Assessment Of Surface Water Potential To Manage Frequent Drought Disaster (a Case Of Dhas District In Borana Zone Of Oromia Region Ethiopia)

The study was conducted in Dhas district, which is located in Borana Zone ofrnOromia region; geographically it is situated 4.00rnorn-4.39rnornN and 38.39rnorn-39.46rnorn E with rnaltitude range of 1082 – 1666m a.m.s.l. Total area of the district is 3,183.22kmrn2rn; its rnlength from West to East is 120 Km and width from South to North is 41km.rnThere is not any river and gauging station in the district; the study was conductedrnaiming at estimation of surface water potential of the district and evaluation of itsrnsufficiency for managing of drought disaster in the district. The surface waterrnpotential assessment of the district was conducted using SCS model with the aid ofrnremote sensing and GIS. The assessment output was contextualized with the studyrnfinding of Genale Dawa integrated Master plan study (Dhas district is located inrnDawa sub-basin; finding from separate analysis of Dawa sub-basin was referred). rnFor the recent land use/ land cover information of Dhas district; satellite imagesrnwere downloaded from USGS (United States Geological Survey) website withrnacquisition dates of December 2018, and the image processing was done usingrnERDAS Imagine 2015. With the aid of HEC-GeoHMS tool that is specificallyrndesigned in the ArcGIS environment to process geospatial data, the curve numberrnwas generated using the required information (hydrologic soil group, DEM, LULCrnmap). rnThe district was divided in to twelve sub-watersheds using Global mappedrnsoftware, and direct runoff estimation was done for each sub-watershedrnseparately; the summation of direct runoff from each sub-watershed was made tornget the total direct runoff amount of the district. Thirty years daily grid rainfall datarnthat was collected from NMA was used for the estimation of the direct runoff.rnEstimation of runoff volume was computed for all thirty years period, and thernestimated minimum and maximum runoff volume were found to be 8Mmrn3rn and rn361Mmrn3rn respectively. Twenty years of forecast was made to estimate the major rnrequirements in the district. Human and livestock’s water requirement estimationrnbased on the population sized of 2039 was computed to be 10Mmrn3rn / year. rnThe abundant of estimated runoff volume was evaluated, whether it is enough orrnnot to satisfy the major water requirements in terms of managing the frequentrndrought disaster. As the analysis shows, Dhas district is having sufficient surfacernwater potential that can be developed for managing of the frequent droughtrndisaster in the district. rnThis study was conducted focusing only on the available surface water potential ofrnthe district, and its sufficiency for managing of the drought disaster in the district.rnIts finding is also expected to be an entry point for development of the resource inrnthe large scale. But for its implementation, it needs further feasibility and detailrnstudies.

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