Every year China suffers disastrous floods, but the unusual severity of last year's summer deluge prompted the government to launch a massive upgrading of its flood prevention and relief facilities.

In the Yangtze River valley last year, the central and local governments spent three times more money than normal on repairing and upgrading dykes, dams and other flood control systems.

Officials believe that in the coming weeks the effectiveness of these measures will be tested by on onslaught of flood waters similar in magnitude to last year's.

Chinese police move sandbags into flood-affected areas

In the longer term, China hopes that the construction of the giant Three Gorges Dam on the upper reaches of the Yangtze River will help to regulate the floods.

But it'll be a few more years before the dam will begin functioning.

And critics of the project say that an accumulation of silt behind the dam or heavy rainfall downstream could undermine its effectiveness.

Limited reinforcements

The government said the overhaul of all dykes along the Yangtze had been completed on target by the end of May. But officials admit that reinforcement of these facilities has been limited to extending their height and width.

"Few things can be done to consolidate the founations," said a senior government engineer quoted by China's state-owned news agency.

In order to relieve pressure on the embankments, the government has engaged in a large scale project to upgrade facilities for diverting flood water.

This will involved the relocation of 2 million people from low-lying areas along the Yangtze - but it will take as long as five more years to complete.

Corruption

One of the government's worries as the new flood season begins must be that the construction and repair of these facilities might have involved the kind of corruption that is now endemic in China's construction industry, with shoddy materials being used to save money that ends up in the pockets of local officials.

There are fears that construction projects meant to protect people will be hit by corruption

The government-run China Daily newspaper said that this year's floods had already exposed the "inefficiency" of flood control projects in some places.

It said local governments in these areas had not been placing "due emphasis" on repairs and improvement and were willing to take a chance that this year's rainfall will not be so heavy.

Underlying causes

No matter how well the dykes may have been fortified, some of the underlying causes of flooding will take years to remedy - the deforestation of mountains upriver and the reclamation of land from lakes that once helped to contain the waters.

The government has now banned logging upstream. It plans to close hillsides to herders to allow the trees to grow again. But the battle between the needs of the land and the needs of farmers and loggers struggling to make a living is likely to hinder these efforts.

In the Yangtze River valley, officials at least learned some valuable lessons in flood control during last year's catastrophe.

Further north on the banks of the Yellow River, China's second largest waterway after the Yangtze, residents have not experienced a devastating flood for 16 years and their vigilance has slackened. Officials say their luck could be about to change.

Simulated floods

The government has already moved many tens of thousands of people from low-lying areas along the Yellow River.

Officials are anxious to avoid the serious flooding seen in 1998

Officials in one county have staged a simulated flood by building two giant pools and then cutting their walls in order to teach the local residents how to combat a possible deluge.

Construction of the giant Xiaolangdi dam which is second only in size to the Yangtze's Three Gorges project has been speeded up. Work is proceeding around the clock to prepare for possible floods.

Soil erosion along the Yellow River has led to serious silting of the river bed. Flood waters would therefore be pushed out into the surrounding land.

Many times in Chinese history the Yellow River has changed its course as a result of floods, causing enormous loss of life.