A new method for determining whether a decrease in the levels of lakes without outlets -- such as the Dead Sea -- is accompanied by a parallel drop in the groundwater level of nearby aquifers has been developed in a new Institute study. Such a drop would mean that less water is available for drinking and agriculture.
The model -- developed by Dr. Daniel Ronen, Dr. Brain Berkowitz and doctoral student Yosef Yechieli of the Institute's Department of Environmental Sciences and Energy Research -- is described in a recent issue of Water Resources Research, published by the American Geophysics Union. Although the research focused on the Dead Sea, it is applicable to similar closed-basin terminal lakes, such as the Great Salt Lake in Utah, the Salton Sea in California and Lake Magadi in Chad.
The water level of the Dead Sea, the terminal lake of the Jordan River system and the lowest lake in the world, has decreased at an average of 0.5 meters per year since 1960. Water from several nearby aquifers seeps through the soil into this extremely saline body of water, adding groundwater of varying chemical compositions to the lake.
The response of groundwater level to changes in the Dead Sea level was found to be rapid -- in fact, a matter of days. This finding, along with data yielded by the study of the structural and hydraulic properties of the aquifer, will now facilitate the forecasting of future correlations between the Dead Sea and its neighboring aquifers.
Measurements of the groundwater were taken via observation wells in Wadi Tze'elim and in Turiebe, while those of the Dead Sea were obtained from records of the Dead Sea Works. The model takes into account a wide variety of factors, such as the distance between the wells and the lake, the slope of the bottom of the lake, and density differences between the salty lakewater and the groundwater.
This work was supported by a grant from the Israel Ministry of Energy and Infrastructure. Dr. Berkowitz holds the Barecha Foundation Career Development Chair. Yechieli, having completed his doctorate, is now employed by the Geological Survey of Israel.