Modelling Hydrological Impact of Climate Change on Lake Hawassa Watershed, Southern Ethiopia

Climate change refers to variations in the mean state of climate or variability of its properties such as rate, range and magnitude that extends for a long period due to external influences. The sign of climate change and its impact is revealing on different natural and manmade systems directly or indirectly. In this study, hydrological impact of climate change on Lake Hawassa water balance components was estimated in response to the A2a and B2a emission scenarios. Hydrological impact of climate change on Lake Hawasa water balance components were estimated in response to the A2a and B2a emission scenarios. Observed and future climatic variables were used to verify the hydrological impact. The future climate variables were predicted by using General Circulation Model (GCM) which is considered as the most used tool for estimating the future climatic condition. Statistical Downscaling Model (SDSM) was applied in order to downscale the climate variables to watershed level. Then, hydrological model soil and water analysis tool (SWAT) was applied to simulate the water balance components and calibrated by SWAT CUP (calibration uncertainty program) with sequential Uncertainty Fitting, Version 2 (SUFI-2) algorithm. The simulation result revealed that, by 2020s, the total average annual inflow volume into Lake Hawassa will rise significantly up to 6.14% for A2a and 5.9% for B2a-scenarios.