Pillar 3: On-Ground Interventions – Riparian Rehabilitation

Quick Tips:

  • Prior to works it is important to assess the current condition of the riparian zone.
  • All riparian management activities must be undertaken in cooperation with riparian landowners.
  • Priority needs to be given to protecting healthy riparian vegetation by preventing clearing, stock and vehicle access.
  • Bank stabilisation should be a priority before rehabilitation works are undertaken.
  • Rehabilitation of degraded riparian habitat may be achievable at low cost by fencing and allowing natural revegetation.
  • Active rehabilitation will involve reseeding or planting of tubestock, together with weed control.

Rehabilitation of riparian vegetation is the most widespread management action undertaken in Australia to restore river health. Riparian zones have been cleared or the vegetation cover fragmented along many river systems. In agricultural land riparian vegetation is often confined to narrow strips subject to overgrazing and weed infestation. In many areas native vegetation has been replaced by introduced plants such as willows.

A healthy riparian zone provides for:

  • Reduction in bank and bed erosion.
  • Increased water quality by trapping sediments, nutrients and contaminants before they enter the river.
  • Shading and cover for aquatic organisms.
  • Reducing water temperature to limit evaporation and the occurrence of low dissolved oxygen
  • Energy input through leaf fall etc.
  • Input of woody debris into the waterway.
  • Control of noxious weeds.
  • Important habitat for terrestrial flora and fauna and landscape connectivity.

Good riparian land management is becoming widely practiced in Australia and there are a number of excellent documents that provide practical guidance. In particular the reader is referred the Australian River Restoration Centre’s Resources page that has a range of information in different formats all focusing on protecting and rehabilitating riparian areas.

Where?

The first step is to assess current riparian condition in the reach and determine where protection and rehabilitation should be targeted. The highest priority should be to manage riparian vegetation that is in good condition. This is the most cost effective approach in the long term. It may also be possible to connect lengths of river with good riparian condition by rehabilitating relatively short sections of river bank.

There are a number of simple techniques that can be used to provide a broad assessment of riparian condition for example, the Stream Condition Checklist produced by the Australian River Restoration Centre.   Aerial photographs, orthophoto maps and results of flora and fauna surveys in the area can also yield important information.

Riparian management should also be coordinated with existing natural resource management activities in the area (e.g. LandCare initiatives) and use existing networks to work cooperatively with landholders to deliver the best results. Good riparian management on one property may provide an example for other landholders to follow (see examples in Example 4e).

Protecting Riparian Vegetation:

Where riparian vegetation is in a healthy condition the goals should be to:

  • Maintain the riparian zone at a width that will retain its structural integrity and effectiveness (maintaining bank stability, filtering sediment, nutrients etc). The effective width will vary depending on the position in the catchment, topography etc.  a minimum of 30 to 50m as a general rule. The width of the riparian zone to be protected has to be negotiated with the landholder as it is removing land from productive use.
  • Avoid disturbance to the riparian zone. This includes working with landowners to avoid any unnecessary clearing etc. Vehicle access may also be an issue particularly along riverine recreational reserves where camping and recreational activities may be permitted. Here it will be a matter of restricting vehicle access to the riparian zone and will involve working with the local council.
  • Restricting stock access. Continuous grazing in the riparian zone will lead to damage to riparian vegetation, reduced levels of recruitment and regeneration of riparian flora, increased levels of weed infestation, stream bank erosion and reduced water quality. Fencing of the riparian zone is the most common approach to restricting stock access. The fences must be sufficiently strong to keep cattle out and to resist flood damage.
  • Control weed infestations. Healthy riparian vegetation with restricted stock access should have limited issues with weed infestations.

The Stock and Waterways: A Managers Guide online resource takes you through these steps, along with practical on-ground activities you can undertake to protect and restore riparian areas.

Protected and rehabilitated section of the Ovens River. Photo: Fern Hames
Weed removal along the Namoi demonstration reach. Photo – Milly Hobson
Namoi Fishing Club planting at the toe of the bank for erosion protection. Photo: Milly Hobson

Rehabilitating Riparian Vegetation:

All the points listed above under “Protecting Riparian Vegetation” can be implemented here, with the additional requirement to undertake rehabilitation actions. Actions that can be undertaken will depend on the funds and other resources available. In highly degraded areas the first question to ask is are there any stream bank stability issues? If the answer is yes, these need to be addressed first before resources are directed at rehabilitating the riparian zone.

  • Natural Regeneration. Where there are limited resources, the area can be fenced off and natural regeneration allowed to occur. There will be a requirement for some initial and ongoing weed treatment.
  • Revegetation. This involves the active reintroduction of plants either through seeding or planting of seedlings. The priority should remain one of replicating nature so replanting native vegetation of local genetic provenance is essential. It is also important to plant the correct species in the right areas. For example small, pliable species should be planted within the banks of the river so that they do not increase flooding (see examples in Example 4f).
Conservation Volunteers Australia planting trees along the Gulligal Lagoon at a Namoi demonstration reach field day. Photo Milly Hobson

Examples:

Dewfish Demonstration Reach – Revegetation Oakey Creek
Grazing livestock has resulted in degraded riparian vegetation including loss of key tree species and ground cover. The initial aim has been to improve vegetation condition and connectivity along a 5km stretch of the 20km reach. The rehabilitation was planned to improve connectivity between two patches of Queensland Herbarium recognised regrowth vegetation and extend the width of the current regrowth area.

Upper Murrumbidgee Demonstration Reach – Riparian Surveys
In 2013, Cooma Waterwatch undertook surveys along the entire length of the NSW section of the Murrumbidge River to assess riparian health. The Key points are:

  • Assessments were made using the RARC methodology.
  • Results will be mapped and used to prioritise riparian management and will also provide a baseline upon which to measure future change.
  • Willow saplings are colonising previously willow free areas including areas with good native vegetation. The results will be used to prioritise willow control activities (see Example 4f).

Dewfish Demonstration Reach-Revegetation of Oakey Creek (see Dewfish Demonstration Reach Revegetation Stage 1 and 2. )
The approach was to replant in degraded areas, remove the weed African boxbrush and improve the diversity of existing regrowth together with landholder supplied fencing. Key points are:

  • Compromise may have to be made regarding the width of the riparian zone. In this case the vegetation Management Code for the Brigalow Belt Region recommends a buffer of 200m for a waterway the size of Oakey Creek. Current agricultural use limited the width to a maximum of just over 100m from the water.
  • There are however significant opportunities to increase the length of health riparian zone.
  • African boxthorn was mechanically removed from within the planting sites but further control measures are required.
  • Mulch was used to suppress other plant growth around the seedlings. The mulch was from locally sourced bluegrass bales. This was free of agricultural propagules and provided a native grassland seedbank.
  • Timing of planting was flexible to avoid drought and flood while ensuring the appropriate amount of moisture for planting.
  • Plant selection was based on species already present at the site and to include a broader range of species when planting beyond the upper bank into the floodplain. Plant species were also selected to improve habitat for the Regent Honeyeater.
  • Plants were selected and placed to increase long-term success in the large ranges of microhabitats present (e.g. cleared ground, gilgais, sparse regrowth canopy etc.).
  • Communication between the landholder, the fencer and the planter is essential. In this case there were occasions when the fencing wasn’t completed before the planting window and covered a larger area that required. Additionally gateways were sometimes narrower that was required by the landholder for maintenance purposes.

Upper Murrumbidge Demonstration Reach- Willow Control
Introduced willows can dominate the riparian zone in many areas of the Basin. Willows do not provide the input of energy and woody debris that native species do and do not provide the diversity of habitat for riparian dwelling fauna. They are also prolific and “choke” shallow sections of waterways. The Upper Murrumbidgee Demonstration Reach Community Willow Control Program is funded by the NSW DPI Habitat Grant program and has the aim of controlling emergent instream willows along 45km of the demonstration reach from Bredbo to Angle Crossing. Key points are:

  • Well established willows are difficult and costly to remove. Targeting young emerging willows growing instream before they become a source of further infection is a cost effective approach.
  • The project uses volunteers e.g. Willow Warriors.
  • Small teams of volunteers paddle the river and remove willows along the way.
  • The willow removal is carried out under the guidance of qualified professionals including trained river guides and uses best practice methods for controlling willows.
  • The project also identifies high value riparian and aquatic habitat for protection against willow invasion and identifies sources of willow spread.
  • Riparian Blackberry is also being mapped and the information shared with Cooma Monaro Shire Council.
  • Control in high value riparian areas of the UMDR are prioritised.

This project contributes to implement Willow control in river reaches prioritised by the UMCCC Willow Management Strategy.