Hydro-Geomorphological Assessment of River Bank Erosion and Channel Change in the Benue River, North Central Nigeria

Riverbank erosion and channel change in the Benue River represent dynamic geomorphological processes with direct consequences for floodplain settlements, farmland, infrastructure integrity, and sediment budgets in the North Central geopolitical zone, yet systematic empirical documentation of channel change rates and driving mechanisms remains sparse. This study conducts a hydro-geomorphological assessment of bank erosion dynamics and planform change along a 120-kilometre reach of the Benue River from Makurdi to Idah, covering Benue and Kogi States. Multi-date satellite imagery from 1990, 2000, 2010, and 2023 was used to map channel centreline position, width, and sinuosity using DSAS in ArcGIS, quantifying migration rates and planform change over three decades. Field surveys at 18 bank erosion sites measured bank geometry, material properties, and evidence of mass failure or fluvial undercutting. Hydrological analysis of peak discharge records from Makurdi gauge station identified statistical relationships between flood magnitude and annual bank migration rates. Sediment budget analysis incorporated estimates of bank material contribution to the channel bedload and suspended load. Results document lateral channel migration of up to 42 metres in the most dynamic meander bends over the study period, with migration rates accelerating significantly in the post-2010 decade coinciding with increased peak discharge magnitude linked to Lagdo Dam operations in Cameroon. Bank material erodibility is highest in sandy bank sections where protective riparian vegetation has been removed for agriculture. The study contributes original empirical data to Nigeria's river geomorphology literature and provides input parameters for flood and erosion risk assessments. Keywords: bank erosion, Benue River, channel change, geomorphology, North Central Nigeria.