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close this bookReversing the Spiral - The Population, Agriculture, and Environment Nexus in Sub-Saharan Africa (WB, 1994, 320 p.)
close this folder10. Managing the natural resource base
View the documentProduction versus protection
View the documentForests
View the documentNatural resource management in farming areas
View the documentDryland and range areas
View the documentWater
View the documentCommon elements
View the documentThe role of governments
View the documentNational environmental action plans


As noted in Chapter 2, water is a critical resource in limited supply in large parts of Sub-Saharan Africa. Conflicts over competing uses are already evident in many cases. In some areas, groundwater reserves are being drawn down for irrigation much faster than they can be replenished. Damming and diversion of rivers for irrigation or hydropower development have often created serious problems downstream. These include the spread of waterborne and water-related diseases, intrusion of saltwater into groundwater aquifers in coastal areas, destruction of riverine woodlands and of wetlands of importance as wildlife habitat, destruction of downstream fisheries and of coastal wetlands critical for marine life and migratory birds, and coastal erosion. Water pollution from domestic sources has become a major concern in many areas, particularly around major cities, but also in countless rural areas where lack of safe potable water is the most serious public health problem In some regions' pollution from agrochemical is emerging as a problem, as it already is in other parts of the world.

With the primary exceptions of parts of coastal West Africa and the Congo/Zaire River basin and adjoining parts of humid Central Africa, most of Sub-Saharan Africa is not endowed with abundant water. Moreover, only a portion of total potentially available water is actually accessible and usable. Geographical distribution of supplies, seasonal and annual variations inflows, topographic conditions, and evaporation losses drive a large wedge between potentially available end realistically accessible water. Conflicting demands on water use and environmental considerations pose further constraints on the utilization of water (Falkenmark and Suprapto 1992:3334). In Europe, water management problems began to be encountered when water demand exceeded 20 percent of potential water availability (Falkenmark 1991:88-89). Water quality is an important consideration as well. Not all sources of water are suitable for all uses, and water impurities and pollution car, severely limit the range of uses to which a particular source of water can be put.

Demand for water is rising rapidly' driven by population growth and economic development Except for the humid regions of Central and coastal West Africa, almost all of Sub-Saharan Africa will be facing water shortages or water scarcity early in the next century. In many of the arid regions, this is already the case—particularly during the dry season. WHO has suggested an average of 30 liters per capita daily (or about 11 m3 per person annually) as the minimum needed to ensure adequate hygiene for urban populations in developing countries. Industrial water requirements depend very much on the size and type of industries; in industrialized countries, these requirements considerably exceed household consumption) even though the latter surpass the WHO standard cited above five to ten times.

Agriculture is, and will continue to be, the largest consumer of water. In dry climates, the photosynthesis process consumes about 1,000 m3 of water to produce one ton of biomass (Falkenmark and Suprapto 1992:31). Depending on agroecological factors (crops grown, soil characteristics, evapotranspiration rates, etc.) and on technical efficiency, feeding people by means of irrigated agriculture requires anywhere from 500 rn3 to 2,500 m3 of water per capita per year.

For many SSA countries, the water that can be utilized at reasonable cost with available technological means will not be more than about 250 m3 per capita annually by the year 2025, and for some (such as Kenya, Burundi, Rwanda, Malawi) it may be as little as half that amount. This has important implications for the agricultural and overall economic development strategies these countries will need to pursue. It certainly underscores the urgency of initiating effective water resource monitoring and planning and of maximizing efficiency in water use.

The many different uses of water can be variably grouped, depending on the objective of the analysis. One categorization distinguishes between consumptive, nonconsumptive, and polluting uses (Frederiksen 1993.24-25). Another differentiates between withdrawal uses and instream uses. Water used by households and industries and for watering livestock and irrigated crops represents withdrawal uses. Instream uses include water flow for fisheries and wetlands, for maintaining downstream water quality, for water transport, and for recreational uses. Power generation may involve instream uses (for hydropower generation) or withdrawal uses (for cooling thermal and nuclearpower plants). While some instream uses are compatible with others, most demands for different water uses compete with each other and, insituations of increasing water scarcity, imply important tradeoffs and potential conflicts.

This points to the urgent need for effective hydrological planning and for prudent demand management which involves planning, regulation. technology, and pricing. Demand rnanagement means allocating among alternative uses, encouraging conservation, and protecting instream flow and water quality. Market mechanisms alone will not be adequate: ".. the nature of the resource makes it difficult and in many cases impossible to establish efficient markets" (Frederick 1993:23). Well-de fined and transferable property rights are usually missing and very difficult, if at all, to establish. The full benefits and costs of a water transfer are not likely to be borne by the buyer and seller, because there are multiple and important externalities. And rarely will there be multiple and competitive suppliers of water, since the nature of the resource makes water supply a natural monopoly (Frederick 1993:24-25).

Water must be recognized as the critical and limiting resource it is. It must be carefully allocated, beginning with the development of local and regional water use plans, and it must be protected against pollution. Project by-project and sector-by-sector planning for water uses (water and sewage services, irrigation, flood control, hydropower, navigation, fisheries, industrial uses, and so forth) is prone to lead to conflicting and inefficient investment decisions. In the absence of prices for water that reflect its scarcity, planning must be based on natural hydrological units such as river basins to ensure that the opportunity costs associated with different water uses are properly considered. Such planning should be integrated with planning for land use and other activities that affect, and are affected by, water development Water management plans will need to assess water availability against likely demand (taking into account anticipated population growth and urban/industrial development) and develop options for water supply (including costs) as well as options for demand management and conservation.

Given the frequent occurrence of drought, many water sources in semiarid and arid parts of Sub-Saharan Africa are very vulnerable to wide annual variations in flow volume and, hence, in supply. In these regions, water use plans must allow adequate margins for safety and establish clear priorities among competing uses. In many arid and semiarid regions, water supply constraints will imply that large-scale irrigation cannot be the first priority in allocating water among different uses. Where this is not recognized, capital investments designed to abstract surface or groundwater for irrigation and to develop land for irrigated farming may later need to be abandoned as the requirements for human and livestock use increase.

Water resources frequently are shared among countries. This underscores the importance of close cooperation in planning for long-term water sharing if riparian disputes are to be avoided.

The economics of water supply are important Many irrigation and water supply schemes are excessively costly—and uneconomic. Conservation efforts on currently used supplies or demand management through more rational water charges can obviate expensive new investments in water supply, especially for irrigation. Water user associations should be given much greater management responsibility in operation and maintenance of rural potable water supply schemes as well as in irrigation systems.