West Africa–Water Resources Vulnerability Using a Multidimensional Approach: Case Study of Volta Basin
Changes in climatic conditions have been evident over West Africa in the past decades. Decrease in rainfall amount led to severe droughts during the 1970s and 1980s. There has been a shift of the climatic zones in a southerly direction. Consequently, most of the Volta Basin in Burkina Faso is now located in the Sahelian and Sudano-Sahelian zones. As a consequence of instability in the rainfall pattern, many rivers have dried up, large tracts of land cover have been degraded, and the water table is drawing down. It has been estimated that 340 km3 of rain must fall on the catchment before runoff occurs at significant levels. This indicates that small changes in rainfall could have dramatic effects on runoff rates. For instance, a rainfall decreased by only 5% from 1936 to 1998 resulted in a runoff decrease by 14% (Andreini et al. 2000). Hydropower dams such as that in Akosombo are therefore vulnerable to even small long-term exclusions of rainfall and, by extension, all socioeconomic activities and already climatic-stressed or water-sensitive ecological systems dependent on these projects. Extreme droughts cause severe land degradation and crop failures. High rainfall that leads to flooding can destroy crops and infrastructure. The unpredictability associated with rains could lead to high risk in agriculture investments and other water-related livelihoods.