Gabion Boxes for Controlling River Flows Gabion Boxes have been traditionally used on river banks for embankment and levees. Gabion boxes are made up of steel mesh wires, stones are placed within the box. Gabion Boxes are attached together by using steel wires to bind them together. Gabion Boxes are placed in columns and rows and act as an embankment wall. Foundation and slope of the surface on which the gabion wall box is to placed must be carefully designed and constructed. Generally, a geotextile is laid on the bottom of the gabion box to guide the seepage flow. Gabion boxes have also been used in river flow for temporary diversion and for crossing post flash flooding. Gabion Boxes for diversion were analyzed based on the following parameters:
Flows: Flows can be controlled and diverted by gabion walls. If the gabion boxes are placed directly in the river there is a high chance of the boxes being washed away. During high flows, gabion boxes tend to be burst and damage embankment structures. Gabion boxes could alternatively be an easy to construct solution for temporary diversions.
Cost Benefit: Gabion Boxes are cheaper than concrete structures. Gabion wires can be used to make mesh on site or can be brought into the area already prefabricated. Local rocks in the lower Rio Chama cannot be used. Rock would need to be bought, so the cost of the structures would also depend on the hauling distance.
Sediment Flow: Walls made of gabion boxes tend to trap sediments. Sediments, if accumulated in large amounts, can build pressure behind the wall which may cause the wall to collapse. Flushing of sediment directly behind the gabion wall would be very difficult. A different outlet for sediment flow is required which will increase the cost of the overall project.
Durability: Gabion Box walls are at their least durable as a material when they are placed in the water itself. They could be used for embankment and or as a supporting diversion structure and can be used in conjunction with grouting or sheet piles.
Maintenance: Maintenance of this type of structure may be difficult especially if there is a flash flood. Damaged gabion boxes would need to be replaced and might end up damaging the entire purpose of a gabion wall.
Based on this study, gabion boxes are not recommended as they are susceptible to impact during high flows. Gabions tend to burst when there is high flow and they are very difficult to retrofit and bring back to their original form after being damaged. However, they are flexible structures and can be effectively used to support embankments during floods or can be placed in rivers where the flow is low.