The Shoalhaven Region is located approximately 200km south of Sydney, encompassing a diverse landscape that includes coastal plains, beaches, mountains and rivers.  The local communities and visitors highly value the local environment and access to the waterways  within the area. The region also has a rich Indigenous history, with many sites of cultural significance.  Council has previously identified riverbank and foreshore erosion across seven sites in the Shoalhaven Region, which is threatening natural habitats, infrastructure, safety and cultural heritage.

While riverbank and foreshore erosion can occur naturally due to streamflow, tidal processes and wave dynamics typical of estuarine environments, these effects are normally balanced by natural deposition. However, anthropogenic disturbances combined with more frequent storm events have disrupted these complex processes across the sites, leading to increased occurrence of erosion.

Shoalhaven City Council engaged Water Technology to assess the extent of bank erosion, determine the feasibility of bank treatment options and develop concept designs of preferred treatment options at each of the seven sites.

Site visits were conducted with representatives of the Department of Climate Change, Energy, the Environment and Water, Council and Water Technology to determine the specific issues, associated risks, constraints and opportunities at each of the sites.

The use of nature-based solutions was considered throughout the optioneering and concept design processes to ensure that nature positive approaches were incorporated and hard engineering solutions were avoided where possible.

The nature-based solutions approach creates opportunities to address environmental challenges through designs that enhance both land and water ecosystems while minimising the negative impacts typically associated with more hard-engineered solutions.

The nature-based solutions considered as part of the options assessment included:

• Vegetation management including:
  • Revegetation of the riparian zone.
  • Not mowing to the foreshore edge to ensure that a vegetated buffer can be maintained.
  • Formalise access points to provide safe and easy access to the water while directing people away from revegetated sections (i.e. preventing informal access points into the water).
• Incorporation of mangroves and / or saltmarshes into the design to provide habitat, in addition to encouraging sediment deposition and toe protection.
• Implementation of environmentally friendly seawalls that mimic natural intertidal shorelines through estuarine and riparian vegetation, artificial reef habitats and surface texture variation.
• Construction of oyster reefs which act as a natural breakwater and they also have the benefit of being able to adapt to climate change and associated sea level rise by naturally growing in height.

Several treatment options were proposed for each of the seven sites, which included high level information on costs, benefits, potential adverse impacts, configuration and expected effectiveness.

Implementation of the recommendations has commenced for one of the sites, with on-ground work to proceed in due course for other sites.