A 34.5 m borehole, which was drilled near the Dead Sea coast (altitude -394 m) in the southern part of the fan delta of Wadi Zeelim, reveals the geological history of that area from the latest Pleistocene to present. The depositional time frame is based on six 14C dates and two U-Th dates. An erosional (or nondepositional) period is implied by the hiatus between 21,100 yr B.P. (U-Th age, depth 33 m) and 11,315 yr B.P. (14C age, depth 32 m). A subsequent arid phase is recorded by a 6.5-m-thick layer of halite; based on 14C dates this phase relates to the abrupt Younger Dryas cold period reported in temperate to polar regions. The fragility of the environment in this region is indicated by the fact that the region experienced such a severe, short aridification phase (less than 1000 yr), evidence of which is found widely in the desert fringes of the Middle East and North Africa. The aragonite found in most of the Holocene section indicates that the well site was covered by the lake for most of the Holocene. Exceptions are the intervals at 0-3 and 10-14 m depths which represent low stands of the lake.

[1] The present study examines the response of groundwater systems to expected changes in the Mediterranean Sea (rise of <1cm/yr) and Dead Sea levels (decline of ∼1 m/yr). A fast response is observed in the Dead Sea coastal aquifer, exhibited both in the drop of the water levels and in the location of the fresh-saline water interface. No such effect is yet observed in the Mediterranean coastal aquifer, as expected. Numerical simulations, using the FeFlow software, show that the effect of global sea level rise depends on the coastal topography next to the shoreline. A slope of 2.5‰ is expected to yield a shift of the interface by 400 m, after a rise of 1m (∼100 years), whereas a vertical slope will yield no shift. Reduced recharge due to climate change or overexploitation of groundwater also enhances the inland shift of the interface.

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