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Tuesday, June 19, 2012

High dam water levels: Flood risk and terms explained

We'll here we are already discussing high water levels in the reservoirs and the fear of floods, clear back in January. I have seen nothing since to relieve me of fear of flooding even through the recent drought that allowed flooding throughout Isaan.,
I will still confused about reservoirs reaching 122% of capacity until I read "The 4,860 meter long and 36.5 meter high dam is an earth-filled dam with an impervious core. The storage capacity is 785 million cubic meter of water at normal water level, with a maximum capacity of 960 million cubic meters. Additionally to the water management the dam also supplies about 6.7 MW of hydro-electric power." about the Pa Sak Jolasid Dam and it finally twigged.
If you take 785 Times 1,22 you get a number near 960. All this really means nothing to the average Joe, but is always discussed during a period of flooding in Thailand. What does have meaning is elaevations in meters above sea level. This is what we used in reservoirs in the U.S.. The operating elevation is where no one or certain designated dwelling were above water and as the water rose more and more people places were inundated. The capacity of the reservoir was at the elevation of the spillway, where water free falls out of the reservoir,
I never see a discussion of silting here in Thailand. That is a reservoir gets filled in with dirt from upstream each year. This can be a significant number and can greatly reduce the reservoir's capacity.

As you can see the definitions given at the end of the article are often contrary to the usage by Thai government officials when discussing situations.
All in all they managed to totally complicate some very simple math.

More on "Where has all the Money Gone" coming soon