Today different regions must balance competing demands for land—most notably for food and bioenergy—amid changes in the local availability of fresh water. One approach is to boost crop yields through improvements in irrigation technology, but its implementation would require actionable estimates on the current scope of irrigated land and how much additional land can be irrigated, in what regions, and at what cost. To that end, this study develops a framework to more accurately represent the value of irrigated crop production and the potential of irrigated land areas to expand within economy-wide, applied general equilibrium (AGE) models.

To represent the value of irrigated crop production, the researchers compute the value of production on irrigated and rainfed cropland at an approximately 10-square kilometer grid-cell level as well as 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 the shares of production on irrigated and rainfed land using estimates of 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. These curves enable regions to adapt to changes in water resources and agriculture demand through irrigation technology and crop production intensification.

The researchers’ new framework allows for more rigorous integrated assessments of regional and global impacts of water availability on land use, energy production and economic activity. They make this user-customizable framework available to enable other researchers to make integrated assessments of the current production value and expansion potential of irrigated land.

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Abstract

We develop a framework to represent the value of irrigated crop production and the expansion potential of irrigated land within economy-wide models, providing integrated assessment capabilities for energy, land, and water interactions. Specifically, we compute the value of production on irrigated and rainfed cropland at both a 5 arcminute by 5 arcminute level (about 10 square kilometers) 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, we estimate the shares of production on irrigated and rainfed land using estimates of production quantities and prices, compared to approximations based on output volumes used in the GTAP-Water Data Base. We construct a global dataset of evaluation metrics to identify region-crop combinations where there are large differences in irrigated production value shares based on direct calculation and approximated by output volumes. The scope to expand the amount of irrigated land and the cost of doing so is quantified through irrigable land supply curves for 126 water regions globally, based on water availability and the costs of irrigation infrastructure. We also make available our adaptable work stream to calculate crop production values and to estimate irrigable land supply elasticities for use in economy-wide models. Altogether, this work can enhance integrated assessment and economy-wide modeling by more accurately capturing the value of crop production and facilitating the representation of endogenous investment in irrigation infrastructure in response to changing water availability. These data and modeling contributions allow for a more rigorous exploration of the regional and global impacts of water availability on land use, energy production, and economic activity.