Evaluation Of Irrigation And Drainage Performance: The Case Of Amibara Irrigation Scheme

Abstract

Irrigation and drainage systems play a critical role in sustaining agricultural productivity in semi arid regions; however, the Amibara Irrigation Scheme has increasingly suffered from water scarcity, poor water distribution, deteriorating drainage, and rising soil salinity, threatening crop production and land sustainability. The objective of this study was to evaluate the performance of the irrigation and drainage systems, as well as irrigation water use efficiency, within the Amibara Irrigation Scheme. A mixed-methods research design was employed, combining quantitative field measurements with qualitative assessments to obtain comprehensive system-level and field-level performance insights. Primary data included canal discharge measurements, soil moisture readings, groundwater levels, soil and water samples, and field observations, while secondary data were obtained from the CLIMWAT database. CROPWAT 8.0 was used for estimating crop water requirements and comparing theoretical and actual irrigation demands. The results showed significant performance limitations at both irrigation and drainage levels. Overall irrigation efficiency was 42%, with conveyance efficiencies of 62–71% and application efficiency of 58%, indicating substantial seepage losses, deep percolation, and non-uniform field application. Storage efficiency was 71%, while distribution uniformity remained below recommended thresholds. Drainage performance was poor, particularly in Middle and Lower command areas, where water tables as shallow as 0.55–0.65 m and soil salinity levels of 3.7–4.1 dS/m were recorded values approaching or exceeding crop tolerance limits. In conclusion, the study found that the Amibara Irrigation Scheme is operating far below expected performance standards due to combined infrastructural, hydrological, and institutional challenges that reduce water productivity and accelerate land degradation. The study recommends (i) rehabilitating and lining canals to minimize losses, (ii) completing drainage upgrading works, including Phase II of the Amibara Drainage Project, and (iii) improving irrigation scheduling and on-farm water management.