Coastal Environment and Management

Open date

Last update date: 05 March 2025

The City, with its 7km coastline, faces coastal hazards like erosion and inundation. It developed the CHRMAP to mitigate these risks.

Overview

The City has approximately 7km of coastline, including iconic beaches.

Erosion is the main coastal hazard impacting the City of Stirling coastline. Erosion can occur in a short time period - for example, a storm event - or over a longer period of time, as the shoreline gradually retreats due to rising mean sea level or changes in local coastal process.

If erosion occurs where assets exist, the damage is generally permanent. Erosion, however, is not necessarily permanent, with sandy beaches often eroding and recovering seasonally. Both erosion and inundation hazard extents will be mapped for the CHRMAP, at various timeframes from present day to 2120.

Coastal Hazard Risk Management and Adaptation Planning (CHRMAP)

In preparation for the CHRMAP, the City consulted extensively with the community and stakeholders to identify high-priority assets and considerations for our precious coastline. The CHRMAP provides strategic guidance for coordinated, integrated and sustainable land use planning and management and is a long-term plan that informs the City’s future decision.

The City engaged a range of specialist advisory services to complete a Coastal Hazard Risk Management and Adaptation Planning (CHRMAP) process.

The purpose of CHRMAP

Set the framework for the assessment, by identifying coastal hazards (erosion and to a basic degree inundation), analysing vulnerability for specific assets, identifying and prioritising management and adaptation responses, and providing an implementation plan;
Inform the community and stakeholders about potential coastal hazard risks; identify community and stakeholders’ values as well as key coastal infrastructure and assets at risk; and provide a clear pathway for the City of Stirling to address coastal hazard risks over time; and
Provide strategic guidance for coordinated, integrated and sustainable land use planning and management decision-making by the City of Stirling, including any necessary changes to the City of Stirling Local Planning Strategy, Local Planning Scheme and other relevant strategies and local planning policies.

Coastal Adaptation and Options Assessment (Watermans Bay and Mettams Pool)

In 2019, an Assessment of Coastal Erosion hotspots in Western Australia (prepared by the Department of Planning, Lands and Heritage and the Department of Transport), identified Mettams Pool and Watermans Bay as two of 55 coastal erosion hotspots along the West Australian coast.

The CHRMAP classified Mettams Pool and Watermans Bay at high risk of being impacted by coastal erosion and recommended further investigation in the immediate term and, depending on the outcomes, active management in the short term.

The recommendation (CHRMAP Chapter 5 R13) is to “Undertake a detailed options assessment to determine the optimal coastal protection technique(s) at Watermans Bay Beach and Mettams Pool Beach” through a working group which incorporates a community/stakeholder feedback mechanism.

A project working team comprising Elected Members, City and State Government representatives, led by specialist coastal engineers, is currently overseeing the technical investigation into feasible options to protect these high risk, high value locations.

The Coastal Adaptation Options Assessment will investigate the feasibility of the various options to mitigate the impacts of changes to the coastline by planning for the most appropriate course of action and implementing mitigation strategies over time.

The CHRMAP eliminated several coastal protection options and identified the following for further assessment and, ultimately most appropriate option for each location.

Beach nourishment
Groyne/headlands enhancements
Nearshore reef/breakwaters
Revetments/seawalls.

As part of the assessment process, key stakeholders and community representatives will be invited to participate in the final two workshops. The assessment will consider community values established through previous extensive community engagement, environmental impacts, previous studies (see below list of Useful documents) and economic criteria including construction and operation/maintenance costs.

See below to view Mettams and Watermans Reference Group workshop presentations.

A CHRMAP is a strategic planning document that outlines management and adaptation pathways for areas and assets at risk of coastal hazards, such as erosion and inundation (flooding). Assets include both built and natural assets, which provide a range of values to the community, including social, environmental, economic and heritage values.

CHRMAPs provide the basis for planning instruments such as Local Planning Schemes, Local Structure Plans and Foreshore Management Plans, by presenting the context around existing and future coastal vulnerability and the framework for managing associated risk.

The CHRMAP is required under the State’s Coastal Planning Policy (SPP2.6), under the Planning and Development Act 2005. The CHRMAP provides long term strategic direction, while identifying risk and required decision making in the shorter term.

Coastal vulnerability is a result of a number of factors including:

Changes to sand movements, in particular a reduction in the available sediment movement along the coastline.
Severe storm events which are probably being exacerbated by climate change
Sea level rise which is projected to increase significantly in the short term and substantially (>900mm) in the longer term.

Due to a combination of these, the coastal vulnerability is expected to increase significantly in the future. These factors are already putting coastal assets at greater risk and requiring a more strategic approach to Coastal Hazard Risk Management and Adaptation Planning.

The CHRMAP eliminated several options and identified the following options that are deemed appropriate:

Beach nourishment
Groyne/headlands enhancements
Nearshore reef/breakwaters
Revetments/seawalls.

The CHRMAP process has considered this, the City does not see an option that does not protect the functionality of West Coast Drive. The retention of access to properties is considered paramount along with the coastal Recreational Shared Path.

The City is committed to hosting ongoing coastal conversations with residents and beachgoers to chat about their experiences of change along our coastline and what solutions are best for the community to preserve these most incredible natural assets.

Coastal Conversations

The City is committed to hosting ongoing coastal conversations with residents and beachgoers to chat about their experiences of change along our coastline.

Please join us at one of our upcoming Walking Together events or drop-in afterwards for a Coastal conversations to meet the City’s Engineering Officers:

Walking Together – Watermans Bay
Date Tuesday 10 September 2024
Time 8.00am to 9.00am
Meeting point Little Bay, 33 West Coast Drive, Watermans Bay
Followed by a Coastal conversation at Watermans Bay from 9.00am – 10.00am

Walking Together – Trigg
Date Thursday 26 September 2024
Time 7.30am to 9.00am
Meeting point Canteen Trigg, 364 West Coast Dr, Trigg WA 6029
Followed by a Coastal conversation at Trigg from 9.00am – 10.00am