Verification of Geophysically Determined Depths to Saltwater Near the Herring River (Cape Cod National Seashore), Wellfleet, Massachusetts
Fitterman DV and Dennehy KF. 1991. Verification of Geophysically Determined Depths to Saltwater Near the Herring River (Cape Cod National Seashore), Wellfleet, Massachusetts. U. S. Geological Survey Open-File Report 91-321. U. S. Geological Survey. Boston, MA
The results of this study confirm the location of the previously determined freshwater-saltwater interface near the Herring River, Wellfleet, Massachusetts. Surface electromagnetic measurements are compared with driller's logs, water conductivity data, and induction logs from observation wells drilled in the study area. Terrain conductivity meter measurements recorded earlier along survey lines correlate with a brackish water saturated zone having a special conductance in excess of 1800 5S/cm. Transient electromagnetic soundings confirm this interpretation and also locate a deeper, more conductive zone saturated with seawater. Throughout the study area the vertical separation between the water-table level in domestic water wells and the top of the brackish water zone was determined to range from 13 to 29 m. At the five observation wells, including the two in the flood plain of the Herring River, an elevation difference of almost 20 m was found between the water table level and the terrain conductivity meter determined conductor. These findings support the idea that increasing tidal flow in the Herring River by adjusting the tidal control structure at the mouth of the river will not have an adverse effect on domestic water wells in the area.
- Type
- Published Report
- Authors
- Fitterman, David; Dennehy, Kevin
- Date of Issue
- 1991-06-04
- Publisher
- U. S. Geological Survey
- Units
- CACO
- Keywords
- Aquatic Sciences, Geology, Herring River, Wells