Residents Challenge Dams, Flood Master Plan: Thailand

[webfact]

Residents challenge dams, flood master plan

The Nation

A network of residents from provinces in the Mae Yom River basin yesterday came out against four executive decrees enabling a new water and flood management master plan, which recommends dusting off the controversial Kaeng Sua Ten dam project in Phrae province.

Network leader, Wutthichai Srikhampha, said the group also opposed another dam project - Mae Wong planned for Uthai Thani. He said both dams, which would cost Bt50 billion, could trap two billion cubic metres of water, while Thailand already had 40 large dams and 2,000 smaller ones.

The group also proposed ideas to solve the annual flooding problem, including placing the restoration and conservation of water-producing forests on the national agenda, along with building medium and small sized reservoirs at all 77 tributaries of the Yom River.

"These reservoirs, which have a joint capacity threefold that of the Kaeng Sua Ten in total, could initially trap the rainwater locally and later drain it gradually," he said. There should also be a policy to promote a 'one tambon one reservoir' scheme elsewhere to trap rainwater locally and use it for irrigation, said Wutthichai.

Meanwhile, deputy Bangkok governor Theerachon Manomaiphibool has blamed political rivalry and the poor standard of flood and water management officials as the main reasons behind the flood crisis last year.

In a 16-chapter pocketbook, he questioned the Yingluck government and its Flood Relief Operations Centre’s policy. He said it protected farmland in the Central plains, which eventually failed, but neglected measures to save industrial estates and Bangkok, which resulted in billions of baht lost in property damage and reduced business profits.

Democrat Party-affiliated Theerachon blamed the Pheu Thai-led government for setting up barriers along the east-west Rapheephat and Rangsit Canals to protect their constituencies. They resulted in the floodwaters rolling westward to Nonthaburi, and flooding northern parts of Bangkok, including Don Mueang, in the process.

Asked about ideas to cope with flooding next year, Theerachon said good management by people with true knowledge in water and flood management was crucial. His Majesty the King’s long-standing projects and suggestions should be also taken into consideration and put into effect.

-- The Nation 2012-01-12

[OzMick]

Yesterday: "Drought has arrived early and in Uthai Thani Province, where local residents are now running short of water for consumption."

Today: " Wutthichai Srikhampha, said the group also opposed another dam project - Mae Wong planned for Uthai Thani."

I hearby nominate k. Wutthichai for the Horse's Anus of the Year (Thai National) Award.

[EvolvingApe]

Yesterday: "Drought has arrived early and in Uthai Thani Province, where local residents are now running short of water for consumption."

Today: " Wutthichai Srikhampha, said the group also opposed another dam project - Mae Wong planned for Uthai Thani."

I hearby nominate k. Wutthichai for the Horse's Anus of the Year (Thai National) Award.

I second the nomination.

[DeepInTheForest]

Contrary to the facile judgments posted above, there are many reasons to question the usefulness of dams to control floods and supply water during drought times.

Rivers provide many benefits if they are allowed to run freely, including recharge of groundwater, the carrying and replenishing of nutrients and minerals to the land, preservation of fisheries (which in Thailand are fundamental to the health and sustenance of entire regions), employment, sustenance, and social stability.

A river is not just the water contained within banks, but many interacting systems, including adjacent forests, marshes, the ever-changing banks and bottom, as well as the life that it sustains -- including humans. The flood cycle's value to agriculture and environmental health should not be underestimated.

Dams can provide some benefits, but these must be measured against the downsides, which include the increased risk of floods, increased risk of waterborne diseases (including malaria), risk of collapse, mismanagement, providing an opportunity for graft and corruption, the trapping of sediment, increased pollution, increased global warming gas emissions, and damage to estuaries, which are some of the richest biological areas in the river, and indeed the globe. And we must not forget the displaced locals, who are never adequately compensated, if at all, for the loss of their homes, sense of place, and even cultural identity.

The Thai locals who oppose this dam have their reasons. We have only scratched the surface here. Readers can inform themselves via many sources on the internet.

Edited January 12, 2012 by DeepInTheForest

[hellodolly]

Contrary to the facile judgments posted above, there are many reasons to question the usefulness of dams to control floods and supply water during drought times.

Rivers provide many benefits if they are allowed to run freely, including recharge of groundwater, the carrying and replenishing of nutrients and minerals to the land, preservation of fisheries (which in Thailand are fundamental to the health and sustenance of entire regions), employment, sustenance, and social stability.

A river is not just the water contained within banks, but many interacting systems, including adjacent forests, marshes, the ever-changing banks and bottom, as well as the life that it sustains -- including humans. The flood cycle's value to agriculture and environmental health should not be underestimated.

Dams can provide some benefits, but these must be measured against the downsides, which include the increased risk of floods, increased risk of waterborne diseases (including malaria), risk of collapse, mismanagement, providing an opportunity for graft and corruption, the trapping of sediment, increased pollution, increased global warming gas emissions, and damage to estuaries, which are some of the richest biological areas in the river, and indeed the globe. And we must not forget the displaced locals, who are never adequately compensated, if at all, for the loss of their homes, sense of place, and even cultural identity.

The Thai locals who oppose this dam have their reasons. We have only scratched the surface here. Readers can inform themselves via many sources on the internet.

+1

[OzMick]

Contrary to the facile judgments posted above, there are many reasons to question the usefulness of dams to control floods and supply water during drought times.

Rivers provide many benefits if they are allowed to run freely, including recharge of groundwater, the carrying and replenishing of nutrients and minerals to the land, preservation of fisheries (which in Thailand are fundamental to the health and sustenance of entire regions), employment, sustenance, and social stability.

A river is not just the water contained within banks, but many interacting systems, including adjacent forests, marshes, the ever-changing banks and bottom, as well as the life that it sustains -- including humans. The flood cycle's value to agriculture and environmental health should not be underestimated.

Dams can provide some benefits, but these must be measured against the downsides, which include the increased risk of floods, increased risk of waterborne diseases (including malaria), risk of collapse, mismanagement, providing an opportunity for graft and corruption, the trapping of sediment, increased pollution, increased global warming gas emissions, and damage to estuaries, which are some of the richest biological areas in the river, and indeed the globe. And we must not forget the displaced locals, who are never adequately compensated, if at all, for the loss of their homes, sense of place, and even cultural identity.

The Thai locals who oppose this dam have their reasons. We have only scratched the surface here. Readers can inform themselves via many sources on the internet.

Straight out of the greeny handbook. You call my post facile, but did you ever stop to think about the propaganda that you regurgitate? 2points come to mind immediately:

1/ How does a dam increase the risk of floods when one of its major purposes is flood mitigation?

2/ How does a dam increase global warming gas emissions?

Re 2/, I am aware that rotting vegetation carried into the dam will give off gases, but that breakdown will occur naturally in the dam or the sea. So where is the increase? I am also aware of the UN World Dams Report which used a bogus comparison of a worst case scenario (large, shallow and tropical) dam which happened to have a very small hydro station to a coal-fired station. The statement that the 2 forms of generation could have equivalent emissions was preposterous psuedo-science - but a concept now included as gospel in the greeny bible.

All your benefits of a free-flowing river disappear when ther is no water in it. Right now would be a good time to ask the locals whether they want a dam or not.

[DeepInTheForest]

Thanks for your reply, OzMick; your questions are excellent and to the point. That dams can cause or exacerbate flooding seems definitely counterintuitive. When I first heard that, I dismissed it as well. How could a dam lead to flooding?

I’m not an expert by any means, just a curious citizen, so take what follows with a grain of salt and do your own searching on the internet. And all this is not to say that dams don’t have a place, when they are properly planned and operated. But there are significant caveats, especially with larger dams. More research is being done all the time, so… hopefully, we’re learning. Obviously, land uses—impervious surfaces—are a large part of our flood problem as well.

Dams do indeed control smaller floods quite well. The problem is with big rainfalls, when the dam nears capacity. This, of course, is when you would most want the dam to hold more water, but it can’t. The rains tend to weaken the earth around the dam, and cause engineers to worry about dam failure. That would be unthinkable, so large quantities of water are often released, again, just when you don’t need it.

The sudden release of such large amounts of water causes another kind of problem downstream beyond what we normally think of. Streams get “scoured”, and become “armored”, when a sudden rush of dam water sweeps away silt, sand, gravel, aquatic plants, leafy debris, and large tree limbs. The result is a river that has less plant and animal life, acts as less of a sponge for water, and—you guessed it—more vulnerable to floods. You would think that this would happen anyway, in normal floods, but people who study dam/environment interactions say that’s not the case.

Dams also begin silting up immediately after construction, so their capacity is immediately diminished. Dams are designed to withstand the pressure of a certain height of water, but silt is much more massive, and as the reservoir silts up, engineers become more wary of dam failures. Dams have a finite lifetime—their usefulness diminishes over time. You would think that the silt could be dredged, but this has not proven economical over the long haul.

Dams rarely serve simply as flood-control devices—their cost is usually leveraged with projected benefits from electrical power generation, or irrigation. This causes management conflicts, as we have recently seen in Thailand.

If you think that dam problems are somehow due to Thailand’s political squabbles or some kind of ineptitude, you might be surprised to find that Westernized countries are not immune to similar problems. One example is the Wivenhoe dam near Brisbane.

http://tinyurl.com/4t4jya5

http://tinyurl.com/7rxmpor

This link makes some worthwhile points, I think. http://www.travelfis...he-thai-floods/

The problem with greenhouse gas production occurs because the level of water behind the dam rises and falls seasonally. When the water is low, vegetation regrows, especially in a tropical, high-sun country like Thailand. When the water rises, it floods the newly-grown green stuff, causing it to rot anaerobically, producing methane. This is in addition to whatever forest material was inundated initially. The cycle will continue as long as the dam operates, since water levels are allowed to rise and fall.

Some other things to consider with dams are that the water behind them is oxygen-deprived, so large releases from reservoirs impact the water quality below, and can kill fish, alter reproduction, etc.

Also, by slowing water flow, dams often increase water temperatures. Fish and other aquatic organisms are pretty sensitive to temperature, and this becomes another area of impact.

Edited January 13, 2012 by DeepInTheForest

[OzMick]

Thanks for your reply, OzMick; your questions are excellent and to the point. That dams can cause or exacerbate flooding seems definitely counterintuitive. When I first heard that, I dismissed it as well. How could a dam lead to flooding?

I’m not an expert by any means, just a curious citizen, so take what follows with a grain of salt and do your own searching on the internet. And all this is not to say that dams don’t have a place, when they are properly planned and operated. But there are significant caveats, especially with larger dams. More research is being done all the time, so… hopefully, we’re learning. Obviously, land uses—impervious surfaces—are a large part of our flood problem as well.

Dams do indeed control smaller floods quite well. The problem is with big rainfalls, when the dam nears capacity. This, of course, is when you would most want the dam to hold more water, but it can’t. The rains tend to weaken the earth around the dam, and cause engineers to worry about dam failure. That would be unthinkable, so large quantities of water are often released, again, just when you don’t need it.

The sudden release of such large amounts of water causes another kind of problem downstream beyond what we normally think of. Streams get “scoured”, and become “armored”, when a sudden rush of dam water sweeps away silt, sand, gravel, aquatic plants, leafy debris, and large tree limbs. The result is a river that has less plant and animal life, acts as less of a sponge for water, and—you guessed it—more vulnerable to floods. You would think that this would happen anyway, in normal floods, but people who study dam/environment interactions say that’s not the case.

Dams also begin silting up immediately after construction, so their capacity is immediately diminished. Dams are designed to withstand the pressure of a certain height of water, but silt is much more massive, and as the reservoir silts up, engineers become more wary of dam failures. Dams have a finite lifetime—their usefulness diminishes over time. You would think that the silt could be dredged, but this has not proven economical over the long haul.

Dams rarely serve simply as flood-control devices—their cost is usually leveraged with projected benefits from electrical power generation, or irrigation. This causes management conflicts, as we have recently seen in Thailand.

If you think that dam problems are somehow due to Thailand’s political squabbles or some kind of ineptitude, you might be surprised to find that Westernized countries are not immune to similar problems. One example is the Wivenhoe dam near Brisbane.

http://tinyurl.com/4t4jya5

http://tinyurl.com/7rxmpor

This link makes some worthwhile points, I think. http://www.travelfis...he-thai-floods/

The problem with greenhouse gas production occurs because the level of water behind the dam rises and falls seasonally. When the water is low, vegetation regrows, especially in a tropical, high-sun country like Thailand. When the water rises, it floods the newly-grown green stuff, causing it to rot anaerobically, producing methane. This is in addition to whatever forest material was inundated initially. The cycle will continue as long as the dam operates, since water levels are allowed to rise and fall.

Some other things to consider with dams are that the water behind them is oxygen-deprived, so large releases from reservoirs impact the water quality below, and can kill fish, alter reproduction, etc.

Also, by slowing water flow, dams often increase water temperatures. Fish and other aquatic organisms are pretty sensitive to temperature, and this becomes another area of impact.

If you had posted as a reply, i would have found this much faster and easier. While your points have some merit I consider them insignificant compared to the concerns of a population with insufficient drinking water.

Re flooding - dams are not built on soil but rock, and I can see no reason why a release from a dam would exceed the inflow i.e.

why would the dam, even if overflowing, have to release more water than was moving downstream anyway, unless they were expecting even heavier flows. The total effect should be that high flows may last longer but the devastating peaks will be reduced.

Re greenhouse - grasping at straws with that. Production of methane rather than CO₂ in an area of hardly more than a few hectares is insignificant to the hydrocarbon burden of any tropical river. Have you seen the ridiculous claim in the WDR that I referred to?

BTW I have a home in Bribane and well aware of the problems here. Much of the flooding was caused by undammed flows, and the flood was certainly mitigated by Wivenhoe Dam.

[DeepInTheForest]

If you had posted as a reply, i would have found this much faster and easier. While your points have some merit I consider them insignificant compared to the concerns of a population with insufficient drinking water.

Re flooding - dams are not built on soil but rock, and I can see no reason why a release from a dam would exceed the inflow i.e.

why would the dam, even if overflowing, have to release more water than was moving downstream anyway, unless they were expecting even heavier flows. The total effect should be that high flows may last longer but the devastating peaks will be reduced.

Re greenhouse - grasping at straws with that. Production of methane rather than CO₂ in an area of hardly more than a few hectares is insignificant to the hydrocarbon burden of any tropical river. Have you seen the ridiculous claim in the WDR that I referred to?

BTW I have a home in Bribane and well aware of the problems here. Much of the flooding was caused by undammed flows, and the flood was certainly mitigated by Wivenhoe Dam.

-----------------------------------------------------------------------------------------------------------------------

Jeesh. I still am dinking around with the reply mechanism-- I didn't want to include my long bit, and the system keeps complaining about the opening quote tags not matching the closing quote tags, which isn't true at all. Anyway.

A few thoughts for you to chew over:

Dams are built into rock to the extent possible. But not always. Rock also varies in strength and durability. Compromises are usually made.

Check this out:

"The study of foundations is ever more complex than the study of dam bodies, as the foundation is a natural and often very heterogeneous material specific to each dam site. It has to withstand great stress, to be watertight at the right places, and internal erosion should be strictly avoided.

"Most low dams are founded on soft soil and most high dams on rock, but this is not a general rule and many dams are founded partly on rock and partly on soil either in the deepest place or in the banks.

"Further, rock quality may vary considerably along each dam." from http://www.hydrocoop.org/publications/2.12.1.1.article.pdf

Minor point: Dams in Thailand are not usually built because of a shortage of drinking water, as far as I can tell. Usual reasons given are flood control, electrical power generation, and irrigation. I think you probably would agree with this.

Releases from dams-- Dams have a listed capacity, which they can exceed during flood times, i.e. store more than their nominal storage capacity. They are allowed to increase over 100% for only a limited time-- then they must release water. This can exceed inflow. Incidentally, this was the case last year at Wivenhoe. http://www.abc.net.au/worldtoday/content/2011/s3190309.htm I am sure you are correct that the dam withheld a great volume of floodwater and thus prevented even greater flooding. But when it released, it did so very quickly, with attendant loss of life. The operators, incidentally, did not want to lower the level of dam waters because of a recent history of drought. This should sound familiar to Thailand residents...

From wikipedia:

"During a flood the dam is designed to hold back 1.45 million megalitres (1.18 million acre feet) of additional water for flood mitigation or 225% capacity. Under the water release plan which is defined by law, excess water must be released from the dam within seven days of it reaching 100% capacity." --http://en.wikipedia.org/wiki/Wivenhoe_Dam

The area of reservoirs is more than a few hectares, as I am sure you are aware. To put a vague number on it, estimates are that there are over 400,000 sq km of dam reservoirs-- that's a third of the area of the world's natural lakes. The scholarly work on methane production is a work in progress. You can go to scholar.google.com, though, and find papers like this one: http://abbeyroad.geocean.u-bordeaux.fr/indiv/Abril/documents/publi/guerin_et_al_2006_GRL.pdf

Again, I am not saying that all dams are a bad idea, or that we should eliminate all dams. But we have been building them like crazy people, and still we have floods. Why is that? And what is the solution? I think it may consist of changing some of the way we do things. Reforestation may be a partial answer, as well as decreasing our impermeable surfaces (parking, paving, etc.).

I thought Wutthichai Srikhampha made some good points.

"The group also proposed ideas to solve the annual flooding problem, including placing the restoration and conservation of water-producing forests on the national agenda, along with building medium and small sized reservoirs at all 77 tributaries of the Yom River.

""These reservoirs, which have a joint capacity threefold that of the Kaeng Sua Ten in total, could initially trap the rainwater locally and later drain it gradually," he said. There should also be a policy to promote a 'one tambon one reservoir' scheme elsewhere to trap rainwater locally and use it for irrigation, said Wutthichai."

Again, thanks so much for this exchange. You've forced me to think more about the issue-- never a bad thing. Cheers.

[OzMick]

If you had posted as a reply, i would have found this much faster and easier. While your points have some merit I consider them insignificant compared to the concerns of a population with insufficient drinking water.

Re flooding - dams are not built on soil but rock, and I can see no reason why a release from a dam would exceed the inflow i.e.

why would the dam, even if overflowing, have to release more water than was moving downstream anyway, unless they were expecting even heavier flows. The total effect should be that high flows may last longer but the devastating peaks will be reduced.

Re greenhouse - grasping at straws with that. Production of methane rather than CO₂ in an area of hardly more than a few hectares is insignificant to the hydrocarbon burden of any tropical river. Have you seen the ridiculous claim in the WDR that I referred to?

BTW I have a home in Bribane and well aware of the problems here. Much of the flooding was caused by undammed flows, and the flood was certainly mitigated by Wivenhoe Dam.

-----------------------------------------------------------------------------------------------------------------------

Jeesh. I still am dinking around with the reply mechanism-- I didn't want to include my long bit, and the system keeps complaining about the opening quote tags not matching the closing quote tags, which isn't true at all. Anyway.

A few thoughts for you to chew over:

Dams are built into rock to the extent possible. But not always. Rock also varies in strength and durability. Compromises are usually made.

Check this out:

"The study of foundations is ever more complex than the study of dam bodies, as the foundation is a natural and often very heterogeneous material specific to each dam site. It has to withstand great stress, to be watertight at the right places, and internal erosion should be strictly avoided.

"Most low dams are founded on soft soil and most high dams on rock, but this is not a general rule and many dams are founded partly on rock and partly on soil either in the deepest place or in the banks.

"Further, rock quality may vary considerably along each dam." from http://www.hydrocoop...1.1.article.pdf

Minor point: Dams in Thailand are not usually built because of a shortage of drinking water, as far as I can tell. Usual reasons given are flood control, electrical power generation, and irrigation. I think you probably would agree with this.

Releases from dams-- Dams have a listed capacity, which they can exceed during flood times, i.e. store more than their nominal storage capacity. They are allowed to increase over 100% for only a limited time-- then they must release water. This can exceed inflow. Incidentally, this was the case last year at Wivenhoe. http://www.abc.net.a...11/s3190309.htm I am sure you are correct that the dam withheld a great volume of floodwater and thus prevented even greater flooding. But when it released, it did so very quickly, with attendant loss of life. The operators, incidentally, did not want to lower the level of dam waters because of a recent history of drought. This should sound familiar to Thailand residents...

From wikipedia:

"During a flood the dam is designed to hold back 1.45 million megalitres (1.18 million acre feet) of additional water for flood mitigation or 225% capacity. Under the water release plan which is defined by law, excess water must be released from the dam within seven days of it reaching 100% capacity." --http://en.wikipedia.org/wiki/Wivenhoe_Dam

The area of reservoirs is more than a few hectares, as I am sure you are aware. To put a vague number on it, estimates are that there are over 400,000 sq km of dam reservoirs-- that's a third of the area of the world's natural lakes. The scholarly work on methane production is a work in progress. You can go to scholar.google.com, though, and find papers like this one: http://abbeyroad.geo...al_2006_GRL.pdf

Again, I am not saying that all dams are a bad idea, or that we should eliminate all dams. But we have been building them like crazy people, and still we have floods. Why is that? And what is the solution? I think it may consist of changing some of the way we do things. Reforestation may be a partial answer, as well as decreasing our impermeable surfaces (parking, paving, etc.).

I thought Wutthichai Srikhampha made some good points.

"The group also proposed ideas to solve the annual flooding problem, including placing the restoration and conservation of water-producing forests on the national agenda, along with building medium and small sized reservoirs at all 77 tributaries of the Yom River.

""These reservoirs, which have a joint capacity threefold that of the Kaeng Sua Ten in total, could initially trap the rainwater locally and later drain it gradually," he said. There should also be a policy to promote a 'one tambon one reservoir' scheme elsewhere to trap rainwater locally and use it for irrigation, said Wutthichai."

Again, thanks so much for this exchange. You've forced me to think more about the issue-- never a bad thing. Cheers.

A couple of quick points;

My OP noted that " "Drought has arrived early and in Uthai Thani Province, where local residents are now running short of water for consumption." a quote from a thread a few days ago.

Wutthichai is NOt a local (to Uthai Thani), just another activist with an agenda.

"A few hectares" referred to the flux of dams, not their total area. When we start considering emissions, dams produce miniscule amounts compared to coal @ 2.5MWh/tonne (ie coal burnt, not tonnes of emissions) The small hydro station at Wivenhoe replaces 200 t/h of coal burnt at Tarong.

Wivenhoe had to release by law and also because it had reached dangerous levels. Blaming the release for loss of life ignores the fact the huge flows were coming down the Lockyer Valley as well as into Wivenhoe. Assuming it was full before the incident, and given that it had reached 225% capacity, it seems that it had held back 3.2 BILLION m³ which would hardly have helped the situation.

The moves to solar power will actually increase the need for hydo-power dams. The only practical method (so far) to store power is to pump water uphill and recover the energy at peak load periods (as in Snowy R. scheme). At present this done at night to maintain minimum stable load on NSW's 660MW generators; with more solar coming on-line this may also happen during the day. Qld (and other states) should be looking at something similar as they are struggling to supply peak load (TV ads - reduce usage) and reluctant to build more C-F stations.

[DeepInTheForest]

A couple of quick points;

My OP noted that " "Drought has arrived early and in Uthai Thani Province, where local residents are now running short of water for consumption." a quote from a thread a few days ago.

Wutthichai is NOt a local (to Uthai Thani), just another activist with an agenda.

"A few hectares" referred to the flux of dams, not their total area. When we start considering emissions, dams produce miniscule amounts compared to coal @ 2.5MWh/tonne (ie coal burnt, not tonnes of emissions) The small hydro station at Wivenhoe replaces 200 t/h of coal burnt at Tarong.

Wivenhoe had to release by law and also because it had reached dangerous levels. Blaming the release for loss of life ignores the fact the huge flows were coming down the Lockyer Valley as well as into Wivenhoe. Assuming it was full before the incident, and given that it had reached 225% capacity, it seems that it had held back 3.2 BILLION m³ which would hardly have helped the situation.

The moves to solar power will actually increase the need for hydo-power dams. The only practical method (so far) to store power is to pump water uphill and recover the energy at peak load periods (as in Snowy R. scheme). At present this done at night to maintain minimum stable load on NSW's 660MW generators; with more solar coming on-line this may also happen during the day. Qld (and other states) should be looking at something similar as they are struggling to supply peak load (TV ads - reduce usage) and reluctant to build more C-F stations.

Good points, worth pondering. The emissions of coal plants are indeed considerable. Even disregarding the CO2/global warming angle, soot and microparticles are a health risk. I know, I live in between two plants situated about four miles apart.

Storage of electrical power from solar is, as you point out, a problem that still needs solutions. The one you mention is interesting, because (I'm speculating here) it may mean that if the main purpose is to generate electricity from the dam, they won't have to be built as high. (A high "head" is usually achieved during the rainy season to provide electricity throughout the dry season.)

Lately there has been talk of using solar power from Spain/the Sahara to help power Europe. Storage will be a problem there, too. No water is available, really. Liquid salt tanks, perhaps?

take care, see you on another thread.

[ResX]

Water management authoroties have to be more specific about building up new dams. The first question they have to establish is whether the current dams are inadequate. If they do by how much? These questions lead to the point I have raised a few times over the other threads about floods in Thailand. My point is Thailand has to define what size of floods it wishes to deal with. I would say the figure is 7 billion cubic meters of rushing waters in 7 days would be adequate. Agree or not they still have to come with a figure.

After knowing your enemy then let start up to strategize the defence. Check whether under the best utilization of resources is there any need to put additional flood control dams? I have never heard the authorities in Thailand have define the enemy that they wish to deal with.

At glance I don't see there is a need for new dams. All that I know, straightly speaking, Bhumibol, Sirkit and Chao Pharaya dams can be strategized to hold up to the maximum of close to 7 billion cubic meters of water safely. This figure is close to the the amount of flood waters during last year's floods. There are many other dams in Thailand besides these three. Probabaly hundreds medium sizes and 2000 over small dams. Based on these facts I don't see new dams are require. Or at least the authorities have to prove that my facts are wrong.

A. Cam dams make flood impact even worse as if the dams were not there in the first place? The answer is yes. B. Can dams always cut down flood size? The answer is also yes. How could they be? I let you to make a test in order to know which dam falls under which category. Fist you have to know the dam's Full Supply Level (FSL). Then you have to know elevation of flood release outlet structure. Then you can draw conclusion based on the followings

If flood release outlet structure draws flood water deep down below the FSL and it uses sluice gates for that purpose, then it falls under A.

If it draws waters from above the FSL than it falls under B.

Do reality check for these two dams, namely Bhumibol and Sirkit. What do you find? If I recall my fact right they all fall under A! Not surprisingly there were severe floods last year.

Bhumibhol and Sirkit dams were the things of the 50's. In my country we started to build very big flood control dams in early 70's to early 80's. None of our major flood control dam has sluice gate to release flood water. All of them release flood waters using natural overflow structure. They draw waters from above the FSLs. Thus our dams cannot cause flood damages to become bigger then as if they are not there in the first place! We can take this almost for granted irrespectively the dams operators go fishing during the coming of major floods.

[ResX]

Thanks for your reply, OzMick; your questions are excellent and to the point. That dams can cause or exacerbate flooding seems definitely counterintuitive. When I first heard that, I dismissed it as well. How could a dam lead to flooding?

I’m not an expert by any means, just a curious citizen, so take what follows with a grain of salt and do your own searching on the internet. And all this is not to say that dams don’t have a place, when they are properly planned and operated. But there are significant caveats, especially with larger dams. More research is being done all the time, so… hopefully, we’re learning. Obviously, land uses—impervious surfaces—are a large part of our flood problem as well.

Dams do indeed control smaller floods quite well. The problem is with big rainfalls, when the dam nears capacity. This, of course, is when you would most want the dam to hold more water, but it can’t. The rains tend to weaken the earth around the dam, and cause engineers to worry about dam failure. That would be unthinkable, so large quantities of water are often released, again, just when you don’t need it.

The sudden release of such large amounts of water causes another kind of problem downstream beyond what we normally think of. Streams get “scoured”, and become “armored”, when a sudden rush of dam water sweeps away silt, sand, gravel, aquatic plants, leafy debris, and large tree limbs. The result is a river that has less plant and animal life, acts as less of a sponge for water, and—you guessed it—more vulnerable to floods. You would think that this would happen anyway, in normal floods, but people who study dam/environment interactions say that’s not the case.

Dams also begin silting up immediately after construction, so their capacity is immediately diminished. Dams are designed to withstand the pressure of a certain height of water, but silt is much more massive, and as the reservoir silts up, engineers become more wary of dam failures. Dams have a finite lifetime—their usefulness diminishes over time. You would think that the silt could be dredged, but this has not proven economical over the long haul.

Dams rarely serve simply as flood-control devices—their cost is usually leveraged with projected benefits from electrical power generation, or irrigation. This causes management conflicts, as we have recently seen in Thailand.

If you think that dam problems are somehow due to Thailand’s political squabbles or some kind of ineptitude, you might be surprised to find that Westernized countries are not immune to similar problems. One example is the Wivenhoe dam near Brisbane.

http://tinyurl.com/4t4jya5

http://tinyurl.com/7rxmpor

This link makes some worthwhile points, I think. http://www.travelfis...he-thai-floods/

The problem with greenhouse gas production occurs because the level of water behind the dam rises and falls seasonally. When the water is low, vegetation regrows, especially in a tropical, high-sun country like Thailand. When the water rises, it floods the newly-grown green stuff, causing it to rot anaerobically, producing methane. This is in addition to whatever forest material was inundated initially. The cycle will continue as long as the dam operates, since water levels are allowed to rise and fall.

Some other things to consider with dams are that the water behind them is oxygen-deprived, so large releases from reservoirs impact the water quality below, and can kill fish, alter reproduction, etc.

Also, by slowing water flow, dams often increase water temperatures. Fish and other aquatic organisms are pretty sensitive to temperature, and this becomes another area of impact.

This statement is taken from one of your posted articles

"Of course, rainfall levels are notoriously difficult to predict and the authorities were apparently concerned that a repeat of last year’s relatively scanty precipitation would leave reservoir levels too low for irrigation needs. But this underscores the broader point that the purpose of dams -- often touted as “multi-purpose” projects to be used for flood prevention, irrigation and electricity production -- ultimately have to be prioritised: in this case, it seems that flood prevention lost out to irrigation and power generation".

In one of my posts related to floods in Thailand I have made the statement that has the same meaning as the texts in bold above. In fact I have come to this conclusion after a few days the floods start to become serious. One of the posters here made a joke out of my conclusion.

I wish to stress it again here. If the autorities related to dams operations do not give flood control its long overdue right, then they should forget about building up new dams. It doesn't work. I can assure you. Forget also about to stop future floods. The monies better spend to buy boats.

Here are two important quotes related to flood control and dams.

" It is not dams that control floods, but the correct flood anticipation and control strategy that do the job"

" A 20billion cubic meters of flood control dam that has 400million cubic meter additional storage capacity worth less than a 1billion cubic meters flood control dam that has 500million cubic meter additional storage capacity during floods"