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Estimating spatial variability of recharge in southern New Jersey from unsaturated-zone measurements

Water-Resources Investigations Report 2002-4288

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Abstract

Spatial variability of recharge in southern New Jersey was studied by sampling the unsat-urated zone at 48 sites distributed over approximately 930 square kilometers. Samples of unsaturated-zone sediment were collected during the summer and fall of 1996. Unsaturated flow was calculated using moisture-content data and estimates of conductivity and matric potential derived from sediment-size data. Matric forces were found to be important at about 70 percent of the sites despite the expectation that unsaturated flow in a humid climate is gravity driven. Upward water movement occurred at about 17 percent of the sites. The lower sediment layer at these sites consisted of sandy loam, indicating that upward movement can occur at depth only where the sediments are relatively fine-grained. At the other extreme, calculated flow at about 17 percent of the sites exceeded 250 centimeters per year. Because of the uncertainty inherent in unsaturated-flow calculations, the method provides only a scaling of recharge variability; however, the median calculated flow of 29.1 centimeters per year compares favorably with recharge estimates from previous water-budget studies. A map developed by spatial analysis of the recharge estimates identified an agricultural part of the study area where recharge was known to be low relative to recharge in other basins.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Estimating spatial variability of recharge in southern New Jersey from unsaturated-zone measurements
Series title:
Water-Resources Investigations Report
Series number:
2002-4288
Edition:
-
Year Published:
2003
Language:
ENGLISH
Description:
iv, 31 p. : ill. (some col.), maps (some col.) ; 28 cm.