There has been a growing recognition that large-scale gravity irrigation systems funded by public investments have performed poorly, and have not shown significant improvements with further investments for rehabilitation. This Policy Note examines three measures of performance of all national irrigation systems from the mid-1960s to 2012. Results show even poorer performance indicators vis-a-vis the World Bank irrigation sector review of 1992 which underscored the disappointing performance of the national irrigation systems due to overly optimistic technical and economic assumptions, inappropriate designs of irrigation systems, and difficulties in operation and maintenance (O&M). The latest assessment revealed the scanty effort to adopt more reasonable assumptions in estimating design areas; overstated estimates of available water supply; the failure of the design of irrigation systems to adequately address drainage problems, location-specific physical characteristics, and rapid urbanization; and the lack of significant improvement in the O&M.
