Experts Play Down Risk To Bangkok: Flood Crisis

[yoshiwara]

The PM said she decided against declaring a state of emergency because the country was fighting natural disasters, not flood-hit people.

I find this statement extremely bizarre.

So if the country was fighting flood-hit people, then she would declare a State of Emergency. Thais should be embarrassed for having her as a Prime Minister.

Please show some respect for Thai people who chose their government.

It's not time to play with words or politics and strumentalize everything. This is the worst thing to do in these situations.

According to that logic no elected government should ever be criticised for their management of a critical situation.

Nonsense of course. Red supporters seem to be getting jittery that the government is no less fallible than any preceding.

Maybe Thaksin should surf in to save the day.

[ResX]

The dams are full only because puyai boneheads at EGAT and other uncoordinated agencies feared they wouldn't have enough water this year and hoarded it instead of releasing it gradually before the heavy rains started. Now they are the main cause of the problem as they release huge volumes of water into already flooded communities.

Point taken. I don't know why I keep on seeing this kind of "greed decision" with regard reservoir operations again and again. Maybe some people have problem to plan for water resources utilization for the competitive water demand environment and with limited resources. This type of problem is not unique to any country alone. Five years ago I had proposed to re define the flood control regime for one of our major flood control & power generation reservoirs. What I was proposing is to increase reservoir draw down by additional 1-1.5m before the expected monsoon every year in order to reduce flood risk from 4 times in 25 years to once in 50 years. It took almost three years before my proposal was accepted. The same reason was quoted that contributed to the delayed, i.e the management of the reservoir preferred to have high water reserve. Coincidentally, the 1 in 50 years flood that I had expected to strike at least once over the next 50 years flood struck the second year after my proposed flood defensive strategy was adopted. We saved one big flood. To date that reservoir can be counted to deal without the biggest flood in 50 years safely without losing a drop of water. This year due to some reasons we are preparing the reservoir t0 take on the biggest flood in 100 years. We increase the draw down by another 1m.

In the competitive water demand environment, a reservoir management tends to sacrifice its flood control capability of its reservoir rather than other capabilities, such as irrigation. The rational in simple. All other demands are firmed demands. The coming of big flood is a speculation. Such flood may come or it may not come this year. I'm not saying they should do it this way. What I'm saying it they have the natural tendency to do it this way. After all people like to gamble right?

Besides the point you have raised there is at least one serious issue related to Bhumibol & Sirikit reservoirs with regard their flood control capability. I have to conduct internet search before I can share it with you.

I have been to these two reservoirs about 10 years ago. It was for a very short visit. Too short for me to learn about their flood control capability. Both reservoir compounds are very nice and well kept.

Edited October 14, 2011 by ResX

[ResX]

Wifey has just told me that all tv channels have been announcing some sort of breach of flood defences in northern bkk and some areas must be urgently evacuated.

I think a water gate in Pathum Thani broke.

This is the thing that worries me even I'm a Malaysian. A flood control reservoir is shall be equipped with free flow spillway rather than gated one as it was mentioned in this article. I have to admit that I don't know whether that reservoir is a flood control reservoir of not. If it does, I think there is an issue to be addressed by your authority.

A flood control reservoir shall have gated spillways for a purpose of emergency release only. Under the normal flood regulation free flow spillway shall be allowed to deal with it. This type of spillway is almost immune from two setbacks that gated spillway possesses namely (1) potential over release of flood water above the desired release (2) can be destroyed by flood flow.

Free flow spillway is resemble to a natural river but it is located above the defined Full Supply Level (FSL) of a flood control reservoir . From FSL to reservoir Flood Level (FL) , that could be 4-8meters above FSL, the volume enclosed between these two elevations is called flood reservation, As the water level goes up above the FSL, the free flow spillway starts to release water very minimum. As the water level increases due to incoming flood flow, the spillage will increase accordingly. Yes. The rate of discharge by this spillway is as a function of water level above FSL. The idea is the reservoir delays the release of the accumulated flood flow that may strike in a few days, by making the release to take longer period says a month. That is how it cuts down the flood level down stream as long as its own FL is not being violated.

Then what's next? Assuming the defined flood level (FL) of the reservoir is 4m above FSL. From FSL to FSL + 4 the free flow spillway will try to strike balance between incoming flow with its outgoing. Says we want to design our reservoir to deal with the maximum incoming flood flow of 5000m3/s to fill up the reservoir area of 260km2, then it takes about less than 2 days for the sustained flood flow to reach FSL, assuming outgoing flow is zero. Thus at FL (4m above FSL) we size up our free flow spillway to discharge 5000m3/s . Therefore the reservoir level will cease to to increase above FL since incoming flow is equal to out going flow at FL. The size of flood will be minimized since the reservoir is holding almost 1billion m3 of water within that 4m column (FSL-FL) and discharges away at the rate of 5000m3/s. It may take weeks to empty that 1billion m3 of that flood water. You can see that if any incoming flood flow with its flow rate less that 5000m3/s, the water level will settle somewhere between FSL and FL. For this kind of flood control reservoir design you need gated spillway to release water if only the flood flow is greater than the anticipated design flow (5000m3/s in our example) and the water level tends to increase above FL. The danger of releasing flood water using this gate will be explained next.

In general gated spillway without free flow spillway is required for the reservoir that does not have flood control capability. This spillway is located below the water surface. We just need to open the gate according to the amount of release we want. The fact that this gate can cause flood even without the help from rainfall. Unlike free flow spillway that allows water level to increase until balance between incoming and outgoing flow is naturally met, this spillway is required to prevent the water level from rising. This is important since the main dam structure of the reservoir cannot be allowed to submerge under water. Otherwise if the structure is breached. We will have inland tsunami scenario then. Probably worse. How the gate achieve this objective? If we have sustain 5000m3/s of incoming flood flow, it takes less than 15minutes to open the gate to release 5000m3/s. Incoming is equal to outgoing for less 15 minutes. In our previous case it takes 2 days right? That is not so damaging. Assuming the flood sustains for two days and the total volume is 1.0billion m3. After two days you will see the reservoir level remains the same. i.e. at FSL. You ask one question, where are those 1billion m3 of water has gone? The answer... "Not in the reservoir" since this type of gate will make sure the water level cannot increase. This reservoir has transfer all the flood flow within that two days to down stream. This actually makes thing worse since this type of design does not allow any water retention upstream. Thus the flood at down stream is actually the combination of its own flood and the flood being transferred from upstream. You can imagine its implication by now.

Bhumibol & Sirikit reservoirs may or may not follow the suggested design that I have mentioned above. This does not mean that I was wrong. Thank you.

Edited October 14, 2011 by ResX

[sirchai]

The government handling of the situation is incompetent and pathetically disorganised. They should be condemned for it, as happens in every democratic country. Nothing else is going to make them lift their game.

And the election was full vote buying. No clean election at all.

Home » Breakingnews » Germany donates 40,000 euro to help flood victims

Germany donates 40,000 euro to help flood victims

October 14, 2011 8:00 am

German Ambassador Rolf Schulze Friday handed over a cheque of 40.000 euro to Phan Wannamethee, Secretary General of the Thai Red Cross Society, to assist the Thai Red Cross Society and the people of Thailand in their efforts to cope with the ongoing flood crisis.

The funds have been released by the government of the Federal Republic of Germany and will be used to buy two lifeboats and other items of humanitarian aid.

The Nation

I'm wondering what will happen to any donated money......