Geophysical Investigation of Depth to Saltwater Near the Herring River (Cape Cod National Seashore), Wellfleet, Massachusetts
Fitterman DV, Brooks GA, Snyder SL. 1989. Geophysical Investigation of Depth to Saltwater Near the Herring River (Cape Cod National Seashore), Wellfleet, Massachusetts. Open-File Report 89-677. United States Department of The Interior, Geological Survey
Abstract of report: "Terrain conductivity meter profiling, VLF resistivity, and transient electromagnetic sounding measurements were made near the Herring River in Wellfleet, Massachusetts to determine the depth to saltwater in the ground-water aquifer. In general, the terrain conductivity meter and VLF resistivity data are modeled with a two-layer model corresponding to the unsaturated zone and freshwater aquifer, and the saltwater saturated aquifer below. The transient sounding data suggest the presence of a transition zone between the freshwater and saltwater saturated zones. The data indicate that the aquifer thickens in the landward direction in the expected manner. Based upon limited water-well data, it is estimated that there is at least 10 m of vertical separation between the water level in wells and the saltwater zone. In some areas the separation is greater. Using a simple analysis of how tidally induced aquifer level variations would respond to increased tidal flow in the Herring River, it is estimated that completely opening the tidal and sluice gates at the mouth of the river would have no effect on water wells in the highlands to the east of the river because the mean river level would be unchanged and the small tidally driven aquifer fluctuations are estimated to persist only a few tens of meters from the river's edge. Wells near the flood plain of the Herring River might be affected by increased tidal flow, but more information on well locations and water depths is needed to make a determination. It is recommended that additional well data be collected, and observation wells be installed and geophysically logged in order that the geophysical interpretation be confirmed and refined."
- Type
- Published Report
- Authors
- Fitterman, David; Brooks, Glenn; Snyder, Stephen
- Date of Issue
- 1989-12-27
- Publisher
- United States Department of The Interior, Geological Survey
- Units
- CACO
- Keywords
- Aquatic Sciences, Aquifer, Geophysical, Groundwater, Herring River, Models, Wells