Geophysical (time domain electromagnetic model) delineation of a shallow brine beneath a freshwater lake, the Sea of Galilee, Israel

The Sea of Galilee is a freshwater lake, into which saline water emerges through onshore and offshore springs and through flux from the lake's sediments. The novel surface marine modification of the time domain electromagnetic method was used to map the spatial distribution of brines in the sediments below the lake. Results indicate that electrical resistivities of 1.0 and 0.5 ohm-m are detected at depths of ~10 m below the lake bottom in most of the lake area, which are equivalent to ~11,000 and 22,000 mgCl/L, respectively. Relatively fresh groundwater was detected beneath most of the shoreline. Faulting controls the vertical interfaces between saline and fresh groundwaters. It is hypothesized that salt transport is dominated by molecular diffusion in the central part of the lake and by advection from regional aquifers in the margins.