This Dam Could Cause the World's Worst Natural Disaster and Impact 5 Million

This Dam Could Cause the World's Worst Natural Disaster and Impact 5 Million

Why you should care

Tajikistan’s Lake Sarez is stunning. But some experts say it’s a ticking time bomb. 

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Geo facts & figures

In its very first moments of existence, the Usoi dam claimed the lives of an entire village. It was formed during a 1911 earthquake that saw the Usoi settlement buried by a massive landslide that blocked the Murghab River and formed Tajikistan’s Lake Sarez. At roughly 1,860 feet, the Usoi dam is the world’s highest natural dam.

Lake Sarez is isolated now, but in 1911 it was even more so: It took six weeks for news of the disaster to reach civilization. Today there are at least 30 villages in the Bartang Valley, and more scattered across surrounding areas. And they’re all in mortal danger.

If the Usoi dam fails — which is inevitable — it could be the worst natural disaster in human history, impacting the lives of as many as 5 million people.

And that’s a conservative estimate.

So how and why will this dam collapse? Take your pick. The most probable and obvious trigger is an earthquake — not unlike the massive temblor that created the dam and the lake in the first place. Were the dam to break, it could trigger another deadly landslide, but that wouldn’t be the worst of it. The lake’s water could cannon out in a 100-foot-high wave, coursing down established waterways and affecting as many as 5 million people, not only in Tajikistan but also in Afghanistan, Uzbekistan and Turkmenistan. The deadliest floods in recorded history occurred in China in 1931, when as many as 4 million people died. But estimates that a Lake Sarez flood would affect 5 million were made two decades ago, and while surveys of the river valley’s population are scarce, records from 2010 indicate that it has increased several times since 1998.

It doesn’t have to be an earthquake: Analysts are worried that the Usoi dam could be a target for terrorists, who with one well-placed bomb could cause untold damage to surrounding communities. Even if the dam doesn’t break, a landslide could cause a wave that triggers mudslides and avalanches onto dozens of local villages.

Move the slider to see the potential path of a Lake Sarez flood.

Terrorism is a question of if; considering the seismic volatility of Tajikistan as a whole, an earthquake is more a question of when. Richard Stone, senior science editor for Howard Hughes Medical Institute’s Tangled Bank Studios, began researching Lake Sarez nearly 10 years ago — and says not much progress has been made on averting the catastrophe. “When I started investigating the situation at Lake Sarez, I discovered it was one of the great untold stories of Central Asia. Even today, it remains a disaster waiting to happen,” Stone says. When Tajikistan was part of the Soviet Union, the situation was monitored by a warning system — but warnings were set up to be sent to Moscow and Dushanbe, Tajikistan’s capital, more than 2,000 and 200 miles away respectively. That system collapsed with the fall of the Soviet Empire.

Fayzmamad Davlatbekov of Pamir, Tajikistan, who has written about Lake Sarez for the Environmental Justice Atlas, says it’s not just human lives at risk, but a whole ecosystem. “The threat is more than just against homes in Tajikistan,” he explains. “It is very likely that high pollution would come from a Lake Sarez disaster.” On top of this, Davlatbekov says, the environmental impact would likely spread to Tajikistan’s neighboring countries.

Some advisers recommended digging a tunnel beneath the lake to drain some of its 16 cubic kilometers of water and reduce the risk of overflow.

In 2000, the World Bank initiated a $4.2 million risk mitigation program around Lake Sarez, but it mostly focused on how to alert the surrounding areas to allow for evacuation in case of a sudden disaster. According to a case study from the United Nations’ Food and Agriculture Organization, engineering solutions to the dam’s instability are rendered virtually impossible by the remoteness of the lake, which is only accessible by two roads — both closed off for much of the year owing to weather conditions. At a 2007 conference, some advisers recommended Tajikistan explore digging a tunnel beneath the lake to drain some of its 16 cubic kilometers of water and reduce the risk of overflow. Meanwhile, many local scientists maintain that the dam is in no danger of collapsing, which — along with lack of funding — may be why the issue has been largely ignored by the Tajik government since the World Bank program concluded.

Instead, Lake Sarez is seen as a potential economic opportunity: Tajikistan’s President Emomali Rahmon visited Uzbekistan last month for the first time since taking power in 1992, in part to discuss using water from the lake as drinking water for the two countries. It could, Davlatbekov explains, mitigate the water’s eventual disastrous effect while bringing much-needed money into Tajikistan. Whether the two nations can arrange to lower the water level enough in time — when an earthquake could hit tomorrow — remains anyone’s guess.

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