Environmental Impacts of the Akosombo Dam and Effects of Climate Change on the Lake Levels

Abstract

The Akosombo dam was constructed on the Volta river primarily for the generation of hydropower. The resultant Volta lake which was formed between 1962 and 1966 in Ghana will probably long be one of the greatest man-made lakes. It produces 912 MW of electricity at its maximum operating capacity. The Akosombo hydroelectric project (HEP) was meant among others to open up Ghana to rapid industrialization and hence modern development. Other positive impacts of the HEP include fishing, farming, transportation and tourism. However, there are equally negative impacts, some of which the project did not envisage and these are felt on the physical, biological and human subsystems within the immediate project environments and places much more distant from them. Recently, there have been declines in the lake levels resulting most probably from inadequate rainfall and/or runoff from the river catchments that feed the lake, and also from the observed rising temperatures. Comparisons of the runoff from two most important tributaries of the Volta (White Volta and Oti) for two time periods of 1951–1970 and 1971–1990 showed reductions in mean streamflows of 23.1% on the White Volta and 32.5% on the Oti. Similarly, a plot of the mean annual temperatures for the upper Volta basin indicated a 1^C rise in temperature from 1945–1993.