IS LARGE-SCALE PUBLIC IRRIGATION THE WAYFORWARD FOR SUB-SAHARAN AFRICA? - Sustainable Irrigation Development in the White Volta Sub-Basin - page 78

deprivation of livelihoods (Konings, 1986). Records show that in some large
irrigation schemes, families residing on the schemes had the lowest food
production for home production (Niemeijer et al., 1985; Diemer, 1988).

4.2.2 Environmental Impact of Large-Scale

Irrigation in sub-Saharan Africa

The development of large reservoirs and irrigation schemes has come at the
environment's expense, degrading ecosystems and reducing water supplies to
wetlands. Large-scale irrigation is also associated with higher prevalence of
malaria, schistosomiasis and other waterborne diseases (Faurès et al., 2007).
The incidence of malaria has increased due to the development of large-
reservoirs for irrigation which serve as breeding ground for mosquitoes
(Keiser et al., 2005).
The environmental impact of irrigation development arises from the
withdrawal, storage and diversion of water from natural aquatic ecosystems
and the resultant changes to the natural pattern and timing of hydrological
flows (Rosenberg et al., 2000). Rivers have in many instances become
disconnected from their floodplains and from downstream estuaries and
wetlands resulting, in some instances, in total and irreversible wetland loss
(Faurès et al., 2007; MEA, 2005).
Wetland water quality has deteriorated in areas under high-intensity
irrigation (MEA, 2005). Nutrient loading primarily from fertilizers (nitrogen
and phosphorous) applied to irrigated areas is one of the drivers of ecosystem
change, resulting in eutrophication, hypoxia and algal blooms (Faurès et al.,
2007).

4.2.3 Challenges facing Large-Scale Irrigation in

Africa

It is important to understand the challenges that large-scale irrigation
schemes face. These challenges are described as problems that should be
considered during the design, development and operation of the large
irrigation schemes. The most prevalent sources of failure are design and
technical flaws, management failures, and political difficulties. Together,
these failures have led to far higher than expected costs and lower than
expected benefits (Moris and Thom, 1990).
One of the important reasons given to the low performance of sub-Saharan
Africa's formal irrigation schemes is that irrigation projects designed by
outsiders frequently assume that people will show the interest and
motivation one would expect from farmers, when in reality these conditions