A method to deter erosion? (Without use of nuclear warheads please!)

[Theophrastus]

Unable to find any proper justification to place this in any other category, I suppose this shall suffice, however I have a question. I'm thinking, for an upcoming science fair, to do a project regarding a possible method to stop shoreline erosion. I've delved into the basic concepts, chemical and physical weathering, transportation erosion, on the general topic, however, I find myself lacking ideas. Asked my teacher for help, which I gained little of, though he gave the hint of looking up how the direction of shoreline currents play an active role. I searched on google, but found little. Any ideas perhaps on the subject. Information is important, however, might anyone also have any ideas about how to prevent erosion, aside from the ideas of building giant concrete walls, and using nuclear warheads, to blow up the moon, so as to deter that actions of the tides. Any thoughts and ideas are most appreciated,

 

-Theo

[Mokele]

The key to preventing shoreline erosion is well-known - keep the reefs and shore ecosystems intact. Unfortunately, this will never happen, because it means morons can't ride their jet skis.

[stereologist]

The stability of the sediments is dependent on a wide range of factors from currents, to storms, to vegetation binding the soils, to land runoff to whatever. One of the issues that is dismissed by the public is that shoreline is a line in flux. The material is in motion and people that build houses on this unstable terrain do not want to hear that.

[Theophrastus]

After performing a variety of research, my plan is to add trees and vegetation, to stabilize the top, and subsoil, both above and below the water. They will also act as a wind break, against wind- induced erosion, and underwater, shall weaken the strength of waves. I was also thinking of building a floating wall of tidal generators, to decrease the speed of waves. Any critique of the above, would be helpful. I'm also thinking of introducing an organic buffer, however, I'm careful to find one that does not disturb the existing ecosystem. For example excess of phosphates (and nitrates) can result in rapid algal blooms, which can lead to hypoxia of the environment. Any ideas?

[Mokele]

Trees won't work on sand - too loose and nutrient poor. There are a variety of beach grasses that work just as well.

 

As for wave breaking, if you put down oddly shaped concrete structures, in tropical and subtropical areas they'll rapidly be colonized by coral, forming a self-repairing system to protect against waves.

[CaptainPanic]

It all depends on the type of soil at and near the coast.

 

Since almost the entire coastal region of the Netherlands is actually below sea level, but we do have sand dunes (natural) to protect us... I suggest you read up on that. The Dutch have a long history fighting erosion by the sea.

 

The next is specific about the Netherlands, and possibly about other countries (but I'm not exactly sure which parts apply, and which don't).

 

The strategies are:

1. Adapting the currents such that the sea deposits sand rather than takes it away. This can be sub-divided into several types of adaptations, but (almost?) all include the construction of something.

2. Plant sturdy types of grass in the dunes so the sand does not blow away.

3. If you can't manipulate the sea: take a giant ship, suck up the sand, and dump it on or near the beach with a huge slurry-jet. I believe it's called "Rainbowing", but the wikipedia text is rather short.

4. You can rebuild the beach with other tools and sand from another location.

5. You can build a stone wall, or concrete, or anything hard.

6. You can close off the sea, and create a sea/lake with negligible current.

7. (something I forgot?)

 

I agree with your teacher that the shoreline currents are massively important. At the Dutch coast, the currents are mostly parallel to the beach. Therefore, the most common defense is a narrow stone construction (like a breakwater) which is meant to slow down the current nearest to the beach. I think I found that this type of structure is called a "Groyne". Anyway, the pictures on the groyne-wikipedia site resemble the ones I mean. At high tide it's completely submerged, and at low tide it's very visible.

 

Our new strategy is to allow the sea to play with the sand. As long as it deposits as much as it takes. Sea currents can easily reach 2-3 m/s, so you can imagine that this is able to move quite a bit of sand.

 

Other keywords related to the topic are in Dutch... I've never found so many Dutch wikipedia sites which have no links to other languages as while searching on this topic.

[Theophrastus]

For my project, I require to actually use grass, so which genuses, would be the most adequate, and secondly, if not, would a network of tight connected sieves, be satisfactory in mimiking the roots' natural capacity to prevent erosion?

[Moontanman]

Post *3 by stereo is the key here, I live on the coast, I've seen the battle against shore line erosion most of my life. The shore is not stable, the beach moves as do the inlets and other structures. Trying to stop it in one place only makes it worse in others and eventually the place you stop it becomes separated from the whole and is washed away in a catastrophic storm. You can pump in more sand and that helps but things like groynes, jetties, and rock and concrete barriers only move the erosion and around and do not really help in the long term.

[Theophrastus]

Two things:

 

1) Does anyone know of any commonly found aquatic plants which can be used to stabilize the sea bed, where undercurrents are prominent?

 

2) In regards to moontanman's post, I'm well aware that retaining walls and dams, often increase erosion in areas along the edges, so its really a matter of redistribution of current, rather than elimination of the problem. (However, if you think about it, groynes can also be seen as almost isolating an area, blocking any redirected currents, thus if combined with another technique, will be beneficial(Correct me if I'm wrong)) That's why I want to address the problem by stabilizing the topsoil layer, while at the same time, improving soil quality. If the effect isn't great enough, I may have to resort to other means however. For their simplicity, in such a situation, I'ld probably use gabions.

[Mokele]

Common sea-grass, aka turtle grass, works well. Thalassia genus.

[Theophrastus]

Oh, one other thing I forgot to mention, given I began relatively late, time is an issue, however I have altogether, about 2 and a half weeks, would this be adequate for the species in question?

[Mokele]

If you can transplant it from another area, yes. It's very hardy stuff.

[CaptainPanic]

For my project, I require to actually use grass, so which genuses, would be the most adequate, and secondly, if not, would a network of tight connected sieves, be satisfactory in mimiking the roots' natural capacity to prevent erosion?

 

Grass (specifically: reed) can be used in 2 ways:

 

1. Grass can hold soil together with its roots.

2. You can use grass / reed inside a sea protection: the same as the metal in reinforced concrete. While the reed is dead, it will still improve strength. I think this will only work with clay as "building material" though - but I'm no expert. If the whole thing is kept wet constantly, then the grass/reed will not rot for hundreds of years.

Edited May 4, 2009 by CaptainPanic

[Theophrastus]

Hey guys, to conclude this thread, assignment complete. I was rather simple with my model, grass, and modeled wetland- type ecosystem, along with gabions, simply to initially stabilize the shoreline, while the longer process of rebuilding ecosystems can begin. In my report I was more thorough, mentioning weathering (chemical and physical), acid rain (chemical weathering), nitrogen fixation (in a reference to general erosion), real situations in which human activity or unstable geological matter has caused excess erosion, why various structures are incapable of long- term erosion protection, etc.. Anyway, thanks for all the help with links and the like: it was most appreciated:-). I don't really know what is to be done with this thread. Perhaps it can be converted to serve further related purpose?

 

ps: It's like recycling!