Past and Future Water Use in the United States--the RPA Water Assessment

The RPA Assessment is produced every ten years in response to the Renewable Resources Planning Act of 1974. The act directs the Forest Service to periodically assess anticipated resource supply and demand conditions of the nation's renewable resources.  The 2010 RPA Water Assessment assesses the vulnerability of the United States water supply to shortage in light of expected climate change. 

• Mahat, Vinod, Jorge A. Ramirez, and Thomas C. Brown. 2017. Twenty-first-century climate in CMIP5 simulations: Implications for snow and water yield across the contiguous United States. Journal of Hydrometeorology 18(8):2079-2099.

• Brown, Thomas C., Travis W. Warziniack, Vinod Mahat, and Jorge A. Ramirez. 2016. Water resources, chapter 10 of Future of America’s forest and rangelands: Update to the Forest Service 2010 Resources Planning Act Assessment. General Technical Report WO-94.

• Foti, Romano, Jorge A. Ramirez, Thomas C. Brown. 2014. A probabilistic framework for assessing vulnerability to climate variability and change: the case of the US water supply system. Climatic Change. 125(3-4): 413-427.

• Foti, Romano, Jorge A. Ramirez, Thomas C. Brown. 2014. Response surfaces of vulnerability to climate change: the Colorado River Basin, the High Plains, and California. Climatic Change. 125(3-4): 429-444. 

• Brown, Thomas C.; Foti, Romano; Ramirez, Jorge A. 2013. Projected freshwater withdrawals in the United States under a changing climate. Water Resources Research. 49: 1259-1276. [This won the journal's Editors' Choice Award for 2013.]

• Foti, Romano, Jorge A. Ramirez, and Thomas C. Brown. 2012. Vulnerability of U.S. water supply to shortage: a technical document supporting the Forest Service 2010 RPA Assessment. Gen. Tech. Rep. RMRS-GTR-295. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 147 p.

• Brown, Thomas C., Romano Foti, and Jorge A. Ramirez. 2012. Chapter 12: Water Resources in Future of America's Forests and Rangelands: Forest Service 2010 Resources Planning Act Assessment. Gen. Tech. Rep. WO-87, U.S. Forest Service, Washington, DC. 198p. 

• Brown, Thomas C. 2000. Projecting U.S. freshwater withdrawals. Journal of Water Resources Research 36(3): 769-780. 

Estimating the Contribution of Forests to the Nation's Water Supply

This project has two main goals. The first goal is to estimate the volumes of water that annually become available on forests (and other land covers) in the U.S. Available water volume (water supply) is being estimated, at the regional scale, as precipitation minus evapotranspiration (ET). Estimating ET at the regional scale for the entire U.S. has been a major hurdle and is being accomplished in cooperation with scientists at Colorado State University. The publications listed below describe our efforts so far to estimate regional ET.

• Brown, Thomas C., Michael T. Hobbins, and Jorge A. Ramirez. 2008. Spatial distribution of water supply in the coterminous United States. Journal of the American Water Resources Association. 44(6):1474-1487.

• Ramirez, Jorge A., Michael T. Hobbins, and Thomas. C. Brown. 2005. Observational evidence of the complementary relationship in regional evaporation lends strong support for Bouchet’s hypothesis. Geophysical Research Letters, 32, L15401. 

• Hobbins, Michael. T., Jorge. A. Ramirez, and Thomas. C. Brown. 2004. Trends in pan evaporation and actual evapotranspiration across the conterminous U.S.: Paradoxical or complementary? Geophysical Research Letters 31(13), L13503. 

• Hobbins, Michael T., Jorge A. Ramirez, and Thomas C. Brown. Trends in Regional Evapotranspiration Across the United States Under the Complimentary Relationship Hypothesis. In: proceedings of the 21st Annual AGU Hydrology Days, Colorado State University, Fort Collins, Colorado, April 2-5, 2001, Jorge A. Ramirez ed., pp. 106-121.

• Hobbins, Michael T., Jorge A. Ramirez, Thomas C. Brown, and Lodevicus H. J. M. Classens. 2001. The Complementary Relationship in the Estimation of Regional Evapotranspiration: The Complementary Relationship Areal Evapotranspiration and Advection-Aridity Models. Water Resources Research 37(5):1367-1387.

• Hobbins, Michael T., Jorge A. Ramirez, and Thomas C. Brown. 2001. The Complementary Relationship in the Estimation of Regional Evapotranspiration: An Enhanced Advection-Aridity Model. Water Resources Research 37(5):1389-1403.

• Hobbins, Michael T., Jorge A. Ramirez, and Thomas C. Brown. The Complementary Relationship in Regional Evapotranspiration: The CRAE Model and the Advection-Aridity Approach. In: proceedings of the 19th Annual AGU Hydrology Days, Colorado State University, Fort Collins, Colorado, August 16-20, 1999, Hubert J. Morel-Seytoux ed., pp. 199-212.