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Gabions

Updated on November 14, 2011

Gabion Baskets...Not Just for Forts!

Gabion Baskets for Soil Stabilization, Dams, or Beautification. Gabion walls can be an inexpensive alternative to masonry retaining walls, will last longer, and perform better. Use gabions for stabilizing stream or river beds, or to keep soil from washing away in gullies. Gabions can actually assist in soil accumulation, rebuilding land that has seen significant degradation due to erosion.

Gabion Dam
Gabion Dam

Chicken Wire Never Had It So Good

Soil Stabilization at its finest!

Ever thought much about gabions? Well, if you found this post it must be either because you were intentionally searching for information on gabions or else you got here by accident. Most people don't really know what gabions are...until they see a picture of one and realize that they have seen them along an interstate or highway, used as a revetment of some type. If you had ever heard of gabions, you might have learned in history class that they were used by engineers or sappers to attack forts. Modern-day gabions have come a long way, and are used in many projects for soil stabilization, from retaining walls to dams.

Gabions are wire baskets, originally with a chicken-wire weave and measure from small 1x1 foot cubes up to larger sizes. The wire baskets are filled with rock or concrete rubble and provide a method of keeping the rocks in place without the use of concrete.

Personally, I think gabions are the most cost-effective means of soil stabilization and revetment that I know of. Gabions are much cheaper (and greener) to use than concrete, and are actually superior to concrete as a retaining wall, check dam, dam, or floodwall in many instances.

One of the unique properties of gabions is that they can use rock or rubble fill from a local supplier. If a gabion is made well, using either galvanized wire or stainless steel wire, it can last from 20-40 years (or longer). You may have noticed that some applications of concrete in retaining walls or floodwalls fail due to freeze-thaw cycles where ice can penetrate concrete and break it apart causing failure in epic proportions.

Gabions also offer superior erosion prevention over concrete retaining walls. Perhaps you've seen where runoff scoured under concrete leaving a huge gap or hole? Gabions are able to flex and actually sink down into the earth providing additional resistance to scour. Actually some applications of concrete can encourage scour if not designed properly (think of culvert drains).

My favorite use of gabions is in the construction of small dams for irrigation. Gabion dams designed as wier-type where the water flows over the top of the entire structure offer superior control and anti-erosion capability and amazing cost-savings over concrete. You may have noticed that water flowing over the top of a dam can cause catastrophic failure in soil dams, but not so in gabion dams. A wier-type gabion dam can allow flash flooding to actually flow over the top of the dam without failure...you wouldn't want to try that with a soil dam!

Whatever your application of gabions (and there are many), you'll find that gabions are extremely cost effective over concrete, have a more natural appeal, are greener than concrete, and offer flexibility that concrete just doesn't offer.

Gabion

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Gabion Manufacture and Use in Afghanistan - You Don't Need a Big Machine To Make Gabions

While on deployment to Afghanistan with the Army, we implemented many projects related to rebuilding agriculture. Agricultural projects were welcomed with open arms. One of the problems facing the Afghans is severe erosion due to rapid flash flooding caused by local deforestation. Flash floods were becoming bigger and scouring wide swaths of farmland away, causing permanent damage to cropland that had been in use for thousands of years. Some locations used masonry stone walls to attempt to protect the land, but these structures would last only one or two years because the extreme freeze-thaw cycle would disintegrate the mortar and the next flood would simply wash the stones downstream. Gabions were the answer, because the galvanized steel strands can keep the stones in place for 15-20 years, allowing enough time for the landscape to regenerate and become strong enough to withstand future floods. While the gabions do not keep the floodwaters out of the cropland, it keeps the scouring force of the ram-like flash flood away from the fertile soil. While much work remains to assist the Afghans in replanting previously forested areas, the quick short-term solution to keep the fields intact and in use is gabion baskets.

Our gabion project resulted in the manufacture of 50,000 gabion baskets. No special machines were needed, and the contractor employed local labor at many different Qalats in Orgun-E Valley. These gabion baskets were later used in making flood protection walls and small dams for irrigation.

How To Assemble - How To Put Rocks In Your Basket

Assembling gabions is fairly straightforward, but has to be done properly so that the internal structure of the build is maintained. After all, you wouldn't want several tons of rocks to come crashing down because you got a bit sloppy with your work, would you? It is important to note that as the gabion baskets are filled to the 1/3 level, internal bracing and wiring is needed in order to keep the face of the gabion basket from bulging out. Likewise, the internal bracing is added at the 2/3 level After the gabion edges and top are finally wired together, then the gabions can be assembled in a chain, with the galvanized steel wire bound at each edge where the baskets join together. A retaining wall built of gabions can be quite formidable and strong when assembled correctly.

Intalling Gabions

This video shows some gentlemen hard at work installing and filling the gabions. Notice that the rocks are faced by hand to present a neat appearance, with the rest of the rubble being a random fill. In order for gabion baskets to function properly, the rocks placed in the basket must be bigger than the mesh holes so that rocks do not slip out later.

HESCO - For Flood Control & Military Force Protection

HESCO brand barriers are a type of gabion that has a geotextile fabric already built in. These barriers can be filled with soil and stacked.

Poor Land Management
Poor Land Management

Land Reclamation

What To Do When Your Gullies Have Gullies

Land overuse by farming, grazing, flash floods, or timber clear cutting can result in severe damage to land and eventually render the land unusable and useless. There have even been entire communities that were forced to relocate due to poor land management practices and runaway erosion that ate huge chasms into once arable cropland. While your own situation might not be as severe, there are several things you can do to ensure that your yard, garden, or farm doesn't become the next Grand Canyon.

Take a hard look at your entire property from the top (highest elevation) to the bottom (lowest elevation), especially during a hard rain. You will notice certain places where the water will gather into rivulets and small streams, causing erosional forces that can threaten to wash away your topsoil. What needs to be done is to slow the water down, and cause it to soak into the earth. Look for places that can be dammed up with small check dams. The check dams can be small porous dams that will slow the water down, allowing the water to soak into the soil, without causing permanent lakes to form.

Gabion check dams are perfect for the job of slowing water down. Gabions hold the rocks together and keep them from washing away with the force of water while slowing the force of the water. If you create multiple check dams on a single rivulet or stream you will be able to slow the water down enough to encourage sedimentation build up. Effectively, you encourage the soil to deposit along the stream and reverse the erosional effects of water. The check dams will encourage natural vegetation to grow, further stabilizing the soil, and also rehabilitate the land.

Gabions offer unique properties to reverse the effects of soil erosion, and encourage land reclamation.

Minanga River Intake and Channel
Minanga River Intake and Channel

Gabion Dams

When you think of dams, you probably envision this huge monolithic structure like the Hoover Dam, right? Or perhaps you thought about your uncle's cattle tank made by a dozer pushing up a levee of dirt, making a lake for our four-footed friends to take a nice mud bath in. However if you were to think about catastrophic failure of a small dam, an earthen dam is almost always involved. Wouldn't it be nice to have a small dam that is not subject to failure from flooding or weakening from animals? Gabions answer this call, providing a cost-efficient alternative to concrete that is more resilient than concrete, and much more stable and erosion-resistant than earthen dams.

Gabion dams can be made as check dams, with no purpose other than retaining runoff for short periods, just long enough to slow water down the slope, encourage sedimentation, and keep erosion at bay. However if you are needing something of a more permanent nature then the gabion dams are slightly modified with the use of a geotextile fabric. In all cases, you usually use a geotextile fabric when making either a check dam or a water-retaining dam any place the soil makes contact with the rocks. This keeps the water from pumping soil between the cracks of the rocks. Use geotextile also on the upstream side of dam and choose a clay soil to pack on the upstream side of the dam. In effect, you are creating a water impervious dam with a backbone of rock and steel.

Dam Failure

"...if you were to think about catastrophic failure of a small dam, an earthen dam is almost always involved."

Reader Feedback - Let me hear from you!

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    • profile image

      skiphirepricessurrey 4 years ago

      I have been building these walls for years. their construction is quite simple but the stone can be quite expensive. One major advantage is that if you are using them for a rataining wall, walls do allow water to pass though. this a major advantage na dprevents the need for weep holes.

    • Countryluthier profile image

      E L Seaton 5 years ago from Virginia

      Really nicely done lens. Thanks for tips on stabilizing the soil.

    • April Wier profile image

      April Wier 5 years ago

      That was very interesting. I've seen these types of dams and actually wondered what they were called. Now I know.

    • KimGiancaterino profile image

      KimGiancaterino 5 years ago

      I've seen these structures around our area, but didn't know what they were called. Thanks for the explanation.