ABSTRACT
This study was conducted in the Hare River basin in Southern Ethiopia and part of the Rift Valley. In this area, climate-related hazards such as floods affect human life and the region’s economy. The morphometric drainage study is essential for river catchment evaluation, flood risk analysis, watershed priority, and catchment management. The study aims to determine the importance of the six watersheds that are part of the Hare River catchment. As a result of the use of GIS tools, toposheets, and Shuttle Radar Topographic Mapper-Digital Elevation Model (SRTM-DEM) data, the boundary of the Hare River sub-watershed and its drainage system were determined. Six sub-watersheds have been identified within the current study area. Morphometric variables such as linear, area, and relief were defined using the conventional formula. Flooding risk is directly related to the following morphometric factors: drainage frequency, bifurcation ratio, stream density and texture, circularity ratio, and form factor. Hence, higher ranks were assigned to high values of the above-mentioned parameters. Furthermore, flood risk is inversely proportional to the compactness coefficient, overland flow length, and elongation ratio. As a result, the higher ranking was accorded to parameters with lower values, as mentioned above. The calculated compound factor values were classified into three categories, namely high priority (2.78–2.89) (WS-2 and 4), medium priority (2.90–3.89) (WS-1, 3 and 6), and low priority (3.90–4.33) (WS-5). In the Hare River catchment, using remotely sensed data, GIS techniques, morphometric drainage assessment, and sub-watershed prioritisation is highly effective in identifying areas at risk of flooding. As a result of the present study, planners and decision-makers may be able to identify flood-prone areas and implement flood control structures in the study area.
