Groynes Along Our Beaches

According to the draft plan, while there is a single groyne planned for Mullaloo Beach, there are clearly 5 in total, with 2 at Point Pinnaroo and 2 at Whitfords Beach all scheduled for 2025 if trigger points have been hit.

Remember: If the Council approves the plan the administration are lawfully required to act on it.

Groynes are protective structures made of stone or concrete that extend from the shore into the water. They are primarily used to prevent a beach from washing away due to erosion. The first known use of groynes dates back to 1582, and they are also known by other names such as breakwater, bulwark, groin, jetty, and seawall.

In terms of their effectiveness, groynes work by interrupting water flow and limiting the movement of sediment along the coast. This can help to reduce erosion and build up the beach on the updrift side of the groyne. However, this can also lead to increased erosion on the downdrift side, as the natural flow of sediment is disrupted.

Plenty! Currently the most important single thing you can do is respond to the City of Joondalup’s “public consultation”. According to the City, if you attend an information session and want to add more to your submission, you can fill out the online consultation form again and your responses will be aggregated.

MBCG has organised a petition you can sign to pressure the council into rejecting the draft plan.

You can contact your local councillor directly to express your concerns (keep in mind they cannot speak against decisions made by council), and direct any questions to info@joondalup.wa.gov.au.

Also importantly, you can stay up to date by following MBCG on Facebook, signing up to our mailing list, and joining the Stop The Groynes group on Facebook (please note: this Facebook group is not associated with MBCG Inc).

“Soft options” refer to non-structural methods of managing coastal erosion and other coastal hazards. These options are often more environmentally friendly and sustainable than “hard options,” which involve the construction of physical structures like seawalls, groynes, or revetments.

Soft options include:

1. Beach Nourishment: This involves the addition of large quantities of sand or sediment to the beach system. The aim is to increase the width and height of the beach, providing a larger buffer against wave action and erosion. This method can be quite effective but may need to be repeated periodically as the added material is eroded away.
2. Dune Restoration: Dunes act as a natural barrier against wave action and can be restored or enhanced through the planting of vegetation to stabilize the sand, and the installation of fencing or other structures to prevent human trampling.
3. Managed Retreat: This involves the deliberate moving back of the line of human development to allow the shoreline to move naturally. This can be a very effective long-term solution, but it can be controversial as it often involves the loss of private property or public amenities.
4. Land Use Planning: This involves the careful planning of development in coastal areas to minimize the risk of damage from coastal hazards. This can include measures such as zoning laws that restrict development in high-risk areas, and building codes that require structures to be built to withstand coastal hazards.
5. Education and Awareness Programs: These programs aim to increase public understanding of coastal processes and the risks associated with living in coastal areas. This can lead to more informed decision-making by individuals and communities about how to manage their own risk.
6. Ecosystem Restoration: This involves the restoration or enhancement of natural coastal ecosystems, such as mangroves, coral reefs, and seagrass beds, which can provide a natural form of coastal protection.

These soft options often work best in combination and need to be tailored to the specific characteristics of the local coastal environment and community. They also require ongoing management and adaptation in response to changing conditions and knowledge.

“Hard options” in coastal hazard risk management and adaptation plans refer to structural or engineered solutions designed to protect the coastline from erosion and other coastal hazards. These options often involve the construction of physical barriers that aim to resist natural forces. Here are some examples:

1. Seawalls: These are structures built parallel to the coast, designed to protect the land behind from wave action. They are typically made of concrete, stone, or other durable materials. While effective in the short term, they can lead to increased erosion in other areas and alter natural coastal processes.
2. Groynes: These are structures built perpendicular to the shoreline, usually made of wood, rock, or concrete. They trap sand moving along the coast due to longshore drift, helping to build up the beach on the updrift side. However, this can cause increased erosion on the downdrift side.
3. Revetments: These are sloping structures placed on banks or cliffs in such a way as to absorb the energy of incoming water. They are typically made of rock, concrete, or other robust material.
4. Breakwaters: These are offshore structures that interrupt wave action, reducing its impact on the shoreline. They can be situated offshore or connected to the land.
5. Artificial Reefs: These are man-made underwater structures typically built for the purpose of promoting marine life, but they can also serve to break up wave action before it reaches the shoreline.
6. Flood Gates/Barriers: These are structures designed to prevent flooding by blocking waterways during times of high water levels.

While these hard options can be effective in protecting specific areas from coastal hazards, they can also have significant environmental impacts, including altering natural coastal processes, damaging marine habitats, and increasing erosion in other areas. They can also be expensive to build and maintain. Therefore, the decision to use hard options should be based on a thorough understanding of the local coastal environment and the potential impacts.

The body of evidence is quite clear that “hard” measures to mitigate erosion need to be carefully considered. The more we are learning, the clearer it becomes that once you start with the first groyne the others will continue to be needed.

The primary disadvantage of groynes is that interruption of longshore drift to promote beach widening on one section of coastline is likely to cause sediment starvation and erosion further downstream. This is because groynes do not add sediment to the shoreface but instead distribute the available materials differently. As such, groyne construction is perhaps most effective when complemented by beach nourishment as discussed above.

By promoting sediment build up on the updrift side of the groyne, there is a consequent sediment deficit on the downdrift side, requiring the construction of further groynes to maintain beach width. At the most downdrift extent of a groyne field, a symptom known as ‘terminal groyne syndrome’ often exists, whereby sediment starvation causes accelerated erosion of the unprotected coastline. This has obvious negative implications.

While groynes promote recreational beach use through beach widening, another problem with their use is related to the formation of rip currents adjacent to groynes. These can

present a hazard to bathers and furthermore, may also lead to sediment being transported to deep water and lost from the coastal system during storm events (Masselink and
Hughes 2003).

While beach widening is typically viewed positively, groynes affect the visual appearance of the coastline by introducing unnatural, shore perpendicular structures. Groynes may also reduce accessibility of the beach to those less mobile.

MANAGING CLIMATE CHANGE HAZARDS IN COASTAL AREAS – pg 63

A Coastal Survey by the City of Joondalup in 2019 demonstrated that there was a clear community preference for soft options over hard options, and that the community values the natural beach area over private or public assets.

The final revision of the draft plan was completed in 2020 but not released to the public.

There was a Freedom of Information application made on 6 May, 2023 to obtain the technical CHRMAP (draft plan) that had previously been deemed “too complex and technical to understand” for the City to allow public access.

At a Briefing Session on 9At a Council Meeting on 23 May 2023, it was discovered the technical points of the CHRMAP had not been peer reviewed for viability. A motion by Councillor Kingston to send the draft plan back to follow the proper State Government guidelines for CHRMAPs was defeated, and after that a majority of council voted to send the draft plan (for 17 groynes) out for “Public consultation”.

As of the of June, 2023 the City have released the full “technical and complex” draft CHRMAP.

A Coastal Hazard Risk Management and Adaptation Plan (CHRMAP) is a strategic plan used in Western Australia to manage and adapt to coastal hazards. These hazards can include things like erosion, storm surge, and sea-level rise, which are all expected to increase due to climate change.

CHRMAPs are developed by local governments in consultation with their communities and other stakeholders. They involve a process of identifying and assessing coastal hazards, evaluating the risks they pose, and developing strategies to manage and adapt to these risks.

The City of Joondalup plan is to establish 5 of these groynes by 2025, without first considering managed retreat, or soft options such dune stabilisation and strengthening through planting.

The City administration has expressed the importance of applying for grant funding to action this plan. In order to apply for funding the City is required to establish a business case.

Local council elections are scheduled to take place October and the council enters a caretaker period, and the conclusion of this process occurs close to the Christmas holiday period.

There are requirements the City of Joondalup must adhere to, the State Planning Policy (SPP) 2.6, SPP2.6 (Guidelines) and the State’s Coastal Hazard Risk Management and Adaptation Planning Guidelines (2019)