Assessment of the Impacts of Climate Change on Some Hydrological Processes of The Densu River Basin, Ghana

Abstract

Water resources are among the most sensitive sectors to climate change due to their direct relationship with climate variables. The current study used projected climate datasets under two Representative Concentration Pathways (RCPs), 4.5 and 8.5, from the Coupled Model Intercompersion Project Phase 5 (CMIP5), remote sensing and Soil and Water Assessment Tool (SWAT) to estimate the effect of projected climate change on some hydrological processes. We focus on rainfall, water yield, soil water storage and evapotranspiration in the Densu Rvier Basin (DRB) for the 2050s. After calibration and validation of the SWAT model, there was a strong correlation between the simulated and the observed stream discharge coefficient of determination (R²) of 0.84 and 0.77, and a Nash Sutcliffe Efficiency of 0.76 and 0.70 for calibration and validation, respectively. The results showed an annual mean increase of 2 ºC in temperature, 61% in evapotranspiration and 20.1 mm in rainfall amount by the 2050s compared to their baseline values. Even though the mean annual soil water storage increases by about 80 mm, water yield declines by about 23 mm by 2050s. This appears to be due to the disproportionate increase in evapotranspiration compared to increase in rainfall. In conclusion, the DRB is projected to experience an overall reduction in water yield.