Bart Schultz
In addition, four major land reclamation projects have been realized: the Greater Mekon Polders with a total area of 51,000 hectares, the Chiengrak-Klongdarn Polder of 24,000 hectares and the Petchburi and Pranburi Polders, each 3,200 hectares. A separate polder was created for the construction of Bangkok's second international airport.
In the polder of the second international airport of Bangkok there are two water management systems. At the design rainfall with a probability of flooding of 20% per year, one system can be full. For the other system the water is then still 25 centimetres below the surface.
Because the design standards for the protection of the polders in Thailand are very low, flooding occurs regularly. For example, in 2011 there was a major flooding, which was said to have a chance of occurrence of 2% per year. There were more than 800 deaths, about 10,000 people had to be evacuated, 13.6 million people experienced problems due to the flooding and the total damage amounted to about 35 billion euros.
In 2012 I attended the conference of the International Commission on Irrigation and Drainage (ICID) in Adelaide, Australia. During this conference there was also a session of the ICID Working Group on Adaptive Flood Management. I always go to the sessions of this working group, because these meetings give you an excellent picture of what has occurred in the various countries in the past period in the field of river management and flooding. This time the representative of Thailand gave an excellent presentation on the flooding in 2011. He outlined how the flooding had been caused, what measures had been taken and what discussions had taken place. There had also been quite a bit of discussion about the discharge from one of the reservoirs, which would have made the flooding worse than it would have been under a different approach. He did not agree with this and thought that the discharge had been optimal under the given circumstances. He showed various graphs to illustrate it.
Because, among other things, there had been a great deal of damage to factories in the vicinity of Bangkok, the companies concerned had taken the initiative to better protect their business premises against flooding. In itself, this was a good measure for those premises, but the question was now whether this would lead to even higher water levels in the areas where the protection had not been improved in the event of another extreme river discharge. Time will tell what problems will occur in the event of another extreme river discharge.
Meanwhile, the subsidence in Bangkok and the surrounding area continues at a rate of 3-4 centimetres per year, as well as the sea level rise of 0.3 centimetres per year. This of course leads to the situation getting worse and that much more drastic integrated measures will be necessary. However, to date, no one has dared to develop and implement such an integrated plan. It will therefore take a number of years and perhaps a few more floods before the necessary measures will be actually realized.
