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Global Change Impacts & Adaptation

Assessment of Hydrologic and Water Quality Sensitivity to Climate and Land-Use Change in a Mid-Atlantic Watershed

Report Information

This page describes a current EPA ORD project. No project report or other download is available at this time. Please see the section Next Steps below for a timeline of anticipated products of this work.

Background:
The Chesapeake Bay suffered severe ecological impairment during the later half of the 20th Century due primarily to nutrient pollution and associated reductions in dissolved oxygen and water clarity. Significant effort has been invested to restore water quality and living resources throughout the Chesapeake Bay watershed. Future climate change could impact the ability to meet restoration goals. Managing any increase in risk associated with climate change will require an improved understanding of potential impacts, and the development of strategies for increasing resilience to anticipated changes. To address this question, EPA is conducting watershed modeling in a Chesapeake Bay subwatershed, the Monocacy River, assessing the sensitivity of key management targets to plausible future climate and landuse change.

The Monocacy River watershed is about 1,927 km² in area, and is a tributary of the Potomac River and Chesapeake Bay. The Hydrologic Simulation Program FORTRAN (HSPF) watershed model was used to assess the sensitivity of mean annual streamflow, the 100-yr flood event, 7Q10 low flow, and mean annual sediment, phosphorus, and nitrogen loads to plausible climate change, landuse change, and implementation of watershed BMPs.

Climate change scenarios were created based on climate modeling experiments using seven GCM models from the IPCC Third Assessment Report (IPCC, 2001) and acquired from the Penn State University’s Consortium of Atlantic Regional Assessments project website (CARA; http://www.cara.psu.edu/). Land-use change scenarios reflecting future 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). All climate change projections show warming mean annual temperatures by 2030. Projections vary with respect to changes in mean annual precipitation, with some showing increases, and others showing decreases. The response of hydrologic and water quality endpoints show a wide range of variability, with decreases in mean streamflow and 7Q10 low flow, increases in the 100-yr flood, and a mixed response for sediment, phosphorus, and nitrogen loads.
History:
  • Contract for modeling support awarded April, 2006
  • Journal paper submitted for publication (anticipated) March, 2010
Next Steps:
None

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

Additional Information

Methods and results are briefly described in Chapter 6 of the report: BASINS 4.0 Climate Assessment Tool (CAT): Supporting Documentation and User's Manual: http://cfpub.epa.gov/ncea/CFM/recordisplay.cfm?deid=203460

Methods and results are briefly described in the journal paper:
http://www.springerlink.com/content/d0822h253686n483

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