The water surface level of the Dead Sea is the lowest natural land or water surface on Earth at more than 400 meters below sea level. That level continues to lower as water from Dead Sea tributaries is diverted for irrigation. In the southern part of the sea, the salt and potash industries use water from the sea in evaporation ponds. Water is not quickly replenished in this closed basin, so the level continues to drop.
The sea is made up of a northern basin and a southern basin. Both basins were once connected by a strait (see the 1973 image), but the strait is now dry.
(The 2005 image has black stripes running through it because the Scan Line Corrector failed on Landsat 7 in May 2003.)
The Dead Sea is fed mainly by the Jordan River, which enters from the north. Because of irrigation projects and other water needs upstream, the level of the Dead Sea has been falling.
Much less water now enters the sea from the Jordan River. The river once brought 1.3 billion cubic meters of fresh water every year into the sea. Now it brings only about 100 million cubic meters, most of it containing agricultural runoff and sewage. These water uses have a bigger impact on Dead Sea levels than rainfall, which only amounts to an average of about 50 millimeters annually.
Over the past 50 years, the level of the Dead Sea has dropped by 45 meters. It continues to drop at a rate of 1 meter per year. The speed of the decline is also increasing. From 1930 to 1973, the sea declined 17 centimeters per year. From 1974 to 1979, it dropped 62 centimeters per year, and from 1981 to 1990, 79 centimeters per year. From 1994 to 2001, the sea experienced its most rapid decline yet at 100 centimeters per year.
The land left behind after the water retreats is so salty that few plants can grow. To make matters worse, as the water retreats, sinkholes form in the salty seabed that is left behind. Studies have inventoried the sinkholes along the coast of the Dead Sea and found that the sinkholes are increasing in number, making development on this land hazardous.
The Dead Sea has no outlet. The only way water exits the sea is by evaporation. When the water evaporates, it leaves behind dissolved minerals, making the water even saltier.
Those minerals produce the basis for a valuable potash industry. Companies from both Israel and Jordan extract this raw material for fertilizer from the evaporation ponds in the southern basin. The industries that produce the potash pump water from the Dead Sea into these evaporation ponds. Potash is gathered by moving water from one evaporation pond to another.
Current studies suggest that as Dead Sea water use continues, sea levels could decline to 100 meters below the 1960s level by 2050. It would then become too expensive to pump water into the evaporation ponds.
Other uses of Dead Sea salt include
- skin products
- bath salts
- water conditioning
- road de-icing
Normally, political boundaries are not visible from space. But in this series of Landsat images, we do see a political feature. The curved line in the southern basin is the border between Israel to the west and Jordan to the east.
The prominent land feature that separates the northern and southern basins is the Lisan Peninsula. (Lisan means “tongue” in Arabic.) The geologic name for this structure is diapir, a mass of low density material that has pushed upward.
On March 22, 2000, the northern part of a salt pan on the Lisan Peninsula collapsed 2 months after it was completed. The February 15, 2000, image shows water in this pan, but in the October 28, 2000, and later images, the water is drained out. About 56 million cubic meters of brine went back into the Dead Sea when the dike collapsed.
As the Dead Sea level declines, the land that becomes exposed is unstable. Future land feature changes similar to the salt pan collapse on the Lisan Peninsula may accompany the decreased water levels and exposure of additional unstable land.