Analyzing Irrigation District Water Productivity by Benchmarking Current Operations Using Remote Sensing and Simulation of Alternative Water Delivery Scenarios

The competition for fresh water is vastly increasing particularly in semi-arid areas. Agricultural irrigation areas are urged to decrease their water use, being the largest consumer of fresh water in these areas. Improvements in irrigation management aim at increasing crop production whilst maintaining or decreasing water use. The analysis of water productivity at the irrigation district scale is challenging due to spatial heterogeneity between fields and temporal variability between growing seasons. This dissertation makes use of satellite-based remote sensing imagery and an irrigation system simulation model to determine the water management at different spatial scales from field scale to the irrigation scheme to the basin scale. Integrated analysis at the various spatial scales determines the potential for improvements in water management and is a comprehensive approach for studying water productivity of irrigation districts. Findings from a decade of satellite remote sensing imagery indicated that water consumption greatly varies annually, therefore management strategies should be flexible to cope with this variability. Assimilation of satellite-based remote sensing data in an irrigation system simulation model enabled benchmarking a spatially diverse system with various farm management strategies. The calibrated simulation model was thereafter applied for the simulation of alternative water delivery scenarios to determine potential for improvement of water productivity. Finally, the impact on downstream water users from changes in irrigation diversions are evaluated using a water accounting approach of the water flows. This study provides quantifiable insight on the consequences and profits of alternative water delivery scenarios and aids regional water managers in their decisions. Additionally, it proposes an approach of benchmarking and improving the management of irrigation districts to cope with future water scarcity