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Assigning land use to supply wells for the statistical characterization of regional groundwater quality: Correlating urban land use and VOC occurrence

Journal of Hydrology

By:
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DOI: 10.1016/j.jhydrol.2009.02.056

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Abstract

Many national and regional groundwater studies have correlated land use "near" a well, often using a 500 m radius circle, with water quality. However, the use of a 500 m circle may seem counterintuitive given that contributing areas are expected to extend up-gradient from wells, and not be circular in shape. The objective of this study was to evaluate if a 500 m circle is adequate for assigning land use to a well for the statistical correlation between urban land use and the occurrence of volatile organic compounds (VOCs). Land use and VOC data came from 277 supply wells in four study areas in California. Land use was computed using ten different-sized circles and wedges (250 m to 10 km in radius), and three different-sized "searchlights" (1-2 km in length). We define these shapes as contributing area surrogates (CASs), recognizing that a simple shape is at best a surrogate for the actual contributing area. The presence or absence of correlation between land use and the occurrence of VOCs was evaluated using Kendall's tau (??). Values of ?? were within 10% of one another for wedges and circles ranging in size from 500 m to 2 km, with correlations remaining statistically significant (p < 0.05) for all CAS sizes and shapes, suggesting that a 500 m circular CAS is adequate for assigning land use to a well. Additional evaluation indicated that urban land use is autocorrelated at distances ranging from 8 to 36 km. Thus, urban land use in a 500 m CAS is likely to be predictive of urban land use in the actual contributing area.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Assigning land use to supply wells for the statistical characterization of regional groundwater quality: Correlating urban land use and VOC occurrence
Series title:
Journal of Hydrology
DOI:
10.1016/j.jhydrol.2009.02.056
Volume
370
Issue:
1-4
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
100
Last page:
108
Number of Pages:
9