Assessing Farm Water Management and Performance of Koga Irrigation Scheme: a Case Study of Inguti Unit, Amhara Regional State, Ethiopia

The principal objective of this study was to assess field water management and performance of Koga irrigation scheme specifically Inguti unit using performance indicators based on the selected performance indicators such as conveyance efficiency, application efficiency, distribution efficiency, storage efficiency, and deep percolation ratio. Primary data such as discharge, soil moisture content, field surveys, and group discussions among the farmers/beneficiaries and Water User Associations (WUA) and secondary data such as crop data, climate data, and design documents were collected. CROPWAT 8.0 models and GIS were used for data analysis in this research. Average conveyance efficiency values ranged from 81 to 86.5% for lined (secondary and tertiary canals) and about 64% for unlined tertiary canals. The maximum water losses observed were 0.19 and 0.2 l/s/m on lined (secondary and tertiary) canals, respectively. The maximum water loss observed in unlined tertiary canals was 0.26 l/s/m. The average distribution uniformity, field storage efficiency, and field water application efficiency were 79.6%, 78.9%, and 53.5%, respectively. Average values of the scheme, cropped area ratio, and infrastructural effectiveness were 94% and 96.2%, which was good sustainability based on the standards. The overall efficiency of scheme in the Inguti unit was found to be 46.3%. In general, the performance of the irrigation scheme was weak due to poor field water managements as indicated by the above indicators due to illegal water abstraction, unequal distribution of irrigation water, sedimentation of canals and lack of institutional support service, and inadequate operation and canal maintenance.