Dams In North Cut Water Discharge: Thailand

[Orac]

Passak dam is down about 70 cm from the highest level a few weeks ago. So they are obviously letting out more water than they are receiving.

That is an awful lot of water they could have held back.

To be fair it was rather full:

- Bhumibol Dam: it reached 99 Percent of retention capacity.

- Sirikit Dam: it reached 99 Percent of retention capacity.

- Kwae Noi Dam: it reached 100 Percent of retention capacity.

- Pasak Dam: it reached 136 Percent of retention capacity.

- Ubonrat Dam (Khon Kaen Province): it reaches 120 Percent of retention capacity.

- Lampao Dam (Kalasin Province): it reaches 100 Percent of retention capacity

http://theenergycoll...onitoring-tools

I would assume there was a risk keeping it at 136% for a longer period of time.

Beside Bhumibol & Sirkit which are other dams located within Chao Phraya catchment?

Kwae Noi is Phitsanulok and Pasak is Lopburi so both in the Chao Praya basin area. I would guess the Ubonrat dam releases down to there as well from Khon Kaen but unsure of Lampao Dam in Kalasin as that is further over in Isaan so may release into Mekong.

[ResX]

there's a seasonal time each year when China releases water, unfortunately at the same time the largest dam got order to hold when it should have been released. As if on purpose.

Which rivers from China run into Thai dams, particularly into the Chao Phraya basin dams?

Really only 2. The Mekong and Salawin Rivers. The Mekong is far east side of Thailand, drains into the South China Sea. The Salawin just touches a small piece in north west Thailand, but enters the Adaman Sea in Myanmar.

The Chao Phraya drainage basin area is entirely in north central Thailand.

When it rains, you get some water in instant runoff from developed areas, and delayed runoff in forested or agricultural areas. It takes time for the water to start as a trickle, flow to a stream, into a river, going from higher elevation to lower elevation. When large amounts of rain fall, there is a large delay from initial flow on land to end of flow due to plant/soil resistance. When the ground is saturated, the runoff becomes much faster, until the saturation ceases.

The rainfall that created this flood was very heavy. Better water management would have helped some up until the time the dams become critically full. It's a question of flood me now, or flood me later. This volume of water that fell greatly exceeded the natural capacity of the Chao Phraya basin. Flooding would have been bad anywhere along the river and the delta, with or without dams, as it has in the past, and will, no doubt, in the future.

Even in Thailand, drought or flood is not unusual. Dams help store water in drought, generate electricity, and help control floods. Massively excessive rainfall overwhelmed the dam capacity. This flood does not have simple solutions, but better planning could have prevented a bunch of the damage.

In the old days, floods would spread silt to the farm fields and revitalize the land. Today, water control keeps the silt from the fields, and necessitates the use of fertilizers.

Ever wonder why a lot of traditional Thai homes are elevated?

It won't be that difficult to control flood. You have to know the root cause than deal with it appropriately. Let the experts help Thailand. For me, I will give free advices to ensure 98% of the times Thailand can beat the floods. If you need to reduce the odd to be beaten from 2% to 1% then increase the storage capacity. The Dutch expert seemed to suggest Thailand shall opt for the odd to be beaten by floods down to 0.5%. Based on the current flood event, I think 0.5% odd to be beaten is fair. Why not reduce the odd to 0%? I'm afraid it is virtually impossible. Moreover, the cost to reduce the odd to be beaten from 0.5% to close to zero could increase by almost 4 folds. Unlike reducing the odd from 2% to 1%. It won't be that much.

1. Build dams with the storage capacity of 17 billion cubic meter. With proper water management approach, Bhumibol & Sirkit can take 7billion cubic meter out of it. You need another 10billion cubic meter storage capacity downstream to Bhumibol and Sirkit.

2. There is no such thing of flood control dam by design. It is not the dam that control the flood. It is the way the dam is regulated that makes it a flood control dam. A 1000bliion cubic meter flood control dam is almost as useless as the water tank in your house as far as flood control is concern if it has achieved its full storage capacity before the battle against the floods even start. So the SOP to regulate the dams operations is equal important as the designs of the dams.

3. Even Bhumibol & Sirkit flood control capabilities have to be revisit. The problem that I can see based on information that I can access from internet, the two dams cannot stay neutral.i.e. not to make the flood to become bigger, once they were beaten. They are either against the floods if they can beat the floods or with the floods if they were beaten. A better design flood control dam has neutral position, i.e. in the case it has been beaten it tries to protect itself by releasing as minimum as possible the uncontrolled flood flow to downstream. Again, I wish to remind you that my conclusion was drawn based on the info that I get from internet. I might miss some vital info although I studied carefully my subject before drawing a conclusion to ensure I don't mislead others to believe the wrong thing.

Think about flood damaged TBH 800 billion once every 50 years. Do you think it cost more to build dams with 10billion cubic meter capacity? Obviously, there is always a default option. Let Thais face the floods based on available resources when they come. I doubt Thais prefer this option.