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Weekly “What is it?”: Gabions

A dense shoreline of native wetland vegetation is the best way to prevent erosion along a water body. Photo credit: Carrie Stevenson, UF IFAS Extension

I became familiar with the term “gabion” 20 years ago when I worked for the Florida Department of Environmental Protection, when helping people manage ongoing erosion problems was an almost-daily task. Northwest Florida’s soils are often full of highly erodible sand. When coupled with our frequent rains, it can be difficult to keep soil in place. While there are many temporary measures used to prevent erosion—like mulch, hay bales, silt fences, and riprap—the only natural and mostly permanent way to keep soil intact is through vegetation. The roots of grasses, shrubs, and trees help to bind soil in one place, preventing erosion and sometimes even building up more land. Living shorelines—vegetated marshes along waterways—are an excellent solution for waterfront property, but deserve their very own blog post.

Beavers have hollowed out this spit of land adjacent to a lake over the years, so a gabion retaining wall prevents washout and further damage. Photo credit: Carrie Stevenson, UF IFAS Extension

Gabions, however, are a reasonable semi-permanent solution for a heavily eroded or sloping area that needs a quicker fix and a little more engineering. Often seen adjacent to bridges and on steep slopes, these “hardscapes” use bundles of rock to hold in the soil. Gabions (from the Italian term for “cage”) are a very old (use dates back to the ancient Egyptians) engineering technique for building walls, dams, or bridges. A common early use was along rivers as a shoreline stabilizer or flood attenuator. They have been popular with military personnel as fortification walls over the years, as they are relatively quick and easy to build using local materials. To form a gabion, wire cages are filled with rocks (and sometimes soil) to make large rectangular blocks. The blocks are then stacked next to and atop one another like Legos to form a more durable retaining wall. Since these are not solid barriers, water can pass through them and vegetation can even grow on them, allowing the gabions to work alongside a more natural system.

The gabion wall at this building supports an earthen berm and walkway, integrating the whole facility into the surrounding landscape.

Particularly in areas with a lot of available native rock, gabions are used as fences, pilings, walls, and in other interesting decorative and structural architectural applications. Gabions are simple enough that a homeowner can install them, although for larger erosion control projects I would recommend hiring a contractor or landscape architect. If you have an ongoing erosion problem on your property that nothing else seems to correct, you may want to consider using a gabion. If the property is on or near saltwater, however, you will want to use a marine grade caging material to avoid rust from salt exposure.