EMPIRICAL MODELING OF HYDROLOGIC AND NFS POLLUTANT FLUX IN AN URBANIZING BASIN

Authors

  • Mark Dougherty,

  • Randel L. Dymond,

  • Thomas J. Grizzard Jr.,

  • Adil N. Godrej,

  • Carl E. Zipper,

  • John Randolph,

  • Christine M. Anderson-Cook

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    • Respectively, Assistant Professor, Biosystems Engineering, Auburn University, 206 Tom E. Corley Bldg., Auburn, Alabama 36849–5417; Director, Center for Geospatial Information Technology and Associate Professor of Civil and Environmental Engineering, Virginia Tech, 308 Patton Hall, Blacksburg, Virginia 24061; Professor and Laboratory Director, Occoquan Watershed Monitoring Laboratory, Virginia Tech, 9408 Prince William Street, Manassas, Virginia 20110; Research Associate Professor and Associate Laboratory Director, Occoquan Watershed Monitoring Laboratory, Virginia Tech, 9408 Prince William Street, Manassas, Virginia 20110; Associate Professor, Crop and Environmental Sciences, Virginia Tech, Blacksburg, Virginia 24061; Director, School of Public and International Affairs and Professor of Environmental Planning, Virginia Tech, 112 Architecture Annex, Blacksburg, Virginia 24061; and Statistical Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico 86544 (E-Mail/Dougherty: doughmp@auburn.edu).


  • Paper No. 04119 of the Journal of the American Water Resources Association (JAWRA)

Abstract

ABSTRACT: Long term effects of precipitation and land use/land cover on basin outflow and nonpoint source (NFS) pollutant flux are presented for up to 24 years for a rapidly developing headwater basin and three adjacent headwater basins on the urban fringe of Washington, D.C. Regression models are developed to describe the annual and seasonal responses of basin outflow and IMPS pollutant flux to precipitation, mean impervious surface (IS), and land use. To quantify annual change in mean IS, a variable called delta IS is created as a temporal indicator of urban soil disturbance. Hydrologic models indicate that total annual surface outflow is significantly associated with precipitation and mean IS (r2= 0.65). Seasonal hydrologic models reveal that basin outflow is positively associated with IS during the summer and fall growing season (June to November). NPS pollutant flux models indicate that total and storm total suspended solids (TSS) flux are significantly associated with precipitation and urban soil disturbance in all seasons. Annual NPS total nitrogen flux is significantly associated with both urban and agricultural soil disturbance (r2= 0.51). Seasonal models of phosphorus flux indicate a significant association of total phosphorus flux with urban soil disturbance during the growing season. Total soluble phosphorus (TSP) flux is significantly associated with IS (r2= 0.34) and urban and agricultural soil disturbance (r2= 0.58). In urbanizing Cub Run basin, annual TSP concentrations are significantly associated with IS and cultivated agriculture (r2= 0.51).

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