Assessing the impact of rainfall and temperature variability on surface water resources: A case study of Manafwa Catchment.

Abstract

This study focused on assessing the effect of variability in rainfall and temperature on surface water resources in Uganda, more specifically, the Manafwa sub-catchment because research on local climate variations especially at catchment level in the country are lacking. Such studies are limited by the lack of publicly available and current data on rainfall and temperature. This study aimed at analyzing and understanding the relationship between rainfall and temperature and its possible effects on the surface water resources, particularly in terms of discharge in this catchment area. In order to do this, rainfall, maximum temperature and minimum temperature data from 1990 to 2019 was statistically analyzed using RStudio and monthly average, seasonal variation and annual variation graphs were plotted whereas the discharge data was compared with rainfall and also simulated using a HEC-HMS model for better trend analysis. The results showed that the rainfall, maximum temperature and minimum temperature variations have a general non-statistically significant trend thus they are within the normal variability. The discharge levels measured from the outlet varied depending on the soil properties, land use and catchment characteristics together with the rainfall received in the area. The implications of this study can be used for planning food security, planning agriculture and water supply together with sustainability of water resources.