Gabions used in coastal or river engineering are best described as which of the following?

Gabions used in coastal or river engineering are best described as which of the following?

• A. A volcanic basalt block wall
• B. A hollow plastic tube system
• C. Steel mesh cages filled with small rocks
• D. A sand-filled burlap bag arrangement

Answer: (C)

Gabions in coastal or river engineering are steel mesh cages that are filled with rocks. This combination creates a permeable, flexible barrier that can conform to irregular ground, dissipate wave and flow energy, and trap sediments while still allowing drainage. The weight and interlocking nature of the rock-filled cages stabilize slopes and riverbanks, and they can be stacked to form revetments or retaining structures that resist movement better than loose rock alone. The cages are typically made from galvanized or PVC-coated wire to withstand harsh environments and are filled with locally available stone. Other described options don’t match how gabions function. A rigid wall made of basalt blocks is a solid block construction, not a mesh-filled cage. A hollow plastic tube system describes a different modular barrier, and sand-filled burlap bags refer to sandbags, which are a distinct erosion-control method.

Gabions in coastal or river engineering are steel mesh cages that are filled with rocks. This combination creates a permeable, flexible barrier that can conform to irregular ground, dissipate wave and flow energy, and trap sediments while still allowing drainage. The weight and interlocking nature of the rock-filled cages stabilize slopes and riverbanks, and they can be stacked to form revetments or retaining structures that resist movement better than loose rock alone. The cages are typically made from galvanized or PVC-coated wire to withstand harsh environments and are filled with locally available stone.

Other described options don’t match how gabions function. A rigid wall made of basalt blocks is a solid block construction, not a mesh-filled cage. A hollow plastic tube system describes a different modular barrier, and sand-filled burlap bags refer to sandbags, which are a distinct erosion-control method.