Geremew Sahilu (PhD)Girma Amare2026-10-132026-10-132016-10https://etd.aau.edu.et/handle/123456789/9131The effect of climatic change and environmental degradation has caused the reduction of water level in Lakes, rivers and streams. For instance, Lake Chad in Chad, Abiyata, Hawassa, Ziway, and Haromaya are good examples. However, the water level of Lake Besaka has been rising for more than three decades. The surface area of the Lake has been expanding from 3 km2 to 46.6 km2 between 1973 and 2008 with corresponding to rise in Lake water Level (Goerner et al. 2009). The main cause for the increase in Lake water level and its surface area is the inflow of groundwater from the western part of the watershed. The average annual increment of Lake water level was 0.2 m and hence the Lake had risen by four meters between 1976 and 1997 (Goerner et al. 2009). The expansion and flooding effect of Lake Besaka has become the cause for the loss of 57 human lives, inundation of about 35km2 of grazing land, and displacement of 910 indigenous people. Methara sugar plantation has also been inundated and the company lost income from 161.55 ha of land (WWDSE 2011). The damages to the nearby railway line and highway caused a loss amounting to 2.6 million US$ (Tessema; Ayenew 2008). The expansion of Lake Besaka have still continued and severely affecting the life of the surrounding community and also becoming the contaminant to Awash River. To minimize the expansion rate of the Lake, Awash Basin Authority had installed six surface pumps of 1.7m3/sec capacity and had been pumping water from the Lake and released to Awash River (WWDSE 2011). However, the pumps were fully submerged due to high inflow and consequently the Lake continued to expand and submerge public infrastructures and becoming a contamination fear to Awash River. If Lake Besaka discharges to Awash River by itself without any control, the river is going to be contaminated forever (Wiliam Davison 2013). Despite, many researchers have conducted studies to mitigate the expansion Lake Besaka and proposed options to maintain the water quality of Awash River, there was no clear demarcation yet put that sustainably mitigate the crisis. However, this research aimed to answer how it is possible to sustainably Control the Expansion Lake Besaka, and maintain the water quality of Awash River through generating hydroelectric power. The research focused on solar energy to pump the Lake Water and generation of hydroelectric power while releasing the pumped water from upper reservoir to Awash River with safe blending ratios.enSolar-Hydroelectric EnergyExpansionLake BesekaEthiopiaThesis