Industry-Driven versus Natural Groundwater Flow Regime at the Dead Sea Coastal Aquifer

The coexistence of nature and anthropogenic development requires continuous monitoring and research to address and respond to unforeseen threatening processes that occur with time. This is particularly relevant to the groundwater flow regime in the coastal aquifer adjacent to the Dead Sea, the level of which is dropping, and the industrial evaporation ponds, whose levels are rising. The increasing hydraulic gradient between the two water bodies has produced severe leakage through the pond embankments. To prevent this leakage, a vertical deep sealing wall was built along the embankment. In this study, the overall leakage is calculated by mass balance, and the subsurface leakage component is numerically simulated, based on the mass balance and hydrological observations. Some of the leakage discharges into surface canals and some at the Dead Sea. The leakage volume increased from 20 mcm/year in the 1980s to 100 mcm/year before the sealing wall was built (in 2012), and from 60 mcm/year once the wall was established to 80 mcm/year today. Using the calibrated model, the leakage volume is predicted to increase in the next few decades, mainly through the Ye’elim alluvial fan. Further research effort is needed to come up with new preventive measures.

Comparison of Hydraulic Conductivity Values Obtained from Empirical Formulae and Laboratory Experiments

Hydraulic conductivity determination plays an essential role in the investigation of groundwater flow regime which can then influence many field problems such as pumping capabilities in the area, transport of contaminant or heat and soil internal erosion. Numerous equations based on dimensional analysis or experimental measurements have been published since the end of the 19th century for the determination of hydraulic conductivity. However, not all of these formulae are applicable for every material and all of them bring some uncertainty in the value of hydraulic conductivity. This paper contains a description of experimental research carried out concerning the determination of hydraulic conductivity for four types of sand with different grain size distribution curves and variable porosity. Obtained values of hydraulic conductivity ranged from 1 × 10-4 to 4 × 10-3 according to the sample porosity. The series of experiments consisted of 160 separate tests conducted in order to obtain relevant statistical sets. In this paper, the experimental data are discussed and compared with hydraulic conductivities obtained from 6 empirical formulae recommended in a previous study. The comparison showed that some empirical formulae provide a good agreement with the experimental data (the most precise were formulae published by Terzaghi and by Sauerbrey). However, some formulae showed high deviation from measured data (formula published by Zamarin).