Gabions are used in erosion control primarily to

• A. Provide decorative feature
• B. Act as a water filtration device
• C. Stabilize slopes with timber
• D. Absorb wave energy

Answer: (D)

Gabions are rock-filled wire baskets used as armor along banks and shorelines. Their main role in erosion control is to dissipate or absorb wave energy, which lowers the erosive forces acting on the slope behind them. The packed rocks create bulk and roughness that break up the flow, reduce wave height and velocity, and slow down turbulent water as it encounters the structure. The design is also permeable, allowing water to pass through while still trapping sediment and stabilizing the face, which helps prevent scour. They’re not primarily for decoration, and they aren’t meant as the main filtration device. They’re also not about using timber to stabilize a slope; their standout function in erosion control, especially against waves, is energy dissipation.