The Great Bangkok Flood

The Great Bangkok Flood

Bangkok, the capital of Thailand, is currently experiencing what is perhaps the greatest flood ever to swamp a city so large in world history. This dynamic Asian megalopolis has a population of around 10 million within the city limits and a metropolitan population of at least 20 million. The flood is affecting virtually every resident and many have evacuated to provinces outside the flood zones.

The worst of the flood was expected to occur on Saturday October 29th as the river that bisects the city, the Chao Praya, was expected to crest at its highest level ever recorded (some 8 feet above normal) and astronomical high tides were expected to peak, possibly causing the drainage of the cities canals and the Chao Praya to back up and push the flood waters into the heart of the city. Fortunately however, it appears that, so far, the dikes have held and the worst-case scenario is not playing out. This could change at a moments notice.

Here are a series of maps outlining the situation:




Above are two satellite views of the south-central Thailand region with Bangkok near the bottom of both images, just north of the Gulf of Siam into which the Chao Praya River flows. The top image shows a typical end of the rainy season flood situation with the flooded portions showing up in black (photo taken on November 13, 2008). The bottom image shows the same view as of October 25th this year.



This map is an overview of the greater Bangkok metropolitan area (about thirty miles by thirty miles square) and what the various flood risks are by district. The downtown Bangkok area is centered on the east side of the Chao Praya River between Nontha Buri and Bang Na. Map produced by Bangkok Post graphics.



Here is a close up of the central Bangkok area and where the flooding situation stands as of Oct. 29th. The color codes are the same as in the top map but the areas in bright yellow are where the flood has most recently expanded into.



This a ‘worst case scenario’ map illustrating the maximum possible depth of flood waters expected in the greater Bangkok area should the dikes fail. One foot is about 25 centimeters.

As of Saturday, much of the Bangkok is shut down and many residents have left the city.

Historical Perspective

It is likely that this flood will surpass the great flood of 1942 both in terms of depth of floodwaters and certainly in terms of economic costs. In recent times, the worst flood to affect the city was in May of 1986 when 15.79” of rain inundated the city in a 12 hour period on May 10-11th of that year. This, however, was a flash flood and although the water reached 3-5 feet deep in much of the downtown area, the waters receded quickly since it was the first rain of the season. Nevertheless, the disruption to city life was such that the mayor lost his job and a new massive sewage infrastructure project was undertaken, the results of which have to some degree alleviated floods in the city since. The system has never been so challenged as now.



A photo of Sanam Luang Park in front of the Grand Palace in Bangkok during the flood of October 1942. Photo source unknown.

Looking into the future, this photo and caption from the Asian Property Report may best sum it up!



Christopher C. Burt
Weather Historian