Strengths

  • Requires minimal space.
  • Provides stability above and below the water level.
  • Stabilises the toe of the slope and protects it against undercutting.
  • The submerged rocks and logs can provide excellent aquatic habitat.
  • Immediate slope stabilisation and protection.
  • Alternatives to structural treatment such as gabions or concrete blocks.

Limitation

  • It is not intended to be used where the integrity of a road or structure is dependent on the crib wall since it is not designed to resist large lateral earth pressures.
  • When used to protect streambanks, live crib walls should not be placed in areas that experience large, lateral earth stresses or mass wasting.
  • A large amount of material and labour is required.
  • Can be costly to construct.

Live crib wall

Application: Bridges, canals, drainage, dykes, embankments, roads, footpaths, wastewater treatment plants

Description: A live crib wall is a three-dimensional structure created from untreated timbers, fill, and live cuttings. Layers of logs are interlocked with long branches protruding out between them. The logs are spiked together and anchored into the bank, with earth fill behind them to create a wall. The cuttings help tie the logs together and extend into the slope. They will sprout and develop a root mass that, in conjunction with the log structure, will armour the stream bank and protect it from erosion. The roots will eventually take over the structural purpose of the timbers. A live crib wall acts as a retaining wall and is effective for reducing erosion and streambank instability, especially on the outer bank of a stream-bend where the strongest currents are, and when reconstructing a streambank where extreme erosion has occurred. It can also be used to reduce the angle of a slope by building a low wall to protect the toe and grade the soil above it back at a gentler grade.

Contribution to climate resilience: Live crib walls prevent erosion, and can be used to reconstruct eroded banks by acting as a retaining wall and developing a root mass that reinforces the banks. By these means they increase the resilience of streambanks to extreme climatic events. Because they are constructed with local labour and materials, they require less energy to produce, are far more sustainable, and can often be constructed in a quicker timeframe than traditional civil engineering works.

Supplementary sources of information:

http://www.ctre.iastate.edu/erosion/manuals/streambank/live_cribwall.pdf

http://riparianhabitatrestoration.ca/575/livecribwalls.htm

https://water.ohiodnr.gov/portals/soilwater/pdf/stream/stfs17.pdf

http://www.ontariostreams.on.ca/PDF/OSRM/Tech15.pdf

http://www.fs.fed.us/t-d/pubs/htmlpubs/htm06232815/longdesc/fig3_68.htm

https://www.ieca.org/photogallery/2013photocontestwinners.asp

This resilience-building measure is sourced from the Water Resource Adaptation Guide (2019) published by the National Council for Sustainable Development at the Ministry of Environment in Cambodia. The full Guide is available to download at URL https://ncsd.moe.gov.kh/sites/default/files/2019-10/Water%20Resources%20Adaptation%20Guide_March%202019_En.pdf