Tidal wave threatens millions

Steve Connor@SteveAConnor
Friday 19 June 1998 23:02

EARTHQUAKES HAVE caused cracks to appear in the Pamir mountains of eastern Tajikistan where a huge lake threatens to flood hundreds of square miles and up to 5 million people.

The president of Tajikistan, Imomali Rakhmonov, has requested help from Russia and the three other neighbouring states - Uzbekistan, Kazakhstan and Turkmenistan - which would be affected if the natural dam holding Lake Sarez is breached.

Scientists have warned for years that Lake Sarez is unstable but their concerns have been heightened by the recent earthquakes in Afghanistan, which killed between 3,000 and 5,000 people and caused cracks in the Pamir mountains.

Tajikistan, a mountainous country of 5.7 million inhabitants and with an economy that has been ruined by civil war and natural disasters, is in no position to deal with the crisis by itself and needs the help of its neighbours, a spokesman for President Rakhmonov said.

"[They should] consider the possibility of sending specialists or financial assistance to put the Sarez lake into a safer condition This [problem] will also threaten the lives of the population of these countries," he said.

Lake Sarez is the youngest lake in central Asia. It was formed by a huge landslip in February 1911 which led to a dam 600 metres high blocking the entire valley of the river Murgob.

The dam completely stopped the flow of water in the river and the result was Lake Sarez. Since its formation it has filled up with 17 cubic kilometres of water.

The lake now stretches back about 70kms up the former river valley, and the surface area is 88 square kms.

There have been more than 30 earthquakes in the region since 1990 which have shaken the dam and the huge slabs of overhanging rocks on the mountainsides above the lake.

The recent Afghan quakes have revived worries that Sarez Lake could be living on borrowed time. What an earthquake created, an earthquake could yet take away.

Since the collapse of the Soviet Union there has been little scientific study of Sarez Lake and its dam. Recently a conference was held to discuss the dangers posed by the lake, but scientific study is hampered by the lake's remoteness, and the poor state of the Tajik economy.

Scientists fear that either the dam itself will be destroyed or that a landslide into the lake would result in a tidal wave sending large volumes of water over the dam into the inhabited valleys below.

Some of the overhanging rocks are the size of five-storey buildings.

Last year a relatively small landslide sent millions of cubic feet into the lake and created a wave six metres high.

Samuel Grigorian, a professor of geology at Moscow State University has warned: "If a powerful earthquake occurs, and it will definitely occur because quakes happen there all the time, rocks will collapse and this mass will fall into the lake, pushing the water out."

If the dam were destroyed the whole lake could spill out and threaten a 20,000-square-mile area inhabited by 5 million people. About 1,500 people live directly below the lake. There are more villages about 19 miles away from the dam but a flood wave moving at 15ft per second would reach them in less than an hour.

Dozens more villages would be obliterated downstream on both the Afghan and Tajik sides of the Pyandzh before the floodwater burst out onto the Central Asian plains. In total it is estimated 52 thousand square kilometres would be affected.

Scientists have noticed that the dam appears to be less stable than in recent years, probably because of the pressure caused by the increased build-up of water in the lake. There is a noticeably increased filtration of water through the dam which appears to be moving down the valley.

Geologists who have studied the problem believe it is impossible to strengthen the dam to make it safe.

They have suggested instead that attempts are made to relieve the pressure on it by siphoning off water from the lake.

Such a project, however, will cost millions of pounds - one estimate suggests more than pounds 1bn - because of the problems of bringing pipes and equipment to this isolated and mountainous region.

Delegates at an international conference last year on the problems of Lake Sarez said that any such project should aim to preserve as much of the lake as possible because it has become the source of freshwater for the many communities is now threatens.

Environmentalists also want to preserve the lake because of the unique plant and animal life that thrives in its pristine water.

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