Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Research notes
Publication Acceptance Date: 7/20/2013
Publication Date: 7/20/2013
Citation: Garbrecht, J.D., Keefer, T.O., Goodrich, D.C., Busteed, P.R. 2013. Report on the projected future climate of the Walnut Gulch Watershed, AZ. Grazinglands Research Laboratory Miscellaneous Publication. Available: http://iapreview.ars.usda.gov/main/site_main.htm?modecode=62-18-05-20. Interpretive Summary: Abstract Only
Technical Abstract: This report is one of several that provides technical information on projected climate change at selected ARS experimental watersheds across the continental United States. The report is an attachment to the main report of the multi-location project titled “Estimating impacts of projected climate change on regional water availability and quality, across diverse physiographic regions in the United States, and their associated implications for conservation needs and agricultural productivity”. The projected climate change information in this report is for the USDA, ARS Walnut Gulch Experimental Watershed in south-eastern Arizona, and serves as the basis for making inferences about potential impacts of climate change on the hydrology, natural resources, and agricultural productivity of the region represented by the Walnut Gulch Watershed (WGW). Based on historical (observed) climate data and climate projections, annual precipitation of the Walnut Gulch Watershed is not expected to change much over the 21st century for the high, middle, and low greenhouse gas emission scenarios studied. Most trends in projected monthly precipitation were not statistically significant. Annual air temperature of the watershed was expected to increase for the three emission scenarios. Average trend of annual air temperature over the 2011-2100 time period was 0.51, 0.35, and 0.20 [degree C/decade] for the high, middle, and low emission scenario, respectively. All trends of projected monthly temperature for time periods 2011-2070 and 2011-2100 were statistically significant. The trend for projected monthly air temperature ranged from 0.42 to 0.58 [oC/dc], from 0.27 to 0.42 [degree C/decade], and from 0.11 to 0.26 [degree C/decade] for the high, middle and low emission scenario, respectively. Projected air temperature increases were higher during the summer and autumn (May through October) than during the winter and spring. Overall, climate change in south-eastern Arizona is anticipated to be primarily in the form of a rise in air temperature for all calendar months with minimal change in annual precipitation. With regard to the precipitation distribution within a year, precipitation decreased in December through June, and the available data suggested an increase in precipitation in September through November.