Evaluating the effectiveness of best management practices under climate change scenarios in gilgel gibe-1basin-Ethiopia

Gilgel Gibe 1 hydropower reservoir is highly threatened by siltation/sedimentation problem due to excessive erosion from the upper catchment. To mitigate the serious erosion from the upper catchment and reduce the sediment delivered to the reservoir so as to increase the life span of the project, implementing a suite of best management practices (BMPs) is needed. However, as climate changes, the effectiveness of the BMPs will be affected. Hence, understanding the effectiveness of the best management practices as climate changes will be important for better planning of watershed management. The objective of this study was to evaluate how the BMPs performance varies due to changes in precipitation and temperature using the Soil and Water Assessment Tool. Sediment loads from the whole watershed was estimated on the annual basis before and after implementation of agricultural BMPs. Climate change data were obtained by the delta change method. The Soil and Water Assessment Tool model was calibrated using Sequential Uncertainty Fitting 2(SUFI2) to simulate the sediment load. The results of the study indicate that the BMPs tested are sensitive to climate change. Therefore, further investigations should be made and caution should be exercised in the decision making process.