1.Chapter 0 Introduction to Water Resources Prof. Dr. Ali El-Naqa Hashemite University June 2013

2. The blue Planet How come we lack of sufficient Water Supply? 2 ??? Source: http://omiusajpic.org/files/2011/05/2935018067_cec6254493.jpg [Accessed: 30.01.2012] Source: http://true101story.com/wp- content/uploads/2010/04/eath-hands.jpg [Accessed: 30.01.2012] 3. What is Water Used For? 3 Agricultural Irrigation Livestock farming Industrial Production of goods and energy Transportation of goods Process water Domestic Drinking water Food preparation Sanitation Personal hygiene Cultural asset Gardening, Car wash ECOSYSTEMHUMANUSE Plants Animals Photosynthesis SoilsAquatic Systems 4. Think in Cycles rather than in linear Processes 4 he Global Water Cycle The energy of the sun constantly transforms the water from solid (ice) to liquid (water) to gaseous (vapour) Constant transformation puts the water into motion and hence activates the global water cycle Characteristics of the cycle: Permanent circulation Renewable resourceSource: OWENS (2006) 5. The blue Planet? 70% of the earths surface is covered by water. (PIDWIRNY 2006) 2.5% is freshwater whereas a fifth is easily accessible for human use. (INFORESOURCES FOCUS 2006) only 0.5% of global water resources are usable 5 3. Freshwater Resources Source: WBCSD (2009) 6. Disparities Distribution of freshwater resources is characterized by strong regional differences annual and seasonal variation (WWAP 2003) Water Scarcity Index 6 Freshwater Distribution Source: REKACEWICZ (2009) 7. We do influence the hydrological Cycle substantially Main drivers for the increasing pressure on water resources: Population growth Increasing living standards Urbanisation Influences On the Water Cycle in Cities 7 Human Influence on the Water Cycle Source: AUCKLAND CITY COUNCIL (2010) 8. Where the Water ends up being used The consumption pattern of water use is influenced by: Living standards Climate conditions Composition of water use in different countries 8 Source: WBCSD (2009) 9. Increasing Water Scarcity 9 Consequences of Water Use Drivers: Population growth Change in living standards Uncontrolled pollution Climate change Growing water scarcity in various regions of the world As of today, 1.2 billion of the worlds population are affected by water scarcity (INFORESOURCES FOCUS 2006) (WBCSD 2009) 10. What are drylands? Different people define drylands in different ways. In terms of the absolute amount of rainfall. For example, the Convention to Combat Desertification defines drylands as areas with between 0 and 600 mm of rainfall per year, depending on altitude and latitude. In terms of the length of the wet season and the temperature. For example, areas with less that three months of enough moisture to support plant growth, and with an average temperature of at least 80 Fahrenheit (27C). By comparing the annual rainfall with the amount of potential evapotranspiration (roughly, the amount of water that evaporates from a pond or a well-irrigated field in one year). One definition is those areas wherethe rainfall is less than 40% of the potential evapotranspiration. 11. What are drylands? In terms of vegetation. Drylands are areas where conditions favour perennial grasses rather than annual cereals. Rainfed cropping therefore has an inherent risk of failure. In terms of land use. Some farming systems are more sensitive to drought than others: for example, cattle in wetter areas may not eat dry grass during a drought. Pastoralists may regard grazing areas as drylands, in contrast to the wetter areas, usually highlands, where crops are grown. 12. What are drylands? The definition of dryland varies from country to country. For example, most of Uganda has relatively high rainfall. If the maize crops fail once in five years, people regard the area as dryland. Such a definition is of little use in countries such as lowland Kenya or Ethiopia, where rainfall levels are generally much lower. Some 80% of Kenya is classified as dryland. Some areas normally regarded as wet may in fact be dryland. For example, not all the East African highlands are wet. Certain areas on the shores of Lake Victoria lie in a rain shadow and receive only 600 mm of rain a year. There is no firm boundary between dryland and wetter areas. One grades into the other, and the boundary changes from year to year. Prolonged drought, unseasonal rains and other climate changes may mean the area expands or contracts. 13. Categories of drylands Drylands are not homogeneous: different categories exist. Understanding this is important to identify whether opportunities exist to change or develop the dominant pastoral production system. Two broad types of dryland can be distinguished: arid and semi-arid; and subhumid, wetter drylands. The dividing line is often put at 600 mm of rain per year 14. Arid and semi-arid drylands In these areas rainfall is the limiting factor for the condition of the vegetation. The number of cattle grazing has no lasting negative effect on the vegetation. Overgrazing is not a problem. Droughts, when they occur, cause the cattle to die, keeping numbers down. The vegetation is very resilient; even after a serious drought, it is able to restore itself. The concept of carrying capacity does not apply. In these areas, pastoralists and their livestock dominate. It is not advisable to replace the pastoral production system as it already uses all available resources to a maximum. 15. Wetter drylands In these areas the condition of the vegetation depends on the number of cattle. Overgrazing may occur when their numbers exceed the so-called carrying capacity. This damages the vegetation, which is not able to regrow after a serious drought. Despite the high risks, the wetter drylands are increasingly used to grow crops. It may be possible to develop new land-use systems that combine various uses. The aim should be to develop a system that is more productive than the pastoral system it replaces. 16. Characteristics of drylands Natural capital Rainfall The rainfall is low, erratic and scattered, and is concentrated in a few heavy storms. The rains may be delayed, and droughts are frequent. Rains may occur at times when they do not benefit crops in the field. Soils The soils are thin and easily eroded. They are low in organic matter (less than 2%) and dry out quickly. Some soil types occur only in dryland areas. Within the drylands there are scattered patches with better soils or a wetter climate. Vegetation The vegetation is sparse, leaving a large proportion of the soil surface exposed. This allows rain to compact the surface, forming a crust which stops water from seeping into the soil. The water runs off instead, causing erosion and flash floods. 17. Characteristics of drylands Physical capital Infrastructure There are few roads, and permanent settlements are sparse. Markets, abattoirs and food storage and transport facilities are poorly developed. Irrigation from groundwater or dams has converted some otherwise dry areas to more productive cropland while preventing pastoralists from grazing their animals on this land. Farming systems The major dryland crops are sorghum, pearl millet, finger millet, short-season maize, cowpeas and haricot beans. In wetter areas or land with irrigation, farmers also grow cassava and pigeonpeas for local consumption, and beans and Asian vegetables for export. Livestock herders keep cattle, sheep, goats, camels and donkeys; sedentary farmers may also keep chickens. Camels, goats and donkeys are hardier than cattle and sheep. 18. Characteristics of drylands Human capital Indigenous knowledge Pastoralists have a rich store of indigenous knowledge about their environment and animals, how to predict drought, where to find pastures and water, and how to prevent and treat livestock diseases. Indigenous sedentary farmers have equivalent knowledge about their crops and soils. However, new settlers may not be as familiar with the problems and opportunities in the drylands. Education Most people in the drylands are poorly educated. Illiteracy rates are high, especially among women. Children often attend boarding schools in the towns, and may be reluctant to return to their original lifestyles after graduating. Dropout rates are high. 19. Characteristics of drylands Social capital Lifestyles The majority of people depend directly on the land. There are two broad groups: nomadic or semi-nomadic pastoralists, and sedentary farmers who grow crops. Pastoralists and sedentary farmers may belong to different ethnic groups, each with its own culture. However, pastoralists and crop farmers are not necessarily distinct: agropastoralists may also grow crops in addition to keeping livestock, and crop farmers also keep livestock and may move with them if required. Mobility Pastoralists, in particular, are highly mobile. They move with their herds in search of grazing and water. They take advantage of the scattered rainfall in a way that no other production system does. They pay little attention to government, and often cross district and international boundaries. 20. Characteristics of drylands Financial capital Poverty The vast majority of both pastoralists and sedentary farmers are poor. They have limited cash. Pastoralists tend to have more capital (in the form of animals) than do sedentary farmers. A few people are wealthier: they own larger herds or more (or more fertile) land. Income sources Pastoralists are commercially oriented: they sell animals in order to buy food (grains, sugar, tea) and things they cannot make themselves (cooking utensils, clothes), to pay school, veterinary and medical fees, and to buyfood in an emergency. However, pastoralists often lack a market for their animals. Crop farmers are more subsistence-oriented: they grow most of their own food. Many men seek employment in the cities for at least part of the year. 21. Characteristics of drylands Changes in the drylands Population The human population is rising, both by natural increase and by immigration from more densely populated high-potential areas. This puts extra pressure on the limited resources. Intensive cultivation degrades the soils, and overgrazing depletes the ground cover. Climate In recent years, the climate has been in a state of flux. Droughts have become more frequent, and rains fall at unusual times of the year. These changes may be caused by global warming. Land use and ownership Settlers erect fences and encroach on traditional grazing lands. Irrigation schemes are built in areas with better soils, which are often the same areas used by pastoralists as dry-season grazing. Common land is increasingly claimed as private property, encouraging a change from pastoralism to crop farming, and removing the best land from the pastoralists. Powerful, city based individuals have grabbed large tracts of land 22. Water Water is the principal limiting factor. The low, unreliable rainfall means that often very little moisture is available for plant growth. The rains may start on time but then stop again, killing seedlings. Or the rains may be late, making the season too short for sustainable growth during the crucial phase of flowering. Recurrent droughts cause frequent crop failures. Farmers respond by using various ways to conserve rainfall and store it in the root zone. 23. Soil and water conservation A significant percentage of rainwater in dryland areas is lost as surface runoff. Much of the rest evaporates or percolates deep into the ground where plant roots cannot reach it. Plants quickly absorb the little moisture still in the soil, and soon the ground becomes dry, incapable of supporting crops. Erosion is a related problem.Dryland soils are often thin, have poor soil structure, are low in organic matter and are bare of vegetation. Crusts form on the surface of many soils, reducing the amount of water that can seep into the soil. The water runs off easily, forming gullies and carrying valuable topsoil with it. 24. Soil and water conservation 25. Soil and water conservation Crop farmers cannot afford to lose the little moisture and soil there is, so they have for centuries used indigenous conservation techniques. These range from stone terraces in mountainous areas to tillage practices in flat areas. They focus on conserving moisture to improve crop yields. However, the main priority (from the farmers viewpoint) is higher production, with soil conservation coming second. Only crop farmers are willing to invest in conservation measures; pastoralists are not very interested because they are mobile. Degradation of grazing lands is a problem in wetter areas with many people and livestock, and around communal watering points. Degradation is caused by continuous grazing and tracking, shifting cultivation, indiscriminate cutting of trees and uncontrolled burning. 26. Soil and water problems, and some ways to address them 27. Irrigation Rainfall in the drylands is usually not enough to guarantee reliable, steady production of crops. So some kind of irrigation is helpful, either to provide extra water to a rainfed crop, or to water a second crop during the dry season. If water is available, the dryland climate favours irrigated crops. High temperatures stimulate plant growth. Pests are few due to the low humidity. The extended dry season and the lack of a winter enables growers to produce crops when demand is high in the export market. 28. Soil and water conservation For small-scale crop farmers, irrigation may mean the difference between a secure harvest and no yield at all. There is a wide range of traditional small-scale irrigation practices, mostly along small rivers in mountainous terrain, along riverbeds, using residual moisture in valley bottoms, or tapping shallow groundwater. Farmers using these practices use very few external inputs and often show a remarkable talent for improvisation when confronted with new situations. New techniques, such as drip irrigation (page 104) and manually operated treadle pumps, have shown promise on small farms ranging from small gardens (1530 m2) to over 1.5 ha. Irrigated areas are generally small, from under 1 ha to 2040 ha. Most farmers own less than 1 ha of irrigated land. The fields are located as close as possible to the source of water. 29. Water sources Irrigated farming is very different from rainfed farming. In rainfed farming, the farmer prepares the field and waits for the rain to come and make the crop flourish. With irrigation, the farmer must obtain and manage the water. This can take a lot of time and money. The cropping pattern is closely related to the amount of water and how it is obtained. The size of the irrigated area depends on how much water is available. Small perennial or seasonal rivers are the main sources of irrigation water. Water can be lifted directly from the river, or diverted into irrigation canals or pipes using dams or weirs. Wells can be dug to tap groundwater, which can be lifted up by hand or with pumps. In some places, it is possible to tap water beneath dry stream beds. Rain and runoff water can collected and stored in small reservoirs or tanks 30. Global Water Resources Only this portion is renewable saline (salt) water: 10 to 100g/L (34g/L) brackish water: 1 to 10g/L (treatable) Fresh water: 1700 m3/c/yr Water stress: