Coastal Management in NSW - evp sem 1

Coastal Management in NSW

Dr. Carla Sbrocchi, EPM 91145, 24 February 2025

Overview of Coastal Management

• Coastal Population: 85% of Australians live within 50 km of the coast.
• Trade: 98% of trade occurs near the coast.
• Outline: The presentation covers:
  • Primer on sand movement
  • Case study on Wamberal, NSW
  • Management options

Sand Movement: Principles

• Longshore Drift: Generally occurs in a south-to-north direction.

Factors Determining Deposition or Erosion

• Wind/Wave Direction: The direction of wind and waves affects deposition or erosion.
• Wave Energy: High wave energy can cause erosion, while low energy can result in deposition.
• Beach Type: Different beach types respond differently to wave action.
• Process: Prevailing winds bring waves at an angle, moving material along the beach in a zig-zag pattern. Changes in coastline direction lead to material deposition in shallow, calm water, forming spits.
• Spit Formation: Spits curve with changes in wind direction.

Dynamic Coastline Changes

• Wave Action: Waves continually change the shape of the beach and coastline, as demonstrated in a timelapse of Manning Point, NSW.

Beach Width Variation

• Timelapse Data: Narrabeen Lagoon data shows beach width variation over time.
• Example: The beach width is measured at 69.7 meters.

Long-Term Sand Movement Effects

• North to South Movement: Long-term sand movement from north to south causes some locations to experience retreat or growth.

Retreat and Growth Measurement

• Measurements: Various locations show retreat (negative values) or growth (positive values) in meters per year.
• Examples: Harrington Waters Golf Course shows growth of $0.5 m \pm 0.2$ m/year, while Manning Point shows retreat.

Case Study: Wamberal, NSW

Wamberal history between1974-2020, Yellowsands, McGee, Pinball Wizard, Wiles Ave etc, different imagery dates.

Coastal Management Framework

• Key Policies: Framework includes:
  • State Environmental Planning Policy (Resilience and Hazards) 2021
  • Coastal Management Act 2016
  • Coastal Management Programs (CMPs)

Coastal Management Act (CM Act) 2016

• Object: Manage coastal development in an ecologically sustainable way for social, cultural, and economic well-being.
• Intent: Plan for and respond to coastal hazards and increase resilience to climate change.

State Environmental Planning Policy (SEPP) 2021

• SEPP Functions: Streamlines coastal development assessment, identifies development controls, and establishes approval pathways for coastal protection works.

Coastal Management Areas

• Four Areas: The coast is defined by:
  • Coastal use area
  • Coastal wetlands and littoral rainforests area
  • Coastal environment area
  • Coastal vulnerability area

Management Objectives and Development Controls

• CM Act Objectives: Establishes management objectives based on different values to coastal communities.
• SEPP Controls: Identifies development controls for consent authorities to apply to each coastal management area to achieve the CM Act objectives.

Development Requirements

• Coastal Wetlands: Development within mapped coastal wetlands requires consent and often an environmental impact statement.
• Impact Management: Development must avoid, minimize, or manage impacts to coastal waters, beaches, and dunes.
• Public Interest: Proposals must address public interest and built form criteria to mitigate impacts on scenic, social, and cultural values.

Coastal Management Program (CMP) Preparation

• Local Council Responsibility: A local council prepares a CMP, identifying issues, actions, implementation, and costs.
• Consent Authority: If actions are in a certified CMP, the consent authority is the council; otherwise, it is the State Planning Panel.
• Example: A CZMP was prepared in 2018, but no CMP exists to date.

WorleyParsons (2015) Hazard Lines Report

• As of January 20, 2010:
  • 69 private lots fronting Wamberal Beach, 68 occupied by a dwelling/building
  • 61 dwellings have some portion seaward of the Immediate ZSA, with 6 dwellings that are located entirely landward of the Immediate ZSA
  • 65 dwellings have some portion seaward of the Immediate ZRFC, with the 2 dwellings that are located entirely landward of the Immediate ZRFC
  • 24 dwellings have a substantial proportion of their footprint seaward of the Immediate ZSA
  • Wamberal SLSC is located entirely landward of the Immediate ZSA and ZRFC, so is at relatively low risk from coastal erosion at present.
• Lots potentially affected by coastal hazards to 2100 are show in Figure 7.4.

Coastal Management Options

• Three Main Options: Accommodate, Protect, Retreat.
• Considerations: Each option involves trade-offs in cost, practicality, acceptability, and risk reduction.

Accommodate

• Application: Generally for low severity, high-frequency events.
• Methods: Raising or controlling habitable space.

Protect

• Examples: Collaroy (1920), Gold Coast (1967).

Protect – Nature Based Solutions

Protect - Seawalls

• Pros: Prevents further dune erosion and protects buildings/critical assets.
• Cons: Undermining over time, visual impacts, loss of beach amenity, high initial cost and ongoing maintenance, end-effects.
• Cost Sharing: Variable, with private owners able to submit development applications to protect their property.

Protect - Seawalls: Conflicting Rights and Interests

• Conflicting private property owners versus public amenity, Whose rights? Whose responsibility?

Protect - Beach Nourishment

• Pros: Lower environmental impact, sand matches natural beach material.
• Cons: Difficulty in sourcing material, continuous replacement required, expensive based on campaign and frequency.
• Cost Example: For $50,000 m^3$, the average cost is $300,000 per year. Is this cost borne by homeowners or the entire LGA?

Retreat - Move Back

June 1978 - Day 1, June 1978 - Day 2

Compare 23a, 23b and 33, Building Line, 2050 ZSA (2014), 2013, 25c

Retreat - Buy Back

• Pros: Allows natural processes to continue and enables management of the dune area.
• Cons: Does not solve sand loss, expensive, social conflict with residents and wider community.
• Cost Example: Estimated $240M$ to buy out homes versus $25-45M$ for a seawall.

Best Option?

• Collaroy Examples: What if the problem is extensive (beyond individual properties)?
  • 1-2km long seawall
  • Coordinated approach/design
  • Collaroy: $25M$, $13.8M$ contribution from private landholders
  • Groups of property owners form ‘strata’ and own stretches of wall
  • Who owns the beachfront?
  • Is Council the determining authority?

Solution for Wamberal

• CMP is in early stages.
• Which options deliver net benefit?

Progress on CMPs in NSW circa 2025

• 11 certified CMPs since 2018
• 40 CMPs in various stages of completion
• Since 2016-2017, $78.9M$ in grants (planning and implementation)
• Largest grant: $5.5M$ for Collaroy Narrabeen sea wall (2018)

Final Thoughts

• Coastal management options are considered as part of the CMP in NSW.
• When a CMP is certified, the council is the consent authority for development and some emergency works.
• Options are ‘filtered’ based on a range of personal biases, including social, environmental, and financial considerations.
• There is no right answer.
• What do YOU think is the most complicated part of coastal management?
• What are YOUR experiences of coastal issues and management?
• What did you assume to be true?