The Thai floods, rain, and water going into the dams – Part 1
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The Thai floods, rain, and water going into the dams – Part 1

BP has already blogged about the poor water management of dams (part 1 and part 2) where a large quantity of water was released between August 1-Oct 16 2011 compared with in the months before and with the previous year, and also how Bangkok has had more rain this year. On this latter topic, New Mandala has had three posts here, here, and here. BP has been looking to blog on this, but initially hand collating the data was proving time-consuming. However, in this PDF on the Meteorological Department website, BP has made screenshots as per below:


NOTE: Data is for September (middle columns) or up until the end of September (right hand columns).


NOTE: With so little rain, perhaps more water could be diverted to Suphan Buri…. Plodprasob: “We should have directed the waterflow to the west to Suphan Buri more, as it was still relatively dry, but we could not. I would not like to say why [political heavyweight Banharn Silapa-archa – who represents the province –  is also adviser to the Charthaipattana Party, which supervises the Irrigation Department.]”


Then the mean,


Source: Met Dept


Source: Met Dept

On rainfall for 2011 by month:


Source: OAE (the English translation has been added by BP)

The Bangkok Post:

The amount of rainfall – 2,000mm  – has already exceeded the average annual rainfall, which stands at 1500mm a year.

BP: If this is correct* then it means there was a large amount so far in 2011, but so far BP can only find 1295.6mm – from a government website of the rainfall throughout the country – up until the end of August and well for there to be over 2,000mm would be so much rain in September and October (double the normal amount) so BP is a little skeptical that the 2,000mm is correct (it is correct for Bangkok). Regardless, it is clear that there is significantly more rain in 2011 than there was in previous years.

Of course, this doesn’t excuse the poor water management and the failure to discharge more water before the flooding started which resulted in such large quantities of water having to be discharged at the height of the flood when there was more rain but it does explain that difficult choices would have to been made and it is highly likely there would be significant flooding this year even with perfect water management (last year with less rain and less water discharged from the major dams, there was flooding which killed more than 200 people). It is simply the scale of the flooding we are talking about. The next post will look at the amount of water going into the two major dams – not all rain goes into the dams…..

*If anyone can find the annual rainfall for all of Thailand up until now then please send BP an e-mail at Please provide a source.