Ongoing landslides triggered by the deadly 8.0-magnitude quake in China's Sichuan Province will dump rocks and sediment into the river beds, said Dr Alex Densmore, director of hazards research at Durham University in north-east England, following investigative fieldwork in the quake zone.

That will raise river bed levels, giving them greater potential to burst their banks, said Dr Densmore, who has been studying the active fault lines in Sichuan province for the past eight years.

'There is a significant risk of a major flooding disaster. At the moment it is very difficult to predict the exact nature of that risk but in 10 years or so we may be in a better position,' he said.

The risk will likely last for several decades and possibly for a century, he said.

Dr Densmore said ongoing landslides were a common occurrence after such strong earthquakes. Rocks and sediment move downstream from the valleys and settle in river beds.

In some areas, river beds are already two to three metres (6.5 to 10 feet) higher due to May's earthquake, the geographer said.

That means that during heavy rain periods, the rivers are more likely to burst their banks.

Chinese officials said on Thursday that the death toll from the earthquake could top 87,000.

Many mountain communities - which bore the brunt of the disaster - have been relocated to the basin, which had been perceived to be a safer area to live.

While praising 'a very impressive response' by Chinese authorities, Dr Densmore said 'in the longer term they will need to have a well-informed discussion about where to permanently move these communities.'

Up to 20 million people live in the western part of the basin, where the provincial capital Chengdu is sited.

'In the longer term, the authorities will need to look at issues such as moving people out of the flood plains and re-routing transportation links in areas where there are high risks of floods,' Dr Densmore said.

There were also knock-on effects on power in the region, he said, due to the potential for sediment buildup in the reservoirs behind the many dams in the area, making them useless for flood control or hydro-electric power generation. -- AFP