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

May 1, 2003

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.

Publication Year 2003
Title Estimating spatial variability of recharge in southern New Jersey from unsaturated-zone measurements
DOI 10.3133/wri024288
Authors Arthur L. Baehr, Leon J. Kauffman, Kimberlie Perkins, Bernard T. Nolan
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Water-Resources Investigations Report
Series Number 2002-4288
Index ID wri024288
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program