Sediment Discharges from Ghanaian Rivers into the Sea

Information on sediment yield of a river basin is an important requirement for water resources development and management. In Ghana, data on suspended sediment yield are limited owing to lack of logistic support for systematic sediment sampling activities. The paper presents the results of a study, using measurements of suspended sediment transport for 21 monitoring stations in southern Ghana to develop simple predictive models for suspended sediment yields of catchments for which no sediment measurements had been undertaken. Regression analysis was used to establish a relationship between specific suspended sediment yield and both the mean annual runoff, and the drainage basin area. One of the prediction models was used to estimate the sediment loads of the southern Ghana rivers and total suspended sediment discharges into the sea, in addition to specific suspended sediment yields from the drainage basins. The specific suspended sediment yield for the south-western and coastal basin systems ranged between 11 and 50 t km–2 year–1. The annual sediment discharges into the sea by the rivers ranged between 15,000 and 1.2 × 106 t, and total yearly sediment discharge into the sea by Ghanaian rivers is estimated to be 2.4 × 106 t.