Baro- Akobo river basin is located in the southwest part of Ethiopia. The objective of thisrnpaper is to assess surface water potential using SWAT model and estimation of waterrndemands using the Water Evaluation and Planning (WEAP) model in the Baro-Akobo Basin.rnAccording to the result obtained from SWAT model, the basin receives a mean annualrnrainfall of 1701.6 mm, which is 115.6BM3. The mean annual actual evapotranspiration isrn30.8BM3 or 27% of the mean annual rainfall of the basin. The mean annual surface runoffrnthat leaves from the basin is 19BM3 that corresponds to 279.68 mm. Out of the mean annualrnrainfall of 115.6BM3 and the other 18.6BM3 that is 273.71mm flows as lateral flow. Thernremaining 2.4BM3 is lost due to percolation for the recharging of the deep aquifer andrn42.17BM3 revap from the shallow aquifer and flows as return flow.rnFor calibration, the model was run for a period of six years and the monthly calibrationrnresults for R2 and NS were 0.83 and 0.56 respectively that are acceptable by the given ranges.rnFor model validation, the model was run for a period of six years and the model validationrnresults on monthly time step shows the results of RÂ² and NS values were 0.81 and 0.67rnrespectively which is acceptable by the given ranges too.rnThe water demand estimation portion of this study was done for six water supply, threernhydropower and seven irrigation projects in the basin. The water demand result shows therernis no shortage of water supply for scenario year 2015 to 2030. The annual overall demand isrn4.085BMC. The annual demand for irrigation projects is 4.077BMC. The water demandrnfound by this analysis is about 21.5% of the total surface water potential of 19BMC ofrnsurface water potential per year.rnThe SWAT model is very sensitive and needs accurate input data. Using sufficient time andrninput data the model can simulate good result, which fits the observed stream flow data. Inrnaddition to this up to date land use and management data is essential for SWAT model. Morernefforts required to find best estimation of the surface water potential using SWAT model.rnThe water demands in the basin is very small so further investigation is essential to use thernavailable surface water potential of the basin.rnKey words: SWAT model, WEAP model, SWAT-CUP, surface runoff and water demands