We Call Them Gabions and They Are Astonishingly Successful

Well Mankind, bless it’s little lecherous heart, has been building walls as long as it developed the mental acuity to balance one rock on another. Then not much happened for a thousand years or so. Those who became a little more skilled we chose to call masons and then they formed a society, built a temple and wall-building fell as dead of creative thought as most better known religious societies.

As a side comment, hedgehogs have existed for fifteen million years and never formed a society or built a temple. Lovely little critters, hedgehogs.

So, what’s that got to do with gabions?

Not much, but stay with me, I thought it was kind of a cool lead-in.

Gabions are simply another way to hold a bunch of rocks together without worrying about a skill-set. Just open up the stainless-steel cage, fill it with rubble and close it up again. One thing to remember, don’t fill them and then try to move ‘em around. It’s a build-in-place skill-set.

Why are you bothering me with all this?

Because everywhere that water laps up against a shoreline, beaches are disappearing and most of us like beaches—sand between the toes, sunburns and all that other great stuff. Gabions can build beaches where they’re on the endangered list. Folks also pay exorbitant sums to reside on or near the edge of water, which is how Florida realtors palmed off all that swampland that is now Mar-a-Lago and got rich doing it in the 1930s.

But recently homeowners on lakes and seashores watched as their homes slowly tipped into the water from ever more severe storms, rising tides and wave erosion. Not a pretty sight to watch a frantic millionaire in the process of becoming frantic. In many cases, Gabions can solve that far better than sea-walls and breakwaters.

The photo doesn’t even show a beach

I know, but it gives you a good idea of what a gabion looks like. And when they’re used to restore beaches they’re mostly underwater, a difficult place for photos. Contractors and engineers make the mistake of building retaining walls at the shore and the solid walls they usually erect get both battered by waves and undermined at their base by receding water. It’s called undertow and—quite remarkably—it tows stuff under.

The better approach is to rebuild what was once there; usually one or two hundred yards of protective beach. It’s still out there, waiting to be restored.

So, it all begins by, after determining how far the beach once extended, inserting a line of gabions there, probably 4-10 feet below the waterline. Inserting sounds easy and it is, in theory, but you know how theories tend to be complicated. This one is no different and there’s some preparatory work to be done, but you probably knew there would be: an anchored barge works well, with an estimated supply of large-size gravel (or rocks) common to the area and a mechanized hydraulic arm with a claw-bucket for filling the gabions.

All set now? Don’t forget a couple of divers in wet-suits to position the gabions, close over the tops when they’re full and set another row.

Repeat until your gabion row is a couple feet above waterline.

Then wait—probably a year or two

Tides and waves will surge over your gabion ‘wall,’ bringing sand on the inflow and dumping it as they retreat. Incoming waves ‘break’ against gabions rather than pound, which is why they remain in place. Receding water is slowed by their porous construction, leaving much of the sand behind that would otherwise be removed by undertow.

Send the barge crew and divers home, they’re too expensive to merely observe.

Depending on erosion at the shoreline, you may need a wall there as well

You might have a bluff to repair and ordinary walls don’t work very well for that because they hold back the natural flow of the soil they retain. The forces building behind a solid wall are enormous, which is why the wall at Hoover Dam is curved inward against those forces. The higher the retaining wall you require, the greater the forces building.

Interestingly (and supportive of my argument, which always pleases me) gabion walls are not subject to those forces, as they ‘bleed’ groundwater through a porous construction. Nearly vertical gabion walls of 40, 50 or 60 feet are not uncommon because (guess what?) they’re enormously heavy. Visually, any kind of climbing or descending vegetation loves a gabion wall.

So, there you have it

The seas are rising and destructive storms more common. Those are facts relevant to the impact mankind has made upon our natural environment. Those facts are aggravated by where we choose to live. We’re learning that a room with a view and watching the sun go down over water has a price.

In many cases, as I propose, there are solutions as well.