"It will be a year of heavy rains and floods in Thailand," said Samith, a former Meteorological Department chief who raised the alarm about the danger of a tsunami striking Thailand -- and was ignored -- well before the Indian Ocean disaster of 2004.

"October to December will be the most critical period for the central region and Bangkok," said Samith, now head of the national disaster warning centre.

Bangkok, a city of 10 million people built on a river delta, is no stranger to floods. One of its worst was in September 1942, when waist-high waters took two months to recede.

The city would have to hope there was not excessive rain in the north as the amount of flooding it suffers depends these days on three dams fed by rivers flowing south.

"If there isn't too much rain in the north and these dams can hold all the water, Bangkok is likely to escape," Samith said.

But the hilly north has rarely suffered flash floods and mudslides on the scale it has this week.

The Meteorological Department -- which says the La Nina phenomenon is weakening -- said more rain was on the way as rescuers slogged through mud and debris looking for at least 53 people still missing.

DEFORESTATION A FACTOR

Scientists and relief officials attributed the disaster to a rare collision of low-pressure areas from the Pacific and Indian Oceans causing unusually heavy rain to fall on deforested hills, particularly in Uttaradit province bordering Laos.

The hills, stripped by illegal loggers of the tree cover which could have held them together, or turned into orchards, could not absorb the water and sections slid away as mudslides.

The slides and flash floods destroyed houses, cut roads and damaged dams as well as inundating towns and forcing thousands to flee their homes. Large areas were littered with trees, making access to more remote communities difficult.

Samith said the collision of low-pressure areas was the result of La Nina -- a pattern of usually cold surface temperatures in the eastern Pacific that leads to greater rainfall in the west.

It would increase Thailand's average rainfall -- around 2,400 mm (94.5 inches) -- sharply, he said.

"This year we will have much more than the average," he said.

Uttaradit, 500 km (300 miles) north of Bangkok, was the worst-hit province with 41 known dead after a deluge that dumped 330 mm (13 inches) in one 24-hour period.

Tens of thousands of people were affected as houses were torn apart by flash floods bearing uprooted trees, or buried under heaps of mud. The military was distributing food and water by truck and helicopter.

In some hilly areas, however, the only way to get food and water into villages where stores had been destroyed was to carry it in on foot or by airlift, officials said.