Recent and projected changes in Dead Sea level and effects on mineral production from the sea
Hydrologic data for the Dead Sea area were reviewed to assess the probable magnitude and rate of change of the water level of the Dead Sea. Historical average annual Dead Sea levels range from a minimum of 399.4 meters below sea level in about 1818 to a maximum of 388.6 meters below in 1896. Present levels are rapidly approaching the historical low. There is a close correlation between Dead Sea level and accumulated departure from the mean of long-term rainfall except for the most recent period since 1964. During that period rainfall has been near the long-term average but water levels have continued to decline, in part due to abstractions for irrigation in the Jordan River basin. The dissolved-solids concentration of Dead Sea water presently is approximately 322,000 milligrams per liter and is generally well mixed throughout. This concentration is at the saturation level, resulting in continuous precipitation of some salts. The increase in dissolved solids to the present high concentration has resulted in an evaporation rate less than that estimated in previous reports. Evaporation rate from the North Basin is estimated at 1,310 millimeters per year at present. The evaporation rate from the South Basin was not estimated due to extensive existing or planned modifications for mineral production facilities. Water budget computations were performed at various inflow rates in order to project water-level changes for 50 years. Computations assumed closure of the South Basin by existing and proposed mineral extraction facilities. The projected 50-year changes ranged from a decline of 51 meters with no inflow from any sources to a rise of 10.2 meters when average annual inflow from the Jordan River was 750 cubic hectometers. An average annual inflow to the Sea of 900 cubic hectometers from all sources is required to stabilize the Sea at the present level. Principal impact of declining water levels on proposed potash production facilities in Jordan would be an increase in power requirements. A cursory review of a proposed plan to divert water from the Mediterranean Sea into the Dead Sea to generate electric power and stabilize water levels indicates a very limited impact on chemical, physical, and ecological characteristics of the Dead Sea in the near future. Water-budget computations indicate that if all but 200 cubic hectometers of tributaries' waters were utilized for irrigation and other purposes, a maximum diversion of 700 cubic hectometers per year into the Dead Sea would be possible without significantly raising long-term average water levels.