Assessment of Sediment Transport and Erosion Along the Benue River Corridor in Benue State

The Benue River experiences significant bank erosion and sediment transport that affects the flood regime, infrastructure, and agricultural land in Benue State, North Central Nigeria. This study assesses sediment transport dynamics and bank erosion rates along a 40-kilometre reach of the Benue River in Makurdi LGA. Suspended sediment load was measured using depth-integrated sampling at three cross-sections over 12-month deployment periods. Bed material samples were collected for particle size analysis. Photogrammetric analysis of historical satellite imagery at five-year intervals from 2003 to 2023 was used to quantify bank migration rates. Bank material erodibility was assessed through pinhole and crumb tests. Results indicate mean annual suspended sediment concentrations ranging from 680 to 1,240 mg/L, with peak transport during July to September. Bank migration rates average 2.8 metres per year on the outer bend of meander sections, with maximum rates of 6.4 metres per year at the most active erosion zones. Bank failure occurs predominantly in silty clay soils with low cohesive resistance. Sediment budget calculations indicate net channel aggradation downstream of the most active erosion reaches. The study recommends bank protection works using gabion mattress revetment at the three highest erosion rate locations and a comprehensive bank stabilisation and monitoring programme for the Makurdi reach.

Keywords: sediment transport, bank erosion, Benue River, fluvial geomorphology, Benue State