CLIMATE CHANGE PROJECTIONS AND IMPACTS ON FUTURE TEMPERATURE, PRECIPITATION AND STREAM FLOW IN THE VEA CATCHMENT, GHANA

Abstract

Climate change has emerged as a global challenge with varied impacts across regions. The Vea catchment, for instance, is identified as particularly susceptible to climate change due to its location and ecological fragility. This study projects climate change’s impact on the area’s temperature, precipitation, and stream flow. Data on temperature and precipitation obtained from the Ghana Meteorological Agency were augmented by incorporating precipitation data from twelve satellite sources using CHIRPS data with a 0.05′ (5km) resolution to complement the existing in-situ datasets. The temperature data for the satellite station was sourced from the NASA power project. Modelled climate data from six GCMs, considering SSP 4.5 and SSP 8.5 emission scenarios, were retrieved from the CMIP6 data portal. R software facilitated the extraction of NetCDF-format GCM data to Excel format, and CMhyd was applied for downscaling GCM data. Temperature and precipitation bias correction utilized the variance and local intensity scaling methods, respectively. The statistical significance of changes and trends in temperature, precipitation and stream flow was determined using the Mann-Kendall (MK) method. The results indicate that temperature is expected to increase on average between 2.10 and 3.5◦C under SSP4.5 and between 2.7 and 4.15◦C under SSP8.5. For SSP4.5, the anticipated decrease in annual average precipitation ranges between 12.34 and 13.1%, while SSP8.5 projects a decrease of 12.6 to 13.6%. Under SSP4.5 and SSP8.5, the projected annual average stream flow will decrease by 28 to 37% and 36 to 42%, respectively. These findings suggest the need for the formulation of long-term water resource management strategies, and existing strategies should be strengthened to address the impact of climate change on the catchment.