Dead Sea

Abstract

The Dead Sea (see map, Figure 14.1), like the Great Salt Lake, has undergone recent physical and chemical changes as a result of human influence. Before 1979, this very deep lake was characterized by two basins: a small, shallow (up to about 8 m deep) southern basin (Figure 19.1a), and a larger, deeper (340 m deep), density-stratified, meromictic northern basin (Figure 19.1b). Details of the Dead Sea have been presented by Neev and Emery (1967), Nissenbaum (1975), and Steinhorn (1985). The Jordan River supplies the major source of water for this terminal lake. After about 1964, the use of water for irrigation from the Jordan River and its watershed reduced the inflow so much that evaporation in the Dead Sea exceeded inflow. Between 1930 and 1979, the water in the lake dropped 10 m and the southern basin was completely exposed. By 1975, the mixolimnion had increased in salinity to the point that cooler winter temperatures in the surface layers reduced the density differences between the upper and lower layers of the lake. This resulted in increased mixing, deepening of the mixolimnion, and eventually complete overturn in February, 1979 (Steinhorn et al., 1979). The changes in the structure of the Dead Sea before overturn were summarized by Beyth (1980) and Steinhorn and Assaf (1980) while those during the 1975–1979 period were reported by Steinhorn et al. (1979) and Steinhorn (1985).