Delineation of salt water intrusion through use of electromagnetic-induction logging: A case study in Southern Manhattan Island, New York

Water
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Abstract

Groundwater with chloride concentrations up to 15,000 mg/L has intruded the freshwater aquifer underlying southern Manhattan Island, New York. Historical (1940–1950) chloride concentration data of glacial aquifer wells in the study area indicate the presence of four wedges of saltwater intrusion that may have been caused by industrial pumpage. The limited recharge capability of the aquifer, due to impervious surfaces and the 22.7 million liters per day (mld) of reported industrial pumpage early in the 20th Century was probably the cause for the saltwater intrusion and the persistence of the historical saltwater intrusion wedges over time. Recent drilling of wells provided new information on the hydrogeology and extent of saltwater intrusion of the glacial aquifer overlying bedrock. The new observation wells provided ground-water level, chloride concentration, hydraulic conductivity, and borehole geophysical data of the glacial aquifer. The glacial sediments range in thickness from less than 0.3 m to more than 76.2 m within the study area. A linear relation between Electromagnetic-induction (EM) conductivity log response and measured chloride concentration was determined. Using this relation, chloride concentration was estimated in parts of the glacial aquifer where sampling was not possible. EM logging is an effective tool to monitor changes in saltwater intrusion wedges.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Delineation of salt water intrusion through use of electromagnetic-induction logging: A case study in Southern Manhattan Island, New York
Series title Water
DOI 10.3390/w9090631
Volume 9
Issue 9
Year Published 2017
Language English
Publisher MDPI
Contributing office(s) New York Water Science Center
Description 17 p.
First page 1
Last page 17
Country United States
State New York
City New York City
Other Geospatial Manhattan Island