中国准备为地震熔岩堰塞湖泄洪

什么是堰塞湖？

堰塞湖是由火山熔岩流，或由地震活动等原因引起山崩滑坡体等堵截河谷或河床后贮水而形成的湖泊。由火山溶岩流堵截而形成的湖泊又称为熔岩堰塞湖。

必须强调说明，堰塞湖的堵塞物不是固定永远不变的，它们也会受冲刷、侵蚀、溶解、崩塌等等。一旦堵塞物被破坏，湖水便漫溢而出，倾泻而下，形成洪灾，极其危险。

堰塞湖一旦形成威胁，必须事先以人工挖掘、爆破、拦截等方式来引流或疏通湖道，使其汇入主流流域或分散到水库，以免造成洪灾。

汶川地震已经过去16天了。然而在每个热爱生命、关爱同胞的中国人看来，这16天每天都是祭日。人们用不同的方式哀悼着逝去的人们。地震已经离我们远去，但受难的同胞依然生活在灾难的阴影中。重建工作更是遇到相当多的困难。由于地震，灾区的很多地方形成了堰塞湖，严重威胁着灾区人民的生命安全。那么，我们将如何解决这一不可忽视的现实问题呢，请看新闻——中国准备为堰塞湖泄洪。

Mianyang, Sichuan--Rescuers are preparing to dynamite the barrier of a swelling earthquake-induced lake at risk of bursting and threatening thousands of people downstream in southwest China.

Experts have proposed a water diversion channel to drain Tangjiashan Lake, formed by landslides that blocked a river known as the Jianhe after the May 12 earthquake in Sichuan Province.

Tangjiashan, one of 35 such lakes, is inaccessible(无法进入)by road and can only be reached by foot or air.

The lake currently holds 130 million cubic meters of water, said Liu Ning, Ministry of Water Resources of China chief engineer, who is in Tangjiashan to oversee the diversion. Its water level was 725.3 meters on Monday, only 26 meters below the lowest part of the barrier, he said.

"Around 100,000 (people) would be evacuated to ensure the safety according to the current drainage plan," Liu told the Shanghai-based Oriental TV.

"It's better for them to complain about the trouble that the evacuation would bring than to shed tears after the possible danger," he added.

Li Huzhang, an engineer with the armed police force, said three emergency(紧急事件)plans had been made to dig out the sluice. He said at least 50,000 cubic meters of debris(碎片)blockage would have to be removed. Rescuers, however, were aiming to remove 100,000 cubic meters of debris if the weather allowed to minimize(尽量减少)the bursting risk.

The water level in the lake rose by 1.6 meters on Monday, a slowdown in recent days, a hydraulic expert at the local observation site was quoted by the People's Daily Online.

As of 9 p.m. on Monday, around 600 engineers and soldiers had gathered at the blockage of the quake lake and were taking turns to work throughout the night.

Because of the lack of tents, some soldiers had to sleep outdoors on the blockage at night.

Helicopters have airlifted professionals and materials for the operation to the blockage at the barrier lake in Beichuan County, Sichuan.

A Mig-26 helicopter transported a large bulldozer from Leigu, near Tangjiashan. By 7 p.m. on Monday, more than 10 diggers and bulldozers and 40-plus tons of relief materials, including tents, drinking water, food and gasoline, had been airlifted to the site.

But experts said more machinery needed to be brought in because of the size of the blockage and the debris was likely to continue to accumulate because of the continuous aftershocks. On Sunday, the area was affected by a strong tremor measuring 6.4 on the Richter scale.

Sunday's adverse conditions hampered(妨碍)the operation, but the weather and visibility were fine on Monday morning, said a spokesman with the Mianyang Airport Headquarters for Quake Relief Flight Operation.

But drizzles projected at Monday night would likely to hamper the work, according to officers at the site.

A contingent of armed police arrived on foot early on Monday to help with the task of draining the lake. The policemen were part of the 1,800-strong force, including People's Liberation Army (PLA) personnel, who started hiking on Sunday toward the lake, 3.2 km upstream from the Beichuan County seat, from which thousands of quake survivors had been evacuated since Wednesday.

A PLA officer told Xinhua the soldiers each carried 10 kilograms of dynamite and planned to carry out small scale blasts to drain the rising water.

More than 30,000 residents downstream of Tangjiashan lake have been evacuated to higher ground, according to the Mianyang City government.

Altogether, 35 barrier lakes were formed by landslides after the quake that left 65,080 people dead and 23,150 others missing as of Monday noon, according to the Information Office of the State Council.

The Ministry of Water Resources said it had completed an inspection of the damaged waterway embankments(路堤)in Sichuan by 5 p.m. on Sunday. Plans have been made to address the risks in about 479 damaged embankments, which totaled 686.71 km.

Ministry experts said priority would be given to reinforcing the embankments at Beichuan, Jiangyou and Mianyang in the downstream of the Jianhe River, as water discharged from the upstream(上游)quake lake may wash against them.