IMPACT OF CLIMATE CHANGE ON THE GROUNDWATER HYDROLOGY OF LAKE ZIWAY WATERSHED, ETHIOPIA

Abstract

Climate change poses uncertainties to the supply and management of water resources. The relationship between the changing climate variables and groundwater is more complicated and poorly understood. Groundwater resources are related to climate change through the direct interaction with surface water resources, such as lakes and rivers, and indirectly through the recharge process. The impact may be worse for developing countries like Ethiopia because of their economies are strongly dependent on basic forms of natural resources. This thesis presents the likely impact of climate change on groundwater hydrology of Lake ziway watershed located in the Rift Valley basin of Ethiopia, The RCP scenarios of types 4.5, and 8.5 were used for the climate projection from the CORDEX Africa domain from CMIP5. The RCM of RCA4 was used to generate future possible local meteorological variables in the study area. These data were used as input to the Soil and Water Assessment Tool (SWAT) model to simulate the corresponding future streamflow Variability in the Ziway watershed. SWAT-CUP, a program for calibration and uncertainty was utilized for uncertainty analysis. The two projected time periods for this study were the 2040s, and 2070s. In the Lake Ziway watershed, there exists a climate change in the study period of 1989-2019. Since, there is a significant change from the base period to the projected time periods, therefore there would exist a climate change impact for the projected time periods under both scenarios in the Lake Ziway watershed. Therefore, climate change shows a significant decreasing impact on the groundwater flow of Lake Ziway watershed, which in turn affects the level of Lake Ziway significantly