Spatial delineation of groundwater salinity using deep TDEM geophysical measurements: a feasibility study
The objective of this study was to delineate the spatial distribution of fresh, brackish and saline groundwater bodies, as well as brine, beneath the Judea Desert, Israel. The deep time domain electromagnetic (TDEM) geophysical system, named Cycle-5M, providing the maximum exploration depth, down to ~1.5-2 km below land surface, was employed. The study was conducted at 21 locations at the desert plateau, where fresh groundwater flows through the upper aquifers from the replenishment area at the Judea Mountains toward the Dead Sea springs. At deeper aquifers, brackish and saline groundwater bodies exist, which originated from lakes and lagoons, existed at the Dead Sea Rift valley during the Pleistocene and Pliocene, respectively. The geophysical calibration results showed that, fresh groundwater (C<10e3 ppm TDS salinity) is characterized by resistivity of more than 15 ohm-m; brackish groundwater (10e3<C<10e4 ppm salinity) by 5- 15 ohm-m; saline groundwater (10e4<C<10e5 ppm salinity) by 0.5-5 ohm-m; and brine (10e5<C ppm salinity) by less than 0.5 ohm-m. The hydrological results of the survey show that the upper Judea Group aquifer is usually saturated with fresh groundwater, while the interface between fresh and brackish water exists within the lower Judea Group aquifer and in the underlying Kurnub Group aquifer. According to the scarce calibration data available, the salinity of the brackish groundwater in most cases does not exceed a half of the normal seawater salinity.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0925 Magnetic and electrical methods (5109);
- 1800 HYDROLOGY;
- 1829 Groundwater hydrology