Public consultation on the Draft Coastal Hazard Adaptation Strategy (CHAS) Our Resilient Coast. Our Future.
Closes Monday 07 December
SCEC's representative on the Community Advisory Group, Jim Cash, provides the following preliminary comments and points in the process of preparing our submission for consideration
The CHAS is a policy document addressing coastal hazards and risks associated with climate change and related factors.
Of particular importance are the adaptive pathways (actions) proposed to mitigate the effects of climate change on our coast.
The CHAS is a weighty document with a fair degree of technical data and can take time to digest.
Here, we outline key points of the draft CHAS SCEC thinks should be included in feedback.
The draft strategy includes Supplements that help you navigate the CHAS.
It is helpful to read these to assist in navigating the draft strategy.
Overall SCEC is supportive of the methodology and most of the actions. However, we feel there is scope for some alterations and additions to the actions currently outlined.
KEY POINTS TO NOTE IN REVIEW OF ACTIONS
- REGION WIDE:
- Co-incident Flooding:
There is no mention of co-incident flooding. We contend the real risks of climate change is not being fully assessed without upstream flooding being included in inundated areas of the floodplains of our estuaries.
The hazards outlined only refer to erosion prone areas and storm tide inundation due to climate change.
The science tells us that there will be an increase in intensity of weather events for our part of the world. This will result in more frequent intense upstream flooding events. Given that all our estuaries are quite small in length these overland flood flows coincide with storm tide inundation. Experience shows this to be true e.g. the June 1983 east coast low.
- Include the synergistic effect of co-incident flooding with storm tide inundation to measure the full risk and adjust the adaptive pathways accordingly.
- At the very least the CHAS should further Investigate the synergistic effect co-incident flooding has on levels, areas and periods of inundation for each of our estuaries”
Blue Heart Area:
We are very supportive of action1.4.4 “investigate and document needs for a thriving Maroochy estuary….” and feel this is closely associated with action 2.1.7 “progress transition planning for the blue heart area”.
Our concern is that the Blue Heart area does not cover all of the erosion prone and storm inundation areas identified in the mapping for the Maroochy floodplain. This added area not only acts as a buffer to flooding of built up areas but also allows for more flexible migration of estuarine wetlands in response to changing salinity regimes. The strategy rightly points out the ‘ecosystem/dollar value of the Blue Heart area (estimated up to $70 million from ecosystem services & carbon sequestration incentives). Our contention is an expansion of the Blue heart is extended to the rest of the hazard area identified in the mapping then there would be a proportionate dollar value increase over existing land use.
Not only is this important initiative an Australian first blue carbon storage project, but an essential part of protecting flood prone areas within the Maroochy River catchment and surrounds. It is integral to the region’s CHAS response to increasing sea level rise, storm surge, tidal inundation and riverine flooding. It also provides long-term sustainable economic, environmental and recreational opportunities
Investigate the opportunities to extend the Blue Heart project to all undeveloped areas of the Maroochy floodplain which are subject to inundation and erosion
Placement and intensification of future development within predicted hazard areas:
There needs to be more definitive statements under the planning and modifying infrastructure themes regarding the placement of future development and infrastructure within the predicted erosion prone and storm tide inundation areas.
- use the updated coastal hazard mapping and emerging hazard to avoid adding future development areas to hazard areas and avoid increase in densities for existing development areas within the hazard areas
- Use the updated coastal hazard mapping and emerging hazard to avoid, where possible, adding major infrastructure to those hazard areas.
Community surveys carried out by the CHAS development team clearly indicated the vast majority of the community want to retain our sandy beaches.
Indeed, the socio- economic value of our sandy beaches is clearly demonstrated by the Maroochydore Beach case study (a combined estimated annual loss of $43 million)
A more general study carried out by Anning et al in2013 for all the Sunshine Coast beaches concluded that the combined annual recreational value and tourist expenditure value at $467 million. This figure would be well over $500 million in present-day dollars given the increase in population and number of tourists.
Given the value locals (and visitors) place on our sandy beaches and their socio-economic value:
- We strongly support the CHAS statement in section (pg. 28) which states “…a strong economic case for erosion mitigation that includes maintenance of a sandy beach system”.
- We again strongly support the CHAS region-wide action summary which puts dune maintenance and enhancement as the baseline action for sustaining sandy beaches.
- We strongly support the action of beach nourishment over seawalls as the next priority action to reduce erosive pressure on coastal infrastructure as this action also maintains the natural and recreational values of the beach.
The recently released “Maroochydore beach management strategy” backs up this approach.
It concludes the more aggressive strategy of adding extra sand from the PBPL commercial sand has an average NPV of $15.6 million higher than the current hybrid strategy of Limited sand recycling and a triggered seawall over a 30 year time span for this unit of coastline.
We feel nourishment should be more clearly prioritised over the last line of defence action of building seawalls to protect infra structure. Seawalls can lead to the loss of sandy beaches and should only be considered when nourishment becomes uneconomical.
We strongly support the progressing of the “regional wide sand sourcing study” to help with the implementation of present and future nourishment of our beaches.
- Develop and implement an updated Shoreline Erosion Management Plan which prioritises beach nourishment over last line of defence seawalls linked to 4.4.1
- The hard engineering option of seawalls should only be considered as a last line of defence option when it becomes clear that beach nourishment becomes uneconomical.”
- Implement the trial beach nourishment project for Maroochydore beach as per the regional sand sourcing study to measure the effectiveness of “bottom dumping” of sand using PBPL commercial sand linked to 4.4.1
- For all the locality summaries replace the word “alternative” with “last line of defence (if triggered)” in relation to seawalls. This wording then clearly prioritises nourishment over seawalls as the preferred strategy.
Given the tight timeframe, SCEC has only identified the following key points on a few local areas below at this stage.
Locality 7. Maroochy Estuary and floodplain adaptive pathway:
- Add: “Maintain a thriving estuary system by allowing saltwater wetlands to naturally migrate in response to changing salinity regimes”
- Add:” Investigate the feasibility of extending the Blue Heart area to include all of the Maroochy flood storage preservation area”
- Alter blue heart reference add: “implement first steps of the special area adaptation plan for the Maroochy flood storage preservation area and blue Heart transition plan for the transition of inundation prone agricultural areas to wetland ecosystem services.*
*progress this through stages to 2100
Locality 8. Maroochy River mouth -Cotton Tree
- In the introduction there should be an acknowledgement of the multiple values of the sand bar zone, including the recreational value due to the sandy connectivity of the Cotton Tree with Maroochydore beach. Any erosion mitigation works need to take this into account along with ensuring that any such work minimises the chance of increasing current velocities.
- Under ‘Planning present day’ Add: any mitigating erosion control strategies should not interfere with the sandy connectivity of the Cotton Tree with Maroochydore beach and should be designed to minimise the chance of increasing current velocities at the river mouth. The retention of the Flathead point spit should be considered as an integral part of any mitigation strategy.
Locality 9. Maroochydore Beach:
SCEC strongly supports the beach erosion strategy for this beach as outlined in the recently released pilot study “Maroochydore Beach Management Strategy” which recommends aggressive sand nourishment from an outside source in favour of the current hybrid strategy of limited sand recycling and a triggered seawall. This project is linked to the sand sourcing study and has regional significance as a pilot scheme to evaluate the practicality of nourishment for other beaches.
- In the introduction: add a statement “to maximise the maintenance of a sandy beach alter the SEMP to reflect the strategy in the “Maroochydore Beach management strategy” study.
- Under planning present day add: “review and update SEMP with the aim of replacing existing hybrid strategy with aggressive nourishment strategy as outlined in “The Maroochydore Beach Management Strategy”
- Under planning, present day Add: Investigate the feasibility of a permanent recycling system using sand from the northern end of the beach, similar to the system used at Noosa Main Beach.
This could reduce the amount of sand required from an outside source over time.
- Under planning, present-day, replace last paragraph with: Review the last line of defence option of planned seawall timing and alignment, to seek opportunity for the most landward alignment and new trigger of constructing when Aggressive Nourishment option becomes uneconomical. As per the “Maroochydore Beach Management strategy”.
- Under modifying infrastructure Add: “Consult with TMR on future infrastructure plans with the aim to investigate the feasibility of reducing the transport corridor width to allow the widening of the esplanade”; a transition strategy which would allow the development of a fully functioning dune system in conjunction with a) above
- Under Coastal management and engineering, present day. Add: undertake trial offshore nourishment project as recommended in the Sand sourcing study.
- Under Coastal management and engineering, present day. Replace last paragraph with: “begin implementation of alternate strategy of Aggressive nourishment as per the “Maroochydore Beach Management Strategy study”
- Under Coastal management and engineering, 2041 – 2100, alter second last paragraph from: “alternative” to “last line of defence (if triggered)
- Under trigger and other considerations, replace existing paragraph with: New trigger for seawall construction to occur when aggressive nourishment strategy becomes uneconomical
Locality 10. Alexandra Headland Beach
- In the introduction emphasise the intent of maintaining the sandy beach as long as possible by altering the second last paragraph to: “The adaption pathway includes a focus on protecting and enhancing dunes and the sandy nature of the beach, confirming and implementing an aggressive nourishment program (as outlined in the “Maroochydore Beach management Strategy”) and reviewing the last line of defence buried seawall, including investigating the extension of the sand nourishment pipeline (Table 23).
- Under planning, Add: To maximise the maintenance of a sandy beach review and update the SEMP with the aim of replacing the present hybrid strategy with the aggressive nourishment strategy as outlined in the “ Maroochydore Beach Management Strategy”
- Under Planning, Add: Carry out feasibility study of reconstructing seawall in front of the skatepark and surf club with the aim of moving the alignment as landward as possible and a design more sympathetic with maintaining a sandy beach. This will be done in consultation with the surf club when the existing wall begins to fail.
- Under modifying infrastructure replace second paragraph with paragraph as per locality 9 paragraph e)
- Under modifying infrastructure -by 2041 and beyond: If feasible implement construction of new seawall with altered alignment and structure as per c) above.
- Under trigger and other considerations, replace second paragraph with: new trigger for seawall construction to occur when aggressive nourishment strategy becomes uneconomical.
- Under Coastal Management and engineering, present day. Add: Undertake trial offshore nourishment as recommended in the sand sourcing study.
OTHER ISSUES….FOR NOW
- The introduction Page 2 makes no mention of the Maroochy River Estuary, its fish habitat reserve or the Maroochy River conservation park.
This reference to the Maroochy should be added to the Coastal environment Paragraph 2 on Pg., 2
- Should add to the second last paragraph on pg.,2 “enjoying the recreational benefits of our estuaries” as another reason for people coming to our region.
- On pg., 18 in beach and foreshore assets there is no mention of the economic loss due to loss of our sandy beaches. There are studies which put a socio-economic value on sandy beaches and we feel there should be reference made to this economic loss.
- On pg., 28 under resilient homes there is no reference made to floor heights in new homes (e.g. houses on stilts). We feel floor heights should be a factor when building new homes in hazard areas.
 co-incident flooding The term flood coincidence is used to denote the simultaneous occurrence of floods in two (or more) rivers. The coincidence of flood flows in a mainstream and its tributaries may lead to catastrophic floods
See previous post-Have your say on Coast's future resilience