Timber revetment

Timber revetment (also known as log revetment) involves the placement of native hardwood timber on a riverbank with the objective of preventing bank erosion. Timber revetment typically extends into the bed of the river to deal with scour of the bed and is connected onto the bank with either timber piles or cables that are anchored at the top of the bank. A gravel filter layer or filter fabric can be placed under the timber to prevent flow permeating and eroding the bank material behind.

This is a combined vegetation management and physical intervention approach. The engineered structure is needed to protect the toe of the bank by increasing its strength. This stops the retreat of the upper bank so that vegetation can establish. This strategy should be focused on vegetation establishment to achieve the objective, eventually making the engineered structure redundant. Compared to rock armouring, timber revetments take a longer time to fully establish bank protection. As such, this management intervention is often undertaken at sites with lower risks than those selected for rock armouring.

Potential benefits from this intervention:

• Allows for rapid stabilisation of bank and associated reduction in sediment inputs.
• Typically involves less design and maintenance requirements compared to other bank erosion management options.
• Encourages deposition of sediments, organic matter, seed propagules and establishment of vegetation.
• Utilises biodegradable materials.

Potential negative implications from this intervention:

• High disturbance during construction including vegetation removal and heavy machinery within rivers.
• It is often difficult to source a suitable and sustainable supply of timber.
• The effectiveness of this technique is dependent upon the works forming a solid barrier to provide protection of the bank (which will be dependent on the size, arrangement, and limits on the likely amount of timber available).

Intervention considerations:

• Seek appropriate specialist advice and check legal obligations (e.g. permits).
• The emphasis of the timber revetment works should be to protect the bank toe.
• Existing in-channel large woody debris should generally not be realigned against the bank face. This timber is providing an important ecological and hydraulic function in its current position.
• The timber revetment works must address the process of erosion.
• Determine if a suitable timber source can be found to form a solid revetment or protection of the bank.
• The disturbance and cost associated with timber revetment should be justified.
• Determine if other infrastructure is threatened and whether it could more efficiently be moved rather than protected.
• Consider the design life required from the structural component and whether vegetation can establish adequately in this timeframe.
• Safety of employees including seasonal exposures (e.g. heat) and high risk areas (e.g. crocodile presence in waterways).

Additional information

Department of Sustainability and Environment (DSE). 2007. Technical Guidelines for Waterway Management, Department of Sustainability and Environment, Victoria.

Rutherfurd, I.D., Jerie, K. and Marsh, N. 2000. A Rehabilitation Manual for Australian Streams, Volumes 1 and 2. CRC for Catchment Hydrology and LWRRDC. Canberra.

Last updated: 22 June 2022