Floating villages in the Tonle Sap

[asakiyume]

Tonle Sap is a lake in Cambodia that expands and contracts dramatically, depending on whether it's the rainy season or the dry season--it goes from being no more than a meter deep and 2,700 square kilometers in area to being 9 meters deep and 16,000 square kilometers in area (says Wikipedia). The floating villages of Siem Reap, on one of its feeder rivers, are well known, but on the lake itself there are also floating villages. When dudeshoes saw this New York Times article ("A Push to Save Cambodia's Tonle Sap Lake," by Chris Berdik), about how the lake was threatened, she sent me the link, knowing I'd be interested.


Girl from the floating village of Akol, Cambodia. Photo by Chris Berdik for the New York Times

The article is largely about the creation of a model to try to predict what will happen to the lake and how much influence the various factors have, and about the problems in designing the model, and with the model more generally. I was more interested, though, in other aspects of the story--in the fact that farmers displaced by grants to agribusiness have come to make a living on the lake, in the mysterious statement that "tropical dams typically generate power for just a few decades" (why is that?), in the fact that there are tiny fish there called money fish, and sharks that will fit in the palm of your hand.


The black shark, Labeo chrysophekadion. Photo by Chris Berdik for the New York Times

1.5 million people depend on the Tonle Sap. Climate change, hydro dams, increased population pressures--all these things spell change for the lake. Since change is coming, it's best to be planning for it:

A food-security expert, Dr. Fraser has studied some of history’s worst famines, as well as those prevented by tactics like stockpiling food and distributing drought-resistant seeds. His research suggests that no matter how the Tonle Sap changes in the coming years, the right adaptive strategies could mean the difference between a tolerable transition and a disaster.

“The policy and development challenge is one of managing the transition,” he said. “There’s no way to stop it.”

Comments

[ckd]

the mysterious statement that "tropical dams typically generate power for just a few decades" (why is that?)

My immediate guess is that they silt up quickly, possibly because it's hard to build them high enough to make that less of an issue and/or because of higher levels of erosion in the watershed than in non-tropical river systems.

[asakiyume.livejournal.com]

Thank you! That makes a lot of sense.

[mnfaure.livejournal.com]

This is what I was going to say, too. Also, another environmentally detrimental factor is all that silt never makes its normal course, depriving lands further on of their relied-upon nutrients. :(

[asakiyume.livejournal.com]

Believe me, I am NO FAN of giant hydro plants; I just didn't know why it would be a particular issue in the tropics and not elsewhere--actually, I guess I still wonder that. Silting is a good explanation for why *any* hydro plant might stop working, but why are the conditions especially that way in the tropics? Maybe the heat makes the rivers sluggish? Or is it just chance that the big powerful rivers that people would tend to want to use for hydro power are in the tropics? Or--?

I never thought you were a fangirl ;)

[mnfaure.livejournal.com]

*nods* The question is interesting and not something I'd ever considered before. Totally just sticking this out there because I have no idea what I'm talking about, but I wonder if, after the plants are built, there is little follow-up in maintenance of the machinery and the river? Could, in some places the plants be build with foreign aid and then the money runs out and the staff drastically reduced? But again, why the tropics? *no clue*

Re: I never thought you were a fangirl ;)

[asakiyume.livejournal.com]

I was thinking those exact same things--and then asking those exact questions.

Re: I never thought you were a fangirl ;)

[khiemtran.livejournal.com]

Probably also things like iron or other mineral sediments, which is bad for the machinery, rather than the dam itself.

Re: I never thought you were a fangirl ;)

[joycemocha.livejournal.com]

Probably less-steep canyons. All reservoirs silt up, eventually. Dredging isn't exactly feasible. It's more likely that it happens more quickly in a flatter tropical basin.

Re: I never thought you were a fangirl ;)

[asakiyume.livejournal.com]

*nodding*

[c-maxx.livejournal.com]

I believe JoyceM has the main part of it. As reservoirs silt up vertically, there is less vertical in a shallow tropical lake. Maybe more sediment load too. I understand most of Bangladesh in delta sediment.

I was at a talk in school discussing the Aswan Dam in Egypt, which has cut off the nutrient-filled sediment from central Africa, along with several other issues. They said it too was rapidly filling with sediment, although a deep reservoir.

The speaker discussed a deep-location sediment outlet tho I have never heard of anyone building one- under lots more pressure at the bottom of the res, much more difficult to build...

[asakiyume.livejournal.com]

I remember hearing that the Aswan Dam contributed to the spread of schistosomiasis, because the snails that are carriers of the parasitic worm live better in … whatever circumstances it is that the dam causes.

Giant infrastructure projects are less in vogue as forms of aid, and for good reason. As lots of people have pointed out, the global donor-aid-industrial complex can be as much about recolonialization and maintaining control (and benefiting the donor country) as it is about actual aid.

[browngirl.livejournal.com]

That was my guess too, so I'm glad to see it also guessed by someone knowledgeable and sensible. :)

[sartorias.livejournal.com]

Adaptive strategies. That gives one cautious hope instead of the constant doom-saying.

[asakiyume.livejournal.com]

YES--this is so important. I believe the doomsaying cripples us, makes us passive when we need to be active. There is *always* a way, *always* something that can be done. Hell, even if we're absolutely doomed, there's going down together singing or going down weeping--there's sharing a last meal or fighting to the death over the last scrap--and I really think we have to keep going for the former, and if we do, it may turn out we're not so doomed after all.

…. sorry…. got my rant on a little.

[c-maxx.livejournal.com]

Yes, can share the last meal and still fight the outcome!

[asakiyume.livejournal.com]

Absolutely.

[snakypoet]

Couldn't agree more!

[khiemtran.livejournal.com]

It sounds like a very interesting model. OTOH, it also sounds like there's a bit of tension between all the different experts - I hope they find a way to work constructively together. And how amazing to have six foot freshwater rays - I hope they can keep those too!

[asakiyume.livejournal.com]

I would love to see the six-foot rays. I'd love to see river dolphins too (train of thought; I'm not sure there are any river dolphins along the tributaries of the Mekong and Tonle Sap. … Now I want to check...

[asakiyume.livejournal.com]

Yes, there is a subspecies of Irrawaddy dolphin called the Mekong dolphin… now threatened by a possible dam…(one article (http://www.huffingtonpost.com/2014/02/20/mekong-river-irrawaddy-dolphins-threatened-extinction-dam_n_4824190.html))

[heliopausa.livejournal.com]

“The policy and development challenge is one of managing the transition,” he said. “There’s no way to stop it.”

Absolutely agreed that managing transition, planning, and intelligent policy-making are important. But as to "there's no way to stop it"... well, that depends which changes are in question. Climate change - yes, it's happening and we have to deal with that. Hydro dams - different scenarios are possible, and no specific project is unstoppable. Water theft (which isn't specifically mentioned, but it's a possibility, as part of the "grants to agribusiness") should never be treated as unavoidable.

[asakiyume.livejournal.com]

I absolutely agree with you, on all points.

mote biodiversity thru meadowscaping, http://www.sandpipercreative.com/biodiversity.html.

[dudeshoes.livejournal.com]

Although he may be right there is no way to stop climate change, there are small actions people can take to feel better while refraining from making the problem worse. One is to give up a lawn and promote biodiversity thru "meadowscaping," http://www.sandpipercreative.com/biodiversity.html. Might not work for young families with soccer-practicing children, but for the rest of us ...

Re: mote biodiversity thru meadowscaping, http://www.sandpipercreative.com/biodiversity.html.

[asakiyume.livejournal.com]

I **totally** endorse this idea.