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Offline tony6789

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Man-made islands?
« on: 04/05/2006 14:18:46 »
Would it be possible to make an island? or would it disrupt nature too much?

- Big T
« Last Edit: 09/05/2006 14:17:33 by tony6789 »


 

Offline neilep

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Re: Man-made islands?
« Reply #1 on: 04/05/2006 14:59:06 »
I think there are already many man made islands, they are an engineering marvel..





http://www.hyflux.com/pj_b_isti.html

http://www.cowi.com/cowi/en/menu/services/nature/coastalengineering/manmadeislands/

http://www.answers.com/topic/list-of-artificial-islands

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« Last Edit: 04/05/2006 15:01:35 by neilep »
 

Offline Laith

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Re: Man-made islands?
« Reply #2 on: 04/05/2006 16:41:45 »
yes its been done before like Neil said
most of the man-made islands are being built in Dubai (a city in the United Arab Emirates), these pictures above show one of the "palm islands" and "the world", which are only 2 projects out of at least 8 that belong for just one company competing with 2 more big companies. it's also possible to have a ski resort in the middle of the desert! its been done in Dubai too
if you wanna see more projects check out the company's website www.nakheel.ae there are more pics and trailer videos, and you can buy yourself a really nice villa on the beach or even a whole island if you want :)

Laith
« Last Edit: 04/05/2006 16:49:21 by Laith »
 

Offline neilep

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Re: Man-made islands?
« Reply #3 on: 04/05/2006 17:02:37 »
quote:
Originally posted by Laith

yes its been done before like Neil said
most of the man-made islands are being built in Dubai (a city in the United Arab Emirates), these pictures above show one of the "palm islands" and "the world", which are only 2 projects out of at least 8 that belong for just one company competing with 2 more big companies. it's also possible to have a ski resort in the middle of the desert! its been done in Dubai too
if you wanna see more projects check out the company's website www.nakheel.ae there are more pics and trailer videos, and you can buy yourself a really nice villa on the beach or even a whole island if you want :)

Laith



Cool Laith.

I saw a program on the discovery channel only a few weeks ago about the very islands that I posted above.....incredible...and ...funny you should mention it....also a separate program about the very ski resort you mention....amazing !!

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Offline Laith

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Re: Man-made islands?
« Reply #4 on: 04/05/2006 17:25:40 »
My good friend's dad was the executive director at Nakheel for 4 years, so he used to bring me calendars and always talk about it and stuff, it's pretty exciting, I got the idea that the owners think they can do anything with money (which they have A LOT of) and they did, they hired engineers from all over the world to do whatever they want, like the longest tower in the world or a ski resort in the desert where you can see the dunes while skiing.
Now they are recreating the pyramids, the Eiffel tower,Ibiza, Petra, + all the wonders of the world (in full size) and even Venice!.. The project is called "The Jewel" but i think it's being built by another company 'Imar'.


Laith
« Last Edit: 04/05/2006 17:30:12 by Laith »
 

Offline Laith

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Re: Man-made islands?
« Reply #5 on: 04/05/2006 17:33:42 »
By the way, there's no tax in Dubai, and UK citizens get paid good there, so if you want to go away for a couple of years to make some money and come back, it might be a good place, but if you buy yourself an island you might not have much money left :D

Laith
« Last Edit: 04/05/2006 18:02:47 by Laith »
 

Offline JimBob

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Re: Man-made islands?
« Reply #6 on: 05/05/2006 00:19:42 »
quote:
Originally posted by tony6789

Would it be possible to make an island? or would it disrupt natire too much?

- Big T



Tony,

Even caissons for bridge supports are subject to a high rate of erosion from moving water. It is the reason that extensive measures are taken to protect the islands with boulders and concrete to SLOW the erosion, but none of these measures can make a large difference or are permanent over time. They may last for 100 or more years but geologically this is a very swift moment. Even the islands off of Dubai need such protection. In the early stages of building these islands erosion was not taken into consideration and long-shore currents made the accumulation of dredged sand a very difficult task.


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Offline ukmicky

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Re: Man-made islands?
« Reply #7 on: 05/05/2006 00:52:40 »
Hong kongs international airport is built on a man made island. and looking at wilki there seems to be quite a few http://en.wikipedia.org/wiki/List_of_artificial_islands

Michael
 

Offline JimBob

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Re: Man-made islands?
« Reply #8 on: 06/05/2006 03:25:49 »
TRUE

There are a lot of man made islands. However, this does not mean that they are often stable for 200 or more years. They are not. In Japan, the artificial islands suffer the most damage because of the problems with all engineering fill - liquifaction. Water and sand & silt, even on a base of boulders, are thixsotropic. Thus, when there is no excess energy in the system it is a stable "gel." When the gel is shaken or subject to vibrations, it stops acting like a gel and acts like a liquid. Things on it sink and foundations fail.

Also, as I mentioned above, water erodes any island where the water flows past it, even if it is slow. Water is the most powerful force in nature over time. The Dutch fight to keep their land even all the time. If they didn't, the Netherlands would not be.

The same reasoning applies to New Orleans on the Mississippi River. New Orleans is sinking below seal level because the amount of mud and sand being deposited is not keeping pace with amount of sand and mud being taken away by the curents in the Gulf of Mexico. This has happened in only 250 years. Vinice is the longest lasting man made group of island I know of. Still, 99% of the buildings are mostly less than 1100 years old. And they have been in serious trouble in the last 25-75 years.

Engineered islands are temporary. They will be here for a while and then dissapears IF they are not constantly added to. It is very difficult to pump sand under a building.

Man made islands are possible, but are not permanant.





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Offline neilep

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Re: Man-made islands?
« Reply #9 on: 06/05/2006 03:54:23 »
Presumably man made islands could be permanent with permanent maintenance !

You bring up a very interesting point there Jimmy Boy !..

Does the same erosion apply to the continental land masses too ? They are also essentially islands are they not ?

Will all the continents eventually be eroded away ?

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Offline daveshorts

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Re: Man-made islands?
« Reply #10 on: 06/05/2006 18:14:57 »
If there was no tectonic activity rebuilding them, then yes the continents would eventually errode away. As it is the continents errode into the continental shelves, and then when the continents collide they scrape all the rock up off the seabed and build mountains - repeat until the earth cools.

The other problem with building permenant islands is that you have to build them in shallow water, and these areas tend to be river mouths, so you are building on unconsolidated sediment which is still having the water squeezed out of it, so as this happens it gets smaller and the land sinks.
 

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Re: Man-made islands?
« Reply #11 on: 07/05/2006 00:45:04 »
quote:
Originally posted by daveshorts
If there was no tectonic activity rebuilding them, then yes the continents would eventually errode away. As it is the continents errode into the continental shelves, and then when the continents collide they scrape all the rock up off the seabed and build mountains - repeat until the earth cools.



Land is not only created by mountain building over subduction zones.

Volcanoes can directly create land (through lava flows), or potential super-volcanoes can raise the land above them as they swell up with hot lava.

Land can be created by sediment deposition.  If you have a water flow that contains a substantial amount of sediment, you could in theory place an artificial island strategically in that water flow, and actually see the island grow as sediment is deposited from the water flow.



George
 

Offline JimBob

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Re: Man-made islands?
« Reply #12 on: 07/05/2006 04:19:43 »
I do not think that there is such a thing as a "strategically placed" island. An island in the mouth of a water flow causes the a reduction in the amount of area in which water can flow. Depending on the amount of restricted area, the same amount of water will need to flow through a smaller area, resulting in higher water velosity (and more erosion) especially on the edges of the island and bounding land. Total land mass will go back to the same amount over time as the system seeks equilibrium again.

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Offline ukmicky

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Re: Man-made islands?
« Reply #13 on: 07/05/2006 05:11:17 »
Sediment would collect in areas around the island and over time could increase the total land mass . and rather than flowing faster couldnt the river just flow deeper.

Michael
« Last Edit: 08/05/2006 02:16:43 by ukmicky »
 

Offline daveshorts

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Re: Man-made islands?
« Reply #14 on: 07/05/2006 10:39:33 »
Ok volcanos can produce land, but most of the ones that produce continental rocks (the less dense ones like granite as opposed to things like basalt) are associated with subduction zones, and therefore can be considered part of the scraping process.

Sedimentation can produce more land, but it can't increase the average height of the land which is what is important in the very long term...

Of course whether the continents would errode away before they froze as there would much reduced volcanic CO2 emmisions, no not enough greenhouse effect to keep the planet warm,  is another matter.
 

another_someone

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Re: Man-made islands?
« Reply #15 on: 07/05/2006 11:40:25 »
quote:
Originally posted by JimBob
I do not think that there is such a thing as a "strategically placed" island. An island in the mouth of a water flow causes the a reduction in the amount of area in which water can flow. Depending on the amount of restricted area, the same amount of water will need to flow through a smaller area, resulting in higher water velosity (and more erosion) especially on the edges of the island and bounding land.



Over the full width of the river this is true; but that does not prevent local deposition.

Firstly, the shape of the island can be designed to create turbulence, which will cause sedimentation to occur.

Secondly, if the island is placed in the bend of a river, the flow on the inside and outside of that bend would be different.

It is most likely that you would have some erosion on the upstream end of the island, so you have to beef up the defences at this end, but very probable that you would get sedimentation in the lea of the island.




George
 

another_someone

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Re: Man-made islands?
« Reply #16 on: 07/05/2006 11:51:10 »
quote:
Originally posted by daveshorts
Ok volcanos can produce land, but most of the ones that produce continental rocks (the less dense ones like granite as opposed to things like basalt) are associated with subduction zones, and therefore can be considered part of the scraping process.



This is true, but volcanic rock can be very fertile.  Over time, volcanic rock will weather, and rivers can carry sediment from it can be spread out over a wide area.

quote:

Sedimentation can produce more land, but it can't increase the average height of the land which is what is important in the very long term...



It cannot increase the land level above the current water level.  On the other hand, water levels rise and fall, so sediment that was laid down when water levels were high, can rise above the water as water levels fall.

quote:

Of course whether the continents would errode away before they froze as there would much reduced volcanic CO2 emmisions, no not enough greenhouse effect to keep the planet warm,  is another matter.



Erosion continues to happen on Mars, through the action of wind – but ofcourse, if the Earth was totally covered with ice (as some now believe was the case at some time very early in its history), it might be difficult to describe something as an island, since there would be the absence of liquid water surrounding it.  It might still be possible to argue for the existence of continents, since the absence of sea separating Europe and Siberia does not prevent one being in another continent that the other.



George
« Last Edit: 07/05/2006 11:53:51 by another_someone »
 

Offline JimBob

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Re: Man-made islands?
« Reply #17 on: 09/05/2006 01:18:25 »
I guess I am not getting to the fundamental aspect of the question. I will try to state my point of view more precisely.

It is very simple, really. A geologic system and its sub-systems, be it an estuary with its sand bars, a delta with the river channels, a long-shore current system with barrier islands, or a "simple" volcano can be considered a closed system. As such, a geological system is subject to all the physical laws to which a car engine, a chemical solution, or a galaxy are subject. ALL laws - no exceptions. Entropy is at work in any system.

Any work put into the system, be it the dredging of a harbor or the building of an artificial island, adds energy to the system causing a disruption in the energy budget. So as with all systems with an energy budget, if the budget is disrupted, a geologic system will seek a stable state.  

In all cases of which I am aware, the islands are only temporary unless energy is added to the system continually to keep the island above water. The most famous island I can think of which shows the needs of continual upkeep is Île de la Cité, home of Notre Dame Paris. In Roman times the island was a low-lying area subject to flooding that offered a convenient place to cross the Seine. It was one of three island in the Seine, only two of which remain. When the Merovingian King, Clovis, made his home on the isle, a small wooden breakwater was added on the up-stream side to prevent the frequent flooding. (anecdotal source, but it had to occur some tine) The island has been continually added to since then, and, along with the construction of a stone breakwater surrounding the island, it keeps the surface dry.  The building up of the surface has buried the Roman fortifications that were uncovered this century in front of the church. Breakwater walls are constantly repaired to keep this island above water. If the islands now remaining in the river had not been maintained by man they would have gone the way of the third island.

Energy and work must balance in a large, complex system. As energy is constantly being expended by the river, man must fight the effects continually. It is the same with ANY man-made construction that tries to impede nature's forces. That is the way it is, not how we might want it to be. If geologic process did not follow natural laws, including the three laws of thermodynamics and their mechanical equivalents, geology would not be a science, but voodoo. And I do not have a license for voodoo! [}:)]


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Re: Man-made islands?
« Reply #18 on: 09/05/2006 02:04:10 »
quote:
Originally posted by JimBob
It is very simple, really. A geologic system and its sub-systems, be it an estuary with its sand bars, a delta with the river channels, a long-shore current system with barrier islands, or a "simple" volcano can be considered a closed system. As such, a geological system is subject to all the physical laws to which a car engine, a chemical solution, or a galaxy are subject. ALL laws - no exceptions. Entropy is at work in any system.

Any work put into the system, be it the dredging of a harbor or the building of an artificial island, adds energy to the system causing a disruption in the energy budget. So as with all systems with an energy budget, if the budget is disrupted, a geologic system will seek a stable state.  

In all cases of which I am aware, the islands are only temporary unless energy is added to the system continually to keep the island above water. The most famous island I can think of which shows the needs of continual upkeep is Île de la Cité, home of Notre Dame Paris. In Roman times the island was a low-lying area subject to flooding that offered a convenient place to cross the Seine. It was one of three island in the Seine, only two of which remain. When the Merovingian King, Clovis, made his home on the isle, a small wooden breakwater was added on the up-stream side to prevent the frequent flooding. (anecdotal source, but it had to occur some tine) The island has been continually added to since then, and, along with the construction of a stone breakwater surrounding the island, it keeps the surface dry.  The building up of the surface has buried the Roman fortifications that were uncovered this century in front of the church. Breakwater walls are constantly repaired to keep this island above water. If the islands now remaining in the river had not been maintained by man they would have gone the way of the third island.

Energy and work must balance in a large, complex system. As energy is constantly being expended by the river, man must fight the effects continually. It is the same with ANY man-made construction that tries to impede nature's forces. That is the way it is, not how we might want it to be. If geologic process did not follow natural laws, including the three laws of thermodynamics and their mechanical equivalents, geology would not be a science, but voodoo. And I do not have a license for voodoo! [}:)]



I have no disagreement with the principle, only with the detail.

The argument that, in the absence of positive action to create land (e.g. volcanism, plate tectonics, climate change, etc.) there will be a continual reduction in land area above the water level I would not disagree with.  What I do have a disagreement with is that there will never be, in such a scenario, any new land created.  Rather, I would say, that in such a scenario, any new land created above water level would have to be compensated by the reduction of land elsewhere, so that the total amount of land above water continues to be no greater than it was before.

The other aspect I would disagree with you is that in the absence of any energy input, there would be a reduction of land at all.  Land reduction is caused by factors such as wind and rain, which is driven by energy from the Sun, the orbital energy of the Moon, the rotation of the Earth, and the thermal energy of the Earth.  In the absence of any of these energy sources, the Earth would remain unchanged (and sterile) in perpetuity.



George
« Last Edit: 09/05/2006 02:07:06 by another_someone »
 

Offline JimBob

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Re: Man-made islands?
« Reply #19 on: 09/05/2006 02:28:31 »
I suspect you are speaking of unbounded system. I am arguing that a finite system with intervention from man would necessitate work to keep the man-made part of the system from changing. Yes, if the system were large enough, there COULD be accomidation in a different part of the system. An island and it's immediate surrondings are a small system. The Sun and the resultant air, wind and water generation is a HUGE system.

I think we are discussing apples and whales.


:D


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Re: Man-made islands?
« Reply #20 on: 09/05/2006 02:43:56 »
quote:
Originally posted by JimBob

I suspect you are speaking of unbounded system. I am arguing that a finite system with intervention from man would necessitate work to keep the man-made part of the system from changing. Yes, if the system were large enough, there COULD be accomidation in a different part of the system. An island and it's immediate surrondings are a small system. The Sun and the resultant air, wind and water generation is a HUGE system.



An island will not exist in isolation.

In the general sense, I would agree that no matter what happens, a natural system will constantly be in a state of change, and the only way to avoid change in constant vigilance and intervention; but is does not follow that all change will lead to a reduction of the size of the island.

If the island is in the mouth of a river that carries a large amount of silt, then careful design of the perimeter of the island can cause that silt to be deposited around the island.  As you have said before, this will not do much to increase the size of the island above water level, but it would at least provide a growing defensive barrier around the island.  Ofcourse, this silt is created by the erosion of land upstream, and so there is a compensating system where land is eroded at the upper reaches of the river, and deposited at the mouth of the river, around the artificial island.



George
 

Offline JimBob

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Re: Man-made islands?
« Reply #21 on: 09/05/2006 04:08:30 »
quote:
Originally posted by another_someone

quote:
Originally posted by JimBob

I suspect you are speaking of unbounded system. I am arguing that a finite system with intervention from man would necessitate work to keep the man-made part of the system from changing. Yes, if the system were large enough, there COULD be accomidation in a different part of the system. An island and it's immediate surrondings are a small system. The Sun and the resultant air, wind and water generation is a HUGE system.



An island will not exist in isolation.

In the general sense, I would agree that no matter what happens, a natural system will constantly be in a state of change, and the only way to avoid change in constant vigilance and intervention; but is does not follow that all change will lead to a reduction of the size of the island.

If the island is in the mouth of a river that carries a large amount of silt, then careful design of the perimeter of the island can cause that silt to be deposited around the island.  As you have said before, this will not do much to increase the size of the island above water level, but it would at least provide a growing defensive barrier around the island.  Ofcourse, this silt is created by the erosion of land upstream, and so there is a compensating system where land is eroded at the upper reaches of the river, and deposited at the mouth of the river, around the artificial island.



George




Now, the definition of an island has changed from something above water level to something level with it. My dictionary says an island is a land mass. I believe what you described is called a bar.



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Re: Man-made islands?
« Reply #22 on: 09/05/2006 11:26:38 »
quote:
Originally posted by JimBob
Now, the definition of an island has changed from something above water level to something level with it. My dictionary says an island is a land mass. I believe what you described is called a bar.



No, I think you misunderstand.  I agree that what I was talking about was a bar, but what I was also saying is that the bar could actually be used to protect the island from erosion.



George
 

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Re: Man-made islands?
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