The paper presents institutional and management arrangements and contrasts water management strategies at farm, system and sub-basin level and shows how these have led to water savings and increases in water productivity. In the water-rich environment of ZIS, farm and canal management of water is much more precise than in the water-scarce environment of LIS. Yet both systems are close to their water-saving potential. Both systems have experienced remarkable increases in irrigation water productivity over time, largely from increases in crop yields, but in the case of ZIS also from changes in management. Controlling supplies and reallocating as much as possible to non-agricultural uses while assuring an adequate supply for agriculture is extremely important in ZIS where water productivity per unit of irrigation supply is the key measurement. At LIS, because of water resource scarcity, there is evidently scope for reducing evaporation from raised watertables. Thus, water productivity per unit of evapotranspiration is the key measurement. We suggest that design improvements at LIS be targeted to reduce any non-beneficial evaporation, a recommendation that holds across many water-scarce environments globally.
