Suspended sediment yield and sediment concentration in dammed Karadua river in Katsina State, Nigeria

Abstract

This study examines the suspended sediment yield in response to dam and its reservoir downstream Karadua river reach in Katsina State, Nigeria. The study river basin is within the Tropical savannah of Northern Nigeria. The watershed covers a catchment area of 1838 km² and the drainage is mainly formed by a 6-order stream. The approach for this study is the comparison the data obtained above the dam river reach with the data obtained below the dam to mark down the changes in suspended sediment concentration. Results show that suspended sediment yielded the highest value of 8.55g/l above the dam, but only 1.25g/l below the dam.  The total sediment yield of the stream above the dam was 24.96 grams per litre and only 4.98 grams per litre below the dam reservoir. This yielded the monthly averages of 4.16g/l at above dam and only 0.83g/l at below dam. The study therefore, concludes that dams reduce the sediment yield of a river by holding the much turbid water after a rainstorm typical of the region, then later releases the settled water with clear variation of up to 80%. The study therefore, suggested more studies and action plan on all aspects of river basin ecosystem for proper monitoring and more detailed studies on all aspects of dams and reservoirs effects on the hydro-geomorphology of rivers and the natural environment below the dam, as well as wide coverage investigation across the country.