Small hydropower dam site suitability modelling in upper Benue river watershed, Nigeria

Small hydropower (SHP) is one of the most critical renewable energy that is well adapted to the rural localities in less developed countries across the world. Most rural communities in Nigeria are off the national power grid and are bedevilled by an inconsistent supply of electricity. The one possible panacea to the rural energy crisis is harnessing the terrain and abundant rivers and streams within their domain. This study aimed to identify and select suitable sites for the SHP dam in the upper Benue river watershed. Ten thematic layers, land use, precipitation, geology, soil, slope, elevation, stream power index, topographic wetness index, drainage density, and flow, were integrated with Geographic information system and Analytical hierarchy process. A composite suitability map created revealed that 7.5% of the watershed is of a very high suitable class, while 17.5% of the watershed is of a very low suitable class. To select an ideal location, a semi-automatic approach was developed to identify narrow valleys by intersecting contour with stream order and the suitability layer. Eighteen (18) potential dam sites were identified after a query operation was done. The developed method was validated using field data which were correlated with the model output using t-Test; paired two samples for the mean. A strong Pearson correlation of 0.71 between the field data and the semi-automatic approach was observed. The approach offers good prospects for dam site selection. Based on a field survey, the potential dam sites are feasible economically and technically for SHP dam construction that will provide cheap renewable energy to millions of inhabitants in the watershed.