Goal: To develop a systems understanding of coastal vulnerability assessment, supporting more targeted and flexible use of available methods. It is hoped that this 'professional research' will help facilitate coastal planning for Western Australia.
Background & Motivation: It is now 25 years since the IPCC Common Methodology was first applied to the Western Australian coast (Kay et al. 1992) to look at the challenge presented by sea level rise to longer-term coastal management. This assessment, like other applications of the Common Methodology, highlighted that there were local attributes which should be considered when transferring the findings to planning policy. This broad finding was equally supported by the Australian Coastal Vulnerability Assessment Project (Waterman 1996), in which a series of case studies around the Australian coast integrated locally relevant coastal hazard assessment with response to sea level rise.
Despite scientific recognition of diversity, the concurrent trend in coastal management policy was towards unification of approach, with most Australian State Governments outlining very similar methods for calculation of coastal hazard zones (Walsh et al. 2004). Consequently, it is unsurprising that the National Coastal Vulnerability Assessment, NCVA (DCC 2009) applied a uniform method of estimating coastal hazard. However, it is arguably equally unsurprising that the results of the NCVA were strongly related to coastal morphology, matching the broad findings of the previous ACVAP. Subsequent research has highlighted the range of techniques available for coastal vulnerability assessment (Woodroffe et al. 2012), but to date, selection of techniques is more commonly driven by information availability and budget than by underlying processes. National classification schemes such as the Australian Beach Classification (Short 2006) and Australian Sediment Compartments Project (Thom et al. 2016) are possibly synergistic with the vulnerability assessment methods, but presently require more detailed consideration before such application.
At a State Government level, similar pressures of scientific divergence and policy-based unification have applied to the evaluation of coastal hazards, through development and application of the State Coastal Planning Policy SPP2.6 (WAPC 2001, 2003, 2013). Efforts to create flexibility within the policy to account for coastal diversity have been partly stymied, either by the perceived need for firm regulatory frameworks, or the commercial benefits accrued by using a repetitive process of assessment.
The present format of SPP2.6 has been developed to incorporate risk management frameworks, through development and application of Coastal Hazard Risk Management and Adaptation Plans (CHRMAP) for sites deemed exposed to coastal hazard. Recognition of the need for flexibility is incorporated in the CHRMAP guidelines (WAPC 2014), which follows from local government applications to support coastal management decision-making (CZM & Damara WA 2008, 2011; CZM et al. 2013, Damara WA 2013). However, regulatory application of the policy has demonstrated the difficulty of applying a flexible approach, with focus on statistically robust hazard assessments and limited attention paid to the basis for adaptive decision-making.
Synthesis of previously completed coastal vulnerability assessments within Western Australia has suggested that more effective use of resources can be brought to CHRMAP development through systems understanding of the active processes, values, available information and decision-making objectives. Constraint potentially provided by each of these factors suggests the need to identify whether the CHRMAP should be strategic, targeted or detailed at an early stage. This project aims to develop frameworks and an evidence base to support cost-effective scoping of CHRMAP.
Coastal Vulnerability Scoping Presentations:
Application of coastal vulnerability studies has gradually widened from a strategic regional tool through to a site specific tool for local government decision making and adaptation planning. This has required increased study complexity, whilst also bringing a greater weight of expectation for any study. Comparison over a range of completed CVS provides insight into key study factors, some of the challenges faced, and degrees of freedom available to make the study more readily applicable. Key study factors are the values of interest; relevant time and space scales; and the corresponding processes which are active. These factors are intrinsic to the issue being assessed, and should be used as the basis for developing a CVS scope. Representation of these factors may vary significantly according to study methodology, affecting study accuracy. Challenges faced in CVS scoping that have been identified through recent studies include balancing policy with site-specific relevance, integrating regional and local-scales processes and finding a common metric for different hazards. Transparency regarding scenario setting, how uncertainty is recognised and the role of interventions is a potential means of increasing study value. For example, the transition between CVS for active management, planning and possible adaptation pathways is essentially related to increasing uncertainty and more severe scenarios. By distinguishing the contribution of uncertainty, a CVS can more readily be interpreted to provide information at multiple levels of coastal management.
Some preliminary points regarding CVS Scoping, largely derived from early applications of the CHRMAP Guidelines (WAPC 2014) and preceding approaches to coastal vulnerability assessment, including AGO (2007) 'Climate Change and Risk Management: A Guide for Business and Government'.
Coastal vulnerability studies undertaken that have informed this synthesis include:
Environment Australia (2000) Assessment and monitoring of coastal change in the Alligator Rivers Region, northern Australia. Supervising Scientist Report 157.
Eliot et al. (2005) Assessment & Development of Tools for Assessing the Vulnerability of Wetlands and Rivers to Climate Change in the Gulf of Carpentaria, Australia.
Coastal Zone Management & Damara WA (2008) Vulnerability of the Cottesloe Foreshore to the Potential Impacts of Climate Change.
GEMS (2009) Carnarvon Cyclonic Inundation and Coastal Processes Assessment.
Coastal Zone Management (2010) Cocos & Christmas Islands Coastal Vulnerability Assessment.
Damara WA (2011) Coastal Erosion Study: Assessment of Climate Change Impacts. Prepared for the Shire of Busselton.
Damara WA (2011) Karratha Coastal Movement Study.
Acil-Tasman Pty Ltd (2012) Climate Change Adaptation Options Assessment - Developing Flexible Adaptation Pathways for the Peron-Naturaliste Coastal Region of Western Australia. Prepared for the Peron-Naturaliste Partnership.
Coastal Zone Management, Damara WA, University of Western Australia & Oceanica (2013) Cockburn Sound Coastal Alliance Coastal Vulnerability Study: Erosion and inundation assessment report
Damara WA (2013) Point Samson Foreshore Assessment. For Point Samson Community Association.
Damara WA (2013) Coastal Hazard Mitigation. 25-27 Second Avenue, Onslow. Megara Constructions Pty Ltd.
Damara WA (2016) Shire of Harvey Coastal Hazard Risk Management and Adaptation Plan.
Other Documents & Presentations:
2006: Coral Bay Inundation Modelling and Setbacks (Presentation)
2010: WA Estuaries and Coastal Wetlands: Physical Impacts of Climate Change (Presentation)
Investigation of historic beach and dune field evolution was undertaken, to develop a probabilistic model of future shoreline change, to be used for coastal vulnerability assessment of foreshore infrastructure at Scarborough Beach. The analysis compared long-term records with previous studies of beach width, to describe relationships with key climate variables. A major finding of the investigations was the significant role of annual alongshore wind anomalies in beach growth or recession.
2012: Cockburn Sound Coastal Vulnerability Study (Presentation)
This presentation summarises investigations and modelling regarding coastal hazards active in Cockburn Sound and Owen Anchorage, as part of Phase I of the Cockburn Sound Alliance Coastal Vulnerability Assessment.
The Study Brief for this project established an aim to: “Provide strategic planning guidance, management strategies and direction on appropriate land uses for future subdivision and development of coastal land in the Mid West, inclusively from the Shire of Coorow to the Shire of Northampton, by the identification of sediment cells that define coastal stability and susceptibility to change in the coastal zone".
The Study Brief for this project established an aim to: “Provide strategic planning guidance, management strategies and direction on appropriate land uses for future subdivision and development of coastal land in the Shire of Gingin and the Shire of Dandaragan, by the identification of sediment cells that define coastal stability and susceptibility to change in the coastal zone".
This coastal hazard management plan has been prepared on behalf of the City of Stirling to cover the area encompassed by the Scarborough and Environs Area Strategy (SEAS) Masterplan.
2013: Geology, Geomorphology & Vulnerabilty of the Pilbara Coast, in the Shires of Ashburton, East Pilbara and Roebourne, and the Town of Port Hedland, Western Australia
This project identifies land systems and the landforms they contain that are likely to alter in response to changes in meteorologic and oceanographic processes along the Pilbara coast between Hope Point in Exmouth Gulf and Tryon Point north of Eighty Mile Beach. The examination was focussed on: (a) provision of regional planning guidance, management strategies and direction on appropriate future use of coastal land broadly in the Pilbara through the identification of compartments defining coastal stability and susceptibility to change; and (b) determination of the vulnerability of landforms in greater detail for those coastal sediment cells which include areas of planning interest. Changes of interest are those occurring over two time scales: observable landform changes presently taking place over sub-decadal time scales; and those projected to occur over a planning horizon of 100 years. Both may be locally obscured by the geological and geomorphological inheritance prevalent along the region’s coast. The study helps to inform regional coastal planning for the Shires of Ashburton, East Pilbara, Roebourne and the Town of Port Hedland. A key task was to provide a high level assessment of coastal land systems and landforms (tertiary coastal compartments) potentially threatened by natural variation in metocean processes or which may be affected by projected climate change. This task builds on the approach developed for the coast from Moore River to Exmouth (Eliot et al. 2011b, c, d) for assessing coastal vulnerability to changing metocean processes that is applicable and consistent across a wide range of planning scales.
This report provides a coastal vulnerability assessment for four communities near to Cape Naturaliste, being Smiths Beach, Yallingup, Bunker Bay and Eagle Bay. It has been developed to support the City of Busselton develop a Coastal Hazard Risk Management and Adaptation Plan (CHRMAP), which will set out the long-term management of assets and land-use exposed to coastal hazards. The public text extract discusses variation of assessment approaches, including the inclusion or exclusion of different coastal processes.
This assessment evaluates the potential scale and extent of locations affected by coastal erosion in Western Australia over the short (0-5 year) and medium (5-25 year) terms. This supports State and local coastal managers' strategic planning for impacts of coastal erosion and confirms the requirement to plan for erosion hazard and adaptation for each hotspot. Management and adaptation options presented are a guide only, and do not replace the need for dedicated comprehensive Coastal Hazard Risk Management and Adaptation Planning for locations subject to coastal hazards.
2021: Non-standard Coastal Hazard Evaluations Estuaries & Other Cases (Presentation)
Coastal hazards affecting the Shire of Murray foreshores have been assessed, to support development of a Coastal Hazard Risk Management and Adaptation Plan (CHRMAP). The Shire is located on the eastern sides of Peel Inlet and Harvey Estuary, with foreshore along the banks of the lower Murray and Serpentine Rivers. The Shire’s foreshore is substantially undeveloped, with urban development at Yunderup along the lower Murray, including South Yunderup Canal Estate, and a low-density semi-rural development at Birchmont, adjacent to Harvey Estuary. Evaluation has focused on the coastal hazards of erosion and inundation, which are the two principal hazards requiring assessment under the State Coastal Planning Policy SPP 2.6. General methods used for coastal assessment have been modified to account for the estuarine setting, including consideration of extremely low-lying land present in the lower Murray River and southern parts of Harvey Estuary. A further complication has been brought about due to opening of Dawesville Channel in 1994, which caused an abrupt change in estuarine water levels and consequently modified foreshore evolution. It is noted that the method is intended to provide ‘best-estimate’ hazard lines suitable for management triggers (i.e. CHRMAP application) rather than a conservative estimate of the coastal hazard zone, corresponding to Schedule One of SPP 2.6.