Abstract:The hydrological component of the soil and water assessment tool (SWAT) model is adapted for two Ethiopian catchments based on primary knowledge of the coherence spectrum between rainfall and stream flow data. Spectrum analysis using the available nearby climatic data is made to limit the temporal and spatial scales (inverse rate coefficients) subject to the calibration of compartmentalized runoff models. The exclusion of unwarranted time scales in the calibration implies that the model efficiency (r 2 values) decrease only moderately between calibration and validation, and the optimization is focused on warranted problems. On the basis of the available data for the two Ethiopian catchments, the implication is that only periods longer than about 50 days can be reliably evaluated in the model. The model structure of SWAT for the surface runoff and groundwater flow response is modified to make the time scales consistent with the results of the spectrum analysis. An optimization algorithm is developed to constrain and combine the model parameters with the spectrum analysis results.

No abstract

Drought is a complex natural disaster unlike flood, which covers a large area when it occurred. This review was conducted on hydrological drought analysis and monitoring status in Ethiopia by reviewing the master plan of eight major river basins and previous research related to drought. A total of 24 article papers was reviewed and it is found that hydrological drought analysis studies cover only 8.33% of all of the river basins in Ethiopia. Researchers in the region have focused primarily on meteorological drought (37.5%) rather than hydrological and agricultural drought analysis. Although Ethiopia has long been dependent on rainfed agriculture for its economy and remains the primary livelihood of the population, the Ethiopian government has begun focusing on transitioning to an industrial economy, placing pressure on the water resource. In a region plagued by drought, drought analysis, and monitoring, drought early warning systems and effective mitigation measures are still limited and even lacking in some areas. Therefore, emphasis on hydrological drought analysis and development of suitable drought mitigation measurements is important to implement strategies for effective and sustainable water resource management by which water may remain available during the long dry seasons and the impacts of hydrological drought may be lessened.