Mega-sinkholes are forming as the Dead Sea shrinks. Israelis feel it’s a disaster, but the Geological Survey of Israel begs to differ and has a quirky suggestion for adapting to the evolving landscape
Ruth Schuster | Jan. 19, 2020 | 6:14 PM

The Dead Sea is shrinking, and parts of the shoreline are collapsing as the waterline retreats. As a result, sinkholes began developing around the salt lake around 35 years ago. So far, the imploding sections of ground have forced part of the adjacent highway and much of the tourism industry to move.

It sounds awful. Parts of the original road look like a mega-quake hit. (It hasn’t, yet, though the whole region is overdue.) The original tourist center associated with Ein Gedi has been abandoned. Not much moves there save the wind and the odd lizard. It can be dangerous to stroll down most of the lake’s eastern shore. A bridge built in 2008 has already had to be abandoned.

By one count, the peak year for sinkhole development was 2015, when more than 700 new pits developed on the Israeli side of this “natural wonder.”

But the sinkhole numbers are meaningless without context. The numbers are an artifact of the counting method, Gidon Baer and Ittai Gavrieli of the Geological Survey of Israel tell Haaretz. If five sinkholes merge into one mega-sinkhole, is that one, five or six? If small sinkholes develop inside a big one – and they do – is that still just one? And if a sinkhole “migrates” – and they do – is that two sinkholes? If sinkholes get filled up with sediment – which they do, especially the ones in wadi beds after floods – do they still count?

“See that sinkhole in the middle of the wadi bed?” Baer inquires. “It will fill up with sediment in the next flood, then collapse again, then fill up again, then collapse again.”

Point taken. So let’s settle for saying that over the course of 35 years, “thousands” of sinkholes have developed along the stark desert landscape of the Dead Sea shoreline, to the dismay of ecologists, truckers and the tourism business.

A better criterion to judge the disruption of the Dead Sea shoreline is total area covered by sinkholes. This has been steadily increasing, Baer explains.

Yet Gavrieli and Baer are irritated by wailing about “ecological catastrophe” at the Dead Sea. So if it isn’t disaster, what is it?

“The sinkholes are the reaction of the ‘natural infrastructure’ to the drop in seawater level, but that reaction shouldn’t be seen as disaster per se,” Gavrieli answers. “It involves none of the problems characterizing ‘ecological disaster’: the water quality isn’t deteriorating; there is little destruction of habitat or harm to biodiversity; there is no impairment of air quality.”

It is true that a date palm plantation had to be abandoned, that a gas station lost its livelihood, that the road had to be moved. For the people living around the Dead Sea and visiting it, the changes can be hard to swallow. Israelis loved the Dead Sea the way it used to be.

“There is no question that heavy economic damage has been caused,” Gavrieli stresses. “People have lost their livelihoods. And it’s a shame, because much of the damage was avoidable – the Geological Survey has been warning about the problem for many, many years,” he adds, about the organization whose brief is to advise the government on all aspects of geoscience.

But nary a life has been lost. Nature has not been hurt. “If we look at the matter soberly, not from the anthropocentric perspective, if anything these developments could be leveraged for tourism,” Gavrieli adds, driving home the point.

Birth of a mega-sinkhole

One method by which the Geological Survey studies the development of the sinkholes and changes to the landscape is monitoring. It uses cameras placed at multiple spots along the shoreline that shoot images every few seconds to every minute, depending on the season. The geologists drive from their headquarters in Jerusalem to the sea every few weeks to replace the memory cards in the cameras and gain personal impressions.

Why does monitoring require so many images? In order not to miss an event, which may be sudden. Reviewing the entire set of images from each camera enables the geologists to watch the events as they happened. Any given sequence may show: nothing, nothing, nothing, nothing, nothing … collapse.

“Some changes take place back and forth, and we track them by looking at the entire set of pictures,” Baer explains.

From detailed mapping using various methods that can be seen on the Geological Survey’s website, they came to realize that sinkhole development is moving eastward as the sea level declines. That is on the Israeli side of the lake. On the Jordanian side, sinkhole development would move west. “Some areas on the Jordanian side, particularly agricultural areas, have suffered significant collapse, with loss of crops, dwellings, etc.,” Baer explains.

Based on the Geological Survey’s mapping, the sections most vulnerable to sinkhole development on our western side of the lake are between the evaporation ponds in the south and Ein Feshkha in the north. The sinkholes are “eating” the area the sea used to cover.

The British leave their mark

Why is this happening? Sinkholes form the world over, but the cause of their development differs in different places. In Russia and Canada, for instance, sinkholes tend to form where the permafrost is melting. In the case of the Dead Sea, the root cause boils down to freshwater dissolving subsurface salt, creating cavities.

Sinkholes may develop where the subsurface contains salt. The subsurface salty layer runs as much as 70 meters (230 feet) deep. As long as the solid salt is saturated by saline water, nothing happens. But as the lake shrinks and the saline water retreats from the ground and is replaced by freshwater – from groundwater encroachment, rain or flooding – the salt dissolves, leaving cavities beneath the crust of the surface that, at some point, implode.

Where the subsurface has no salt layer, for instance, the northern shore, it is not being “dissolved” by freshwater, and sinkholes are not forming.

Inquiring minds wonder why the Dead Sea built up thick salt layers at its bottom, since not all lakes do that. The answer is that it is the lowest surface on the planet. Water enters the Dead Sea by the Jordan River, rain and floodwater from the whole region. Water molecules can escape from the Dead Sea by evaporation; salt and minerals can’t, and are there for eternity (or until mined by the potash works in the Dead Sea’s south).

The beaches around the Dead Sea, and cliffs, have vast salt concentrations because, historically, the lake’s water level was higher. Its highest point in recorded history was in 1896, when it was a whopping 44 meters higher than now.

Prehistorically, when the Dead Sea and Sea of Galilee were a single body of water called Lake Lisan, its highest level was about 170 meters below sea level (some 20,000 years ago, during the Last Glacial Maximum), compared with 433 meters below sea level today. For decades, Israel and Jordan have both been diverting the Dead Sea’s main source, the Jordan River – leading the Dead Sea to drop by a meter to 1.2 meters a year.

As Gavrieli drives the Geological Survey vehicle south along the highway skirting the Dead Sea, Baer in the passenger seat draws attention to a mark on the cliff to the right of the road. The road itself at that point is tens of meters above the sea and the mark is several meters above the tarmac – put there about 80 years ago by British Mandate officials in a boat.

World’s first sinkhole park

It is now clear why the sinkhole development zone is moving eastward: As the lake shrinks, the shoreline on the Israeli side is “moving” east, and so is the area where freshwater replaces saline water in the ground.

Some describe the landscape around the Dead Sea as being like a moonscape. Not really: For one thing, some of its “craters” are surrounded by scrubby local vegetation, nourished by the very groundwater that contributed to the sinkhole formation. If there’s any life on the moon, it’s the tardigrades Israel accidentally put there when its Beresheet lander crashed last April.

Some sinkholes have green rims with thriving (if scrubby) plants and some do not because the groundwater level in the region is also falling, the two geologists explain. Vegetation that has died around sinkholes indicates where the groundwater too is gone.

Some of the sinkholes contain water – but don’t jump in, Baer cautions. In summer, if the water is highly saline, it can get hot enough to burn you.

And they are beautiful. The landscape is beautiful, and not only if you’re into stark desert coated in salt, which has heaved and cracked here and there for reasons unknown.

The pools of water within the sinkholes come in different colors and even gradations of hue: orange, red, green, yellow. Blues too. White salt coats the ground, crunching underfoot. Those strange upwellings frozen in salt are beautiful too.

“The pictures that Israel has been presenting of the Dead Sea as a World Heritage site are all the result of the decline in sea level, or are based on the industrial evaporation pools,” Gavrieli points out. (The pools are in the sea’s southern part – the hotels now actually stand by these giant artificial bodies.)

The Dead Sea had been breathtakingly beautiful and it still is, with some differences. This is no ecological disaster, Gavrieli and Baer maintain, as we pass the dead date palm plantation, gingerly tread over the shattered stretches of ex-highway, admire the enormous cavity that opened in the middle of the road and stroll through the ruins of a former leisure center – developments the Geological Survey had long foretold.

There is no question about it: this land is beautiful. And Gavrieli and Baer have a dream.

Here at the Dead Sea, Israel could create the world’s first sinkhole park. It would not only be a unique experience for visitors: it could provide a significant economic boost to the region, the geologists point out.

This begs the question of whether tourists admiring a pretty pit in the ground might get swallowed by a sudden collapse of the land. One answer is that the Geological Survey has been working assiduously on forecasting techniques, which – it bears noting – are special to the conditions at the Dead Sea. These methods include cutting-edge technologies for monitoring the surface movement and the subsurface collapse.

The Geological Survey’s various activities will lead it to predict whether and where the newly constructed road is safe, sinkhole-wise, Baer explains.

Adapting to irreversible change by turning the pit-riddled shore of the Dead Sea into a national park is quite an original idea. But wouldn’t one need a guide to avoid the, shall we say, pitfalls? “Paths could be signposted by the Nature and Parks Authority,” Baer replies. “You wouldn’t even necessarily need a guide.”

Sounds like Chernobyl tourism. Looking at the abandoned wreck of the gas station and tourism facilities, the splintered tarmac of the former road, the mega-sinkholes formed of multiple merged sinkholes that likely have yet more sinkholes inside, the dead date palms – this isn’t ecological disaster? “No – it’s an economic disaster, if you will,” Gavrieli insists as we walk between the sinkholes, the salt crunching beneath our feet. “It is change. Nature changes.”

The Dead Sea had been beautiful before and it’s beautiful now, albeit in a different way. We can’t change it; even building the much-vaunted and oft-stymied Dead Sea-Red Sea canal can’t “save” the Dead Sea, Baer explains – in the sense of restoring it to “what it was.” The canal could theoretically transport enough volume to reverse the trend of the Dead Sea’s contraction, but the environmental costs to both the Red Sea and the Dead remain unclear, nor is there any consensus on the “desirable” water level for the Dead Sea. But when nature or human nature gives us lemons, let us make lemonade and visit Sinkhole Park.

There is a foreseeable snag, though, other than what insurance companies might charge to cover tourists hiking in a future Sinkhole Nature Reserve. Or that – as Gavrieli points out – the park wouldn’t be terribly relevant for half the year. “After 10 A.M. in summer, the heat is simply unbearable,” he explains.

The snag is that, even now, the area is dry as a bone. (If you visit, bring plenty of water.) Under all scenarios of global warming, North Africa and the Middle East, including Israel, are expected get drier and hotter.

It’s already starting to happen. Temperatures at the Dead Sea average “only” about 37 degrees Celsius (99 degrees Fahrenheit) from July to September, but last July the mercury in Sodom reached 49.9 degrees, almost 122 degrees Fahrenheit. That is hot as hell, and not much more survivable. Moreover, climatologists warn that the entire region could become unsurvivable if climate change continues on its present trajectory. But until that time – from which we can only hope to be spared – we are going to have to learn to adapt. Turning the weirdly attractive “changing” shore of the Dead Sea into a park where we can admire the beauty of the sinkholes sounds like an intriguing way to do it.

https://www.haaretz.com/israel-news/.premium.MAGAZINE-dead-sea-sinkholes-look-like-ecological-catastrophe-they-re-an-opportunity-1.8412446