Hydrologic and water quality sensitivity to climate and land-use change in 20 U.S. watersheds
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Background:Projected changes in climate during the next century could cause or contribute to increased flooding, drought, water quality degradation, and ecosystem impairment. The effects of climate change in different watersheds will vary due to regional differences in climate change, physiographic setting, and interaction with land-use, pollutant sources, and water management in different locations. EPA is conducting watershed modeling to develop hydrologic and water quality change scenarios for 20 relatively large U.S. watersheds.
Watershed modeling will be conducted using the Hydrologic Simulation Program-FORTRAN (HSPF) and Soil Water Assessment Tool (SWAT) watershed models. Study areas range from about 10,000-15,000 square miles in size, and will cover nearly every ecoregion in the United States and a range of hydro-climatic conditions. A range of hydrologic and water quality endpoints will be determined for each watershed simulation. Endpoints will be selected to inform upon a range of stream flow, water quality, aquatic ecosystem, and EPA program management goals and targets.
Model simulations will be conducted to evaluate a range of projected future (2040-2070) changes in climate and land-use. Simulations will include baseline conditions, climate change alone, land-use change alone, and the combined effects of climate and land use change. Future (2040-2070) climate change scenarios were developed using regional climate change simulations (50 km resolution) from the National Center for Atmospheric Research NARCCAP project. Land-use change scenarios reflecting future (2050) changes in housing density (i.e. developed land only) were based on projected demographic changes allocated spatially using the SERGoM model (Spatially Explicit Regional Growth Model).
The resulting hydrologic and water quality change scenarios will improve our understanding of the sensitivity of key management targets to climate and land-use change, and present a plausible range of potential future changes that could result in different regions of the country. This information can be used in a risk management context to help guide the development of strategies for responding to climate change. This work will also identify research needs for improving the science and practice of climate change impacts assessment.
- Contract for modeling support awarded August, 2008
- Project completion (anticipated) September, 2010.
Next Steps:The results of this project will contribute to an EPA ORD report assessing the potential impacts of climate change on U.S. water quality to be completed by 2013.
For information about land-use change scenarios (Integrated Climate and Land Use Change Scenarios; ICLUS)