Coastal Management Report: Collaroy Beach

Introduction

The issue of coastal management involves the sustainable management of coastal development to meet the needs of present and future generations while maximizing the utilization of coastal areas for residential and commercial purposes. Coastal regions are dynamic and ever-changing, making effective management crucial to address various challenges such as erosion and its consequences.

Report Focus

This comprehensive report delves into the critical issue identified during our field trip – the gradual erosion of the foredune on Collaroy Beach. It explores the multifaceted aspects of coastal management, encompassing the environmental, social, and economic dimensions.

Our analysis covers the impacts of erosion on stakeholders, including residents, developers, and specialist groups, while also shedding light on the decision-making processes adopted by local and state authorities. Furthermore, we delve into the actions and strategies implemented by these authorities and their consequences on the coastal ecosystem.

Location

Collaroy Beach, our site of interest, is situated in the suburbs of Northern Sydney, within the state of New South Wales, Australia.

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It falls under the jurisdiction of the Warringah Council and is part of the Northern Beaches region. Collaroy Beach is renowned for its scenic beauty and excellent surf, seamlessly connecting with Narrabeen Beach to the north and Long Reef and Dee Why Beach to the south. The geographical location is complemented by the presence of natural features such as the Dee Why Lagoon and Long Reef Head, making it a popular and cherished destination for residents and tourists alike.

Geographical Process: Coastal Erosion

Coastal erosion is the gradual loss of land along the shoreline due to the natural removal of beach and dune material in response to changing wave and water conditions.

This ongoing process poses a significant challenge for coastal communities and their development aspirations. Buildings and infrastructure located within the 'active' beach system, which includes areas subject to coastal erosion, are vulnerable to instability and potential collapse.

Approximately 60 percent of the NSW open coastline consists of sandy beaches. These dynamic environments experience continual cycles of erosion and accretion in response to the action of tides, wind, and waves. Importantly, many existing foreshore developments have been established within this 'active' beach system, rendering them susceptible to the relentless forces of coastal erosion.

Factors Influencing Coastal Erosion

Understanding the factors that influence coastal erosion is essential for effective management:

• Wave Conditions: Coastal erosion during storm events is heavily influenced by wave conditions, including wave height and energy generated by storms.
• Rip Cells: Rip cells, characterized by strong surface water flow returning seaward from near the shore, exacerbate erosion by removing beach sediments.
• Beach Condition: The condition of the beach, specifically the beach profile, determines its susceptibility to erosion. Different profiles emerge depending on the state of erosion.
• Dune Vegetation: The presence and health of dune vegetation can significantly impact the volume of sand in the dunes, which serves as a natural buffer against erosion.

Key Interest Groups

The erosion issue at Collaroy Beach has garnered attention from various interest groups, each with distinct perspectives and agendas:

• Sydney Coastal Councils Groups (SCCG): SCCG has criticized the Warringah Council for focusing on short-term solutions like sand replenishment, deeming them unsustainable in the long run. Their primary concern is the long-term sustainability of the coastal area.
• Surf Rider Foundation Club: This group is actively involved in advocating for the protection of the coastal environment, particularly the surf conditions, which are influenced by erosion patterns.
• Collaroy Surf Club: The local surf club is deeply invested in preserving the safety and amenity of the beach for its members and the community.

Decision Making Process

Addressing the erosion issue at Collaroy Beach involves a complex decision-making process, marked by cooperation between various levels of government and community engagement:

The NSW and Commonwealth governments have played a pivotal role by providing guidelines and materials for coastal management. The Coastline Management Manual, Coastal Management Plans, and inquiries such as 'The Injured Coastline' and 'The Coastal Zone Inquiry' have guided local councils like Warringah in their decision-making processes.

The establishment of the Warringah Coastal Committee in 1993, with diverse stakeholders including council members, government representatives, surf club members, and residents, has facilitated unbiased views and increased community involvement. The committee meets regularly to advise the council on actions to combat erosion.

Community engagement is a key aspect of the decision-making process, with the public invited to comment and provide feedback before major strategies are implemented. However, achieving consensus has proven challenging, leading to differences of opinion within the community and between the committee and council.

Management Actions and Strategies

The erosion issue at Collaroy Beach has prompted the exploration of various management actions and strategies:

1. Voluntary Purchase of High-Risk Dwellings:

Historically, repurchasing high-risk dwellings damaged by erosion was successful. However, soaring beachside property prices have made this strategy economically unfeasible. It could take decades and significant funding to repurchase properties located in the high-risk zone.

2. Construction of a Seawall:

A proposed 1 km long seawall to protect foredune properties faces challenges. The cost, estimated at around 11 million dollars, with at least 40% expected to be paid by property owners, makes it an unattractive option. Seawalls can also accelerate erosion and are not environmentally friendly.

3. Minor Beach Nourishment:

Temporary solutions include sand nourishment from the mouths of the Dee Why and Narrabeen Lagoons to mitigate erosion effects. This method relies on replenishing sand at the beach, albeit on a smaller scale.

4. Artificial Surfing Reef:

An innovative approach being explored is the creation of an artificial surfing reef. This underwater structure amplifies surf, reduces erosion, and is more cost-effective than other strategies. While its effectiveness is debated, promising results and affordability make it a viable solution in the near future.

Currently, the council plans to rely on minor beach nourishment from the mouths of Narrabeen and Dee Why Lagoons while investigating new strategies. Coastal imaging cameras installed on Flight Deck will aid in monitoring and evaluating the effectiveness of these strategies.

Conclusion

The erosion issue at Collaroy Beach presents complex challenges that encompass economic feasibility, environmental impact, and community consensus. Ongoing efforts to address erosion involve a combination of strategies, with a focus on innovative approaches like the artificial surfing reef to secure the long-term sustainability of this beloved coastal area. Effective coastal management requires continuous adaptation and collaboration among stakeholders to safeguard the coast for future generations.