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Techniques of contributing-area delineation for analysis of nonpoint-source contamination of Long Island, New York

January 1, 1995

Ninety shallow monitoring wells on Long Island, N.Y., were used to test the hypothesis that the correlation between the detection of volatile organic compounds (VOC's) at a well and explanatory variables representing land use, population density, and hydrogeologic conditions around the well is affected by the size and shape of the area defined as the contributing area. Explanatory variables are quantified through overlay of various specified contributing areas on 1:24 000-scale landuse and population-density geographic information system (GIS) coverages. Four methods of contributing-area delineation were used: (a) centering a circle of selected radius on the well site, (b) orienting a triangular area along the direction of horizontal ground-water flow to the well, (c) generating a shaped based on direction and magnitude of horizontal flow to the well, and (d) generating a shape based on three-dimensional particle pathlines backtracked from the well screen to the water table. The strongest correlations with VOC detections were obtained from circles of 400- to 1 000-meter radius. Improvement in correlation through delineations based on ground-water flow would require geographic overlay on more highly detailed GIS coverages than those used in the study.

Publication Year 1995
Title Techniques of contributing-area delineation for analysis of nonpoint-source contamination of Long Island, New York
Authors P. Misut
Publication Type Article
Publication Subtype Journal Article
Series Title Models for assessing and monitoring groundwater quality. Proc. symposium, Boulder, 1995
Index ID 70018890
Record Source USGS Publications Warehouse