Climate change during the past century has resulted in changes to precipitation amounts, form (rain vs. snow), as well as frequency and intensity in the northeastern US (Huntington et al., 2009). Additional changes in precipitation are forecast for the 21st Century as the global and regional climate is expected to warm substantially (Hayhoe et al., 2007). These ongoing and projected future changes in precipitation along with other related changes to evapotranspiration rates and land use patterns will result in changes in streamflow patterns as well (Hayhoe et al., 2007). Although precipitation amounts have generally increased in the Northeast during the past 20-30 years (Huntington et al., 2009), climate models show a wide range of variation in future precipitation trends, though a consensus has emerged that: (1) snow will make up a declining proportion of total precipitation, (2) the size and intensity of large storms is likely to increase, and (3) droughts will become more frequent and severe (Trenberth et al., 2003).
These changes in precipitation patterns must be accounted for by engineers to safely design and build infrastructure; ensuring that these projects can withstand changes in peak streamflow. Therefore, design of new, and redesign of aging, infrastructure requires information about how predicted changes in precipitation will affect peak streamflow in the future.
The relationship between land-use, topography, and precipitation and streamflow has been well documented (http://streamstats.usgs.gov/; accessed Jan. 18, 2013). These relationships often take the form of non-linear multivariate equations. Equations have been developed for New York, excluding Long Island, and have been programed into an easy-to-use, point-and-click computer software package (Lumia and others, 2006). This computer program, Streamstats, developed by the U.S. Geological Survey (USGS), can be accessed by anyone with a personal computer and a connection to the World Wide Web. Streamstats can be used to estimate streamflow statistics at almost any point on any stream in New York, within the constraints of the characteristics used in model development. Leveraging Streamstats, and assuming that the physical characteristics responsible for the observed relation between precipitation and streamflow remain constant; it might be possible to estimate changes in peak streamflow that might be realized by predicted climate change.
With the above in mind, the USGS New York Water Science Center (NYWSC), in cooperation with the New York Department of Transportation (NYDOT), and the Nature Conservancy (TNC) proposes to construct a Geographical User Interface (GUI) that would allow the user to estimate changes in peak streamflow from predicted changes in precipitation. It is envisioned that changes in precipitation would be either user defined or predicted from downscaled models of global climate change. Briefly, the proposed GUI would query Streamstats, retrieve basin characteristics and calculate streamflow statistics under existing average-annual precipitation. At the same time, streamflow statistics will also be calculated using predicted values of average-annual precipitation from downscaled models of Global Climate Change. Geographic Information System (GIS) data layers of predicted average-annual precipitation from select downscaled models of global climate change will be preloaded into the proposed GUI.
Planned revisions (not done as part of this proposal) to the existing equations that make up Streamstats will include more data and most likely will include a number of new rainfall statistics (not available at the time the original equations were developed). In addition, equations built for a subset of smaller (less than 50 square miles) may increase predictive power for smaller drainage basins, which are more likely susceptible to predicted changes in storm intensify and volume. Once completed, these updated equations will be loaded into Streamstates. The GUI interface constructed as part of this project would be able to take advantage of this planned upgrade to the Streamstats; thereby, improving our ability to predict streamflow statistic under future climate conditions.
The USGS NYWSC proposes to design and build a computer program that predicts changes in peak streamflows resultant from estimated changes in climate. Changes would be estimated using existing equations and predictions of changes in average annual precipitation from downscaled models of global climate change or user defined changes.
Hayhoe, K, PW Cameron, TG Huntington, L. Luo, MD Schwartz, J. Sheffiled, E. Wood, B Anderson, J. Bradbury, A. DeGaetano, TJ Troy, D Wolfe, 2007, Past and future changes in climate and hydrological indicators in the US Northeast, Climate Dynamics, 28: 381-407.
Huntington, TG, AD Richardson, KJ McGuire, K Hayhoe, 2009, Climate and hydrological changes in the northeastern United States: recent trends and implications for forested and aquatic ecosystems, Canadian Journal of Forest Research, 39: 199-212.
Lumia, Richard, Freehafer, D.A., and Smith, M.J., 2006, Magnitude and Frequency of Floods in New York: U.S. Geological Survey Scientific Investigations Report 2006–5112, 152 p.
Trenberth, KE, A Dai, RM Rasmussen, DB Parsons, 2003, The changing character of precipitation, Bulletin of the American Meteorological Association, 84: 1205-1217.
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“Rondout Creek flood April 2005”