Mudslides Devastate A Town In North West China

Chris Buckley PlanetArk 10 Aug 10;

Mudslides engulfed a town in northwest China on Sunday, killing at least 127 people and leaving nearly 1,300 residents missing as rescue teams dug out crushed homes and tried to blast away debris clogging a river.

The mass of flood water, mud and rock hit Zhouqu County in Gannan Tibetan Autonomous Prefecture in Gansu province, a region dominated by steep and barren hills, after torrential rains late on Saturday, Xinhua news agency said, citing local officials.

Runoff from the downpour built up behind a landslide on the Bailong River, which runs through the main town in Zhouqu.

The clogged river in the narrow valley then spilled over its banks and caused flooding and mudslides that struck the town after midnight, smashed a small hydro station, and left at least 127 dead, according to Xinhua.

More heavy rain is forecast on the river on Tuesday.

"Many single-storey homes have been wiped out and now we're waiting to see how many people got out," one resident of Zhouqu, a merchant called Han Jiangping, told Reuters by phone. "We've had landslides before, but never anything this bad. People are trying to find their families and waiting for more rescuers."

The disaster follows flooding in Pakistan which has killed more than 1,600 people and in the Indian state of Jammu and Kashmir. Flash floods have also killed at least 132 people in the Himalayan region of Ladakh.

China's death toll could rise sharply and Premier Wen Jiabao rushed to the scene. There were 1,294 people missing, Xinhua reported late on Sunday, and it was unclear how many of them had fled and survived. That count was lower than an earlier estimate that nearly 2,000 were missing.

One village with 300 homes was "buried," said official news reports.

"It's very hard to locate the people washed away by floods. It's hard to say what their chances of survival are," He Youxin, a People's Armed Police officer organizing rescue efforts, told Xinhua. "Since excavators can't reach the site. We can only use spades and our hands to rescue the buried."

At one point, the flooding covered about half of the Zhouqu county seat, which has about 40,000 residents. The flood water reached up to three storeys high on some buildings, enveloping them in mud unlikely to yield many survivors.

About 2,800 troops and 100 medical workers rushed to help and 5,000 tents were being sent to the town, Xinhua said.

"Now the sludge has become the biggest problem to rescue operations. It's too thick to walk or drive through," said the head of the county, Diemujiangteng, according to Xinhua.

China's ruling Communist Party has become adept at showing its strength by mobilizing troops, aid and propaganda in the face of natural calamities, such as a massive earthquake in 2008. Chinese President Hu Jintao and Premier Wen told officials to "spare no efforts to save lives," said Xinhua.

HOMES HIT AS FAMILIES SLEPT

More than 1,400 people have been killed this year in floods that have devastated areas of central and southern China, according to the national disaster relief authority.

Pictures from Zhouqu showed mud and water covering town streets, motor vehicles being swept downstream and troops frantically digging through debris to hunt for victims, including a boy pulled from a shattered house. Xinhua said the mud dumped on the streets was up to two meters deep.

"There was thunder and huge rain, and then the landslides started coming down," said a resident of Zhouqu contacted by Reuters. He gave only his surname, Bai. "That was about midnight, so some people must have been in their homes, asleep and didn't know what was happening."

Many residents of Gannan are ethnic Tibetan herders and farmers and the rough terrain may hamper rescue efforts. Zhouqu County has 135,000 residents, about a third of them ethnic Tibetans, according to the county government.

Residents had rescued about 680 people by midday, and the water level in the town was falling, said Xinhua.

Troops prepared explosives to blast away the mud and rocks that have choked up the river and created a backlog of water 3 km (2 miles) long and 100 meters across, Xinhua said.

Wen, a geologist, told officials to develop a plan as soon as possible to unblock the river safely. About 19,000 people living in two town below the blockage were moved away, the reports said.

The Gannan meteorological bureau forecast heavy rains on the Bailong River from Tuesday.

(Editing by Nick Macfie/David Stamp)

What Causes Mudslides?
Remy Melina, LiveScience.com 9 Aug 10;

Heavy rains in China set off mudslides that washed away part of the town of Zhouqu, in the province of Gansu, and left more than 330 people dead and many more missing.

But heavy rains aren't the only thing that can trigger a mudslide, according to experts.

A sub-category of landslides, mudslides are rivers of rock, earth and other debris that are saturated with water, according to the U.S. Geological Survey (USGS). Mudslides can be slow- or fast- moving, though they tend to grow in size and momentum as they pick up trees, boulders, cars and other materials.

Mudslides can occur at any time of the year, regardless of weather conditions, according to the Federal Emergency Management Agency (FEMA). And they can strike without any prior warning signs, making for a dangerous phenomenon.

"Mudslides occur in all 50 U.S. states and can happen at any time - with or without rainfall," said Lynn Highland, a geographer at the USGS National Landslide Center.

Earthquakes, volcanic eruptions, changes in groundwater levels, alternate freezing and thawing, and the steepening of slopes by erosion all contribute to mudslides.

Construction and reckless modification of land - such as not draining an area properly before building on or near it - can also create the conditions ripe for a mudslide, Highland said.

She added, prolonged, intense precipitation and run-off can contribute to landslides, as can wildfires. Fires lead to mudslides because burning can kills the plants' roots. Roots hold soil together, stabilizing the land and making it less likely to be swept away, according to Highland. In this way, overgrazing can also contribute to mudslides.

Because different areas of land have different soil compositions, as well as varying slopes and geographic characteristics, it is difficult to determine how prone a place is to mudslides and therefore near impossible to predict when one will hit - although they are known to occur in areas previously hit by mudslides, according to the USGS.

"The West Coast is especially susceptible to mudslides because of the earthquakes, rainfall and wildfires that happen in that region," Highland told Life's Little Mysteries. "In California, there is a 'mudslide season' lasting from December to April, during which time the rainfall is fairly predictable."

Because California wildfires leave behind charred slopes, the region is especially susceptible to mudslides during and immediately after major rainstorms. However, sometimes damage caused by a mudslide can take days or even weeks to surface.

An example of this 'delayed triggering' of deeper landslides occurred in Los Angeles, Calif., in 1998, when mudslides forced the evacuation of more than 100 people and destroyed several houses five days after the rain had stopped, according to the California Geological Survey (CGS).

More than 100 Californians have been killed by land and mud slides during the last 25 years, according to the CGS. Most of these deaths were due to people being buried by debris flows as they slept in lower-floor bedrooms that were near hazardous slopes.