The impact of climate and land-use changes on the hydrological processes of Owabi catchment from SWAT analysis

Study region: The 69 km2 Owabi catchment in Ghana. Study focus: The Soil-Water-Assessment-Tool (SWAT) was used to assess the hydro-climatic variability resulting from anthropogenic activities from 1986 to 2015. Specifically, the model simulated historic and projected stream-flow and water balance. Future stream-flow projections were modelled for three climate ensembles under three different representative concentration pathways (RCPs) for two land-use categories. New hydrological insights for the region: Initial results revealed that forest and topography played major role in water loss, whereas evapotranspiration and surface runoff were the dominant modulating processes. Monthly calibration/validation of the model yielded acceptable results with NSE, R2, PBIAS and RSR values of 0.66/0.67, 0.67/0.67, 8.2%/8.0% and 0.59/0.58 respectively. Uncertainty was fairly low and the model enveloped about 50% of the observed stream-flow. The RCP projections for all land use categories showed decreasing rainfall and streamflow trends. The model proved efficient in determining the catchment hydrology parameters and has potential to be used for further modelling of water quality and pollution to aid in effective water management. Keywords: Hydro-climate, Stream-flow, Water resource management, Climate change, SWAT model