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These may be greatly helpful for those near where they will be built. But this technique does have a cost, it will kill the downstream deltas By stripping off

These may be greatly helpful for those near where they will be built. But this technique does have a cost, it will kill the downstream deltas By stripping off the alluvial soil, and depositing it at the dams, it never reaches it original destination. There is a reason that much of this planets life comes from delta regions, and robbing them of the minerals and fresh water they need to thrive is costing a lot more than providing people the ability to create farms in areas where they shouldn't. This isn't terraforming, it's shifting resources to a place that can't sustain themselves naturally, and killing an ecosystem that could without interferences. It also seems to not mention that natural waterways including rivers, streams, and tributaries shift and move overtime, largely because once a water way fills up with deposits and debris its no longer the path of least resistance.

quixoticelixer- 8y ago
I would argue that the cost of this is worth it, these aren't first world alluvial plains where you can afford to farm and buy food from elsewhere, this is Africa.
- Meph504 8y ago
  Removing the human factor from this, we are creating non-self sustaining environments at the cost of delta's which are sustainable, and play a vital role in survival in their regions. I assure you, if there are people living upstream of a delta in places that can't sustain life, there are people living in that delta region, who rely on it just as much. this isn't solving a problem, it's at best moving them, and at worst creating additional problems. Instead of attempting to make every region on the planet farm land, we should focus on solutions that take into account a balanced ecosystem, and where that can't be achieved, relocation the human population.
  - yayana 8y ago
    The same complaints can't be addressed along the Rio Grande with 80% diversion and no one is talking about relocation for the environmental catastrophe called Las Vegas. That is in a country that includes plenty of fertile land.
Jedd 8y ago
> ... will kill the downstream deltas By stripping off the alluvial soil ... It clearly won't. The article/video discusses how a) the dams are low profile and allow most water to flow over the top -- they are designed to trap sand while allowing alluvial material over / through, and b) they're also designed to fill within a few years which means the bulk of alluvial material in subsequent events will bypass the site entirely. > There is a reason that much of this planets life comes from delta regions ... Can you explain what you mean by this please? > Instead of attempting to make every region on the planet farm land, we should focus on solutions that take into account a balanced ecosystem, and where that can't be achieved, relocation the human population. I appreciate your point of view here, though I'm now curious where you happen to live and how you'd feel about being forcibly relocated if/when climate change renders your home unlivable without being modified. I'd suggest that much of this work is trying to recover recently ruined, or maintain currently precarious human habitations, and perhaps halt the desertification of currently habitable regions.
specialist 8y ago
It's good to ask these questions. As others linked below, there are orgs working this strategy. We can ask them, look at their results. Sand dams may very well improve downstream conditions. Because anything that holds, slows down the surface water is a good thing. I'm reminded of a widespread mitigation project where simply removing non-native plants and replanting native trees restored water ways. These man made oases may do the same. Think of them as beaver dams, without the beavers.
thinkcontext 8y ago
> a place that can't sustain themselves naturally Many places where this technique is used were once more lush but humans degraded the environment, often through overgrazing. So, the degraded landscape of today may not be the "natural" state. Take China's efforts to restore the Loess Plateau, probably the largest restoration effort ever undertaken. https://en.m.wikipedia.org/wiki/Loess_Plateau https://en.m.wikipedia.org/wiki/Loess_Plateau I've not heard of concerns you raised about the impact on deltas. I'm not a scholar but I've done some research on the issue. Can you point me to any papers that address your concerns?

quixoticelixer- 8y ago

I would argue that the cost of this is worth it, these aren't first world alluvial plains where you can afford to farm and buy food from elsewhere, this is Africa.

Meph504 8y ago
Removing the human factor from this, we are creating non-self sustaining environments at the cost of delta's which are sustainable, and play a vital role in survival in their regions. I assure you, if there are people living upstream of a delta in places that can't sustain life, there are people living in that delta region, who rely on it just as much. this isn't solving a problem, it's at best moving them, and at worst creating additional problems. Instead of attempting to make every region on the planet farm land, we should focus on solutions that take into account a balanced ecosystem, and where that can't be achieved, relocation the human population.
- yayana 8y ago
  The same complaints can't be addressed along the Rio Grande with 80% diversion and no one is talking about relocation for the environmental catastrophe called Las Vegas. That is in a country that includes plenty of fertile land.

Jedd 8y ago

> ... will kill the downstream deltas By stripping off the alluvial soil ... It clearly won't. The article/video discusses how a) the dams are low profile and allow most water to flow over the top -- they are designed to trap sand while allowing alluvial material over / through, and b) they're also designed to fill within a few years which means the bulk of alluvial material in subsequent events will bypass the site entirely. > There is a reason that much of this planets life comes from delta regions ... Can you explain what you mean by this please? > Instead of attempting to make every region on the planet farm land, we should focus on solutions that take into account a balanced ecosystem, and where that can't be achieved, relocation the human population. I appreciate your point of view here, though I'm now curious where you happen to live and how you'd feel about being forcibly relocated if/when climate change renders your home unlivable without being modified. I'd suggest that much of this work is trying to recover recently ruined, or maintain currently precarious human habitations, and perhaps halt the desertification of currently habitable regions.

specialist 8y ago

It's good to ask these questions. As others linked below, there are orgs working this strategy. We can ask them, look at their results. Sand dams may very well improve downstream conditions. Because anything that holds, slows down the surface water is a good thing. I'm reminded of a widespread mitigation project where simply removing non-native plants and replanting native trees restored water ways. These man made oases may do the same. Think of them as beaver dams, without the beavers.

thinkcontext 8y ago

> a place that can't sustain themselves naturally Many places where this technique is used were once more lush but humans degraded the environment, often through overgrazing. So, the degraded landscape of today may not be the "natural" state. Take China's efforts to restore the Loess Plateau, probably the largest restoration effort ever undertaken. https://en.m.wikipedia.org/wiki/Loess_Plateau https://en.m.wikipedia.org/wiki/Loess_Plateau I've not heard of concerns you raised about the impact on deltas. I'm not a scholar but I've done some research on the issue. Can you point me to any papers that address your concerns?