Comparative Performance Assessment of Two Irrigation Schemes in Buno Bedele Zone, Oromia, Ethiopia

Abstract

Comparative performance Assessments of irrigation schemes is an instrument to demonstrate bench marks for both lands and water productivity, and to identify performance gaps and suggest improvement options. Accordingly, the objective of this study was to evaluate and compare the performance of Gella and Gepha community managed small scale irrigation schemes using selected comparative performance indicators. Primary data were gathered by field measurements, household surveys, focus groups, and key informant interviews. Secondary data were taken from various written publications. CROPWAT8.0 computer program was used to calculate the crop water requirement and irrigation requirement. To test the soil FC, PWP, TAW %, and TAM (mm/m), soil samples were taken by auger. Additionally, soil for bulk density test was collected by core samplers, and soil infiltration rate was determined by double-ring Infiltrometers. Flow velocity is measured with a current meter at 36°05'36'' and 21°51'53'' longitude, 8°25' 22'' and 8°92’88’’ latitude, and 1513 and 1498 m elevation for Gella and Gepha, respectively using area velocity method and mid-section method. With the exception of wheat production, which was assessed by the field sampling method, data on output, prices and the productivity of land and water were gathered through questionnaires. Then the schemes were assessed using water supply, physical, agricultural output and financial indicators. As a result, the conveyance efficiency of Gella and Gepha main canals was 94.12 and 95.58 % respectively. The values of relative water supply and relative irrigation supply were 2.2 and 2.6 for the Gella, whereas they were 1.9 and 2.3 for Gepha scheme respectively. The results showed that both schemes withdrew excess water. Moreover, the irrigation ratio and sustainability of the irrigated area showed 0.97 and 1.05 for the Gella scheme and 0.96 and 1.12 for the Gepha schemes respectively. The Output per unity irrigated area was 342744.4 and 298880.4 ETB/ha, and the Output per unity per unity command area was 661007 and 562268.75 ETB/ha for Gella and Gepha schemes respectively. The Output per unity water supply and Output per unity per unity water command area were 37.17 and 49 ETB/m3 for Gella and 33.5 and 43.9 ETB/m3 for Gepha respectively. Therefore, the Gella SSI scheme performed better in terms of land productivity than it did in terms of water productivity due to the water indicators values are the same vaue at both irrigation schemes. Accordingly, it’s crucial to compare the schemes using indicators of land productivity rather than water productivity. The Gella SSI scheme performed better and can be used as a benchmark based on these indicators.