Environmental Monitoring and Assessment

, Volume 81, Issue 1–3, pp 73–84 | Cite as

A Hydrologic Network Supporting Spatially Referenced Regression Modeling in the Chesapeake Bay Watershed

  • John W. Brakebill
  • Stephen D. Preston
Article

Abstract

The U.S. Geological Survey has developed a methodology for statistically relating nutrient sources and land-surface characteristics to nutrient loads of streams. The methodology is referred to as SPAtially Referenced Regressions On Watershed attributes (SPARROW), and relates measured stream nutrient loads to nutrient sources using nonlinear statistical regression models. A spatially detailed digital hydrologic network of stream reaches, stream-reach characteristics such as mean streamflow, water velocity, reach length, and travel time, and their associated watersheds supports the regression models. This network serves as the primary framework for spatially referencing potential nutrient source information such as atmospheric deposition, septic systems, point-sources, land use, land cover, and agricultural sources and land-surface characteristics such as land use, land cover, average-annual precipitation and temperature, slope, and soil permeability. In the Chesapeake Bay watershed that covers parts of Delaware, Maryland, Pennsylvania, New York, Virginia, West Virginia, and Washington D.C., SPARROW was used to generate models estimating loads of total nitrogen and total phosphorus representing 1987 and 1992 land-surface conditions. The 1987 models used a hydrologic network derived from an enhanced version of the U.S. Environmental Protection Agency's digital River Reach File, and course resolution Digital Elevation Models (DEMs). A new hydrologic network was created to support the 1992 models by generating stream reaches representing surface-water pathways defined by flow direction and flow accumulation algorithms from higher resolution DEMs. On a reach-by-reach basis, stream reach characteristics essential to the modeling were transferred to the newly generated pathways or reaches from the enhanced River Reach File used to support the 1987 models. To complete the new network, watersheds for each reach were generated using the direction of surface-water flow derived from the DEMs. This network improves upon existing digital stream data by increasing the level of spatial detail and providing consistency between the reach locations and topography. The hydrologic network also aids in illustrating the spatial patterns of predicted nutrient loads and sources contributed locally to each stream, and the percentages of nutrient load that reach Chesapeake Bay.

SPARROW Chesapeake Bay nutrients loads regression modeling reach stream RF1 DEM 

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References

  1. Alexander, R.B., Brakebill, J.W., Brew, R.E., and Smith, R.A.: 1999, Enhanced River Reach File 1.2 (ERF1), U.S. Geological Survey Open-File Report 99–457 (scale 1:500,000) accessed January 1999 at URL http://water.usgs.gov/GIS/metadata/usgswrd/erf1.htmlGoogle Scholar
  2. Brakebill, J.W., and Preston, S.D.: 1999, Digital Data Used to Relate Nutrient Inputs to Water Quality in the Chesapeake Bay Watershed, Version 1.0: U.S. Geological Survey Open-File Report 99–60, accessed May 2000 at URL http://md.usgs.gov/publications/ofr-99–60/report.htmlGoogle Scholar
  3. Brakebill, J.W., Preston, S.D., and Martucci, S.K.: 2001, Digital Data Used to Relate Nutrient Inputs to Water Quality in the Chesapeake Bay Watershed, Version 2.0: U.S. Geological Survey Open-File Report 01–251, accessed July 2001 at URL http://md.usgs.gov/publications/ofr-01–251/report.htmlGoogle Scholar
  4. ESRI (Environmental Systems Research Institute, Inc): 1992a, Arc/Info Users Guide, ARC/INFO Data Model, Concepts and Key Terms, 2d ed.: Redlands, California, 201 pp.Google Scholar
  5. ESRI (Environmental Systems Research Institute, Inc): 1992b, Arc/Info Users Guide, Cell-based modeling with GRID, 2d ed.: Redlands, California, 267 pp.Google Scholar
  6. Langland, M.J., Lietman, P.L., and Hoffman, S.A.: 1995, Synthesis of Nutrient and Sediment Data for Watersheds Within the Chesapeake Bay Drainage Basin: U.S. Geological Survey Water-Resources Investigations Report 95–4233, 121 pp.Google Scholar
  7. Preston, S.D. and Brakebill, J.W.: 1999, Application of Spatially Referenced Regression Modeling for the Evaluation of Total Nitrogen Loading in the Chesapeake Bay Watershed: U.S. Geological Survey Water-Resources Investigations Report 99–4054, 12 p. Available online at URL http://md.usgs.gov/publications/wrir-99–4054/report.htmlGoogle Scholar
  8. Smith, R.A., Schwarz, G.E., and Alexander, R.B.: 1997, ‘Regional Interpretation of Water-Quality Monitoring Data’: Water Resources Research 33 (12) 2781–2798, available online at URL http://water.usgs.gov/nawqa/sparrow/wrr97/results.htmlGoogle Scholar
  9. USEPA (U.S. Environmental Protection Agency): 1996, Reach File Version 1.0 (RF1) for the conterminous United States: U.S. Environmental Protection Agency accessed January 1998 at http://www.epa.gov/ost/basins/metadata/rf1.htmGoogle Scholar
  10. USGS (U.S. Geological Survey): 1997, HYDRO1K Elevation Derivative Data Base: U.S. Geological Survey accessed January 1998 at URL http://edcwww.cr.usgs.gov/landdaac/gtopo30/hydro/namerica.htmlGoogle Scholar
  11. USGS (U.S. Geological Survey): 1999a, National Elevation Data Base (NED): U.S. Geological Survey Fact Sheet 148–99, available online at URL http://mapping.usgs.gov/mac/isb/pubs/factsheets/fs14899.htmlGoogle Scholar
  12. USGS (U.S. Geological Survey): 1999b, National Hydrography Data Base (NHD): U.S. Geological Survey Fact Sheet 106–99, available online at URL http://mapping.usgs.gov/mac/isb/pubs/factsheets/fs14899.html http://mapping.usgs.gov/mac/isb/pubs/factsheets/fs10699.htmlGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • John W. Brakebill
    • 1
  • Stephen D. Preston
    • 2
  1. 1.U.S. Geological SurveyBaltimoreUSA
  2. 2.Chesapeake Bay ProgramU.S. Geological SurveyAnnapolisUSA

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