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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #61432
Title: GIS-BASED DELINEATION OF SOURCE AREAS OF PHOSPHOROUS WITHIN AGRICULTURAL WATERSHEDS OF THE NORTHEASTERN USA

Author
item Zollweg, James
item Gburek, William
item Pionke, Harry
item Sharpley, Andrew

Submitted to: International Union of Geodesy and Geophysics Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/14/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Transport of nutrients and chemicals from agricultural land to waterways in surface runoff is a major problem. Cost-effective management requires identification of those areas most likely to be sources of these pollutants. We have developed a new computer model which is able to predict the amount of phosphorus (P) exported from a watershed and the areas where that P originates. Model results illustrate that the areas o the watershed controlling P export are consistently a relatively small and definable portion of the watershed. Use of this model as a management tool will provide significant savings because expensive ameliorative measures can be directed to those specific locations where the greatest potential for pollution generation exists.

Technical Abstract: A GIS-based methodology is developed for modeling the extent and contributions of dissolved phosphorous (DP) exporting areas of a watershed. A physical process based, variable source area runoff model is supplemented with algorithms for P availability and transport by surface runoff. The overall model requires data layers describing topography, soils distribution, land use, and soil test P within the catchment. The distributed modeling approach enables identification of source areas of runoff an DP, as well as total delivery to the outlet. For model verification, simulated DP losses are compared with observed values of surface runoff and concentration of DP in streamflow within a 25.7-ha agricultural watershed in east-central Pennsylvania, USA. The model is then used to illustrate potential for management of critical source areas to reduce DP loss from the watershed.