It isn't just sand. What is also happening is that China is building an endless supply of hydrodam's along the Mekong (and other) rivers in Cambodia, Laos and Vietnam. I've seen this first hand. This is screwing up the natural flow, which is also affecting the sand 'production'.
This is all part of China taking over the whole region by providing power and thus building a silkroad all the way to Sihanoukville, where they ship goods south to Jakarta and west to Africa. Google what is happening there and you'll see it.
This is me driving a motorbike across what is now a totally dry riverbed in northern VN all because of unseasonably dry weather and hydrodam's upstream... https://imgur.com/a/7hfxRD7
I just learned about this last week watching "Seamen" on prime video[0]. It is pretty terrifying.
But one thing I don't get is: once the dam is built and filled up, shouldn't the water be back to flow regularly? It seems the dam should only act as a buffer, but not cause a dramatic decrease in water flow. Is it because evaporation at the water basin is much higher than on the river?
[0] an episode of the show called "The Grand Tour" where they usually drive cars, but here they drove boats on the Mekong.
Persistent unseasonably dry weather. There is no water, even at the top. A lot of the water held at the dams is also diverted to local farms so it never continues 'down the hill'...
Then what happens is that the water is further away (lower) and people build houses closer... a big rain comes in and wipes away the houses. That is why in the wet season, you see stories in the news about all the landslides... which are a combination of building and deforestation for farming.
The artificial lakes cause a lot of water absorption to surrounding land and air. Grounswater levels can go down when the river bottom deepens downstream of the dam.
> by providing power and thus building a silkroad all the way to Sihanoukville
Yes, China is why Cambodia has a GDP increase of 7% each year and so many are leaving poverty. Death rates are going down. College Education is going up.
Amazing what a country can do if it comes in and actually helps others rather than the West with its puritans values.
Japan is still helping though. I guess not quite the West but they still are doing infrastructure.
Once you see environmental problems as, despite each being unique, mostly arising from overpopulation, you can't help substitute for the proximal cause "overpopulation".
> The scramble for sand is destroying the Mekong
Becomes
> Overpopulation is destroying the Mekong
You might add "one way is the scramble for sand" though there are plenty others.
Learning about various nations' successful, noncoercive programs to lower birthrate that are as far from China's policy, forced abortions, or eugenics as day from night, and that increased prosperity and happiness, leads you to embrace such programs. The book Countdown by Alan Weiss https://www.amazon.com/Countdown-Last-Best-Future-Earth/dp/0... describes several such programs, including in Thailand, Iran, Costa Rica, Mexico, and others.
The most effective solution to the Mekong situation, however partial, is contraception and family planning education.
They’re not though. That’s a vast oversimplification. There are many individuals who consume and pollute 1000x more than others. You could probably add a few zeroes there and still be accurate.
Many problems would continue to exist and continue to get worse if local populations were to start decreasing over time.
Desert sand is too smooth to bind to make concrete, so sand is taken from river beds such as the Mekong
That's really interesting, but makes sense. The sand in most deserts has been blowing around for millennia (or longer), and so would be extremely smoothed-off. Sand in the Mekong is relatively young, and not that far removed from when it was a rough chip off a rock upstream. The difference here is called sediment maturity [] IIRC from first-year geology.
But can anyone answer: why is mature, rounded, fine sand not suitable for binding concrete or for glassmaking? And how fine can the sand be -- wouldn't extremely fine grains classify as clays instead?
Not to argue with the BBC, but this statement is just factually incorrect. Desert sand is not suitable for concrete because it is poorly graded and is all essentially the same size. Concrete mixes call for sands of various grain sizes, and so to use desert sand you would need to mix in these other sizes of sand.
I have seen this rumor repeated often and I think it is journalists trying to explain something they don't understand in a way that seems intuitive.
"But can anyone answer: why is mature, rounded, fine sand not suitable for binding concrete or for glassmaking?"
It's the jagged edges on 'fresh' sand that gives the mix strength. Smooth sand is fine for glassmaking (something I do along with metal and jewelry work) but horrible for construction, as it doesn't grip into the binding agent as well, and any serious load makes it turn straight into dust.
The sand can be as fine as possible, as long as it isn't rounded, and still be useful for construction work.
I'm not a concrete mix design expert by any means, but I disagree with this post on a few levels. Concrete strength is derived from multiple sources, and grain interlocking is just one of them. I think recent research has shown that grain interlocking does not play a large role in concrete strength. It's unclear to me if your post is talking about grain interlocking or cement/aggregate bonding. I'm not up to speed on research in this area, but I do not believe that you can have a rounded sand that is so smooth that bonding doesn't occur and the idea that the concrete "turns to dust" under any serious load is something that I personally have never heard of.
In fact, the more angular the aggregate is the less workable the concrete becomes. There is a sweet spot of angularity that is desired. I believe the main advantage to increased angularity is in durability (which is due to interlocking, I think, as well as increased void ratio leading to better air entrainment).
Also - the size of the grains is more important than angularity, so I also disagree with the statement that sand "as fine as possible" can be useful for construction work in the context of concrete. While tautologically true because anything too fine (passing #200) would be classified as a silt instead of a sand, the way that it's written is deceptive.
"Also - the size of the grains is more important than angularity, so I also disagree with the statement that sand "as fine as possible" can be useful for construction work in the context of concrete."
Disagree all you want but that doesn't change the fact I've done building construction, including laying foundation, and finer sand is far superior to coarser sand. In fact, coarser sand is rather horrible for construction.
I still don't understand what exactly you're talking about. Are you talking about sand used for concrete or sand in general (e.g. - for subgrade soils).
Sand used in concrete needs to meet a gradation requirement. The gradation requirement uses all sizes of sand as aggregate.
And if we are comparing credentials (which I assume is what your building construction story and youtube link is for?), then I've done nothing but put holes in the ground and fill them up with concrete for almost a decade. Here's what I was doing in 2014: https://www.youtube.com/watch?v=E4Ixw69woSA
I did the construction globally, from USA to UK to Saudi Arabia.
I'm talking about both sand in construction and in general (like for glassblowing, etc.) Portland cement uses the finest sands possible for holding concrete aggregate, which you only really tend to find in desert areas (if you're lucky enough to find a spot that hasn't been above water for more than a million years, that's one reason construction-grade stuff is so hard to find.)
Now days, I do very similar to your link, except it's through mountains, and terminates inside the mountain. Minerals extraction is fun!
I suppose then there's something else about desert sand (all deserts??) that the article claims makes it unsuitable for glassmaking. Maybe compositional.
The composition doesn't matter once you melt and everything undergoes specific gravity separation. Melt a bucket of sand, swing it around in a circle for three minutes at high speed, you have a cullet of purified glass with contaminated exterior layers.
Sand is just a classification of grain size of soil. We make sand all the time at quarries by crushing rocks. Most of the aggregate used in construction is made this way or taken from a pit/dredged.
Because crushing rocks costs more money than dredging rivers. Especially when there are weak or no environmental protection laws or regulations for dredging, like on the Mekong.
If you're willing to do that, it's probably easier to just start with gravel/rocks (also abundant) and crush them. I'm pretty sure this is where most of the construction material near me comes from.
Desert sand can be used in concrete. Concrete can be up to 40% stronger, after 90 days, with addition of up to 20% of dune sand instead of Portland cement.
See "Compressive strength and hydration with age of cement pastes containing dune sand powder" Salim Guettala, Bouzidi Mezghiche, Algeria.
This is a topic with very scant literature. I'm curious if there's an account of global sand reserves. Unlike oil/shale, other mineral resources, it seems like available construction sand is basically all discovered by virtue of being on the surface. I'm wondering if there are predictions for peak sand, what current sand reserves translates to in total tons of future concrete production etc. Otherwise it seems like the kind of resource that need to managed properly, seeing how land reclamation projects will be increasingly necessary with raising water levels. Engineered timber can replace some building needs, but I can't think of an alternative to concrete for other critical infrastructure like roads.
I'd be really interested to know the economics here too. Forestry is something that can be done for a profit, but what if it takes 1000 years to make sand?
The sand mafia is real. It’s happening in India too.
Sand isn’t ‘renewable’ ..loss of river sand is just going to make things worse.
I don’t want to sound like a curmudgeon..but human extinction is imminent is we don’t protect our ecosphere and biosphere..this is assuming climate change can’t be stopped and so let’s not take that into account..lets assume that it won’t happen.
As a super apex predator, we need the underlying structure of our ecology and environment and all the habitats below us in the food chain..most importantly insects and frogs and birds...for us to survive here on this only planet we know.
The solution is just a severely whittled population with measures that will get us to a desired 2-3 billion in 150-200 years.
We have to maintain genetic diversity and dna code hygiene..it’s not genocide or eugenics if we don’t target a particular people or group for erasure. It’s for ALL of us.
This can be achieved by incentivizing those who subscribe to a non transferable quota of 1/2 surviving progeny. And preservation of their genetic material. Quality over quantity. The crush of human population will be our undoing.
That’s fearmongering. Not even WWII managed to kill even 10% of the human alive then. Climate change could have caused half of humans to die which would be exceedingly extreme in our civilization but I don’t buy extinction argument.
For other species, population goes down by half is just another day. It wouldn’t even be classified as vulnerable if it were just going down by half. A large proportion of us will suffer or die, but that is not extinction, there’s no need to over dramatize things when the fact is serious enough.
A good insight on how daming and sand dredging is destroying the Mekong is in the latest Grand Tour episode. The extent of the damage that humans have caused to other humans surviving on the river is unfathomable.
I read somewhere recently that the melting of ice in Greenland is exposing vast quantities of sand. I am not sure if this will make a difference as transporting the sand would then be a problem.
But by the time it becomes too expensive to dredge we may have majorly fucked up some ecosystems. The loss in depth of the Mekong means seawater comes in and destroys plants, and sand is also part of the natural ecosystem as described in the article.
>"But by the time it becomes too expensive to dredge we may have majorly fucked up some ecosystems."
I know it may be unpleasant to hear this... But some of us don't actually care. Seriously, somewhere we got "stuck" into thinking that we should (or can) perfectly preserve ecosystems whilst simultaneously advancing our civilization into amazing new levels.
However, if you look at it objectively we've already demolished and transformed huge swathes of the planet anyways without blinking; but now selectively decide to "preserve" some other things. Just look at all the land our cities take up, the roads that cut our landscape, the beaches that are peppered with housing, the rivers we've diverted, the dams we've constructed, the changes we've caused in the evolution of plants and animals, etc. Maybe even imagine how (perhaps horrible) our planet looks at night from outer space due to the lights we've erected all over it instead of letting it be naturally dark as it's been for eons.
Now is the time to plan for 2040 and beyond. I’m in a “developed” country and were looking at options regarding acquiring multiple inherited citizenships to maximise our options for this unknown future.
is it some specific type of sand or whaT? i mean... china has loads of desert, it's a big issue there :D don't they just take their own sand?? is there some special type of sand required for good cement which is rare or something?
The article states that the sand in a desert is to "smooth" to properly bind in concrete. So yes, the demand is for sand with characteristics that work in concrete. The article also states that Cambodia has banned exporting sand and also that Singapore recorded record exports from Cambodia. I suspect that large scale corruption is in play.
This is all part of China taking over the whole region by providing power and thus building a silkroad all the way to Sihanoukville, where they ship goods south to Jakarta and west to Africa. Google what is happening there and you'll see it.
This is me driving a motorbike across what is now a totally dry riverbed in northern VN all because of unseasonably dry weather and hydrodam's upstream... https://imgur.com/a/7hfxRD7