Rainfall and temperature changes under different climate scenarios at the watersheds surrounding the Ngorongoro Conservation Area in Tanzania

Abstract

Considering the high vulnerability of Northern Tanzania to climate change, an in-depth assessment at the local scale is required urgently to formulate sustainable adaptations measures. Therefore, this study analyzed the fu- ture (2021-2050) changes in rainfall and temperature under the representative concentration pathways (RCP4.5 and RCP8.5) for the watersheds surrounding the Ngorongoro Conservation Area (NCA) at a spatio-temporal scale relative to the observed historical (1982-2011) period. The climate change analysis was performed at monthly and annual scale using outputs from a multi-model ensemble of Regional Climate Models (RCMs) and statistically downscaled Global Climate Models (GCMs). The performance of the RCMs were evaluated, and the downscaling of the GCMs were performed using Statistical Downscaling System Model (SDSM) and LARS-WG, with all the models indicating a higher accuracy at monthly scale when evaluated using statistical indicators such as corre- lation (r), Nash-Sutcliff Efficiency (NSE) and percentage bias (PBIAS). The results show an increase in the mean annual rainfall and temperature in both RCPs. The percentage change in rainfall indicated an increase relative to historical data for all seasons under both RCPs, except for the June, July, August and September (JJAS) season, which showed a decrease in rainfall. Spatially, rainfall would increase over the entire basin under both RCPs with higher increase under RCP4.5. Similar spatial increase results are also projected for temperature under both RCPs. The results of this study provide vital information for the planning and management of the studied watershed under changing climatic conditions.