Climate Change Impact on Water Resources; The case of Tono Irrigation Dam in Ghana

Abstract

West Africa (WA) in recent past experienced decreasing rainfall and increasing temperature. A preliminary assessment of these trends in the future (2025-2045) was conducted to evaluate its potential impact on water resources, specifically the Tono irrigation dam in Ghana. The climate change assessment was based on future climate data of Representative Concentration Pathways (RCPs) 4.5 and 8.5 projected with ECHAM6 model and downscaled by the Weather Research and Forecasting (WRF) model in reference with historical data (1990-2010). A 2-domain configuration was used: an outer domain at 25 km horizontal resolution encompassing the West African Region and an inner domain at 5 km horizontal resolution centered on the Tono basin. The assessment was done based on the annual mean, relative percentage change and spatial seasonal change of the simulated precipitation and temperature. The results show that for precipitation, both scenarios do not agree on the signal of change. RCP4.5 indicates an increase (+7%) in annual precipitation amount whereas RCP 8.5 indicates a decrease (-9.6%). For temperature, both scenarios agree on increasing temperature. These results shows that future streamflow will be influenced by climate change. The indications are that the flows will reduce does the dam levels will also reduce does affecting irrigation activities. This studies therefore provides information to the managers of Tono irrigation dam what measures to put in place for its sustainability.