Subaerial morphology affected by groundwater aggressiveness: Sinkhole susceptibility above karstified salt, Dead Sea

Abstract

Evaporite karst is intensively developing at the Dead Sea (DS), both along its western and eastern shores. The collapse of overlying sediments into evaporite karst cavities results in sinkhole formation. The dissolution is produced by undersaturated water, aggressive concerning halite. The evaporite karst is developing rapidly, in the time scale of months to years, so groundwater aggressiveness is a relevant factor for sinkhole susceptibility assessment. The present study analyzes sinkhole development concerning groundwater aggressiveness. The aggressiveness is evaluated from bulk resistivity (ρx) of the aquifer, measured from the surface using the Transient Electromagnetic (TEM) method, and from resistivity (ρw) of groundwater filling its pores. We suggest a methodology for water aggressiveness determination and its classification concerning salt. We then demonstrate a significant correlation between water aggressiveness and the actual distribution of sinkholes in five study areas along the Dead Sea. Conversely, we show that the timing of sinkholes occurrence within recent decades does not correlate with water aggressiveness. The timing is attributed to the multiple factors that control the dissolution of salt and consequent collapse. Acknowledging that the real hydrogeological conditions involve multifactorial processes, we shortly analyze other concurrent factors, including water table depth, existing salt karstification east of the salt edge, and site location relative to the salt edge.