GEOSTATISTICAL ESTIMATION OF HORIZONTAL HYDRAULIC CONDUCTIVITY FOR THE KIRKWOOD‐COHANSEY AQUIFER¹

Abstract

The Kirkwood‐Cohansey aquifer has been identified as a critical source for meeting existing and expected water supply needs for southern New Jersey. Several contaminated sites exist in the region; their impact on the aquifer has to be evaluated using ground water flow and transport models. Ground water modeling depends on availability of measured hydrogeologic data (e.g., hydraulic conductivity, for parameterization of the modeling runs). However, field measurements of such critical data have inadequate spatial density, and their locations are often clustered. The goal of this study was to research, compile, and geocode existing data, then use geostatistics and advanced mapping methods to develop a map of horizontal hydraulic conductivity for the Kirkwood‐Cohansey aquifer. Spatial interpolation of horizontal hydraulic conductivity measurements was performed using the Bayesian Maximum Entropy (BME) Method implemented in the BMELib code library. This involved the integration of actual measurements with soft information on likely ranges of hydraulic conductivity at a given location to obtain estimate maps. The estimation error variance maps provide an insight into the uncertainty associated with the estimates, and indicate areas where more information on hydraulic conductivity is required.

Vapor Intrusion in Homes over Gasoline‐Contaminated Ground Water in Stafford, New Jersey

“…The site was located above the Kirkwood‐Cohansey Aquifer, a large unconfined sand aquifer that has an outcrop area over nearly the entire outer Coastal Plain of southern New Jersey (New Jersey Geological Survey 2004a, 2004b). The water table was shallow (∼3.3 m), and the estimated Darcy ground water flow was 100 to 150 m/year in an SSW direction, based on spatial data layers of estimated hydraulic conductivities and hydraulic gradients for this aquifer (Vyas et al 2004; Spayd and Johnson 2003). Given the permeable soil, the proximity of several buildings to the contaminant source (as close as 25 m), and the short transport distance from the water table to building foundations (1.6 m for buildings with basements), the vapor intrusion pathway was expected to be an exposure pathway of concern.…”

Sensitivity and uncertainty analysis of the recharge boundary condition

“…The computational grid was refined around pumping areas. The permeable Cohansey‐Kirkwood unit forms the primary aquifer in the area [e.g., Vyas et al , 2004], and is underlain by the basal clay Kirkwood formation. The hydraulic conductivity distribution was estimated from numerous well records and ranged from 1.5 m/day to 50 m/day across the domain.…”

Hydrological responses to defoliation and drought of an upland oak/pine forest

“…The interaction between transpiration and groundwater recharge is particularly important because groundwater is a valuable natural resource. In 2005, the US Geologic Survey (USGS) estimated that the withdrawal of groundwater in the USA was approximately 236 Gl per day, of which 2.2 Gl were withdrawn in New Jersey alone (Vyas et al ., ; Kenny et al ., ). Water is a critical component for almost all aspects of the economy including manufacturing, energy production and agriculture as well as private residential uses.…”