For centuries the great Yangtze and Yellow rivers have broken their banks, causing huge loss of life and misery for the inhabitants of large parts of China.

Floods have now hit the normally arid north-west, with several hundred people dead and many more missing in what is described as the worst such crisis there for more than a century.

Lots of lessons have been learned, the Chinese Red Cross is better prepared to deal with massive displacements of people

Denis McClean Red Cross

The flood is being seen as a prelude to a new devastating season, and some fear a repeat of the disasters of the late 1990s when thousands were killed.

Though much of the flooding is the consequence of the natural cycle of seasonal change, international aid and donor organisations have in the past criticised China for exacerbating the problem with extensive deforestation and reclamation of wetlands for farmers' use.

At the time, China invested in civil defence, and launched an environmental programme designed to deal with the man-made causes.

This time round, there are indications that some of these measures may be paying off.

Community response

Aid agencies say there is as yet no comparison between the current floods and those of 1998 and 1999, though they are prepared to launch an international appeal for assistance should the need arise.

Many roads have been destroyed

But Denis McClean, a spokesman for the International Federation of Red Cross and Red Crescent, told BBC News Online Chinese people were now responding more effectively to such crises at community level.

They are trained to take heed of early warning signals and move to higher ground in a timely fashion.

As many as 18 million volunteers can be mobilised to deal with rescue and clearance work.

"Lots of lessons have been learned," Mr McClean said. "The Chinese Red Cross is better prepared to deal with massive displacements of people."

He was also hopeful that the environmental programme was having an effect.

"One can only believe that after the catastrophe of 1998-9 these measures are being put into practice," he said.

Policy changes

China's 6.6bn Renmimbi ($800m) programme of "ecological engineering" was supposed to bring about the "relocation" of more than one million logging employees into non-forestry industries - a massive change in the Yangtze's economic profile.

Preventing floods: China's action plan

National Forestry Policy agreed 1992 60 million forest hectares protected One million loggers "relocated" Import of 40m cubic metres of timber

The government put more than 60 million hectares of upstream forest under protection and is replanting trees on deforested hillsides.

Beijing is also pressing ahead with several major dam projects, notably those at Xiaolangdi and the Three Gorges.

But some experts believe the dam projects are an inefficient use of the funds set aside for flood prevention.

"Give the people in the villages more money," water specialist Wang Wei-luo told BBC News Online. "Thirty per cent of investment goes to company profits."

Logging explosion

At the end of the 1990s, the United Nations estimated that logging had led to the deforestation of an area of land four times larger than Hong Kong.

This had a massive impact on the environment and the lower reaches of the Yangtze river.

Dr Lei Guangchun, head of the China programme for the World Wide Fund for Nature (WWF), told BBC News Online at the time that about 30% of the forest cover in the area of the floods had been lost over the previous 15 years.

Once deforestation had taken place, the land suffered soil erosion and sediment was washed downstream from mountainous areas, arriving in the central and lower regions of the river where it built up on the river bed, raising the level of the water far higher than normal.

At the same time, the reclamation of entire lakes meant a dramatic change in the ratio of agricultural land to wetlands and a significant loss of important flood plain waterways.

Then there is the long-term issue of global warming and rising sea levels.

Within 80 years, 30 million Chinese people's homes could disappear under the sea.