PERFORMANCE ASSESSMENT OF COMMUNITY MANAGED IRRIGATION SCHEME: A CASE STUDY OF MUTEFECHA IN NORTH SHEWA, ETHIOPIA

Abstract

The purpose of performance assessment of an irrigation scheme is to achieve an efficient and effective use of available water resources. However, in the Ethiopia performance evaluation of irrigation schemes is rarely conducted. This study was conducted to assess the performance of community managed irrigation scheme found in the Awash basin during October to December, 2016. Secondary data such as climate, design document were taken from Shewarobit meteorological station and from Amara National, Regional State Water Resource Development Bureau respectively. Primary data which collected through field measurements and field survey (field observation) were also taken. The conveyance efficiency and losses were measured using inflow-outflow method in the main, secondary, and tertiary canal. Flow of main and secondary canals were determined using Area-Velocity method via determining canal cross-sectional area and flow velocity using current meter. Discharge of field canal off-takes and tertiary canals were determined using Parshall flume. To evaluate conveyance efficiency of the system 16 canal segments were taken. To determine the water delivery indicators 15 field canal off-takes were also taken. Field canal off-takes measurements were taken two times a month and canals three times over the months respectively. CROPWAT 8.0 and Geographical Information System (GIS) software were used to analyze the collected data. The performance level of the scheme was assessed using different indicators such as: adequacy, dependability, efficiency, effectiveness of infrastructure and conveyance efficiency of the scheme. The result of this study revealed that, adequacy, dependability, efficiency, equity and effectiveness of infrastructure were 0.62, 0.24, 0.94, 0.43 and 42.86% respectively. Those values indicate poor performance level of the scheme except efficiency which was good. The overall average main, secondary and tertiary canals conveyance efficiency was 89.9, 87.4, and 56.3% and conveyance loss of 1.33, 1.46 and 2.43 ls -1 100m -1 respectively which were below standards. This revealed that, overall, maintenance and repair work on the conveyance canals were not sufficient. Generally performance level of the scheme was poor. So, to use the water resources effectively, efficiently and equitably water allocation to the farm should be carried out based on crop water demand with irrigation scheduling. The conveyance systems should be improved through regular canal cleaning and maintenance of infrastructures and constructing silt entrance controlling structures are basic remedial measures