Kuala Lampur, Sept. 30 -- Flash floods are no longer exceptional events in Southeast Asia.

They are becoming an increasingly familiar feature of urban life.

The latest floods in Thailand should therefore concern the whole of Asean, not merely Bangkok.

By September 29, floods across Thailand had killed at least 23 people and affected more than 2.6 million. Bangkok itself was badly hit, with approximately 700,000 people affected. All 50 districts of the capital were declared disaster zones.

The amount of rainfall was extraordinary. Bangkok received roughly 320mm of rain within two to three days - close to what the city would normally receive during the entire month of September.

But rainfall alone does not explain the problem. What Sou...