Reconfiguring an irrigation landscape to improve provision of ecosystem services

Abstract

Over-allocation of fresh water resources to consumptive uses, coupled with recurring drought and the prospect of climate change, is compromising the stocks of natural capital in the world's basins and reducing their ability to provide water-dependent ecosystem services. To combat this, governments worldwide are making significant investment in efforts to improve the sharing of water between consumptive uses and the environment. Many investments are centred on the modernisation of inefficient irrigation delivery systems and the purchase of consumptive water for environmental flows. In this study, we applied spatial targeting within a cost-benefit framework to reconfigure agricultural land use in an irrigation district to achieve a 20% reduction in agricultural water use to increase environmental flows, and improve the provision of other ecosystem services. We demonstrate a targeted land use reconfiguration policy approach using spatial planning and optimisation models. Our model estimates a potential increase in the net present value of ecosystem services of up to $A 347 million. The increase in ecosystem services include recovering 62 GL of water for environmental flows, the sequestration of 10.6 million tonnes of CO2e/year, a 12 EC (μS/cm) reduction in river salinity, and an overall 9% increase in the value of agriculture. Without a spatially targeted approach to planning, a 20% reduction in water for irrigation could result in the loss of $A 68.7 million in economic returns to agriculture which may be only marginally offset by the increased value of ecosystem services resulting from the return of 62 GL of water to the environment. Crown