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.