A disaster 23 million years in the making
The Dead Sea is an endoreic lake that it is said was connected to the Mediterranean Sea some 23 million years ago. “Endoreic” is a big word for saying that water flows into the Dead Sea but not out of it.
Because of the desert conditions over the years this basin of water evaporated at a rate faster than it’s sources of new fresh water creating a sea with a salt content six times higher than that of the ocean. However salt retards the rate of evaporation and level of equilibrium had been maintained at least for the last millennium. Long ago salts had precipitated at the bottom of this sea and geologic conditions had created stratum of salt some of which had pushed out and up to form landscape features such as Har Sedom. Water flowing down from mountain rains had dissolved some of this salt creating the Sedom Cave.
Water sources of the Dead Sea are the mountain aquifers on both the Jordanian and Israeli sides of the sea and the Jordan River. Man’s intervention has all but eliminated the water from the Jordan River and has reduced the water flow from the mountain aquifers.
On the above diagram red lines show the flow of the water in the mountain aquifer of Israel. This diagram is a bit misleading because the bulk of the water is on the Mediterranean side of the watershed.
This is due to the fact that the amount of moisture that is retained in air is a function of the air’s temperature and that temperature is very much related to air pressure. Warmer air holds more moisture. As air cools water precipitates as clouds (water droplets) and rain. As air rises its pressure is reduced and so is its temperature. As air descends its pressure and temperature increase. Winds from the west laden with moisture from the Mediterranean rise over the mountains that bisect Israel. The air becomes cooler and the moisture precipitates as rain on the Mediterranean side of the mountains. As the air descends into the Dead Sea area it becomes warmer and the rain ceases. The watershed is not exactly in line with the crest of the mountains and thus some water descends ultimately to find its way into the Dead Sea. This is illustrated in this sketch below.
With the reduction of the water flowing into the Dead Sea the equilibrium that maintained the level of the Dead Sea for the last millennium has been destroyed. Consequently the level the Dead Sea has been dropping by as much as a meter per year. This drop has had a dramatic effect on the shoreline but until the last few years this was regarded as at most an inconvenience. At least until a tourist bus almost fell through the road going along the shoreline Large sinkholes which had appeared for some time along the shores of the Dead Sea were developing with a vengeance at Ein Gedi.
One of the sinkholes attempted to swallow Eli Raz our lecturer at Ein Gedi. Eli noticed a Date Palm tree had fallen. A few days later the sinkhole which caused the fall had swallowed the Date Palm completely. Another tried to entrap the equipment servicing the Date Palm Plantation forcing its closure. A worker at the Ein Gedi Spa area was almost a casualty forcing this lucrative part of Ein Gedi’s economics to close. When the adjacent army base was warned about the problem they cut and ran.
To understand what had caused this disaster one should remember the flow of salt water from the Mediterranean into the coastal aquifer that we discussed with Avner Goren. In this case the Dead Sea is depleted causing the underground fresh water aquifer to flow into the Dead Sea. The stratum of salt discussed above is easily dissolvable by this flow. The declining level of the sea had caused the water coming from the mountain aquifer to begin to dissolve the underground stratum of salt manifesting in the development of large sinkholes.
Eli Raz believes that this flow of fresh water dissolving the salt and creating the sinkholes has only been along a fault line within which he has been mapping. But one must wonder with both the propensity for earthquakes in the area such as the one at the end of 2003 and the continued reduction in the level of the Dead Sea how new areas of sinkholes will not be manifested.
There is a paucity of information in the media about the problem. A search of the archives of the Jerusalem Post produced only one article A bitter end for the Dead Sea? Tovah Lazaroff. Jerusalem Post. Jerusalem: Apr 27, 2001 and in it the reference to the sinkholes was only incidental. In September of 1998 the world seems oblivious to the problem as evidenced by an article in the New Zealand Herald, Dead Sea Faces Death by Tourism, which worry’s over the plans to “add 50,000 new hotel rooms as well as roads and more industry, further shrinking the sea and polluting its shores.”
A lonely voice, the Friends of the Earth Middle East, however, in a recent news letter, is predicting more direful consequences.
“At this time, experts cannot point to any site along the Dead Sea shores and claim with any certainty that it is safe, with no potential for the creation of sinkholes on the surface.”