The Dead Sea: Impacts of the Rapidly Declining Water Level and the Expected "Anthropogenic" Meromixis Upon Water Level Stabilization

The Dead Sea (DS) is a highly perturbed terminal lake experiencing major changes in its limnology. Exploitation of water resources in its drainage basin as well as salt extraction through brine evaporation by Israeli and Jordanian chemical industries have resulted in a decline of its water level by more than 25 meter over the past few decades. The DS current level, which is the lowest surface on Earth, is 418 meters below mean sea level, and the level continues to drop at a rate of about 1 m/yr. This represents annual water deficient of about 650 MCM/yr, which is equivalent to more than a third and a half of the water consumptions in Israel and Jordan, respectively. The declining water level is having negative environmental impacts on the lake's surroundings such as exposure of large mud flats and development of sinkholes in the vicinity of the lake. Yet, it is unlikely that in this water scarce region, stabilization of the DS level would be achieved through new freshwater allocation. Introduction of seawater, which is being considered today as a mean of stabilizing or raising lake level, will however have other environmental impacts, including changes in the DS chemical composition. We present a study providing forecast for the evolution of the DS under different operational scenarios, including conveyance of seawater from the Red Sea. The impact of increasing inflows (fresh or seawater) on the lake's dynamics is considered. All scenarios assumed continuation of operation of the chemical plants. Modeling was carried out using the modified 1-D POM-based code adopted for the DS chemistry. Long term dilution and the development of meromixis is expected to occur when lake level is raised. However, we show that meromixis would occur also when inflow volumes are smaller but enough to stabilize water level or decrease the current rate of water level decline. This seemingly unlikely behavior of a terminal lake experiencing a negative or a balanced water regime will be due to the continued operation of the chemical industries. Stratification develops because of excess inflow over evaporation, while water level decline occurs due to brine withdrawal from the hypolimnion by the industries. Anthropogenic impact would thus continue to control the DS evolution, even if lake level is stabilized. If the additional inflow is derived from seawater, the anthropogenic impact on the DS evolution would be even more pronounced.