Balancing water resources development and environmental sustainability in Africa: a review of recent research findings and applications

Abstract

Sustainable development in Africa is dependent on increasing use of the continent's water resources without significantly degrading ecosystem services that are also fundamental to human wellbeing. This is particularly challenging in Africa because of high spatial and temporal variability in the availability of water resources and limited amounts of total water availability across expansive semi-arid portions of the continent. The challenge is compounded by ambitious targets for increased water use and a rush of international funding to finance development activities. Balancing development with environmental sustainability requires (i) understanding the boundary conditions imposed by the continent's climate and hydrology today and into the future, (ii) estimating the magnitude and spatial distribution of water use needed to meet development goals, and (iii) understanding the environmental water requirements of affected ecosystems, their current status and potential consequences of increased water use. This article reviews recent advancements in each of these topics and highlights innovative approaches and tools available to support sustainable development. While much remains to be learned, scientific understanding and technology should not be viewed as impediments to sustainable development on the continent.

Fig. 1

Regional averages of annual mean precipitation for three regions of Africa illustrating differential drying of the continent during the latter decades of the 20th century. Black bars are based on 1930–1995 data from the Climatic Research Unit of the University of East Anglia (Hulme 1992). More recent annual mean data (1979–2005) depicted by the solid red line come from the Global Precipitation Climatology Project (Huffman et al. 1997). The separation between the solid green and dashed red horizontal lines depicts the shift in annual means during the two time periods considered. From Giannini et al. (2008); used with permission

Fig. 2

Rainfall seasonality patterns based on monthly accumulated rainfall estimates from the Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis (TMPA) for 1998–2010 (Huffman et al. 2007). The predominant patterns are a single wet season (1 WS unimodal or bimodal) north and south of the humid tropical rain belt and a dual wet season (2 WS unimodal–unimodal) in eastern tropical Africa. Other more complex seasonality patterns also occur in isolated areas. From Herrmann and Mohr (2011); used with permission

Fig. 3

Regional averages of precipitation from 1950 to 2100 as simulated in IPCC 4AR. Gray lines depict results of individual models while the heavy black line depicts the multi-model mean. 2000–2100 simulations based on A1B scenario. From Giannini et al. (2008); used with permission

Fig. 4

Simulated annual transpiration water fluxes related to rainfed (a) and irrigated (b) crops in the years 2000 and 2050, reflecting expected agricultural expansion and intensification in western, eastern, and southern regions. Simulations for 2050 are based on Policy First and Security First scenarios of the UNEP Global Environmental Outlook-4 Report (GEO-4) (Rothman et al. 2007). Policy First is a more optimistic scenario based on a high level of international cooperation in development and implementation of strong policies to protect the environment while pursuing economic growth. Security First is a more pessimistic scenario with less cooperation and more intense resource exploitation and fewer environmental protections. From Weiss et al. (2009); used with permission

Fig. 5

Location of 135 large dams (≥500 000 m³) and 1072 secondary dams (<500 000 m³) based on data from FAO-Aquastat. From Darwall et al. (2011); used with permission

Fig. 6

Richness of threatened species based on occurrence in countries, including fish, odonates, crabs, molluscs, and plants. Areas with the largest concentrations of threatened species include high-biodiversity equatorial regions and areas of western, eastern, and southern Africa targeted for increased dam building and water abstractions. From Darwall et al. (2011); used with permission