We have outlined below the recommended methods commonly used in the Broads.
All drawings are intended for guidance only and precise specifications will depend on site conditions and the agreement of the Broads Authority and other consenting bodies.
The cost (low, medium or high) of the various types of stabilisation methods will depend on the size and quantity of moorings. Additionally maintenance requirements and costs will be affected by the quality of the initial work.
Drawings (click green headings) in this guide are for illustrative purposes only.
Do the minimum
Many methods impact on the environment and involve a cost so natural stabilisation should be considered first.
It is also important to look at the cause of erosion to see whether this can be deterred without any need for stabilisation work. For example if livestock on the bank are contributing to erosion, simple fencing might solve the problem.
Signage could also deter the activity causing the erosion. Providing a different location or suitable alternative for a particular activity is another option.
This involves reshaping the bank to provide a more stable slope which will be less prone to erosion. Natural vegetation can establish or the bank can be planted.
- Requires the use of an excavator to profile the bank and subsequent planting.
- Need to ensure planting establishes. May require goose fencing or replanting.
- Potential for trampling by livestock but could be combined with suitable fencing.
- Appropriate for most locations in the Broads with medium and low tidal ranges.
- Beneficial to wildlife once vegetation is established.
- Can help enhance the local landscape character.
- Low material cost, but moderate on site costs from machinery hire and operator time.
A protective toe to the bank allows natural vegetation to establish behind. There are four types considered in this guide: faggots, coir rolls, rock rolls and stone filled gabions.
Faggots and coir (coconut fibre) rolls can be installed manually. Rock rolls and gabions are likely to require machinery. All tend to require staking to secure in place.
- It is important to ensure planting establishes behind.
- Faggots and coir roll have a shorter life than rock rolls and gabions.
- The life of rock rolls and gabions depends on the quality of the mesh.
- Rock rolls and gabions are not suitable in brackish waters as the wire mesh can corrode quickly and only last a few years. You could consider plastic or plastic coated meshing instead of steel wire.
- Faggots and coir rolls are suitable for areas of low tidal range.
- Faggots and coir rolls are beneficial to wildlife once vegetation is established.
- Gabions and rock rolls are more of an engineering solution but do allow vegetation to establish behind them.
- The landscape character impact of bundles is minimal if vegetation establishes well. But gabions could have a high impact as the metal mesh and rocks can be seen.
- Faggots and coir rolls are biodegradable and designed to degrade leaving established vegetation to protect the bank. Stakes may need removal in future.
- In terms of cost, faggots are low, coir rolls are medium and rock rolls and gabions are high.
These methods provide a vertical edge to the bank and retain soil behind them while enabling vegetation to establish. There are three types considered in this guide: alder pole piling, dead willow or hazel spiling and geotextile, which can be pocketed.
All types require back filling and therefore may require heavy posts and ties. All may require work from within the water.
- Fairly low maintenance if installed well.
- Suitable for low or medium tidal
- Will result in a modified bank. Likely to be beneficial to wildlife once vegetation is established especially if finished close to average water levels.
- The impact on landscape character will depend on height of the finish. The nearer it is to the water, the lower the impact. However the potential for navigational hazard has to be considered.
- Medium cost as they do require skills and equipment but cost will depend on availability or proximity of site to suitable materials.
- Geotextile membranes should be installed at or below waterline to allow burrowing animals to access the bank.
Matting may be appropriate for some stabilisation projects but needs to be used in the right way and with care to ensure it does not get caught up in the stern gear of a boat and cause damage.
- Natural fibre matting (jute, coir or hemp) and asphaltic matting provide a protective surface to a shallow slope.
- Natural fibre matting can be installed by hand but asphaltic matting will require machinery due to its weight. Any matting requires robust pinning to secure in place.
- It is important to ensure planting establishes through the material. Matting is low maintenance if planting establishes. If planting does not establish then relaying and re-pinning of matting is likely to be required.
- Matting will need monitoring and failed fixings must be replaced promptly to prevent navigation hazards.
- Natural fibre matting is suitable for low to medium tidal ranges. Asphaltic is suitable for most locations although as it is the most robust type of matting, it may be excessive in low tidal range but more appropriate in areas of wave action.
- Vegetation grows through the matting which is beneficial to wildlife once it is established.
- There is minimal landscape character impact if vegetation establishes well and it could help improve the character of the area.
- Jute matting is biodegradable and designed to degrade leaving established vegetation to protect the bank. Stakes may need removal in future.
- Cost will depend on scale although jute is a medium cost and asphaltic is a high cost.