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Global Change Impacts & Adaptation

Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds (Final Report)

Notice

EPA announces the release of the final report, Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds.

Report Information

Watershed modeling was conducted in 20 large, U.S. watersheds to assess the sensitivity of streamflow, nutrient (nitrogen and phosphorus), and sediment loading to a range of plausible mid-21st Century climate change and urban development scenarios in different regions of the nation. This final report describes the structure―including methods, models, scenarios, and results―of this effort.

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Thomas Johnson
  • by phone at:   703-347-8618
  • by fax at:   703-347-8694
  • by email at:  johnson.thomas@epa.gov

Background

Cover of the 20 U.S. Watersheds Final Report There is growing concern about the potential effects of climate change on water resources. Watershed modeling was conducted in 20 large, U.S. watersheds to characterize the sensitivity of streamflow, nutrient (nitrogen and phosphorus), and sediment loading to a range of plausible mid-21st century climate change and urban development scenarios. The study also provides an improved understanding of methodological challenges associated with integrating existing tools (e.g., climate models, downscaling approaches, and watershed models) and data sets to address these scientific questions.

Watershed simulations were conducted using the Soil Water Assessment Tool (SWAT) and Hydrologic Simulation Program―FORTRAN (HSPF) models. Scenarios of future climate change were developed based on statistically and dynamically downscaled climate model simulations representative of the period 2041−2070. Scenarios of urban and residential development for this same period were developed from the EPA’s Integrated Climate and Land Use Scenarios (ICLUS) project.

Results provide an improved understanding of the complex and context-dependent relationships between climate change, land-use change, and water resources in different regions of the nation. As a first-order conclusion, results indicate that in many locations future conditions are likely to be different from past experience. Results also provide a plausible envelope on the range of streamflow and water quality responses to mid-21st century climate change and urban development in different regions of the nation. In addition, in many study areas the simulations suggest a likely direction of change of streamflow and water quality endpoints. Sensitivity studies evaluating the implications of different methodological choices help to improve the scientific foundation for conducting climate change impacts assessments, thus building the capacity of the water management community to understand and respond to climate change. This information is useful to inform and guide the development of response strategies for managing risk.

History/Chronology

Jul 2012Internal review draft report released for internal peer review.
Mar 2013External review draft report released for external peer review and public comment. [Federal Register Notice Mar 1, 2013]
Sep 2013EPA released the final report.

Citation

U.S. EPA. Watershed Modeling to Assess the Sensitivity of Streamflow, Nutrient, and Sediment Loads to Potential Climate Change and Urban Development in 20 U.S. Watersheds (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-12/058F, 2013.

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