Experts may disagree about the rate at which sea levels are rising, but they do all agree on one thing; Bangkok is sinking. Although part of Bangkok’s predicament is attributable to rises in sea levels, there are other factors at play which have placed the city at risk of being submerged. Bangkok is built on clay rather than bedrock and with groundwater being pumped out (both legally and illegally) to supply residential and industrial demand, the effect has been to gradually lower the ground surface which bears the weight of Bangkok’s buildings. It’s a bit like pushing down on a wet sponge to squeeze out the water.
When King Rama I established Bangkok as the new capital on the banks of the Chao Phraya River, the mangrove swamps and forests on the coast acted as a natural flood defence system for the city. However, during the industrial age as the city grew and modernized, more and more land was needed and concrete replaced the mangroves. Bangkok was once dubbed the ‘Venice of the East’, but in the 1950’s many of the canals were replaced by roads. This was done in response to calls from international development agencies who advised that the reduction in canals would help to prevent the spread of malaria. Unfortunately, the side-effect of the road construction was to disrupt the natural drainage system which helped to control the annual monsoon season flooding.
A 2009 scientific study of 33 major river deltas in the world revealed that 24 of them are sinking. The Chao Phraya in Thailand was shown to be one of the worst affected and in some years, parts of the Chao Phraya Delta have sunk 15cm relative to sea level. This is partly due to climate change, but a much bigger contributor are man-made initiatives such as dams and irrigation schemes which have adversely impacted on the flow of sediment which naturally raises the height of the land.
What are the Prospects for Bangkok?
Some experts say that if things carry on as they are, Bangkok could be completely under water at some stage during this century. Various projects have been discussed to address the problem but no definitive plan has so far been agreed. Bangkok isn’t unique with other major cities including Buenos Aires, Tokyo, Cairo, New York and Los Angeles all facing the prospect of a watery future. Whilst that scenario may be some generations off for other cities, it could be sooner rather than later for the Thai capital if a solution can’t be found and acted upon.