Cost effectiveness of sediment management strategies for mitigation of sedimentation at Jebba Hydropower reservoir, Nigeria

In this study, a calibrated hydrologic model, Soil and Water Assessment Tool (SWAT) interfaced with Geographical Information System (GIS) tool was used to study the effect of different sediment management methods in a watershed (12,992 km2) upstream of Jebba Lake, Nigeria. Sediment management strategies considered are (i) reforestation of the watershed, (ii) application of vegetative filter strip (VFS) and (iii) construction of stone bunds. Cost analysis of implementing the selected erosion control measures within the watershed was also carried out to compare the cost effectiveness of each of the management strategies. The results showed that application of VFS, reforestation, and stone bunds to critical zones of the watershed reduced the sediment yield up to 65.6%, 63.4% and 12% respectively while the financial analysis of implementing reforestation, VFS and stone bunds revealed 84.9%, 73.3% and 70.5% reduction respectively in the costs to be incurred if sediments are allowed to accumulate in the dam. From this analysis, it can be concluded that the sediment management scenarios considered in this study are cost effective and sustainable when compared with the costs incurred in tackling the effect due to reservoir sedimentation. Overall, the study showed that hydrological models such as SWAT can be used to study strategies for water resource management. In addition, it can provide policy makers the decision support tools to evaluate the cost and benefits of adopting Best Management Practices (BMPs) particularly for sediment control in erosion prone watersheds.