Dead Sea Desiccation

Dead Sea Desiccation

 The Dead Sea is a large salt lake on the border of Israel and Jordan. It’s surface lies at -1388ft making it the lowest place on Earth. The Dead Sea is about 34mi long and 11mi wide on average, and it reaches a maximum depth of 1,237ft, making it the deepest salt lake in the world. It is also one of the saltiest bodies of water in the world at 8.6 times saltier than the ocean. This high level of salt makes life impossible for all but the most well adapted microbes, hence its name. Water in the Dead Sea has a density of 1.24kg/L compared to 1.03kg/L for ocean water, making flotation very easy.

The Dead Sea lies in the Jordan Rift Valley, which was formed by the Dead Sea Transform fault. This transform fault lies along the tectonic plate boundary between the African and Arabian plates. The Dead Sea is fed (at least historically) by the Jordan River and by rain falling in its watershed. However, rain contributes little to the level of the Dead Sea; the northern areas receive on average 4”/yr and the southern areas about 2”/yr. This is due to the rain shadow effect of the Judean Hills to the west. The Dead Sea has no outflows, and it’s level is maintained through evaporation. It formed about 3 million years ago when the Jordan Valley was inundated by frequent floodwater from the Mediterranean. About 2 million years ago the land rose, preventing further floods and isolating what was called Lake Amora. As the climate became more arid, Lake Amora shrank and became saltier forming what was known as Lake Lisan. Today, we call it the Dead Sea.

Beginning in the middle of the last century, the Dead Sea had begun to rapidly shrink. The surface of the Dead Sea has fallen from -1,296ft in 1970 to -1,371 in 2006, falling roughly 3ft a year. As the population and agricultural production of Israel and surrounding areas has increased, so has the demand for water. Multiple dams have been constructed along the Jordan River, the Dead Sea’s only tributary, and most of its water has been diverted for consumption or irrigation. Currently, most of the water that reaches the Dead Sea via the Jordan River is treated wastewater.

In 1929, the Palestine Potash Company was formed by a Jewish engineer seeking to exploit the mineral wealth of the Dead Sea. The company was ruined by the Arab-Israeli War of 1948, but later was nationalized and reformed as the Dead Sea Works company. Today, the southern end of the Dead Sea has been extensively diked to form shallow evaporation ponds. Dead Sea water is pumped into these ponds where it’s left to evaporate, and later the precipitated minerals are collected and processed to form primarily potash (potassium salts), bromine, magnesium, and sodium chloride. The evaporation ponds of the Dead Sea Works contribute significantly (40%) to the overall evaporative losses of the Dead Sea and are hastening it’s desiccation.

One negative environmental impact of the Dead Sea’s falling level is the formation of sinkholes. Over time, massive halite (salt) layers and formations have been deposited around and under the Dead Sea. As the level of the sea drops, groundwater in the surrounding water table advances, dissolving some of these underground formations, which leave huge hollow cavities underground. When the roof of these cavities (the ground surface) collapses inwards, they form sinkholes.

Overall, the desiccation of the Dead Sea and its effects are troubling and require attention. Fortunately, the Dead Sea is not beyond fixing, and plans have been proposed to halt the decline and possibly even restore the Dead Sea to a previous state.