Impact of Climate Change on Hawassa Lake Level Fluctuation

Abstract

One of the most important consequences of climate change is the changing nature of climate variables such as temperature and precipitation. This in turn leads to change in the hydrological cycle influencing the components of water balance of drainage basins by affecting the availability and distribution of water resources in space and time, stream flow, and Lake Level. In such circumstance, proper simulation of water resources and demands of the basin is needed to find effective solutions for saving the Lake. As a result, this study is intended to assess the impact of climate change on Hawassa Lake level fluctuation in the Central Rift Valley River Basin of Ethiopia. To achieve this objective, Water Evaluation and Planning (WEAP) Model were used to simulate water resource system of the Lake Hawassa catchment and to assess the impact of climate change on the Lake level. The performance of the model was assessed through calibration process of streamflow and lake level resulting NSE 0.93 and 0.9 respectively. Based on this, two Hypothetical scenarios were used to project future temperature and precipitation changes in the Lake catchment for the period of 2013 to 2035. Besides, the result from the two scenarios reveals that, a wetter and drier climate is anticipated for the lake catchment. In each scenario, the water resource implications were compared to the year of 2012 as a baseline for simulation. The results of projections indicates that, evaluation of the climate changes impact on Lake level fluctuations with Dry and Wet scenario the Lake level will reach 3.6m below and 3.72m higher than the observed level respectively by 2035. As a result, the simulation outcome reveals that both scenarios have a considerable impact on the Lake level fluctuation. Generally, the finding reveals that, global warming which is caused by climate change in the basin is a potential problem for effective water management in the Lake Hawassa catchment. Therefore, properly managing the consumption of the lake’s water resource is desirable particularly and for other lakes in the basin generally.