The role of the Akosombo Dam on the Volta river in causing coastal erosion in central and eastern Ghana (West Africa)

Abstract

Sediment supply from the Volta river in West Africa is greatly affected by the Akosombo Dam built recently on the river. Approximately 99.5% of the river drainage basin is now blocked by the dam, and the river is at present supplying to the shoreline only a minor quantity of sand derived from the low-lying areas of coastal plains below the dam. The effects of the reduction of the river's contribution in changing shoreline position in central and eastern Ghana were examined by comparisons of the average rates of shoreline retreats determined from aerial photographs and maps during the periods before and after dam construction. Construction of the dam does not have any effect on coastal change in the areas which did not receive sand from the river before dam construction. In the areas where river contribution was a major process, the effects are manifested by an acceleration of shoreline retreat.