Evaluation Of Existing Water Conveyance, Storage And Control Structures: A Case Of Amibara Irrigation Scheme, Ethiopia

Abstract

Agricultural Development May Be Limited Due To Shortage Of Water Unless Efficient Use Of Irrigation Water Is Applied. Assessment Based Evaluations Of The Irrigation System?�?S Physical Condition With The Functionality Of The Infrastructure Components Are All Needed To Overcome Water Scarcity Problem. This Study Was Done Primarily To Identify The Causes That Lead The Scheme To Perform Below Expectation And Recommend Remedial Measures For Sustainability Of Amibara Irrigation Scheme (AIS) In Afar Region, Ethiopia. The Conditions Of Existing Water Conveyance, Storage And Control Infrastructures Were Assessed And Evaluated Through Field Investigation, Predefined House Hold Questionnaires And Interview With Operational Staffs. Priority Was Also Set Using Priority Indexing Method For Rehabilitation Of The Scheme For Future Development And Sustainability Of The Scheme. Issues That Potentially Affect The Performance Of The Scheme Were Identified And Ranked Based On Their Level Of Influence On The Scheme performance. The Priority Index Was Defined By Combining The Assessed Condition Of Components Of The System With A Measure Of Its Strategic Importance And The Area Served By That Specific Component. The Overall Score And Ranking Was Judged For Sampled Irrigation Hydraulic Structures For Further Actions Of Rehabilitation. The Research Included Investigation And Condition Assessment Of The Headwork, 1 Main Canal, 7 Out Of 10 Secondary Canals, 10 Out Of 42 Tertiary Canals, All The 6 Gated Check Drops (CD) On Main Canal, 7 Out Of 10 Gated Off takes That Are Off taking Irrigation Water From Main Canal To The Secondary Canals. The Evaluation Of The Scheme Infrastructures Indicated That The Major Causes For The Scheme To Perform Under Expectation Were Change Of Institution In Fast Rate, Significant Load Of Sediment From High Lands To The Head Work, Flooding, Poor Drainage Network And Salinity Problems. The Analysis Indicated That The Headwork Took The Highest Value (180) Of Priority Index And It Was Failed To Deliver Irrigation Water To The Scheme. It Was Found That The Headwork Comprising The Weir, The Intake, The Head Regulator And The Scour Sluice Was Almost Collapsed And Not Maintainable. The Main, Secondary And Tertiary Canals Were Observed With Diminished Shape, Size Due To Sediment Load, And Weed Growth On The Section And Banks Of The Canals. The Main Problems Observed On The Check Drops & Gated Off takes Were The Failure Of Gates For Operation Due To Lack Of Annual Maintenance. Most Of The Concrete Structures Are In A Good Condition With Minor Maintenance Requirements. The Research Recommended Changing The Location Of The Headwork And Reconstruction Of New One Where River Section Is Stable With Non-Silting Velocity. Rehabilitation Of The Canal Networks And All Structures Along The Canal Network Is Mandatory. Deterioration And Failure Of Drainage Infrastructures Needs Special Attention For Sustainability Of The Scheme. Moreover, There Should Be Responsible Institution That Took The Responsibility Of Coordinating And Organizing Stakeholders For Operation And Maintenance Of The Scheme.