High Plains Irrigation, Trego County, KS

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Does crop irrigation cool surface temperatures?

Project PI: Charles W. Rice, Department of Agronomy, Kansas State University

Research funded by Kansas NSF EPSCoR has shown that the practice of irrigating agricultural crops will cool surface temperatures during warmer months. Atmospheric scientists for some time have questioned whether the effects of irrigation could mask regional warming signals in the Great Plains.

This study and subsequent research will help climate scientists better understand how agricultural irrigation practices affect the climate and, possibly, how agriculture will be impacted by climate change. Understanding the influence of irrigation on climate is important since it is also probable that water for irrigating crops will decrease in availability. In areas where irrigation comes from a finite ground water supply, the studies will provide a better understanding of how rapidly local summer temperatures will increase if irrigation is curtailed.

University of Kansas researchers Johan Feddema, professor of geography; Nate Brunsell, associate professor of geography; David Mechem, assistant professor of geography; and David Huber, a graduate student in atmospheric sciences, conducted the study. To assess the differences in impacts between an intensely irrigated area with an area that was not irrigated, they used computer modeling techniques. Model results for precipitation and temperature document how temperatures are lowered in the irrigation area and how precipitation increases several hundred kilometers downstream.

Previous studies by other researchers on irrigation and surface temperature were focused on either relatively small areas, such as the Texas Panhandle, or were performed on a global scale. The studies on a global scale didn’t allow for the level of detail provided in the Kansas NSF EPSCoR study, which focuses on several states.

The following maps depict model output of surface temperatures (°C) in the month of July 2001 (a climatically average July in several respects) in irrigated areas and the same areas with no supplemental irrigation. Note the differences in color/temperature in the western half of Kansas.

With irrigation

Without supplemental irrigation

 

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