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Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 8:18 am
by phuketrichard
I count 19 dams on the mekong

Image
A confluence of drought and dams along the Mekong River has renewed concerns about the future of the 4,700-kilometer waterway, upon which tens of millions of people depend for their livelihoods in China, Laos, Myanmar, Thailand and Vietnam.

The number of dams impeding the Mekong’s flow is fast multiplying, drying up segments of the once fast-flowing river and leaving the region facing imminent drought, according to the Mekong River Commission, a regional intergovernmental body that aims to jointly manage the river’s water resources.

Laos’ Don Sahong, the newest of dozens of Mekong dam projects, began generating electricity close to the Laos-Cambodia border in November. Most of its generated power will be exported to Thailand and Cambodia.
https://www.asiatimes.com/2019/12/artic ... ain-death/

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 11:20 am
by chiltern
Forgive me if I am being thick. l can understand the environmental damage caused to migrating fish unable to transit dams and flow would be reduced until the catchment area behind the dam is full. But once this has been acheived wouldn't normal flow return also the reservoirs created behind the dams could be stocked with fish and their margins a heaven for wildlife

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 1:00 pm
by SternAAlbifrons
chiltern wrote: Sat Dec 07, 2019 11:20 am Forgive me if I am being thick. l can understand the environmental damage caused to migrating fish unable to transit dams and flow would be reduced until the catchment area behind the dam is full. But once this has been acheived wouldn't normal flow return also the reservoirs created behind the dams could be stocked with fish and their margins a heaven for wildlife
What a charming theory (please note, i'm trying to be generous here)

I don't mean to be unkind Chil
so I will forgive you
for being very very very thick.
(gentle indulgent smile, good-natured chuckle)

May i kindly, gently and patiently suggest you do a couple of hours researching the topic on the internet first.
Bridging the gap between your current comprehension and a very basic understanding of how this complex system works is simply far too big a job for one poor man to do.
I spent over an hour trying to figure out where and how to start, i really did, and totally failed.

'Happy to take it further with you, if you do the very basics yourself first.
(smile encouragingly, grind my teeth)

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 1:47 pm
by chiltern
SternAAlbifrons wrote: Sat Dec 07, 2019 1:00 pm
chiltern wrote: Sat Dec 07, 2019 11:20 am Forgive me if I am being thick. l can understand the environmental damage caused to migrating fish unable to transit dams and flow would be reduced until the catchment area behind the dam is full. But once this has been acheived wouldn't normal flow return also the reservoirs created behind the dams could be stocked with fish and their margins a heaven for wildlife
What a charming theory (please note, i'm trying to be generous here)

I don't mean to be unkind Chil
so I will forgive you
for being very very very thick.
(gentle indulgent smile, good-natured chuckle)

May i kindly, gently and patiently suggest you do a couple of hours researching the topic on the internet first.
Bridging the gap between your current comprehension and a very basic understanding of how this complex system works is simply far too big a job for one poor man to do.
I spent over an hour trying to figure out where and how to start, i really did, and totally failed.

'Happy to take it further with you, if you do the very basics yourself first.
(smile encouragingly, grind my teeth)
I wasnt proposing a theory mearly asking a question which by your reply you don't seem to know the answer, why you need to be so rude escapes me perhaps its something in the water.

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 2:28 pm
by SternAAlbifrons
Sorry Chil,i didn't mean to be rude, sincerely.
you mentioned the "thick" thing so i was just attempting to good naturedly play on that theme.

So to answer your question as simplistically as i can -
No, stocking fish in dams will in no way compensate for the fish produced by the free migration, the nutrient and sediment flow, and the annual flooding cycle - all of which are needed to produce the 70-80% of cambodia's protein that this system currently produces.
And a dams edge is not a haven for most wildlife.

Yes, there was a bit of exasperation expressed in my reply (nothing more) - i am sometimes mystified at peoples lack of basic understanding. The Mekong/Tonle Sap ecosystem is one of the primary foundation stones of how and why this country exists the way it does. And hardly a secret,
I know i need to be more patient, thank you for the reminder of that. (sincerely again)

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 2:49 pm
by Clutch Cargo
chiltern wrote: Sat Dec 07, 2019 11:20 am flow would be reduced until the catchment area behind the dam is full. But once this has been acheived wouldn't normal flow return
Yeah, I wondered this too..eventually the water would have to released..assuming decent rainfall in the catchments. Yeah, I haven't done research either but I suspect this might be factors:

More evaporation with still water in the reservoir...(and more seepage into the associated ground)

The dam reservoir is used for irrigation?

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 2:57 pm
by frizzie77
clutchcargo wrote: Sat Dec 07, 2019 2:49 pm
chiltern wrote: Sat Dec 07, 2019 11:20 am flow would be reduced until the catchment area behind the dam is full. But once this has been acheived wouldn't normal flow return
Yeah, I wondered this too..eventually the water would have to released..assuming decent rainfall in the catchments. Yeah, I haven't done research either but I suspect this might be factors:

More evaporation with still water in the reservoir...(and more seepage into the associated ground)

The dam reservoir is used for irrigation?
No, the dam reservoirs have to fill up every year to keep up the pressure to produce that electricity.
So, there's no way the river flows normally after dams are built.

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 3:13 pm
by Clutch Cargo
frizzie77 wrote: Sat Dec 07, 2019 2:57 pm
clutchcargo wrote: Sat Dec 07, 2019 2:49 pm
chiltern wrote: Sat Dec 07, 2019 11:20 am flow would be reduced until the catchment area behind the dam is full. But once this has been acheived wouldn't normal flow return
Yeah, I wondered this too..eventually the water would have to released..assuming decent rainfall in the catchments. Yeah, I haven't done research either but I suspect this might be factors:

More evaporation with still water in the reservoir...(and more seepage into the associated ground)

The dam reservoir is used for irrigation?
No, the dam reservoirs have to fill up every year to keep up the pressure to produce that electricity.
So, there's no way the river flows normally after dams are built.
I suppose it depends on how big/much reservoir capacity has become for the river as a whole. Does it exceed the normal catchment rainfall such that water is only released for electricity generation and nothing else?

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 3:21 pm
by IraHayes
It’s not the water being held back that is the problem... the issue is everything suspended in the water. That stuff doesn’t make it past the dam. Therefor depriving everything downstream of the dam.

Re: Mekong River dying a slow but certain death

Posted: Sat Dec 07, 2019 3:33 pm
by frizzie77
IraHayes wrote: Sat Dec 07, 2019 3:21 pm It’s not the water being held back that is the problem... the issue is everything suspended in the water. That stuff doesn’t make it past the dam. Therefor depriving everything downstream of the dam.
That's indeed a big part of the problem. But the water held back is a problem, too, as it reduces water levels further downstream.