How to control river erosion

Gabion river and stream erosion benfits are…

  • Rapid construction and immediate use
  • Dissipate flowing water energy
  • Semi flexible building blocks for channel stabilisation.
  • Have an irregular surface to diffuse and reduce river bank scouring
  • Gabions are able to use smaller rock for river bank protection, when larger rip rap is unavailable
  • Much cheaper, more flexible and greener than concrete
  • Can be installed in wet or dry conditions
  • Free draining with no hydrostatic pressure issues
river bank erosion

How gabion erosion cages work

Gabion baskets placed on the outside of the river bend to prevent river bank erosion during floods. Geotech filter fabric is placed behind and underneath the gabion baskets to prevent the movement of soil material through the gabions.

gabion erosion cages

Design for expected maximum scour depth

The base layer of gabions must be placed below the expected maximum scour depth, or the toe can be protected with gabion mattresses

Design for peak flood events

Gabion flood projection must be designed to cope with peak river flows often referred to to as 1 in 50yr, or 1 in 100yr floods. This often requires larger gabion walls and foundations, than envisaged. An engineer is able to examine historical weather data, and design for the expected flood events over the life time of the wall.

gabbion flood control

Gabions are ready for immediate use

Machine and hand filling gabions, is often possible without having to divert the river with a bund

Temporary bund

Building a temporary bund, to often done, to speed up construction

Scour protection

Placing large rocks, at the base of the gabion, provides added erosion protection. These rocks may need to be inspected and replaced after flood events

gabion scour protection

Purpose built lifting cradle

This allows gabions to be pre filled and lowered into place for immediate protection

prefilled gabion

Gabions can flex to ground movement

Gabions can flex to ground movement, dissipate energy from flowing water, and drain freely. Their strength and effectiveness may increase with time, as silt and vegetation fill the voids, and reinforce the structure.

Uses the strongest wire mesh

In locations where high flood water velocities are expected, carrying woody debris and gravels in suspension, the stronger 4ga or 5ga  welded gabions are the preferred choice, to resist damage to the gabion structures during floods.

Rock grading

The rock grading for erosion control gabions must be .between 3″ to 8″ sizing
Non durable fine material is not acceptable

Bad gabion placement
good gabion design