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We document and analyze the rapid development of a real-time karst system within the subsurface salt layers of the Ze'elim Fan, Dead Sea, Israel by a multidisciplinary study that combines interferometric synthetic aperture radar and light detection and ranging measurements, sinkhole mapping, time-lapse camera monitoring, groundwater level measurements and chemical and isotopic analyses of surface runoff and groundwater. The >1 m/yr drop of Dead Sea water level and the subsequent change in the adjacent groundwater system since the 1960s resulted in flushing of the coastal aquifer by fresh groundwater, subsurface salt dissolution, gradual land subsidence and formation of sinkholes. Since 2010 this process accelerated dramatically as flash floods at the Ze'elim Fan were drained by newly formed sinkholes. During and immediately after these flood events the dissolution rates of the subsurface salt layer increased dramatically, the overlying ground surface subsided, a large number of sinkholes developed over short time periods (hours to days), and salt-saturated water resurged downstream. Groundwater flow velocities increased by more than 2 orders of magnitudes compared to previously measured velocities along the Dead Sea. The process is self-accelerating as salt dissolution enhances subsidence and sinkhole formation, which in turn increase the ponding areas of flood water and generate additional draining conduits to the subsurface. The rapid terrain response is predominantly due to the highly soluble salt. It is enhanced by the shallow depth of the salt layer, the low competence of the newly exposed unconsolidated overburden and the moderate topographic gradients of the Ze'elim Fan.

[1] This paper examines, for the first time, the unique situation of a groundwater system adjacent to a long-term stratified (meromictic) lake. Using conceptual and numerical models, the configuration of groundwater interfaces between the three different water bodies (regional groundwater and upper and lower lake waters) and the flow patterns were quantitatively evaluated assuming a homogenous aquifer. A complex flow system, controlled by density difference, is created near the lake, where three circulation cells are developed. These results are different from the classic circulation cell that is found adjacent to nonstratified water bodies (lakes or oceans). Sensitivity analyses reveal that the results are sensitive to changes in thickness and density of the upper water mass of the lake. The Dead Sea, under its possible future meromictic conditions, serves as an ideal example of such a system. Thus, the model's results can be used as a preliminary assessment for groundwater behavior adjacent to the lake, if and when stratification will develop.

[1] The high-degree of spatial variability of dissolved As levels in shallow aquifers of the Bengal Basin has been well documented but the underlying mechanisms remain poorly understood. We compare here As concentrations measured in groundwater pumped from 4700 wells

[1] The Dead Sea is a hypersaline terminal lake experiencing a water level drop of about 1 m/yr over the last decade. The existing estimations for the water balance of the lake are widely variable, reflecting the unknown subsurface water inflow, the rate of evaporation, and the rate of salt accumulation at the lake bottom. To estimate these we calculate the energy and mass balances for the Dead Sea utilizing measured meteorological and hydrographical data from 1996 to 2001, taking into account the impact of lowered surface water activity on the evaporation rate. Salt precipitation during this period was about 0.1 m/yr. The average annual inflow is 265–325 × 106 m3/yr, corresponding to an evaporation rate of 1.1–1.2 m/yr. Higher inflows, suggested in previous studies, call for increased evaporation rate and are therefore not in line with the energy balance.