Assessing the Impacts of Climate Change on Streamflow in Malaba River Catchment, Uganda

Abstract

Malaba River in Uganda a focal area to the Lake Kyoga basin is prone to climate change because of its heavy reliance on rainfall as its major flow contributor. The impacts of climate change on streamflow in Malaba River were assessed using LARS-WG downscaling model and Soil and Water Assessment Tool (SWAT) model. This was achieved by downscaling the future (2020-2050) precipitation and temperature variables for A1B and A2 scenarios and simulating the projected climate with calibrated LARS-WG and SWAT models for the two scenarios. The SWAT calibration (1992 - 1999) and validation (2000 - 2004) NSE results were respectively 0.55 and 0.35. Results indicated that the projected areal rainfall will increase by 0.34 mm per year for A1B which is averagely 1% less than the baseline period. Areal rainfall for A2 scenario will increase by 0.41 mm per year which is averagely 9% more than the baseline period. The Flow Duration Curve analyses indicated that the A2 scenario displayed higher flows for all the percentiles as compared to the baseline flows while A1B scenario has lower flows for percentiles less than 50, and equal or slightly higher flows for percentiles greater than 50 as compared to the baseline flows.