requirements. Need for land and water development in rural and urban areas. Principles of

land and water development. Economic and social incentives and history. Physical planning

and environmental impact aspects. Various aspects of water management.

5 periods

Oral discussion


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Contents

September, 2006 v

CONTENTS Page

1 INTRODUCTION 1.1

1.1 Scope of the subject and definitions 1.1

1.2 These lecture notes 1.2

1.3 References 1.2

2 NEED FOR LAND AND WATER DEVELOPMENT 2.1

2.1 Need for land and water development for agriculture in view of 2.2

population growth and sustainable rural development

2.1.1 Food supply on a global scale: past, present and outlook 2.7

to the future

2.1.2 Factors that determine crop yield 2.21

2.2 Need for land and water development for urban and industrial growth 2.23

2.3 Crucial questions 2.24

2.4 References 2.27

3 PRESENT AND FUTURE AVAILABILITY OF LAND AND 3.1

WATER RESOURCES

3.1 Land resources 3.1

3.2 Water resources 3.3

3.3 References 3.10

4 CONCEPTS OF LAND AND WATER DEVELOPMENT 4.1

4.1 Development approach 4.1

4.2 Development strategies 4.1

4.3 Development stages 4.7

4.4 Socio-economic requirements 4.11


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Contents

September, 2006 vi

Page

4.5 Environmental considerations 4.134.6 References 4.14

5 PHYSICAL PLANNING IN RURAL AND URBAN AREAS 5.1

5.1 Area and time scales 5.1

5.2 Future changes and developments 5.7

5.3 References 5.8

6 WATER MANAGEMENT IN RURAL AND URBAN AREAS 6.1

6.1 Water management 6.1

6.1.1 Factors influencing the design of water management systems 6.1

6.1.2 Flood management and flood protection 6.6

6.2 Irrigation 6.9

6.2.1 Irrigation in sloping areas 6.16

6.2.2 Irrigation in level areas 6.17

6.3 Drainage 6.19

6.3.1 Drainage in sloping areas 6.33

6.3.2 Drainage in level areas 6.34

6.4 Combined and separate irrigation and drainage systems 6.38

6.5 Basic components in urban drainage systems 6.40

6.5.1 Role of water in an urban environment 6.41

6.5.2 Review of urban water management systems 6.41

6.5.3 Properties of and requirements regarding urban water 6.44

management systems

6.6 References 6.48


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Introduction

September, 2006 1.1

The pace of change in our world is speeding up, accelerating to the

point where it threatens to overwhelm the management capacity ofpolitical leaders. This acceleration in history comes not only from

advancing technology, but also from unprecedented world

population growth, even faster economic growth, and the

increasingly frequent collisions between expanding human

demands and the limits of the earth's natural systems.

Lester R. Brown, 1996

1 INTRODUCTION

1.1 SCOPE OF THE SUBJECT AND DEFINITIONS

These lecture notes are dealing with the utilisation of natural and man made land areas and the

physical measures to make these suitable or improve the conditions for various land uses,

like:

agriculture (area of special attention);

urban and industry;

nature reserves;

recreation areas.

Land and water developmentis the technology of adapting and managing land and water

resources for specific forms of land use in rural, urban and industrial areas.

Land reclamation is dealing with the technical methods and institutional aspects of land

utilisation, given the specific conditions and potential land use of a particular natural area.

Land consolidation is dealing with the technical and institutional aspects to modify rural areas

in order to improve the land use conditions rationalise agricultural production.


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Introduction

September, 2006 1.2

1.2 THESE LECTURE NOTES

These lecture notes start with a description of the need for land and water development,

primarily for agriculture in view of population growth and sustainable rural development. The

various aspects of food supply on a global scale in the past, at present and in future will be

reviewed. This will be followed by a description of the need for land and water development

related to urban and industrial development. In chapter 3 a brief review will be given of the

present and future availability of land and water resources. In chapter 4 the various concepts

of land and water development will be reviewed, including socio-economic requirements and

environmental considerations. In addition a review will be given of physical planning aspects

in rural and urban areas. Finally the water management issues in rural and urban areas will be

reviewed, including the various aspects of irrigation, drainage and flood management, with

their interactions.

The lecture notes cover primarily hydraulic and hydrological engineering aspects of land

utilisation. Also involved are: structural engineering, soil science, agronomy, economy,

sociology, and environmental aspects and impacts.

1.3 REFERENCES

Brown, L.R., et al., 1996, State of the World 1996, The Worldwatch Institute, Earthscan

Publications Ltd., London, United Kingdom.


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Need for land and water development

September, 2006 2.1

2 NEED FOR LAND AND WATER DEVELOPMENT

Developments depend on the physical conditions at any given place.

Looking at the situation in various countries, several developments

can be distinguished, which sooner or later will ask for intensive

attention. Why certain developments occur depends on the needs of

society, how they occur can be seen as the result of the interaction of

the will to develop, vision on desired developments, available means

(capital, labour, materials), technology and management

Van Dis, 1993

In analysing the need for land and water development, for the rural areas distinction should be

made between the need caused by the increase in population and in the consumption per

person, compensation for the loss of agricultural land, and the reduction in existing yield

levels. For the urban and industrial areas, the need is caused by the rapid development of such

areas all over the world (Schultz, 1993).

There is a great need for land and water development, aiming at the improvement of living

and production conditions in the rural areas, land reclamation, and the development of urban

and industrial areas with related facilities. The projects will have to be developed and

implemented in such a way that on the one hand the objectives are realised, and on the other

hand the environmental impacts are at an acceptable level. The projects may strongly differ in

type and scale. Answers to the following crucial questions determine the living conditions of

the users for many decades:

what will be the need for development;

which level of service will be required;

what will be the role of the government;

what will be the side effects of the development.


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September, 2006 2.2

Through the history land and water development has gone through different stages. In a wet

country like the Netherlands, for example, first water management activities aimed at

reclaiming lowlands by simple small-scale drainage systems. Due to the resulting subsidenceproviding safety against floods followed this. This was initially realised by making artificial

mounds and in a later stage by building dikes (Van de Ven, 2004 and De Bruin and Schultz,

2003). Then came the stage of agricultural water management, which implied the discharge of

excess water during winter. Later it also included the provision of irrigation water for the

higher areas. In the twentieth century, the Dutch ran into a wide variety of water quality

problems, which drew much attention in the seventieth and eightieth. In the ninetieth,

attention was drawn to a wider concept of water management, called integrated water

management. In this concept, account is taken of all functions waters fulfil, including those

of nature and environment, so that these functions can be secured on the long term. In the

beginning of the twenty-first century we are still in this phase. However, in studies for future

development even the approach is based on integrated environment management.

2.1 NEED FOR LAND AND WATER DEVELOPMENT FOR AGRICULTURE IN

VIEW OF POPULATION GROWTH AND SUSTAINABLE RURAL

DEVELOPMENT

Initially man used to live from collecting, hunting and fishing. By this way of living the

density at which the system would be in balance amounted less than 1 person/km 2. Some

10,000 years ago man started with the domestication of animals and cultivation of land (most

probably in the Middle East, or China, or simultaneously). Shifting cultivation allowed for an

increase in density to 3 persons/km2.

In the period prior to the Industrial Revolution (1650 - 1750) the average population growth

amounted to only some 0.3% annually. The rate of growth of the worlds population showed a

sharp increase in the seventeenth and eighteenth century. This increase was closely related to

the Agricultural Revolution and the Industrial Revolution. The Agricultural Revolution

resulted in a change in the way of living. Before the Industrial Revolution biological energy


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September, 2006 2.3

converters controlled the supply of energy. With the Industrial Revolution fossil energy

became available to cultivate land, breed animals and to produce fertilisers. After the

Industrial Revolution the population growth raised to 3% annually. The following causes forthis explosive growth may be mentioned:

the invention of the steam engine by Watt in 1752, which can be considered as the start of

the Industrial Revolution;

the introduction of fertilisers in the nineteenth century increased crop yields tremendously,

for example for cereals from less than 1,000 kg/ha to more than 8,000 kg/ha at present;

many diseases, such as cholera, pest and small pox, common in the Middle Ages and

decimating entire populations, became controlled, or even extinguished. This also applied

to agricultural crops;

large regions in the world with a low population density, such as North America and

Australia became immigration areas. For example in the period 1846 - 1930 some 50

million people immigrated to new areas, where they introduced the new techniques of the

Industrial Revolution.

In 1804 there were 1 billion people. 2 billion was reached in 1927. By December 2005, there

were 6.5 billion people of which almost 80% lived in the developing world with an average

growth rate of 2.2%. The others inhabited the industrialised countries, with a growth rate of

0.6%. Projections for the year 2025 show an increase in population up to 8 billion people,

from which the major part is expected to take place in developing countries (Figure 2.1) (UN

Population Bureau, 2005).

The population and its growth for the least developed countries, the emerging countries and

the developed countries are given in Figure 2.2. In this figure the three categories of countries

have been identified based on the Gross National Income per capita (GNI) and the

classification as given by UNCTAD (The World Bank, 2003 and UNCTAD, 2002). GNI

being defined as the Gross Domestic Product (GDP) plus net receipts of primary income

(compensation of employees and property income) from abroad, divided by the midyear

population. The UNCTAD classification is based on factors, viz.: low national income (per

capita GDP under US$ 340), weak human assets (a composite index based on health, nutrition


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September, 2006 2.4

and education indicators) and high economic vulnerability (a composite index based on

indicators of instability of agricultural production and exports, inadequate diversification and

economic smallness). Based on these considerations the categories are: developed countries (GNI > ~US$ 14,000). Most of the countries in Western and Central

Europe, North America, the larger countries in Oceania and some countries in Asia;

emerging countries (a higher standard of living than the least developed countries as

identified by UNCTAD and a GNI < ~US$ 14,000). Most of the Eastern European

countries (including Russia), most of the countries in Central and South America, most of

the countries in Asia (including China, India and Indonesia), and several countries in

Africa;

least developed countries (based on the UNCTAD classification). Most of the countries in

Africa, several countries in Asia, 1 country in Central America and most of the smaller

countries in Oceania.

0

1

2

3

4

5

67

8

9

10

1950 1970 1990 2010 2030 2050

Figure 2.1 Growth of the world population since 1950 and medium projection up to 2050

(UN Population Bureau, 2005)

Population density is generally expressed compared to the total area of a country. If we look,

however, at the population density with reference to the arable land then the result per

Continent is shown in Table 2.1 (International Commission on Irrigation and Drainage, 2004

and Schultz, et al., 2005). From Table 2.1 it can be easily observed that the Asian continent


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September, 2006 2.5

has by far the largest population and the highest population density, both with reference to the

total area, as well as to the arable land. If we also take into account the population growth as

shown in Figures 2.1 and 2.2, than it will become clear that in the coming decades most of theactivities with respect to water management and flood protection may be expected in Asia. If

we have a closer look on a country basis than Table 2.2 shows the five most densely

populated and the five least densely populated countries with respect to the arable land.

0

2

4

6

8

10

Million

2005 2025 2050

Year

Least DevelopedCountries

Emerging Countries

Developed Countries

Figure 2.2 World population and growth in least developed countries, emerging countries

and developed countries (Schultz, et al., 2005)

The world economy is growing even faster than the population. It has expanded from US$ 4

trillion in output in 1950 to more than US$ 20 trillion in 1995 (Brown, 1996). Due to this

development the standard of living in many countries is rising rapidly. This results amongothers in an increase in consumption and a change in diet per person. This is an extra

contribution to the required increase in food production, which, together with the increase in

population results in the expectation that duplication in food production will have to be

achieved in the coming 25 years (Van Hofwegen and Svendsen, 2000).


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September, 2006 2.6

Table 2.1 Continents and types of countries ranked according to population density with

reference to arable land (International Commission on Irrigation and Drainage,2006 and Schultz, et al., 2005).

Continent Total area

in 106 ha

Arable land

in 106 ha

Total

population

in million

Population density

in persons/km2

with reference to

total area Arable

land

Asia

Africa

Europe

America

Oceania

3,177

3,032

2,299

3,997

806

558

213

297

390

53

3,911

906

729

892

33

123

30

32

22

4

701

425

245

229

63

World 13,311 1,511 6,471 49 428

Developed countries

Emerging countries

Least developed countries

3,186

8,046

2,079

375

996

140

961

4,751

759

30

59

37

256

477

541

2.1.1 Food supply on a global scale: past, present and outlook to the future

Food requirement

Agriculture has the objective to supply man with energy. The daily food requirement per

person is 10,000 kJ energy from carbohydrates (sugar) and fat and 70 g protein (including

minerals and vitamin).

In case of a vegetarian Table 2.3 gives the amount of cereals, pulses and vegetables that are

required to meet the daily energy and protein requirement. In the same table the area of land

needed to feed one vegetarian is indicated, given the average production rates in the world. So


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September, 2006 2.7

for one vegetarian about 1,600 m2 of agricultural land is needed. In other words, with present

average production rates 6 vegetarians can be fed from one hectare of agricultural land.

Presently 6 billion people have their food from 1.6 billion ha of agricultural land, whichmeans that on average less than 3 persons are fed from one hectare. The difference is, among

others, caused by the fact that most people eat meat to get protein. The production of energy

through meat is very inefficient. It requires ten times as much land to produce the same

amount of energy in the form of meat.

Table 2.2 Some characteristic data for the five most densely and five least densely populated

countries with reference to the arable land (International Commission on

Irrigation and Drainage, 2006 and Schultz, et al., 2005).

Country/

geographic unit

Total area

in 106 ha

Arable

land

in 106 ha

Total

population

in million

Population density

in persons/km2

with reference to

Economic

status *)

total area arable land

Five most densely populated

Chinese Taipei

Japan

South Korea

Egypt

Bangladesh

4

38

10

100

14

0.7

4.8

1.9

3.4

8.5

23

128

48

74

142

596

339

481

70

985

3,243

2,691

2,543

2,074

1672

D

D

D

E

L

Five least densely populated

Australia

Congo, Republic

Kazakhstan

Canada

Russia

774

34

273

997

1,708

49

8

22

46

126

20

7

15

32

143

3

12

5

3

8

42

51

68

70

114

D

L

E

D

E

*) D = Developed country E = Emerging country L = Least developed country

Regarding the actual food consumption there is a striking difference between developing and

developed countries. Per capita consumption in the least developed countries averages 180 kg

of grain per year. The same consumption in the developed countries amounts to a figure of


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September, 2006 2.8

1,000 kg (World Resources Institute, 1992).

Table 2.3 Area required to feed one vegetarian for one year for assumed average worldproduction rates

Food Amount per person

in gram/day

Average yield

in kg/ha

Required area

per person in m2

Cereals 600 1,800 1,200

Pulses 100 1,000 360

Vegetables 250 23,000 40

The best indicator for the food situation is the number of calories per capita and per day as

given in Table 2.4. The figures differ widely from one region to another. The absolute

minimum is 1,600 to 1,700 calories. Sub-Saharan Africa is only little above it. In spite of the

target set by the FAO at the first World Food Conference in 1974 to abandon hunger within

ten years world-wide, 800 million people in 88 countries suffer from acute lack of sufficient

food. Half of these countries are situated in Africa, 23 in Asia, 12 in Eastern Europe and 9 in

Latin America. Moreover, 2 billion people suffer from permanent under nourishment, which

situation may already occur for many generations. The under nourishment is caused by too

little variation in the total food package.

Cereals form the most important part of the food. Table 2.4 gives yields in kg/ha, which are

highest in Western Europe and North America and very low in Africa. There are various

reasons for this fact, one being the prevailingly low quality of the African soils.

Relation between crop yield and population growth

Until 1950 there was a close relation between crop production and size of the population. The

growth in agricultural area was more or less equal to the growth in population. If there was

not enough food, the agricultural area extended. The yield per ha remained until the beginning

of this century more or less constant. For realising the increase in yield the best soils were

selected. Thus, during calamities there was no buffer and the extent of the population


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September, 2006 2.9

declined, which was rather common in Europe, even in the middle of the nineteenth century.

An example is Ireland, where the population decreased from 8.5 million around the middle of

the nineteenth century to 4.5 million at present.

Table 2.4 Production of food and cereals in 1990 in different regions

Area Population

in million

Food consumption Cereals

cal/

cap.-day

Yield

in kg/ha

Availability

in

kg/cap.-year

Cropland/

capita

in ha

World 5,293 2,700 2,600 340 0.28

Western Europe 498 3,400 5,000 590 0.28

Eastern Europe - 4,000

Russia 288 - 1,800 680 0.81

Asia 3,109 2,400 2,600 250 0.15

North and Central

America

427 3,650 3,600 800 0.65

South America 297 2,700 2,040 270 0.49Africa 648 1,150 130 0.30

Sub-Saharan Africa - 2,100 - - -

Figure 2.3 shows that between 1950 and 2000 the agricultural area has increased by 21% and

the population growth was 123%. This would have meant starvation if the production per ha

was not increased. Figure 2.4 shows the growth in world grain production. In the period 1950

- 2000 the grain production increased by 2.6 times the production of 1950. This could be the

case because of better varieties, tillage practices, and water management. The increase in the

production per ha realised up to now can be summarised as follows:

1950 - 1960 26%

1960 - 1970 21%

1970 1980 20%


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September, 2006 2.10

Figure 2.3 Development of world grain land

Figure 2.4 Development of world grain production

0

2

4

6

8

10

12

14

16

18

20

1950 1960 1970 1980 1990 2000

Year

106

ton

0

100

200

300

400

500

600

700

800

900

1 000

k

World rain roduction in 106ton

Per ca ita rain roduction in k

0

100

200

300

400

500

600

700

800

1950 1960 1970 1980 1990 2000

Year

106

ha

0.00

0.10

0.20

0.30

ha

Total rain land in 106 haPer capita grain land in ha


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The increase in production with time is an S-shaped curve with a certain limit. In other words,

the increase in agricultural production is slowing down. Unfortunately, the increase in

slowing down of the population growth is at a much lower level than for agriculture.Although the population increase during the second half of the twentieth century is

substantially higher than the increase in agricultural area the grain production per person is

not much affected due to the increase in production per ha.

Required increase in worlds food production

The growth in population and worlds economy results in a tremendous growth in the demand

for natural resources. Since 1950 the need for grain and for the principal rangeland products -

beef and mutton - has tripled, consumption of seafood has increased more than four times and

water use has tripled. The increase in human demands for resources is beginning to outgrow

the capacity of earths natural systems. As this happens, the global economy is damaging the

foundation on which it rests. Evidence of the damage to the earths ecological infrastructure

takes the form of collapsing fisheries, falling water tables, shrinking forests, eroding soils,

dying lakes, crop-withering heat waves, and disappearing species (Brown, 1996).

Worlds food production, although steadily growing, fluctuates widely because of adverse

weather conditions, or natural disasters. The neck and neck race between food demand and

food production is presently in balance in most of the countries, while in the industrialised

countries food surpluses are found. Present problems with food shortage are mainly related to

matters of distribution and regional imbalance. During the last decades, the required global

increase in agricultural production has been realised, amongst others by the introduction of

High Yielding Varieties of rice (HYV) and the improvement of water management systems.

In this period, China, Indonesia and India, with a total of more than 2 billion inhabitants,

became self-sufficient in rice.

Urbanisation and industrialisation, erosion, desertification, waterlogging, salinization,

environmental considerations, or degeneration of existing irrigation and drainage systems are

the causes of loss of agricultural land and reduction in agricultural yields (Schultz, 1993). On


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a global scale not less than 2 billion ha are subject to deterioration. Degeneration in an

extreme and irreparable form has occurred on 9.5 million ha (5.2 million in Africa).

Urbanisation and industrialisation result in a loss of about 13 million ha cultivated landannually. In arid and semi-arid regions, the introduction of irrigation has gradually resulted in

waterlogging and/or salinization problems, so that approximately 1.5 million ha have to be

taken out of production annually. In addition, most agricultural production in the world uses

farming practices that are environmentally unsustainable. Efforts are ongoing in the

industrialised countries to encourage more sustainable practices. Environmental sound

agriculture may result in more extensive agricultural practices, or may demand for highly

advanced irrigation and drainage systems with water treatment and recycling. These

developments make it doubtful whether agricultural exploitation will remain feasible under

these conditions. Degeneration of existing irrigation and drainage systems, due to lack of

attention to operation and maintenance, is a worldwide phenomenon.

In the sixtieth half of the total growth rate in food production came from newly reclaimed

areas. This dropped to one third in the seventieth and still more in the eightieth. The rate of

reclaiming new lands was 1% per year in the fiftieth but not more than 0.2% per year in 1990.

The spectacular increase of food production in the period 1960 - 1990 was mainly due to the

expansion of irrigation, which secured 70% of the production growth in the period 1961 -

1980, the proportion for Asia being even higher.

In order to get an impression of the distribution of the present agricultural production and the

net realised export surplus, data over the period 1999 - 2004 with respect to cereals have been

collected (FAO, 1999 - 2004). Under cereals the following crops are covered: rice, wheat,

maize, sorghum and millets. Because rice is a very important crop in most of the emerging

and least developed countries separate tables are shown for rice. The data for the continents as

well as for the categories of countries are shown in the Tables 2.5 to 2.8. Table 2.5 and 2.6

show respectively the cereal and rice production in million tonnes. In the Tables 2.7 and 2.8

the net trade (export) surplus of cereals and rice is shown in million tonnes, as well as in

percentage of the own production.


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Table 2.5 World cereal production in million tonnes for the period 1999 - 2004

(FAO, 1999 - 2004)1999 2000 2001 2002 2003*) 2004**)

Asia

Africa

Americas

Europe

Oceania

1,031

112

525

385

36

996

113

531

386

35

1,001

118

518

429

40

982

115

475

434

20

997

132

559

356

39

1,024

127

554

419

36

World 2,088 2,060 2,106 2,025 2,083 2,160

Developed countries

Emerging countries


857

1,118

114

862

1,081

118

887

1,099

119

843

1,070

112

846

1,105

132

906

1,124

130

Global stock in million

tonnes

611 630 599 571 475 398

*) estimated **) forecasted

Interesting in Table 2.5 and 2.6 is that we see more or less a stable production over the past

six years in the continents, as well as in the type of countries. While in the same period the

population has grown, this implies that the global stock will have decreased. Table 2.5 and 2.6

show indeed a gradual decrease in the global stock, both for cereals and for rice.

From the Tables 2.7 and 2.8 it can be derived that the developed countries have a net trade

surplus, although it is only about 12% and 1.5% of their own production for respectively

cereals and rice. The emerging countries have a modest trade deficit of about 5% and 1.5% of

their own production for respectively cereals and rice. The least developed countries,

however, have the major trade deficit of about 38% and 12% of their own production for

respectively cereals and rice. Some characteristic average data on the cereal production are

shown in Figure 2.5 and on the rice production in Figure 2.6.


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Table 2.6 World rice production in million tonnes for the period 1999 2004

(FAO, 1999 - 2004)1999 2000 2001 2002 2003*) 2004**)

Asia

Africa

Americas

Europe

Oceania

555

17

34

3

1

545

18

32

2

1

545

17

32

3

2

517

18

32

3

1

538

18

31

3

0

556

18

35

3

1

World 610 599 599 572 592 613

Developed countries

Emerging countries


26

533

51

25

519

55

26

519

53

26

491

55

23

511

57

25

530

58

Global stock in million tonnes 136 150 148 141 116 103

*) estimated **) forecasted

Figure 2.5 clearly shows that the largest cereal production is taking place in Asia, which takes

the major share of the cereal production in the emerging countries. However, the production

in kg/inhabitant is by far the largest in the developed countries. From Figure 2.6 it can be

easily derived that by far most of the rice production takes place in Asia. The net export

surplus is in all cases marginal.

The critical issue with which the world is confronted today is the problem of how to double

the global food production in the next 25 years and to triple it with says 50 years (double

population and more food per person, especially in Asia and Africa) (Van Hofwegen and

Svendsen, 2000). It is unclear whether these production increases indeed can be achieved.

Some factors foresee well for global production - for example, improvements in the emerging

market economies of Central Europe and agreements to liberalise agricultural trade. In the

longer term, improvements in for example Russias farm economy are certainly possible.

Better control of diseases (human and farm animal) could also open up large areas of


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potentially productive farming and grazing land in Africa.

Table 2.7 Net cereal trade surplus in million tonnes (T), or in % of own production (OP)1999/00 2000/01 2001/02 2002/03 2003/04* Average

T OP T OP T OP T OP T OP T OP

Asia

Africa

Americas

Europe

Oceania

-81.1

-40.7

82.4

18.7

20.7

-7.9

-36.5

15.7

4.9

57.7

-74.0

-43.5

82.1

12.5

20.6

-7.4

-38.7

15.5

3.2

58.4

-76.8

-44.8

80.7

17.9

21.0

-7.7

-38.0

15.6

4.2

52.6

-54.7

-50.2

59.6

34.6

13.4

-5.6

-43.6

12.6

8.0

67.7

-60.0

-43.1

93.8

-6.7

18.0

-6.0

-32.8

16.8

-1.9

46.2

-69.3

-44.5

79.7

15.4

18.7

-7

-38

15

4

56

Developed countries

Emerging countries

Least developed

countries

116.9

-74.5

-41.5

13.6

-6.7

-36.4

103.5

-62.4

-43.5

12.0

-5.8

-37.0

106.4

-62.8

-45.4

12.0

-5.7

-38.2

98.2

-41.9

-53.5

11.7

-3.9

-47.6

91.7

-43.8

-45.8

10.8

-4.0

-34.6

103.3

-57.1

-45.9

12

-5

-39

*) estimated

Table 2.8 Net rice trade surplus in million tonnes (T), or in % of own production (OP)1999/00 2000/01 2001/02 2002/03 2003/04* Average

T OP T OP T OP T OP T OP T OP

Asia

Africa

Americas

Europe

Oceania

5.4

-5.2

0.9

-1.6

0.3

1.0

-29.7

2.7

-51.6

21.4

5.8

-5.8

1.2

-1.3

0.1

1.1

-33.0

3.7

-40.6

9.1

7.1

-6.6

0.4

-1.4

0.2

1.3

-38.2

1.3

-43.8

11.1

8.2

-8.0

1.2

-1.5

0.1

1.6

-44.9

3.7

-46.9

7.7

8.3

-7.7

0.0

-1.5

-0.2

1.5

-42.5

0.0

-46.9

-50.0

7.0

-6.6

0.7

-1.5

0.1

1

-38

2

-46

0

Developed countries

Emerging countries

Least developed

countries

0.3

6.3

-6.6

1.2

1.2

-12.9

0.5

5.5

-6.0

2.0

1.1

-10.9

0.2

6.1

-6.3

0.8

1.2

-11.8

0.1

7.8

-7.9

0.4

1.6

-14.4

0.6

6.9

-7.5

2.6

1.4

-13.1

0.3

6.5

-6.9

1

1

-13

*) estimated


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-200

0

200

400

600

800

1000

1200

Asia

Africa

Europe

Americas

Oceania

D

evelopedcountries

E

mergingcountries

Leastdeveloped

countries

Pr. in million ton

Pr. in kg/inhabitant

NTS in million ton

NTS in kg/inhabitant

Pr. = production NTS = net trade surplus

Figure 2.5. Some characteristic average data on the situation with respect to cereal production

-100

0

100

200

300

400

500

600

Asia

Africa

Europe

Americas

Oceania

De

velopedcountries

E

mergingcountries

Leastde

velopedcountries

Pr. in million ton

Pr. in kg/inhabitant

NTS in million ton

NTS in kg/inhabitant

Pr. = production NTS = net trade surplus

Figure 2.6. Some characteristic average data on the situation with respect to rice production

At first sight and considering the world as a whole the problem to achieve the required


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increase in food production does not look insurmountable. The objective would be realised

within an average annual growth of 2.4%. There do not seem to be reasons why such a

percentage could not be maintained in future. Two favourable factors can be observed:increase of yield and reserve of agricultural land. With respect to the yields there is no

biological reason why the global average of cereals in the year 1990 (2,600 kg/ha) could not

be doubled. Besides the cropland area of 1990 (1,500 million ha) there is a reserve of 2,000

million ha of potential agricultural land of which some 600 million ha consist of lowland. In

some areas (for instance the delta of the Mekong river in Vietnam) spectacular results have

been booked with the introduction of 100-days rice varieties enabling to raise two crops per

year avoiding critical periods of deep flooding or low flow and intrusion of sea water.

This optimistic picture is offset by a number of negative factors. First of all there is the

slowing down of the reclamation of new agricultural land. This is due to the fact that the best

areas have already been reclaimed. In Asia, for instance, it is estimated that 82% of the

potential agricultural land area is already under production. There are still large reserves of

potential agricultural land in America and Sub-Saharan Africa but for much of these reserves

the soil is marginal, being suitable only for perennial tree crops, or rainfall is unreliable.

There is much ecological opposition against conversion of the tropical rain forests (Amazon,

Yunnan forests in China, Thailand, and Myanmar) into agricultural lands. The lowlands,

which have a high potential, comprise the wetlands (swamps and marshes, lakes, lagoons, or

lower flood plains), which also form a valuable ecological asset. In recent years development

of irrigation slowed down accordingly. Whereas between 1950 and 1980 the irrigated area

increased with about 4 million ha per year, in 1990 it was only about 2 million. This reduction

of irrigation investments is the result of the fall of product prices and disappointing low yields

after the implementation of new projects. The frontiers of land resources are attained in

countries with large irrigation systems. Either the available land resources are fully developed

(Pakistan, Egypt, Japan, the Netherlands) or the costs of future expansion are becoming too

high (India, China). In developing countries there remains an unused potential of over 100

million ha of irrigable land but a substantial part of it lies outside the regions of greatest need.


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Relation water management and agricultural production

With respect to water management related to agricultural production there are broadly

speaking three agro-climatologic zones, being: temperate humid zone, arid and semi-arid

zone and humid tropical zone. In addition, in principle, four types of cultivation practices may

be distinguished, being:

rainfed cultivation, without or with a drainage system;

irrigated cultivation, without or with a drainage system.

Dependent on the local conditions different types of water management with different levels

of service will be appropriate (Schultz, 1993). In the temperate humid zone agriculture

generally takes place without a water management system, or with a drainage system only.

Supplementary irrigation may be applied as well. In the arid and semi arid zone agriculture is

normally impossible without an irrigation system. Drainage systems may be applied as well

for salinity control and the prevention of waterlogging. In the humid tropical zone generally a

distinction is made in cultivation during the wet and the dry monsoon. During the wet

monsoon cultivation is generally possible with a drainage system only, although quite often

irrigation is applied as well to overcome dry spells. In the dry monsoon irrigation is generally

required to enable a good yield.

The total cultivated area on earth is about 1.5 billion ha, which is 12% of the total land area.

At about 1.1 billion ha agricultural exploitation takes place without a water management

system (Table 2.9). Presently irrigation covers 270 million ha, i.e. 18% of worlds arable land.

Irrigation is responsible for 40% of crop output and employs about 30% of population spread

over rural areas. It uses about 70% of waters withdrawn from global river systems. About

60% of such waters are used consumptively, the rest returning to the river systems. Drainage

of rainfed crops covers about 130 million ha, i.e. 9% of worlds arable land. In about 60

million ha of the irrigated lands there is a drainage system as well. From the 130 million ha

rainfed drained land it is roughly estimated that about 15% crop output is obtained. No figures

are available of the employment of the population in these areas, but it is supposed to be about

10%, which is relatively smaller than for the irrigated areas, while a significant part of these


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areas is located in the developed countries with relatively large farm sizes.

Table 2.9 Role of water management in agricultural cultivation practices in the differentcontinents (International Commission on Irrigation and Drainage, 2006 and

Schultz, et al., 2005).

Continent Total

area

in 106 ha

Arable land

in 106 ha

Total

population

in million

Water management practice

in % of the arable land

No

system

Drainage

*)

Irrigation

**)

Asia

Africa

Europe

Americas

Oceania

3,177

3,032

2,299

3,997

806

558

213

297

390

53

3,911

906

729

892

33

56

92

74

73

90

10

2

18

17

4

34

6

8

11

5

World 13,311 1,511 6,471 70 12 18

Developed countries

Emerging countries

Least developed

countries

3,186

8,046

2,079

375

996

140

961

4,751

759

64

70

86

25

8

3

12

22

11

*) In total about 130 * 106 ha rainfed and 60 * 106 ha drainage of irrigated areas

**) Irrigation may include drainage as well

The present situation and in particular the present development trends make it plausible that

future expansion of the production will mainly be achieved by increase in yields and by

cropping intensification. Reclamation of new land will be limited to special areas, which by

virtue of location and quality are most promising for growing special crops (vegetables and

fruits) and for urban and industrial expansion. The increase in agricultural yields can be

realised through improved agricultural practices, water management, transport and marketing

facilities. Studies into the world food supply in the coming decades underline that about 90%

of the extra food should come from the present 1,500 million ha cropland of the world (World

Resources Institute, 1992 and Van Hofwegen and Svendsen, 2000). However, a certain


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amount of food about 10% - needs to be produced on new agricultural land. These new

lands can be reclaimed in upland and in lowland areas. For development of upland areas,

irrigation and sometimes also drainage will be required, whereas for development oflowlands, drainage and in most cases also irrigation will be needed.

Form Table 2.9 it can be seen that still the largest agricultural area is without any water

management system. In the rainfed areas without a water management system water

harvesting, and watershed management can make some improvements. Such measures may

undoubtedly help to improve the livelihood of poor farm families. There is, however, no way

that the cultivated area without a water management system can contribute significantly to the

required increase in food production. Due to this the share of irrigated and drained areas in

food production will have to increase. This can be either achieved by installing irrigation, or

drainage systems in the areas without a system, improvement, or modernisation of existing

irrigation and drainage systems, installation of irrigation systems in the rainfed drained areas,

or installation of drainage systems in irrigated areas. My personal estimate is that over the

next 25 years this may result in a shift to the contribution to the total food production in the

direction of 30% for the areas without a water management system 50% for the areas with an

irrigation system and 20% for the rainfed areas with a drainage system. It has to be realised

that these percentages refer to two times the present day food production. In addition it has to

be realised that it will be extremely difficult to achieve this in an environmentally sustainable

way, especially in the emerging countries.

2.1.2 Factors that determine crop yield

Factors that determine the crop yield are:

soil conditions

In the past the type of soil was governing the possibilities and constraints for agriculture.

Soils used to be divided in poor and rich soils in order to distinguish between the

nutrient availability for the crops. The introduction of fertilisers made this distinction

redundant. Nowadays good and bad soils are distinguished, indicating the suitability of the

soil for crop production in relation to water management, and tillage practices. In other


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words the soil physical conditions which determine the management of the soil are

nowadays much more important than the chemical properties (nutrient supply). The

following aspects play an important role:* water

Deep-ploughing and organic matter can improve the moisture retention in the soil;

* air

Aeration of the root zone is of importance, as most plants get their oxygen via the

roots. Aeration can be improved by drainage and improvement of the soil structure;

* temperature

The optimum temperature for most crops is between 15 and 35 oC. Temperature is an

important reason for draining agricultural land in North-western Europe. By removing

water from the soil in spring, the soil is heated at a faster rate and the cultivation of

crops may start earlier;

* nutrient supply

During the last 40 years the use of fertilisers in the world has increased by a factor 10

from 14 to 145 million tons per year. It is expected that food production will decrease

by 40% if the supply of fertilisers is abruptly discontinued;

* root penetration

The soil is the food hold for crops. Where required a good root penetration can be

realised by measures like deep ploughing, subsoiling, drainage and fertilising;

* injurious factors

Injurious factors refer to soil toxicity, soil-born diseases and the like;

CO2 concentration

For the process of photosynthesis the plant uses water from the soil, taken up by the roots,

CO2 from the air, taken up through the leaves and energy from the sun to produce sugars

(and oxygen). The CO2 content in the air affects the photosynthesis process. In green

houses the CO2 content is artificially increased. However, the natural CO2 content in the

air of 0.03% cannot be influenced, although on a global scale it shows a tendency to rise

due to the world-wide use of fossil energy and deforestation;

radiation from the sun

Radiation varies with latitude and during the year. Moreover it is influenced by the


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weather (cloudiness). Radiation determines to a large extent the agricultural production

capacities. This can be illustrated by the fact that in tropical areas three to four crops per

year can be grown whereas in temperate zones this is usually one crop per year; control of pests and diseases

The introduction of monocultures necessitated the control of accompanying pests and

diseases. Next to mechanical and chemical control, nowadays biological control is more

and more applied, because of the limited unwanted side effects. Important is also the

breeding of varieties resistant to pests and diseases;

production efficiency

Some crops show a relatively high photosynthetic efficiency, for example sugar cane,

maize (corn), sorghum and millet. Other crops are less efficient. The difference between

efficiencies is highest at low latitudes (high temperature, high light intensity);

breeding of new varieties

Introduction of high yielding varieties with favourable characteristics, such as resistance

for lodging, quick leaf growth, and favourable grain/straw ratio;

tillage practices

Present low yields are often due to a lack of knowledge and capital to realise optimal

tillage practices.

Table 2.10 shows for a number of crops the theoretical maximum yield and the target yield,

which is to be obtained on a large scale.

2.2 NEED FOR LAND AND WATER DEVELOPMENT FOR URBAN AND

INDUSTRIAL GROWTH

Due to the rapid expansion of urban and industrial areas, the percentage of people living in

urban areas increased from 30% in 1950 to 43% in 1990 (United Nations, 2000). It is

expected that this development will continue to an estimated 61% in 2030 (Figure 2.7). The

major part of urbanisation is expected to take place in deltaic and coastal areas. This means

that lands have to be prepared for new urban and industrial areas. As the suitable locations

have already been developed, this will be increasingly difficult (Oudshoorn, et al., 1999).


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Table 2.10 Potential crop yields in different climatic zones

Temperate zone (one crop) Tropics (per year)theoretical

maximum

target yield in theoretical

maximum

target yield in

in ton/ha ton/ha 106 kJ in ton/ha ton/ha 106 kJ

Cereals

Wheat 12 9 130 25 18 259

Rice 12 9 93 30 20 207

Maize (corn) 15 11 167 38 24 364

Sorghum and millet 15 11 147 40 26 347

Root crops

Potato 100 65 173 140 80 213

Cassava - - - 100 65 345

Sweet potato and yam 80 50 197 160 100 396

Legume crops

Soybean 9 7 112 20 15 240

Ground nuts 12 9 153 30 20 339

Dry beans 8 6 85 18 12 169

2.3 CRUCIAL QUESTIONS

The above shows that there is a great need for land and water development, aiming at the

improvement of living and production conditions in the rural areas, land reclamation, and the

development of urban and industrial areas with related facilities. The projects will have to be

developed and implemented in such a way that on the one hand the objectives are realised,

and on the other hand the environmental impacts are at an acceptable level. The projects may

strongly differ in type and scale. Answers to the following crucial questions determine the

living conditions of the users for many decades:

what will be the need for development;

which level of service will be required;


34/126



what will be the role of the government;

what will be the side effects of the development?

0

10

20

30

40

50

60

70

80

90

Percentage

World Africa Asia LAC MDR

1950

1990

2030

LAC = Latin America and the Caribbean MDR = More Developed Regions

Figure 2.7 Percentage of urban population

Need for development

The need for development in rural areas is generally determined by the need to increase

and/or to rationalise food production and to promote sustainable rural development. In other

words, there is a direct link between the investments to be made and the benefits to be

expected. These benefits generally include the increase in yields, but may also be expressed in

a more efficient production by better transport facilities, an improved marketing system and

sustainable development. This direct link enables planners to identify which investments may

be justified. Land and water development projects for rural areas have been generally purely

agricultural development projects. Recently also other land uses, like recreation and nature

conservation, are integrated in the plans. From a technical point of view, the questions to be

solved refer to the water management system, the infrastructure, the drinking water supply

and sewerage, and required facilities. As all physical structures need to be maintained, all

these questions have to be taken into account from a design point of view, and from an


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operation and maintenance point of view.

Investments in urban areas are generally justified by the need for areas for living, industry,and/or commercial development. In this case government investments generally have to be

repaid by the sale of land, or through taxes. These projects are more complex than projects for

rural areas, as many more components have to be developed and integrated. Another essential

difference is that investments per square metre are much higher in urban areas than those

needed in rural areas. From a technical point of view the questions to be solved refer to the

preparation of building sites, foundation aspects, storage and removal of surplus rainwater,

water supply for the green areas, infrastructure, drinking water supply and sewerage, and

required facilities. The maintenance of public facilities is generally the responsibility of the

municipality, who will levy taxes to finance the maintenance.

Required level of service

The success of a project is strongly determined by the creation of an attractive environment

for the users to initiate and continue the proposed activities (Constandse, 1988). This means

that the project has to be attractive and implies that it can be maintained adequately. From the

development projects of the last decades it can be concluded that several land and water

development projects did not improve the living conditions of the users. In the case of

improved areas, this resulted in an unwillingness or incapability of the users to contribute to

the required recovery of investments and/or operation and maintenance. In the case of newly

developed areas, this simply meant that the settlers either tried to return to their previous

living areas, or moved elsewhere.

In the design of water management systems for rural areas, the determination of the required

level of service is a complicated matter, as the interaction between water management and

crop yield is difficult to quantify. Insight in the sustainability of such systems requires first of

all insight in the expected crop yield, farm practices and the capacity of the farmers to

contribute to the required maintenance activities. Based on such information and on the

meteorological, hydrological and soil conditions, water management systems can be designed.


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Where required, a legal framework and an organisational structure have to be developed to

realise the operation, maintenance and management.

In urban areas, investments in property are generally that high, those investments in the urban

water management system are easily justified. Here, however, the level of service also

concerns various recreational facilities, like parks and sports fields, to make living in the

urban area attractive.

Role of the government

In most land and water development projects the government plays an important role, as she

initiates developments that fit in her development policy, and by preventing unwanted

developments. Concerning the technical aspects, she is in charge for land use, or development

plans, the required legal framework, standards concerning the functioning of systems, and in

many cases for the actual implementation. It will be clear that the different levels in the

government will play different roles.

Side effects of development

Each development will result in side effects. In many cases these side effects caused a lot of

trouble (Volker, 1987). It is the responsibility of the organisation in charge of the

development, to identify possible side effects and to prevent the negative ones as much as

possible. This can be realised by adapted designs, and by establishing a legal framework and

control mechanism. Some typical side effects are impact on the existing (geo)hydrological

regime, damage to existing natural values, and pollution of air, soil and water. Especially this

last aspect resulted and still results in many problems, leading to substantial costs afterwards

for cleaning what was polluted. To prevent negative side effects as much as possible, many

countries demand an environmental impact analysis and appropriate measures.


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2.4 REFERENCES

Brown, L.R., et al., 1996, State of the World 1996, The Worldwatch Institute, Earthscan

Publications Ltd., London, United Kingdom.

Bruin, Dick de and Bart Schultz, 2003, A simple start with far reaching consequences.

Irrigation and Drainage 52.1.

Constandse, A.K., 1988, Planning and creation of an environment, IJsselmeerpolders

Development Authority, Lelystad, the Netherlands.

Dis, M.M.U. van, 1993, Key-factors, Water Management in the Next Century, Address

presented during the SOTA-symposium, Royal Institute of Engineers in the Netherlands,

Division of Water Management (in Dutch), the Hague, the Netherlands.

Hofwegen, P.J.M. van and M. Svendsen, 2000, A vision of water for food and rural

development, the Hague, the Netherlands.

International Commission on Irrigation and Drainage (ICID), 2006, Updated statistics on

irrigation and drainage in the world, www.icid.org, New Delhi, India.

Oudshoorn, H., Bart Schultz, A. van Urk, and P. Zijderveld, ed., 1999, Sustainable

development of deltas. Proceedings International conference at the occasion of 200 year

Directorate-General for Public Works and Water Management, Amsterdam, the Netherlands,

23 - 27 November, 1998, Delft University Press, Delft, the Netherlands.

Schultz, Bart, 1993, Land and water development. Finding a balance between

implementation, management and sustainability, Inaugural address, IHE, Delft


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Schultz, Bart, 2001, Irrigation, drainage and flood protection in a rapidly changing world,

Irrigation and Drainage, volume 50, no. 4.

Schultz, Bart, 2001, Opening Address, 18th Congress of the International Commission on

Irrigation and Drainage (ICID), Montreal, Canada.

Schultz, Bart, C.D. Thatte and V.K. Labhsetwar, 2005, Irrigation and drainage. Main

contributors to global food production. Irrigation and Drainage, volume 54, no. 3.

Ven, G.P. van de, 2004, Man-made lowlands. History of land reclamation and water

management in the Netherlands, 4th edition, Matrijs, Utrecht, the Netherlands.

UNCTAD, 2002. The Least Developed Countries Report. United Nations Conference on

Trade and Development, Geneva, Switzerland (www.unctad.org).

United Nations, Population Reference Bureau, The 2000 World Urbanization prospects.

UNDP Population Reference Bureau, 2005. 2005 world population data sheet, Washington

DC, USA.

Volker, A, 1987, Negative Side effects of Irrigation and Drainage, Gulhati Memorial Lecture,

13th Congress of the International Commission on Irrigation and Drainage (ICID),

Casablanca, Morocco.

World Bank, 2001. Global economic prospects and the developing countries, Washington

DC, USA.

World Bank, 2003, World Bank Atlas, 35th Edition, Washington DC, USA.


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The World Resources Institute, 1992, Towards Sustainable Development, World Resources

1992 - 1993, A Guide to the Global Environment, Oxford University Press, NewYork/Oxford.


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Present and future availability of land and water resources

September, 2006 3.1

3 PRESENT AND FUTURE AVAILABILITY OF LAND AND WATERRESOURCES

Land and water resources are among the most basic elements of human life. In this chapter

some figures will be given about the present resources, the present use of these resources and

the future needs and availability of resources. It is of importance in view of the rapidly

growing population of the earth, the gradual improvement of the standard of living of a

considerable portion of the population and the deterioration of the resources. The

considerations will be focused on land resources but development of land resources to meet

the future needs cannot be carried out without the development of water resources.

The analysis that will be given is referring to global and regional entities. Because of the

uneven distribution of the resources and needs over the globe and within its regions this is not

sufficient for policy formulation and planning. This has to be carried out for much smaller and

more homogeneous areas such as hydrological units (river basins and sub-basins) and political

entities (international river basins, countries, and provinces).

3.1 LAND RESOURCES

The present agricultural area of the world amounts to some 1,500 million ha, which is 12% of

the total land area of 13,100 million ha. Presently irrigation covers more than 270 million ha,

i.e. 18% of worlds arable land. It is responsible for 40% of crop output and employs about

30% of population spread over rural areas. It uses about 70% of waters withdrawn from

global river systems. About 60% of such waters are used consumptively, the rest returning to

the river systems enabling its reuse downstream. Drainage of rainfed crops covers about 130

million ha, i.e. 9% of worlds arable land. In about 60 million ha of irrigated lands drainage

systems have been installed as well.


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September, 2006 3.2

Higher yields and higher crop intensities can only be obtained with a number of provisions,

which all require investments and entail financial problems. These are:

protection from floods; full control of water supply;

adequate irrigation and/or drainage;

advanced water management and cultivation practices;

optimum use of farm inputs;

institutional arrangements (irrigation and/or drainage associations with farmers

participation, credit systems and extension services);

modernisation of existing irrigation and drainage systems.

It is in these fields that the main obstacles are encountered in finding solutions for the future

food needs of mankind.

Land development

Land development may concern (Segeren, 1983):

reclamation of upland areas;

reclamation of lowland areas;

land consolidation.

Characteristic aspects of land reclamation

When reclamation is under consideration, the envisaged water management system and the

projected land use are of importance. The water management system depends on irrigation

and/or drainage requirements. The land use is mostly agriculture. However, lowland areas

might also be developed for urban expansions, new towns and/or industry.

Measures to be taken during reclamation of upland areas, to improve the texture of the soil

and to make it suitable for agriculture, refer to:

leaching of salts and toxic elements;


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September, 2006 3.3

erosion control;

terracing;

water harvesting.

Measures to be taken during reclamation of lowland areas, to improve the texture of the soil

and to make it suitable for agriculture, refer to:

lowering of the groundwater table;

leaching of salts and toxic elements;

soil improvement, by adding for instance lime;

application of chemicals;

landfill.

Related to the reclamation of lowland areas also the level of protection is of importance. The

level of protection depends on:

values inside the projected area: value of property and human life;

outside conditions, viz. sea, river, lake or canal.

Characteristic aspects of land consolidation

Land consolidation projects and programmes are generally executed in already cultivated

areas, which may have a long social tradition. These projects or programmes can only be

successful if they are developed and implemented in close consultation with the existing

population, which will normally also be the users. Generally these projects or programmes are

implemented at a smaller scale and over a longer time period than the land reclamation

projects.

3.2 WATER RESOURCES

Land development will not be possible without a proportionate development of the water

resources. Water is used for a great variety of purposes: irrigation and some special


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September, 2006 3.4

agricultural applications, domestic water, water in industries, navigation, recreation, and

nature conservation. In many areas there is an increasing competition between these

categories of users who have different requirements.

Water destined for irrigation occupies a special position among these categories, because it is

the largest item on the balance (70%) and this water is to a large extent irretrievable in that

most of this water does not return to the river like other withdrawals offering possibilities of

reuse.

Water resources development

Since more than 5,000 years people have tried to make use of water and to protect themselves

against it. Until about the seventeenth century various projects were implemented at a local

scale, without a clear recognition of the phenomena involved and of the side effects. Some

important events of the old history are shown in Table 3.1 (Biswas, 1972 and Postel, 1999).

The direct influence of mans water management activities concerns less than 1% of the water

resources, the fresh water lakes, watercourses, and groundwater (Table 3.2). However, the

side effects of mans activities influence almost all accessible waters on earth.

The hydrological cycle is the succession of stages, through which water passes from the

atmosphere to the earth and then returns to the atmosphere (World Meteorological

Organisation, 1974). Nearly all the precipitation falling on the land is derived from the

oceans. Only 10% of it originates from evapotranspiration from the land surface. Within the

hydrological cycle a cycle of water diversion, including water consumption through irrigation

and domestic water supply and drainage, exists. This branching cycle - expressing the

influence of man - is exerting significant influence on the primary hydrological cycle (Figure

3.1).

In studies on water resources development, water balances and possible changes by mans

activities play an important role. Several types can be distinguished, like the water balance of


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September, 2006 3.5

the earth, of the human-social sphere, of a river basin, or of a local area, like a city or a polder.

An important unit in water resources studies is the river basin. Water balances of river basins

may show large differences. Discharges range from less than 15% of the precipitation for theriver Nile in Egypt, to 70% for the Orinoco River in Venezuela. Initially, water balances and

the influence of mans activities were only studied from a water quantity point of view; in

some cases salt balances were made as well. Nowadays, there is an increasing requirement to

include all relevant quantity and quality aspects in water balance studies. These studies should

result in such an approach for land and water development projects, that they will be

technically and economically sound, and will result in a sustainable development and

exploitation of the concerned water resources (United Nations, 1992).

Table 3.1 Some recorded ancient hydraulic engineering events

(Biswas, 1972, Postel, 1999 and Fahlbusch, ed., 2001)

Date (BC) * Event

4000

3200

3000

2690 - 2950

2750

2200

1750

1700

1300

750

714

Irrigation in the plains between Tigris and Euphrates rivers in a place called Eridu

Reign of King Scorpion in Egypt. First recorded evidence of an irrigation system in

Egypt

King Menes constructed a dam along the Nile to protect the city of Memphis

Sadd-el Kafara dam built in Egypt probably for drinking water and irrigation. The

worlds oldest large dam

Origin of the Indus Valley water supply and drainage systems

Various waterworks of the Great Y in China

Water codes of King Hammurabi

Josephs Well near Cairo, nearly 100 m in depth

Irrigation and drainage systems in Nippur

Marib and other dams in river Wadi Adhanah in Yemen

Qanat system gradually spread to Iran, Egypt and India

* In the absence of accurate information, several of these dates are approximate

In relation to land and water development projects, the meteorological factors precipitation

and evapo(transpi)ration are of special importance. For precipitation this regards the annual

rainfall, the distribution over the year, and the short-term intensity. In case the difference


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September, 2006 3.6

between precipitation and evapo(transpi)ration is negative, it determines the need for an

irrigation system. In case of a surplus, it is decisive for the total amount of water to be

discharged. The short-term rainfall extremes are important in the design of drainage systems.Depending on the ratio between the rainfall intensity and the interception and infiltration

capacity of the soil, all the rainfall can infiltrate, or part of the rainfall is stored on the surface

and may cause overland flow. In the urban areas infiltration is much lower or even zero, as a

part of the soil is covered by streets, houses and squares, so there is a quick discharge.

Table 3.2 Amount of water on earth according to the survey conducted within the

international geophysical year (Holy, 1982)

Water incidence 103 km3 % of total

water

% of fresh

water

World oceans

Salt lakes and inland seas

Icebergs and polar ice

Water in atmosphere

Water in plants and living organisms

Fresh water lakesWater courses

Soil and subsurface water

Groundwater

1,300,000

100

28,500

12

1

1231

65

8,000

97.2200

0.0080

2.1360

0.0010

0.0001

0.00900.0001

0.0050

0.6200

-

-

77.630

0.035

0.003

0.3350.003

0.178

21.800

Fresh water total

Water total

36,700

1,337,000

2.7700

100.0000

100.000

-

With respect to groundwater, the unsaturated zone and the saturated zone can be

distinguished. The conditions in the unsaturated zone, like actual moisture content, wilting

point, field capacity and saturation are of importance for the growth of dry food crops.

Related to water management soils show a wide variety. For example, the average porosity

may range from 5% for limestone to 45% for clay, and the permeability from 10-4 m/day for

certain clay soils to more than 200 m/day for gravel. These differences influence the

suitability of the various soil types as well as the design criteria for field irrigation and

drainage systems.


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September, 2006 3.7

Evaporation

90%

Branching cycle

Land

interchange

Water vapour

Precipi-

tation

Water vapour in

atmosphere above land

Water vapour in

atmosphere above ocean

Ocean

Runoff

into ocean

Precipitation

Evaporation

10%

Intake of

water

Drainage

Water users

Water

consumption

Figure 3.1 Scheme of the hydrological cycle with the branching cycle, expressing the

influence of man (Rodda and Matalas, 1987)

All the rainwater that falls on the earth and is not evaporated, transpired, or withdrawn

artificially, contributes to the flow of the rivers. Dependent on different components, like the

size of the river basin, the slopes in the terrain and soil texture, the discharge to the river

differs. Depending on mans activities, the quality and quantity of water that enters the rivers

may differ as well. Rivers can transport natural, or artificial components. The load can differ

in relation to the discharge. Both quantity and quality of the river water will determine if it is

useful for irrigation or domestic water supply.

Table 3.3 indicates for 1990 and 2025 the estimated and projected volumes of available

renewable water resources and water use by continent. Table 3.4 shows the estimated and

projected global water use by sector in 1950, 1990 and 2025. As can be seen from the tables

on a global scale the use is only a small percentage of the resources and it seems that there is

still a considerable reserve to meet the future needs. However, since the resources are formed

by the river runoff not all that water can be used. Only a certain percentage can be abstracted,

the remaining has to be drained off to the sea during floods and a minimum flow to the sea

has to be maintained during other periods. On the other hand the possible contribution from

groundwater comes in addition.


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September, 2006 3.8

Table 3.3 Estimated and projected volumes of available renewable water resources and

water use by continent, 1990 and 2025 (Shiklomanov, 1997)Available renewable water

resources

Water use

Area 109

m3/year

m3/person

in 1990

m3/person

in 2025

1990

with-

drawal in

109 m3

1990

consump-

tion in

109 m3

2025

with-

drawal in

109 m3

2025

consump-

tion in

109 m3

Africa

North America

South America

Asia

Europe

Australia and

Oceania

4,047

7,770

12,030

13,508

2,900

2,400

6,180

17,800

40,600

3,840

3,990

85,800

2,460

12,500

24,100

2,350

3,920

61,400

199

642

152

2,067

491

29

151

225

91

1,529

183

16

331

836

257

3,104

619

40

216

329

123

1,971

217

23

World 42,655 7,800 4,800 3,580 2,196 5,187 2,879

For industrialised countries like France and the UK the annual water use is about 550 m 3 per

person. In these countries there is relatively little irrigation. In Egypt the only water supply for

agriculture is by water from the Nile corresponding with 1,200 m3 per person for year-round

irrigation and withdrawal of water for industrial purposes is only 5%. Assuming that in the

forthcoming five decades irrigation and industrialisation will expand all over the world it

seems reasonable to ascertain that as a world average the water use for all practical purposes

will be equivalent to about 1,000 m3 per person per year against the present figure of 660 m3.

Considering that the world population is supposed to double in fifty years and the readily

available resources are about half of the figures in Table 3.3 it is evident that on a global basis

the water resources will still be sufficient but that more or less severe water shortages may

occur in certain regions. These are North Africa (Maghreb and Egypt) and the Middle East

followed by Southeast Africa. In some regions such as North Africa and China and parts of

South America there is a growing competition for both land and water from the industrial and


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September, 2006 3.9

urban sectors. On the other hand there are regions where water resources will remain plentiful

for many decades to come, such as South America (Amazon) and Middle Africa. This,

however, will require regulations to cope with the uneven seasonal distribution of the riverflow. So far this has only been achieved on a relatively small scale.

Table 3.4 Estimated and projected global water use by sector in 109 m3 /year for 1950,

1990 and 2025 (Shiklomanov, 1997)

Item 1950 1990 2025

withdrawal consump-

tion

withdrawal consump-

tion

withdrawal consump-

tion

Agriculture use

Industrial use

Municipal use

Reservoirs

1,124

182

53

6

856

14

14

2,412

681

321

164

1,907

73

53

3,162

1,106

645

275

2,377

146

81

Total 1,365 894 3,580 2,196 5,187 2,879

World population in

millions

2,493 5,176 8,284

Irrigated area in 106 ha 101 243 329

More than 45,000 large dams and an estimated 800,000 smaller ones have been built around

the world, the major part in the period 1955 - 1990. The total effective capacity of these

basins is more than 5,000 km3, which is 12.5% of the runoff of all rivers of the globe

(ICOLD, 2006). This percentage is due to the fact that most of the largest rivers of the world

(Amazon with 18% of this total, Congo, Brahmaputra, Mekong, Orinoco) are not, or hardly

exploited. Much opposition exists for reasons of environmental concern, or resettlement

issues against building of new major dams.

3.3 REFERENCES


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Biswas, A.K., 1972, History of hydrology, 2nd edition, North-Holland publishing company,

Amsterdam/London, the Netherlands/Great Britain.

Fahlbusch, H., ed., 2001, Historical dams, International Commission on Irrigation and

Drainage (ICID), New Delhi, India.

Holy, M, Irrigation systems and their role in the food crisis, ICID bulletin, volume 31, no. 2,

July 1982.

International Commission on Large Dams (ICOLD), 2005. Data on web site: www.icold-

cigb.org

Postel, S., 1999. Pillar of Sand. Can the irrigation miracle last? W.W. Norton & Company,

New York, USA and London, Great Britain.

Rodda, J.C. and N.C. Matalas, 1987, Water for the future. Hydrology in perspective, IAHS

Publication no. 164, Proceedings of the Rome Symposium, April 1987, International

Association of Hydrological Sciences, Wallingford, Great Britain.

Segeren, W.A., 1983, Introduction to Polders of the World, Polders of the World, Final report,

International Institute for Land Reclamation and Improvement, Wageningen, the Netherlands.

Shiklomanov I.A., 1997, Assessment of water resources and water availability in the world.

UN report: Comprehensive assessment of freshwater resources of the world. St. Petersburg,

Russia.

United Nations, 1992, Agenda 21, chapter 18, Protection of the quality and supply of

freshwater resources: application of integrated approaches to the development, management


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and use of water resources, Conches, Switzerland.

World Meteorological Organisation (WMO), 1974, Guide to Hydrological Practices, 3

rd

edition, WMO publication no. 168, Geneva, Switzerland.


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Concepts of land and water development

September, 2006 4.1

4 CONCEPTS OF LAND AND WATER DEVELOPMENT

4.1 DEVELOPMENT APROACH

In general, land and water development projects have to fit into the development policy of a

country or a region. Land and water development projects may strongly differ in type and

scale. This refers to the reclamation and development of new areas, as well as to the

improvement of existing areas. Various development approaches can be followed. Distinction

can be made in:

large scale rapid development;

small-scale gradual development.

Another distinction in approach exists between:

directly based to the final stage;

step wise development.

For the different approaches it has to be taken into account that a project will have to follow

various stages, and should include the socio-economic and environmental consequences of the

proposed development.

4.2 DEVELOPMENT STRATEGIES

Different development strategies have been followed and may be followed in the

improvement of existing areas, or the reclamation of new areas (International Commission on

Irrigation and Drainage, 2005).

For the improvement of existing areas, the following aspects play a role:

role of the government;

determination of improvement options;


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Concepts of land and water development

September, 2006 4.2

consultation with the users;

institutional reforms and cost recovery;

land ownership.

Regarding the reclamation of new areas, the possible approaches regard the following aspects:

role of the government;

installation of the physical infrastructure;

identification of future users;

establishment of new institutions.

Improvement of existing areas

Role of the government

In the improvement of existing areas the government generally plays a guiding role during the

whole process. In the case generally different levels of government will have to co-operate,

with their different responsibilities.

Determination of improvement options

In

Documents

Land and Water Development