Sustainable management of erosion prone areas of upper watershed of Kainji hydropower dam, Nigeria
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Date
2018-05-05
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Abstract
Reservoir sedimentation has been a major concern to stakeholders around the world in the implementa
tion of sustainable management of hydropower dams. Not only that it reduces the storage capacity of
reservoirs, several sediment related problems such as reduction in water quality and acceleration of abra
sion of underwater parts can impair the primary purpose of which the reservoir is built. Therefore, sus
tainable management of watersheds upstream of hydropower dam is necessary to combat the issues of
sedimentation and to extend its useful life. In this study, Soil and Water Assessment Tool (SWAT) was
interfaced with MapwindowGIS to model and predict sediment yield and concentration into sub
basins of the upper watershed of Kainji hydropower dam in Nigeria which has an area of 30,350 km2.
The model was run daily for 30 years and performance evaluation was carried out using Coefficient of
Determination (R2) and Nash Sutcliffe Efficiency (NSE). Model calibration and validation as well as iden
tification of erosion prone areas were equally achieved. The results showed that average annual sediment
yield and concentration were 35.29 t/ha/year and 11,903.7 mg/l respectively. Application of filter strips
on critical erosion prone region showed that sediment yield and concentration could be reduced up to
37% and 34% respectively. Also, construction of stone bunds in the watershed showed a reduction of
up to 75% and 84% for sediment yield and concentration respectively. The outcome of this study could
allow control effort to be focused effectively on an area identified as extreme cases and could also be used
by relevant authorities in prioritizing implementation of Best Management Practices (BMPs) for the area.