5 ms·

The main expense of building an artificial island is the massive amount of material that is needed to be laid beneath the habitable patch of land, all the way d

by rdancer 11y ago

The main expense of building an artificial island is the massive amount of material that is needed to be laid beneath the habitable patch of land, all the way down to the sea floor. Seeing that if you are already level with (or only slightly below) the surface, your job is almost done, how much would it cost to dump concrete, rock, and sand on top of the atolls, to either keep them from submerging, or make them emerge once more?

jacquesm 11y ago
Build dikes, keep pumping out the water as it seeps back in or rains down. A good chunk of NL is below sea level and that's how they did it (with old school tech like windmills no less, just use enough of them and it will work).
- dalke 11y ago
  Take a look at the map of the Marshall Islands. Here's a satellite view of Majuro, where the capital is located - https://www.google.com/maps/@7.1298596,171.2318474,28259m/data=!3m1!1e3?hl=en https://www.google.com/maps/@7.1298596,171.2318474,28259m/da... . Like all atolls, it's a very thin circle enclosing a lagoon. By my estimate it's about 100 meters wide, from ocean shore to lagoon shore. As a very rough estimate, 1 meter of dike height needs 3 meters of surface, so 6% of the island will be a dike. The Dutch can do this because their dikes enclose a lot of land. That's not possible here. The Dutch also have good soil and rainfall. The ground of the Marshall Islands is made of porous coral. aaron695 elsewhere in these comments pointed to a NatGeo article at http://news.nationalgeographic.com/2015/02/150213-tuvalu-sopoaga-kench-kiribati-maldives-cyclone-marshall-islands/ http://news.nationalgeographic.com/2015/02/150213-tuvalu-sop... . Towards the bottom is a picture with the caption 'Flooding during king tides is a problem on Fongafale, when water percolating up through the coral matrix laps even at the door of the meteorological office.' Thus, dikes won't prevent salt water from percolating through the coral under the dikes and flooding the other side.
  - jacquesm 11y ago
    It looks as if the situation is not one that would benefit from interference by man as it is. The eco-system is rather special and any messing around with it is going to make things worse, not better. Some places on earth are simply not fit for human habitation, this may be one of those. If you wanted to 'go Dutch' on this then it would mean a total transformation of the environment, basically a ring around all of the Marshall Islands anchored to the sea bed. But that would transform the whole thing into a sweetwater archipelago in no time and would likely kill off everything inside it. This is more or less what happened to an inland sea that we had here, it's now a lake and sweet (IJsselmeer).
    - dalke 11y ago
      "Some places on earth are simply not fit for human habitation" The last 3,000 years of human habitation on those islands would suggest that this is not one of those places.
      - jacquesm 11y ago
        It's not the last 3000 years that determine fitness, it's the next 50.
        dalke 11y ago
        Then why did you not write 'Some places on earth are no longer fit for human habitation'? Because that's clearly true. All of those old strip mines, and Superfund sites, and nuclear test sites, and the region around Chernobyl, and the former fishing towns of the Aral Sea are trivial examples of how sites have been rendered less fit for human habitation. However, that logic of the argument is a bit silly, since it sets aside considering how human agency may be responsible for the removal of that part of the human ecosystem. There really are places which "are simply not fit for human habitation" include the top of Mt. Everest, effectively all of Antarctica (the few highly subsidized settlements not withstanding), and a number of small islands (like Bishop Rock). The Marshall Islands do not fit into that category.
i_feel_great 11y ago
Is it all feasible to build groynes around the islands to trap sand, and then, say, use bulldozers to pull the sand inland as it accumulates? Groyne: https://en.wikipedia.org/wiki/Groyne https://en.wikipedia.org/wiki/Groyne
dalke 11y ago
With a surface area of 181 sq. km * 1 meter thick = 181,000,000 cubic meters. I'm seeing numbers like $20/ton for sand and rocks and there's not quite 2 tons of sand / cubic meter, giving $7 billion in materials, or $100K/person or >50x the GDP. Plus transport costs, which I can't even begin to estimate. And that's mostly just to cover the estimated sea level rise since the 1950s. It doesn't handle 3 meter waves from the recent storm events. And of course this doesn't change the decrease in rainfall.

by rdancer 11y ago

jacquesm 11y ago

Build dikes, keep pumping out the water as it seeps back in or rains down. A good chunk of NL is below sea level and that's how they did it (with old school tech like windmills no less, just use enough of them and it will work).

dalke 11y ago
Take a look at the map of the Marshall Islands. Here's a satellite view of Majuro, where the capital is located - https://www.google.com/maps/@7.1298596,171.2318474,28259m/data=!3m1!1e3?hl=en https://www.google.com/maps/@7.1298596,171.2318474,28259m/da... . Like all atolls, it's a very thin circle enclosing a lagoon. By my estimate it's about 100 meters wide, from ocean shore to lagoon shore. As a very rough estimate, 1 meter of dike height needs 3 meters of surface, so 6% of the island will be a dike. The Dutch can do this because their dikes enclose a lot of land. That's not possible here. The Dutch also have good soil and rainfall. The ground of the Marshall Islands is made of porous coral. aaron695 elsewhere in these comments pointed to a NatGeo article at http://news.nationalgeographic.com/2015/02/150213-tuvalu-sopoaga-kench-kiribati-maldives-cyclone-marshall-islands/ http://news.nationalgeographic.com/2015/02/150213-tuvalu-sop... . Towards the bottom is a picture with the caption 'Flooding during king tides is a problem on Fongafale, when water percolating up through the coral matrix laps even at the door of the meteorological office.' Thus, dikes won't prevent salt water from percolating through the coral under the dikes and flooding the other side.
- jacquesm 11y ago
  It looks as if the situation is not one that would benefit from interference by man as it is. The eco-system is rather special and any messing around with it is going to make things worse, not better. Some places on earth are simply not fit for human habitation, this may be one of those. If you wanted to 'go Dutch' on this then it would mean a total transformation of the environment, basically a ring around all of the Marshall Islands anchored to the sea bed. But that would transform the whole thing into a sweetwater archipelago in no time and would likely kill off everything inside it. This is more or less what happened to an inland sea that we had here, it's now a lake and sweet (IJsselmeer).
  - dalke 11y ago
    "Some places on earth are simply not fit for human habitation" The last 3,000 years of human habitation on those islands would suggest that this is not one of those places.
    - jacquesm 11y ago
      It's not the last 3000 years that determine fitness, it's the next 50.
      - dalke 11y ago
        Then why did you not write 'Some places on earth are no longer fit for human habitation'? Because that's clearly true. All of those old strip mines, and Superfund sites, and nuclear test sites, and the region around Chernobyl, and the former fishing towns of the Aral Sea are trivial examples of how sites have been rendered less fit for human habitation. However, that logic of the argument is a bit silly, since it sets aside considering how human agency may be responsible for the removal of that part of the human ecosystem. There really are places which "are simply not fit for human habitation" include the top of Mt. Everest, effectively all of Antarctica (the few highly subsidized settlements not withstanding), and a number of small islands (like Bishop Rock). The Marshall Islands do not fit into that category.

i_feel_great 11y ago

Is it all feasible to build groynes around the islands to trap sand, and then, say, use bulldozers to pull the sand inland as it accumulates? Groyne: https://en.wikipedia.org/wiki/Groyne https://en.wikipedia.org/wiki/Groyne

dalke 11y ago

With a surface area of 181 sq. km * 1 meter thick = 181,000,000 cubic meters. I'm seeing numbers like $20/ton for sand and rocks and there's not quite 2 tons of sand / cubic meter, giving $7 billion in materials, or $100K/person or >50x the GDP. Plus transport costs, which I can't even begin to estimate. And that's mostly just to cover the estimated sea level rise since the 1950s. It doesn't handle 3 meter waves from the recent storm events. And of course this doesn't change the decrease in rainfall.