Today different regions must meet growing demand for land—most notably for food and bioenergy crops. Expansion of irrigation can dramatically boost yields, but potential expansion is limited by varying regional availability of fresh water. The potential additional irrigable land depends on water availability within a region, and the ability to stretch resources further through expansion of storage capacity and improvements in conveyance and irrigation efficiency. This study develops irrigable land supply functions that emulate a complex global water resource model that includes estimates of water resource availability and the cost of adding storage capacity and improving water-use efficiency.
The researchers’ new framework allows for more rigorous integrated analyses of regional and global impacts of water, land, energy and economy interactions. The emulator framework is available to other researchers, and can be customized to match regional configurations of various integrated, multisector dynamic models.
The researchers use data on the value of production on irrigated and rain-fed cropland at an approximately 10-square kilometer grid-cell level and for the 140 regions and eight crop sectors in Version 9 of the Global Trade Analysis Project (GTAP) Data Base. For each crop category, they estimate and compare the dollar value of irrigated and rain-fed crop production using production quantities and prices. To represent the potential of irrigated land areas to expand, the researchers use irrigable land supply curves for 126 water regions globally, based on water availability and the costs of irrigation infrastructure from a detailed water resource model. These curves enable estimates of each region’s ability to adapt to changes in water resources and agriculture demand through improvement in irrigation efficiency and expansion of water storage capacity.