Investigation Of Water Availability And Water Demand Secenarios Of Mojo River Watershed In The Upper Awsh River Basin In Ethiopia.

Abstract

This Study Was Conducted To Assess Availability Of Mojo Stream Flow For Irrigation Using Soil And Water Assessment Tools (Swat). The Assessment Of Stream Flow Availability Was Conducted For Mojo Watershed, Which Is Having A Total Area Of 2017.09km. The Performance Evaluation Of The Model To Obtain The Water Balances Was Conducted. The Crop And Irrigation Water Demand Of Major Crops Of The Area Such As: Cabbages, Onion, Maize, Tomato And Pepper Were Analysed Using Cropwat 8 Modelling. The Other Data Required To Calculate The Demand Of Water Like Livestock And Human Consumptive Use Were Obtained From The Four Woreda Included In The Watershed. In This Study For Stream Flow Yield Simulation The Parameters Involving Surface Runoff (Cn2.Mgt) And Ground Water (Alpha_Bnk.Rte Was Found To Be The Most Sensitive Parameters. A Good Agreement Between Observed And Simulated Discharge Were Observed, Which Was Verified Using Both Graphical Technique And Quantitative Statistics. The Value Of R2=0.80, Nse=0.75, Rsr=0.5 And Pbias=-10.6 Obtained During Calibration And R2Value 0.76, Nse Value 0.69, Rsr Value 0.56 And Pbias -14.4Obtained During Validation As Well As The Uniformly Scatter Points Along The 1:1 Line During Calibration And Validation Justify That The Model Is Very Good In Simulating Observed Steam Flow. From The Results The Total Annual Surface Water Available Yields Is Estimated Around0.401billion Cubic Meters (Bcm), Irrigation Water Requirement, Human And Livestock Water Consumption Were Found To Be 0.279, 0.13 And 0.106bcm/Year Respectively. So, There Was Shortage Of Water Around 0.114bcm/Year Occurred. This Shows That The Demand Exceeds The Availability By 0.011bcm During The Study Period. During The Dry Month (Dec-May) There Was Highest Water Deficits Occurred, Which Is About 0.0096bcm/Month. During This Periodb There Was Also Conflict Between Users At Diversion And Water Allocation. Therefore, In Order To Solve Water Shortage, Alternative Source Of Water Supply Like Ground Water And Water Harvesting Technologies Should Be Studied And Integrated Water Management System Should Be Implemented. In Addition To This, To Improve The Efficiency Of Irrigation Water, DifferentIrrigation Methods Like Drip Irrigation And Sprinkler Irrigation Should Be Improved In The Area.