Coastal Hazard Planning

The Shire of Ashburton is undertaking a review of the Onslow Coastal Hazard Risk Management and Adaptation Plan (CHRMAP) to help guide the long-term management of coastal hazards and support informed planning decisions for the future of Onslow's coastline. The review considers the potential impacts of coastal erosion and inundation associated with climate change and sea level rise over the next 25, 50 and 100 years.

What is a CHRMAP?

A Coastal Hazard Risk Management and Adaptation Plan (CHRMAP) is a strategic planning document that identifies current and future coastal hazards and outlines options for managing associated risks. The plan examines a range of hazard scenarios and helps guide future land use, development and infrastructure planning in coastal areas.

The current Onslow CHRMAP was adopted by Council in 2017 and provided an assessment of coastal hazard risks affecting the Onslow Townsite shoreline, together with recommendations for managing those risks.

Why is the CHRMAP Being Updated?

CHRMAPs are typically reviewed every 5 to 10 years to ensure they remain current and reflect the latest information, planning frameworks and community priorities. The original Onslow CHRMAP was developed in 2017 and many of its recommendations have since been implemented. 

Since then, additional studies, data collection and infrastructure projects have improved understanding of local coastal processes and risks. These include:

  • Assessments of the condition and effectiveness of the Onslow seawall
  • Extension of the seawall to protect key assets
  • Catchment modelling to identify inundation risk areas
  • Stormwater upgrades and new ocean outfalls
  • Coastal monitoring and metocean studies
  • Collection of geotechnical and survey data
  • Updated local planning strategies, planning schemes and coastal planning policies

How Could the CHRMAP Affect Me?

The CHRMAP helps guide future decisions about how coastal areas are planned, used and managed. If you live, work, own property, operate a business or regularly visit Onslow's coastal areas, the outcomes of the CHRMAP may influence future management of beaches, public facilities, infrastructure and foreshore areas.

Project Timeframe

The CHRMAP review commenced in 2026 and includes the following key stages:
Timing Project Stage
April – May 2026 Project Establishment
June 2026 Risk Identification (Mapping Updates)
July 2026 Risk and Vulnerability Analysis
July 2026 Risk Evaluation
August 2026 Community Engagement
August – September 2026 Risk Treatment
September Implementation Planning
September Monitor and Review
October Draft CHRMAP open for public comment
December Final CHRMAP adopted by Council

Get Involved

Contact Alan Sheridan, Project Manager, via email [email protected] or phone 0419 741 618.

Download the 2026 CHRMAP Fact Sheet

FAQ

What is a Coastal Hazard?

Coastal hazards are natural events and processes that affect the coastline, including:

Coastal Erosion

The wearing away of land by waves, tides, wind and other coastal processes, which can result in loss of shoreline and changes to coastal landforms.

Coastal Inundation

The flooding of land by seawater during storm events, high tides, large waves or as a result of long-term sea level rise.

Coastal Values

The review also considers the values that are important to the community. Coastal values include:

  • Scenic and environmental values
  • Recreation and tourism
  • Cultural and Indigenous heritage
  • Community use and enjoyment
  • Economic and commercial activity
  • Public infrastructure and assets

Coastal Planning Timeframes

The CHRMAP assesses coastal hazards across three planning horizons:

  • 25 years – Short-term planning considerations
  • 50 years – Medium-term coastal management and adaptation planning
  • 100 years – Long-term coastal hazard management and future land use planning

These timeframes help the Shire understand how coastal risks may evolve and identify appropriate management options over time.