ASSESSMENT OF PERFORMANCE AND ECONOMIC BENEFITS OF LARGE-SCALE IRRIGATION SCHEME: A CASE STUDY IN ABOBO WOREDA, GAMBELLA ETHIOPIA

Abstract

Assessment of large-scale irrigation performance and its economic contribution is one of the key factors for the sustainability of large irrigated agricultures. This paper, focuses on Saudi Star Agricultural Development Project, a large irrigation scheme holding 10,000ha of land in western Ethiopia of Gambella’s Abobo woreda. The scheme has not been assessed since its commencement. Therefore, this paper is the first in its kind to identify the on-farm performance management gaps of the large scheme and its economic contribution to local community at Abobo. Many indicators were developed for the assessment of scheme performance. Among few evaluated at Saudi Star farm were; internal indicators such as conveyance efficiency and application efficiency, where as external indicators evaluated were agricultural productivity indicators, water supply indicators and physical indicatiors. In this study, the production outputs of the irrigated area were obtained in terms of gross or net value of production measured at local and international prices. As a result of the scheme analysis, the agricultural productivity of the scheme production’s output per unit irrigated area (OPUIA), output per unit command area (OPUCA), output per unit irrigation supply (OPUIS) and output per unit water consumed (OPUWC) were determined as 2,099.50 US$/ha, 4,087.46 US$/ha, 0.99 US$/𝑚3 and 0.40 US$/𝑚3 respectively. The calculated water supply indicators were 1.32 for relative water supply (RWS) and 0.99 for relative irrigation supply (RIS). The computed physical indicators were 0.85 for irrigation ratio and 0.82 for sustainability of irrigated agriculture. The mean conveyance efficiency of the main canal was 81.1% and that of secondary canals was computed as 67.5%. The canal losses were 5.61 l/s/100m and 6.88 l/s/100m at the main and secondary canals respectively, with 52% of application efficiency at the scheme. The high water holding capacity of clay soil indicated that the scheme has improving application efficiency. The low output production of Saudi Star large farm was triggered by the low value crops grown in the scheme. The high water loss revealed that, overall, maintenance and repair work on the conveyance canals were not sufficient. Moreover, the analysis of socio-economic benefits of the scheme to the local community at Abobo revealed that technology transfer and employment opportunity were nearly met, but contrary to market and infrastructural development.