Mankind has actually been creating artificial islands for thousands of years. Breakwalls, ocean pylons, artificial reefs, and offshore drilling platforms are all examples of kinds of artificial islands. Dozens of artificial islands already exist in many parts of the world, particularly in ocean-locked countries like Japan.
This article concerns itself with the modern trend of creating artificial islands of truly colossal scale--large enough to be considered able to support permanent populations of hundreds or more.
OFFSHORE ARTIFICIAL ISLAND
Tech Level: 10
An offshore artificial island is any landmass constructed in the water immediately off shore of an established coastline, in the relatively shallow depths near land.
A number of large offshore island projects have been completed or begun construction within the last twenty years or so. They include the Kansai and Kobe airports in Japan, and the Palm Islands and World Island projects in Dubai. Some of these artificial islands were designed to add on or give more room to crowded urban coastal areas, as was the case with the Kansai and Kobe airports. Others are meant as showcase tourist attractions, such as with the Dubai projects. Given the commercial success of all of these islands, we can expect to only see more such undertakings in the future.
The process of creating one of these immense structures is much more complicated than just dumping a bunch of earth into the water until you get a mound that breaks above the surface. Environmental impact studies have to be carried out in length, to ensure that the new islands will not adversely affect the local ecosystem as a whole. Proper underwater sediment is also required, and if not present the whole project could be scuppered. Both New Orleans and Venice show the dangers of building on improper sediment--both cities are very slowly sinking because they were built on spongy sediment, at a rate of a few inches a century. It makes no sense to invest billions of dollars in an island that will only start sinking in a few decades.
The prospect of global warming and rising ocean levels also has to be taken into account for the same reason. The islands off Dubai are being built in anticipation of a possible rise in ocean water levels by as much as six inches.
Like with supports for bridges, pylons are sunk into the bedrock underwater to offer added stability and support. A cap of coarse rock follows to function as a firm foundation, followed later by millions to tons of sand and crushed rock form up the actual body of the islands.
The actual configuration of an island will depend on its purpose. The Kobe and Kansai islands had to be shaped to accommodate long runways. The Dubai islands, meant primarily as tourist attractions, were given more emphasis on aesthetic visuals. However, one requirement for all artificial landmasses in the ocean is a breakwall, to help prevent erosion of the multi-billion dollar investment.
As an example of the kind of economic advantage an artificial island can provide, the creation of the two palm-shaped artificial islands will increase Dubai's usable shoreline by 120 km. Situated on the Palms will be over 60 luxury hotels, 5000 residential villas, 5000 apartments, marinas, water theme parks, restaurants, shopping malls, sports facilities, health spas, cinemas and numerous dive sites.
However, some critics decry the negative environmental impact of the islands on the local marine ecosystem. It is too soon yet to determine the islandsí true long range affect, and studies are ongoing.
DEEP OCEAN ARTIFICIAL ISLANDS
Tech Level: 12
So far, techniques for building artificial islands are feasible only in water depths that are only about fifteen meters or less. Techniques for creating deep ocean manmade islands are being investigated, and may become a reality in the coming decades.
For depths up to about 30 meters, artificial islands could be constructed on groups of large concrete and steel pylons driven deep into he ocean floor for stability. These pylons would probably be very wide (up to 10 meters or more across) and assembled slowly multi-ton slice by multi-ton slice by deep ocean barges.
The surface platform of the island would probably not be one huge, unified construction. Rather, it would be sectionalized with flexible joints between the individual platforms, to better accommodate, withstand, and even dampen the effects of waves hitting it and rolling under it. Like with modern skyscrapers and wind, an artificial island would have to have some flexibility and leeway against the forces constantly pushing on it in order to give it a greater overall stability. From above it could be made to look as it were all one conglomerated surface, but below the main occupied levels the illusion can be dispensed with.
Each platform section would also be composed of multiple levels, in order to fully utilize every cubic inch of the structure. Projecting from the underside would be large bottom-heavy pylons similar to whatís used on oil rigs to provide additional stability and buoyancy. The outer platform sections may also be further anchored into the sea floor with cables.
The island would be large enough and would have enough wave-dampening techniques built into it that it would feel very stable most of the time. Only during heavy storms and very rough seas would residents begin feeling the roll and pitch of the waves under them.
A series of breakwater floats anchored to the seafloor around the island, taking the shapes of long, broad horizontal pipes, may also be present with these constructs.
In the very deep ocean off the continental shelves, the cost of the pylon scheme above becomes prohibitive. Instead, proposals for floating deep-ocean islands have abounded. Similar to the platform sections described above, except in this case all of them would be made self-buoyant and anchored individually to the ocean floor by cables. Platforms would slowly be added and networked together until an island-sized surface area eventually emerges.
Deep-ocean artificial islands can serve a number of purposes, not the least of which is operating as both a mid-ocean port and air support facility, to accommodate transoceanic ships and aircraft alike. They can also be used to support a number of ocean-based industries, such as deep water fishing, mining, oil drilling, and more. Their uses as military bases and as space launch platforms have also been discussed.
Under an artificial island is also an ideal place to put tidal turbines to help generate electricity for the structure. Its floating breakwall may also be good places to place wave-pitch generators for the same purpose.
Very large deep-ocean artificial islands (those able to support 10,000 permanent residents or more, sometimes called ocean cities or ocean colonies) would probably closely resemble arcologies in form and function. Refer to the article of arcologies for further information.
http://www.esa.int/esaEO/SEMKRXZO4HD_index_0.htmlhttp://www.planetark.com/dailynewsstory.cfm/newsid/34922/newsDate/07-Feb-2006/story.htm http://www.oceansatlas.org/unatlas/about/oceansofthefuture/background/seemore3.html http://2100.org/w_oceancitieslegal.html
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