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 caseparticularly 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
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 costlyand 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