Geospatial Water Resources Allocation Modeling and Prognostic Scenario Planning in Lower Benue River Basin, Nigeria.

Water allocation management in an equitable and sustainable way is intrinsically complex. Climate change and managerial policy have further adversely altered the hydrologic cycles thus, threatens to worsen the current supply-demand imbalance. This study was conducted in Lower Benue River Catchment in the North Central crevice of Nigeria, to assess the consequences of climate change due to changing rainfall patterns in the area and proposes different prognostic scenarios adaptation on the current and future water allocation sharing in the area. The Soil and Water Assessment Tool (SWAT) was interfaced with Map window - Geographic Information Systems (GIS) for the basin hydrological modeling to assess the impact of the watershed characteristics on runoff and subsequent quantification of the catchment water yield before been allocated optimally based on percentage dependable flow rates of 70% and 85% reliability flow regime at Makurdi, Nigeria discharge station. Furthermore, the Water Evaluation and Planning tool (WEAP) model was used for the water resources utilization simulation and adaptation scenarios by the different riparian users. The SWAT model performed satisfactorily for streamflow and water yield prediction both in the calibration and validation phases with a R-2 of 0.57-0.68 and RSR of 0.66-0.82, while the WEAP model calibration and validation at the same station with rainfall data posted a R-2 of 0.64 and 0.89. Planners and decision-makers on water resources allocation, therefore, need to consider several integrated plans as alternatives to the adaptation to climate change impacts and anthropogenic activities in resolving the unmet demands.