Synthesis of Irrigation Water Use in the United States: Spatiotemporal Patterns

The role of large-scale drivers-climate, population, and adaption of efficient irrigation practices-in controlling irrigation water use efficiency has rarely been addressed. The primary objectives of our study are to (1) investigate the long-term changes in irrigation water use over the contiguous United States using a nationwide, multidecadal database created by USGS; and (2) understand the role of large-scale drivers in the water application rate, an indicator of irrigation efficiency. The authors find that the eastern states are currently withdrawing more surface water than in the past, while groundwater withdrawal has increased across all states. An increase in efficient irrigation schemes is leading to a decrease in traditional flood irrigation schemes. Spatiotemporal analyses confirm that the eastern states are presently withdrawing more irrigation water per acreage than in the past. While the choice of efficient irrigation practices (sprinkler and drip) is the major driver influencing the application rate, other factors such as cost and type of crops predominantly determine the type of irrigation system chosen for improving the application rate.