Tap water salty as seawater enters Chao Phraya

[JohnThailandJohn]

A simple internet search will show that using boats and paddles are a common aerators tools used to add oxygen to water especially when you don't want to disturb the lower levels of water and kick up debri and dirt. Not to mention a good solution when there is a need to act quickly or the need is is not something needed constantly.

[Ned]

People have been warning for decades about the looming salination of the Chao Phraya......and the sinking city of course. Eat salt Bangkok! Eat salt!

[JohnThailandJohn]

People have been warning for decades about the looming salination of the Chao Phraya......and the sinking city of course. Eat salt Bangkok! Eat salt!

I would think this is not a decades old issue but one that goes back centuries on a regular basis during droughts and the dry season. Normal occurrence in rivers where they open into an ocean. Having lived near beaches most of my life I've lived numerous places with brackish water and depending on the season and river current will dictate how salty the water is and how far upstream it goes.

[impulse]

OK, we have a picture of an axial pump...now picture a boat in a wide deep river per the Chao Phraya...can you see the difference in the physics ?

Using your approach, I can say an axial pump is similar to a helicopter...

The main difference in the "physics" of a boat prop and an axial flow pump is whether the water moves or the impeller (propeller) moves. Both work on the same principle- adding energy to water in the form of velocity (which is a vector quantity). There are other features in a pump that change the kinetic energy to pressure, but it can be converted back and forth between pressure, temperature, velocity and elevation- it's still just adding energy.

In fact, you could use a boat prop in an axial flow pump and you could use an axial flow pump's impeller as a boat prop. They wouldn't be the optimum design for each other's application, but they would function quite nicely- albeit less efficiently. If you hold the boat stationary, you have an axial flow pump- less efficient, but functional nonetheless. It will add energy to the water in the form of velocity, which has both a magnitude and a direction.

If you don't believe it, tie your bass boat to the dock, rev it up and see if the water behind you is moving faster than it was. See if it's moving in any particular direction (vector quantity). Keep revving the engine parallel to shore and sooner or later, all the water in a small lake will be moving in a big circle. You may have to be patient if it's a bigger lake.

A helicopter's rotor would pretty much disintegrate running in water. Air is a compressible fluid and helicopter blades won't work worth a flip in an incompressible fluid like water. Not very similar at all. A better comparison would be an airplane propeller and a helicopter rotor.

Edited February 22, 2014 by impulse

[fab4]

'Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water.'

If this is possible [i'm no expert but I can't see how it is, could be wrong though], what good will it do?

It's a report in The Nation, and as such should be taken, as the "Bankokians" will soon do, with a pinch of salt.

[CraigSchuler]

Think I might be a little more worried about the raw sewage floating down the river than salt.

[Crushdepth]

"Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water."

Because we all know that oxygen evaporates salt in Thailand.

What the really need to fix is the river flow, its the low flow that is letting the saline water intrude further upstream than normal. Unless they are trying to improve water quality in a stagnant area these boats are a waste of time.

[noitom]

But a Thai big cheese was just in the news yesterday with a photo op drinking a glass of Thai tap water and saying that there was no need for concern. But, he stated, don't drink "too much." Certainly, we can rely on the opinion of a top Thai official yesterday that the tap water is not a concern. Right?

[canuckamuck]

OK, we have a picture of an axial pump...now picture a boat in a wide deep river per the Chao Phraya...can you see the difference in the physics ?

Using your approach, I can say an axial pump is similar to a helicopter...

The main difference in the "physics" of a boat prop and an axial flow pump is whether the water moves or the impeller (propeller) moves. Both work on the same principle- adding energy to water in the form of velocity (which is a vector quantity). There are other features in a pump that change the kinetic energy to pressure, but it can be converted back and forth between pressure, temperature, velocity and elevation- it's still just adding energy.

In fact, you could use a boat prop in an axial flow pump and you could use an axial flow pump's impeller as a boat prop. They wouldn't be the optimum design for each other's application, but they would function quite nicely- albeit less efficiently. If you hold the boat stationary, you have an axial flow pump- less efficient, but functional nonetheless. It will add energy to the water in the form of velocity, which has both a magnitude and a direction.

If you don't believe it, tie your bass boat to the dock, rev it up and see if the water behind you is moving faster than it was. See if it's moving in any particular direction (vector quantity). Keep revving the engine parallel to shore and sooner or later, all the water in a small lake will be moving in a big circle. You may have to be patient if it's a bigger lake.

A helicopter's rotor would pretty much disintegrate running in water. Air is a compressible fluid and helicopter blades won't work worth a flip in an incompressible fluid like water. Not very similar at all. A better comparison would be an airplane propeller and a helicopter rotor.

You are trying hard to show that a boat propeller can be a type of pump. Well of course it is a type of pump. It's not a very efficient type of pump for moving unconstrained water, energy is quickly sluffed off by the massive drag of the water and against a reversing tide comically useless.

I have seen these water pushing boats and they don't do a lot of aeration either, as they are submerged propellers. But even if they were fantastic at aeration. What possible effect could that have on salinity? And if aeration is what they are after, why not use air pumps?

Edited February 22, 2014 by canuckamuck

[ESDinBKK]

'Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water.'

If this is possible [i'm no expert but I can't see how it is, could be wrong though], what good will it do?

Substitute the words "portable pumps" for "water pushing boats" and you'll find they are used all over the world to manipulate water levels, water flow and aeration.

A boat's propeller is a type of axial flow pump. Not as power efficient as a purpose made axial flow pump, but you use what you have, not what you wish you had.

If you remember, Thailand bought these boats last year at great expense, much higher than the price of pumps, for the sole reason of pushing water. At the time it was noted that they could have purchased three times as many pumps for the price of the boats.

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[Somtamme]

With the decision to treat the salty water by reverse osmosis (RO), there is a risk that this can make the water aggressive to plumbing systems and generate taste complaints. It may be the water will be re-blended with freshwater after the RO plant. It would be interesting to know how long this treatment is to last?

[Dogmatix]

'Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water.'

If this is possible [i'm no expert but I can't see how it is, could be wrong though], what good will it do?

It will be as effective as the flotilla of boats used to pump water down the Chao Phraya quicker to avert flooding in Bangkok in 2011.

Owners of boats benefit from these stunts and to people with low IQ it might appear that government is doing something useful but really just wasting fuel and causing more pollution.

[impulse]

You are trying hard to show that a boat propeller can be a type of pump. Well of course it is a type of pump. It's not a very efficient type of pump for moving unconstrained water, energy is quickly sluffed off by the massive drag of the water and against a reversing tide comically useless.

I have seen these water pushing boats and they don't do a lot of aeration either, as they are submerged propellers. But even if they were fantastic at aeration. What possible effect could that have on salinity? And if aeration is what they are after, why not use air pumps?

No, I am trying hard to get posters like #2, #3 and #4 to realize that there are Thai people who know a lot more about hydrology, hydro geology, water treatment and fluid mechanics than the average keyboard know-it-all.

I don't have a clue whether the boats are the best way to handle this particular problem. I don't have enough information. And I move fluids around for a living- here in Thailand. If I don't have enough info, the average retired expat sure doesn't have enough info to be poking fun at something they don't understand- as they seem to diss all things Thai. It's insulting to a lot of very competent Thai engineers, and pretty tiresome reading, too. On the other hand, there's some folks with expertise who have made excellent comments and observations without resorting to insulting all things Thai.

The boats- they are at hand, they can easily be moved from one problem area to the next, and similar solutions are being used around the world by very competent engineers and scientists to change the natural flow of water. That makes them a pretty reasonable choice for some problems- in fairness, not all problems. But I'm not qualified to make that judgment.

Nobody tuned in here knows if they were effective in the 2011 flood because the flood was so bad that nothing was going to stop it. The boats may (or may not) have kept the water out of some areas, and may (or may not) have helped clear the floodwaters days or weeks earlier than otherwise. Those of us living in downtown Bangkok may have the boats to thank that we stayed dry in 2011. I don't know. I haven't seen the white paper yet. If anyone has, I'd appreciate a link.

Edited February 22, 2014 by impulse

[Thai at Heart]

'Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water.'

If this is possible [i'm no expert but I can't see how it is, could be wrong though], what good will it do?

Substitute the words "portable pumps" for "water pushing boats" and you'll find they are used all over the world to manipulate water levels, water flow and aeration.

A boat's propeller is a type of axial flow pump. Not as power efficient as a purpose made axial flow pump, but you use what you have, not what you wish you had.

So does it work more effectively to push water upstream or downstream.

I am.just concernened they might cause flooding I. Ayyutaya again if they get these monstrous water pushers working.

[Thai at Heart]

'Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water.'

If this is possible [i'm no expert but I can't see how it is, could be wrong though], what good will it do?

Substitute the words "portable pumps" for "water pushing boats" and you'll find they are used all over the world to manipulate water levels, water flow and aeration.

A boat's propeller is a type of axial flow pump. Not as power efficient as a purpose made axial flow pump, but you use what you have, not what you wish you had.

Er I can power a small model airplane with a elastic band attached the prop, but this doesnt mean an elastic band will power a full sized plane and get if off the ground....

a boats prop is nothing like an axial pump...

Nothing like it, eh?

OK, we have a picture of an axial pump...now picture a boat in a wide deep river per the Chao Phraya...can you see the differencein the physics ?

Using your approach, I can say an axial pump is similar to a helicopter...

Oh stop it.

Plodpraop thinks he has discovered something that no other physics experts globally have been able to do.

Push water in an open body of water.

Tell you what. Singapore better watch out if they really rev things up. Putting a boat propeller into an river up to 80m wide and 10,metres deep and expecting it to significantlt "push" water. The propeller and engine needed to make a significant difference would need to be enormous. The energy required to add velocity to a river that big would have to be gargantuan

Oh my lord. Will make a lot of fumes and noise mind.

[marko kok prong]

The pasak river here in Wichianburi is now totally dry,no flow at all,this leads into the chao praya i think, i don't know why,last year at this time it was higher and still flowing a bit,plus we have had cool weather this year,i can only thing it is be pumped dry for irrigation,the country up here is very dry,much more so than last year,but we had flooding in september,would the cooler weather have any bearing on this,i would have thought less evaporation,not a drop of rain since october,and last year at least we had a huge storm in january with heavy rain,i dont expect rain until after songkran,it is starting to look a bit like australia here,at present.

[waza]

The pasak river here in Wichianburi is now totally dry,no flow at all,this leads into the chao praya i think, i don't know why,last year at this time it was higher and still flowing a bit,plus we have had cool weather this year,i can only thing it is be pumped dry for irrigation,the country up here is very dry,much more so than last year,but we had flooding in september,would the cooler weather have any bearing on this,i would have thought less evaporation,not a drop of rain since october,and last year at least we had a huge storm in january with heavy rain,i dont expect rain until after songkran,it is starting to look a bit like australia here,at present.

I suspect you are right, the water has been diverted for irrigations and I also suspect that the rice scam has a lot to do with it.

[ozzydom]

The thing in the photo is an aerator mounted on floating pontoons, not a 'boat'. It's also highly inefficient. The only efficient way to add dissolved oxygen to water is by pumping compressed air through perforated pipes laid on the channel bed.

And yet, as I recall, every one of the hundreds of fish farms and water treatment plants I've ever visited use surface agitation to aerate their water.

Some use paddles, some use propellers, some use waterfalls, and some use fountains- but every single one uses physical agitation. Possibly because you need to aerate the water, and then move it around so all the water is aerated.

It may be highly inefficient, (I'm not an aeration guy) but it's very practical. Probably why it's the preferred method of Mother Nature. I've never seen a natural air compressor, but I've seen lots of naturally aerated water.

.

Surface aeration is indeed widely used and it does an adequate job. A boat prop is useless as an aerator because it's designed to push water horizontally without entraining air. Compressed air through perforated pipes is by far the most efficient way of getting oxygen into water because you can control the bubble size and pressure.

I am, as it happens, an aeration guy.

Unless the prop is adjusted to be near enough to the surface to create cavitation.

[mikemac]

'Water-pushing boats were also sent to the Prem Prachakorn and Lat Phrao canals to help add oxygen to the water.'

If this is possible [i'm no expert but I can't see how it is, could be wrong though], what good will it do?

It's a report in The Nation, and as such should be taken, as the "Bankokians" will soon do, with a pinch of salt.

As most of us do with your anal comments..................