- Email: [email protected]
Clarence's adaptation journey
Ocean & Coastal Management 86 (2013) 119e123
Contents lists available at ScienceDirect
Ocean & Coastal Management journal homepage: www.elsevier.com/locate/ocecoaman
Clarence’s adaptation journey Ian Preece Environment and Sustainability, Clarence City Council, Rosny Park, Tasmania 7018, Australia
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 19 November 2013
The coastal communities of Clarence were increasingly concerned at the continual foreshore erosion and flooding which was occurring in their communities. Uncertainty surrounding the impacts of climate change through rising sea levels and severe storm events was of most concern to local residents. Council embarked on a program to assess these vulnerable locations and the resultant Integrated Assessment Report has provided Council with direction to act upon these concerns. Erosion hazard mapping based on 5 scenarios (present day, 2050 high & low and 2 100 high &low) and inundation mapping indicating the impact of rising sea levels for present day, 2050 and 2100 have been embedded into Council’s Planning Scheme. This provides a framework for developers and Council to account for potential impacts of climate change when planning development. The Integrated Assessment Report also provides recommended adaptive actions for Council to assess and consider for implementation. The Report identified 4 highly vulnerable locations and these have been Council’s focus over past years when implementing the recommendations. This paper describes the journey taken by Clarence City Council from the initial community concerns through to implementation of adaptation treatments. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction The City of Clarence is situated on the eastern shore of the River Derwent in Hobart, Tasmania, Australia. There is 191 km of coastline, with many coastal communities that are low lying and built on soft sediment foreshores. The coastal communities have experienced frequent inundation and storm surge events in recent decades. Clarence City Council received community concerns about the erosion of beaches and flooding events in these coastal communities. Uncertainty about the impacts of sea level rise and sustainable coastal management led Council to seek funding to undertake an assessment of its coastline to address these community concerns. In 2007 the Clarence City Council received funding from the Integrated Assessment of Human Settlements Sub-Program of the Australian Greenhouse Office (AGO) now Department of Climate Change and Energy Efficiency (DCCEE) Climate Change Adaption Program to undertake a coastal vulnerability assessment of its coastline. Council also received funding from the Tasmanian Risk Mitigation Fund through the State Emergency Service. The purpose of the vulnerability assessment was to provide an integrated assessment of risks derived from the impacts of climate change and to begin the process of selecting and implementing
E-mail address: [email protected]. 0964-5691/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ocecoaman.2013.10.008
effective adaptation strategies for priority areas of Clarence’s most vulnerable coastal locations. 2. The Integrated Assessment Report The Integrated Assessment Report began in mid 2007, this project was one of 5 climate change impact assessments funded through the AGO/DCCEE Climate Change Adaptation Program: Integrated Assessment of Human Settlements Sub-Program. Approximately $130,000 was awarded in grants from the AGO/ DCCEE and the Tasmanian Risk Mitigation Fund for the Integrated Assessment. The Council itself contributed approximately $300,000 and a further in-kind contribution of $200,000 bringing a total project cost of approximately $630,000. The purpose of the study was to provide an integrated assessment of climate change risk on coastal areas, which included; An investigation into community concerns at present day vulnerability to storm events at the beginning of the project; Consultation with community groups, real estate and insurance institutions and State Government agencies concerning their awareness and response to climate change issues; A review of literature covering experiences of similar issues relating to the impacts of climate change elsewhere throughout the world; An assessment of 18 localities and infrastructure within the City of Clarence which may be vulnerable to coastal hazards both at
120
I. Preece / Ocean & Coastal Management 86 (2013) 119e123
present and due to sea level rise and climate change into the future. Coastal hazards were assessed for the present day scenario, mid-range of 20 cm by 2050 and 50 cm by 2 100 scenarios and high range of 30 cm by 2050 and 90 cm by 2 100 scenarios; Investigation of adaptive management options in response to present and future coastal hazards; and Preparation of a communication plan to inform the community of the findings; initiate discussion about the preferred response and report on the community response. The Integrated Assessment Report consisted of 2 components, one being a socio-economic component and the other being a technical component. Project briefs were developed and tenders called for both components of the Integrated Assessment Report. The Water Research Laboratory (WRL) from the University of New South Wales was awarded the technical component and SGS Economics and Planning was awarded the socio-economic component of the Integrated Assessment Report. Both a Steering Committee and a Technical Reference Group were appointed to oversee the project. The Steering Committee comprised of representatives from Clarence City Council, WRL, SGS Economics and Planning, AGO/DCCEE, the Local Government Association of Tasmania (LGAT), and the Tasmanian Government’s Department of Primary Industries Parks, Water and the Environment (DPIPWE) and the State Emergency Service. The benefits of the technical reference group and peer review panel provided assurance to the integrity, robustness and legitimacy of the research and created strong branding to build community confidence in the project. This aspect of the project has been again utilised when implementing the recommendations of the report.
Table 1 Preferred outcomes and goals (SGS, 2007). Rank
Type
Measure
Yes %a
No %a
1
Mitig.
94
2
2
I
91
3
3/4/5
A
87
5
3/4/5
P
86
6
3/4/5
A
87
8
6
R
81
8
7
A/R
57
29
8
A
47
26
9
Anti- R
48
34
10 11
R A
Take further action to reduce the rate of sea level rise by attempting to cut greenhouse gas emissioins Publish and promote maps etc. showing areas at risk from storm surges and flooding Set up warning systems to alert residentes about potential storm events, including evacuation plans Put shoreline protection in vulnerable areas Introduce additional planning controls to protect property from the effects of storm surgers and flooding Limit housing development in areas at risk from sea level rise Make development in risk areas at the owner’s risk e with limited community liability Compensate house owners for property damage or loss due to sea level rise Continue to develop services, such as roads, water, sewage, in areas that are at risk Remove existing housing in high risk areas Compensate house owners for property depreciation to being located in defined risk areas
37 35
38 38
I e Inform, A e Accommodate, P e Protect, R e Retreat (all are adaptation measures). a The values do not add up to 100 because some respondents provided a response of ‘don’t know’.
2.1. Socio-economic component
2.2. Technical component
The initial community consultation was based on two principles. Firstly early engagement with the community was seen as essential to create ownership and involvement in the project whilst the second principle focused on what was the community’s knowledge and interests in climate change. The main tools used were 3 focus groups with key stakeholders, being Clarence residents living in coastal areas, Clarence residents living in non-coastal areas and local business owners in coastal areas and a phone survey for the broader community. The focus groups and key stakeholder interviews were conducted first and their responses helped form the questions for the phone survey. The phone survey participants were categorised by the proximity of their house to the coast, to provide differentiation between those that will be potentially more or less affected by the impacts of Climate Change. The phone survey obtained responses from 150 coastal residents and 150 non-coastal residents, with a further 20 local business owners interviewed. A key output of the Socio-economic component was the communities preferred outcomes and goals as can be seen in Table 1. In response to the survey question What do you think Council should do to address the issue of sea level rise and its likely impacts? Residents provided responses over a range from 5-yes definitely to 0 e don’t know for 11 prompted questions covering issues such as future development/planning controls, shoreline protection, information, compensation and cutting greenhouse gas emissions. The above results have guided Council in responding to climate change events in the foreshore areas. The strong community support (>80%) identified the top 6 outcomes and goals to be mitigate greenhouse gas emissions, provide information (maps), provide shoreline protection, introduce planning controls that protect from the impacts of climate change and limit development in high risk areas.
The study identified the various coastal processes that were impacting on the Clarence Coastline: Astronomical tides; Tidal anomalies caused by barometric setup, wind setup and coastal trapped waves; Ocean swell waves; Local wind waves; Wave setup; Wave run up and overtopping; Long shore sand transportation; and On shore and off shore sand transport. As a result of those processes, the following coastal hazards were considered:
Beach erosion and dune stability; Shoreline recession; Beach rotation; Unstable creek or lake entrances; Wind blown sand; Coastal inundation; Stormwater erosion; Climate change including sea level rise, changes to waves, wind and rainfall; and Sea water increasing into ground water table causing displacement of fresh water. A scientific and technical analysis of the above coastal hazards found that the majority of these did not pose a significant risk and as such, the majority of the report focused on 3 main hazards;
I. Preece / Ocean & Coastal Management 86 (2013) 119e123
coastal inundation, storm erosion and climate change including sea level rise, changes to waves, wind and rainfall. Based on IPCC (2007, 2011) and NCCOE (2004) estimates for global sea level rise the assessment modelled impacts using 5 scenarios: present day scenario, mid range of 20 cm by 2050 and 50 cm by 2 100 scenarios and high range of 30 cm by 2050 and 90 cm by 2 100 scenarios. Hazards were considered using a 100 year Average Recurrence Interval (ARI)/1% Annual Exceedance Probability (AEP) events. Key outputs from the assessment were an analysis of the impacts to properties due to coastal erosion, recession and inundation and were expressed in mapping, number of houses/buildings at risk and the value of houses/buildings at risk. Estimated costing for protection strategies were another key output. Table 2 shows the impacts to properties for inundation only. One of the planning scheme initiatives was to include a 0.3 m freeboard above the present day sea level as a component of the minimum floor level for developments. This was to provide an indication on how many current dwellings would be impacted by not including the 0.3 m freeboard allowance. Modelling to analyse the extent of inundation for each scenario was first applied using existing 2 m contours which were further refined with higher resolution LIDAR data (0.25 m contours) (Fig. 1). This accuracy enabled superior modelling of the potential effects of events such as storm surge and inundation and consequently more accurate hazard assessments. As a result of these hazard assessments, adaptive management options were recommended in the draft integrated report “Climate Change Impacts on Clarence Coastal Areas e 2008”. This report deals with issues over a 100 year timeframe, so whilst the maps indicate indicative levels of inundation and erosion hazards, this will not occur in the immediate future but over several decades. The initial adaptive management options to be dealt with first are; Planning controls: - Development applications to be assessed as “discretionary”; - Performance based assessment for the life of the structure; - Assessments at the cost of the developer by suitably qualified engineer; - Ensure access to and from the coast; - Ensure no off-site built and environmental impacts; - Adopting minimum floor levels; - Erosion setback distances; and - Erosion risk management plan. Physical works: - Sand nourishment; - Groynes; or - Rock revetment walls. Table 2 Indicative houses/buildings at risk due to inundation (WRL 2008). Indicative Houses/Buildings at risk due to inundation
Kangaroo Bay Bellerive Howrah Seven Mile Beach Roche’s Beach Cremorne Beach Clifton Beach South Arm Beach Glenvar Beach Opossum Bay Total Number Potential Improved Value ($M)
Present day depth>0.3 m
Present day all depths
2 100 High SLR all depths
0 2 0 0 101 15 9 2 0 0 129 65
8 13 2 0 161 95 21 5 0 0 305 153
23 61 9 84 491 118 26 8 0 0 820 410
121
Fig. 1. Lauderdale, inundation areas, from Ralphs Bay, north section (WRL 2008).
Ongoing monitoring; and 5 year reviews. The report identified 4 high priority locations having significant present day vulnerability, they being Roches Beach, Lauderdale, Ralphs Bay, Lauderdale, Ocean Beach, Cremorne and Pipe Clay Lagoon, Clifton Beach. A series of triggers form part of Council’s adaptive management process to raise awareness and response to risk issues before the risk becomes excessive, so Council can manage the risk as it develops. Council monitors its beaches for change which triggers action before the risk become excessive. 3. Project release The draft integrated report was released at a well attended press conference and was launched concurrently on Council’s website. Letters were sent to all the residents in the 18 vulnerable locations inviting them to comment on the draft report and attend public meetings to discuss issues of concern with Council and the consultants. The public meetings were well attended with considered and well informed issues raised. The Council was thanked for the initiative and the way it has communicated the information to the community. 4. Implementation of integrated report recommendations 4.1. Planning scheme amendment Derived from the “Climate Change Impacts on Clarence Coastal Areas e 2008 Report”, Council’s planning scheme was submitted to
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I. Preece / Ocean & Coastal Management 86 (2013) 119e123
the Tasmanian Planning Commission to amend one existing overlay (1) and add 1 new overlay (2), these being; Subject to Inundation Overlay; and Coastal Erosion Hazard Overlay. The amendment provides Council with the statutory authority to condition development applications that fall within the above overlay areas requesting developers to meet planning scheme requirements with respect to the impacts of sea level rise and coastal erosion. These requirements include building setbacks, minimum floor levels, appropriate engineering assessments and appropriate construction techniques. After a lengthy period of consideration and legal debate, the planning scheme amendment was approved by the Tasmanian Planning Commission in September 2011. Council will now be required to regularly assess and amend relevant information that will influence development applications as its coastlines continually change. The first of these was to reassess the hazard line along Roches Beach based on photogrammetry from the 1950’s to present day. This is a far more detailed analysis than contained in the original report and will require a further amendment to Council’s Planning Scheme. 4.2. Dune nourishment using beach scraping techniques One recommendation from the Integrated Assessment Report was to nourish the dunes to the extent of its availability and cost effectiveness. Council engaged WRL to assess and provide advice on the possibility of gaining sand by using beach scraping techniques to nourish the dune systems at Roches Beach, Lauderdale and Ocean Beach, Cremorne. The report “Dune Building using Beach Scraping Techniques” was presented to Council and adopted in February 2010. The main implications arising from the report were;
Level of dune to be present day 1% ARI; Increase dune volume to buffer against storm erosion; Sand quantity required to be 13 500 m3; and Estimated cost of $250,000 for both beaches.
Council has and continues to undertake bi-annual land surveys of Roches Beach and Ocean Beach and this has formed a continual picture of the impacts of storm events on the dune system. As the report used a survey from 2008, by the time the report was to be implemented there were further erosive storm events that altered the volumes required to nourish the dunes. There needed to be confirmation that there was sufficient sand present on the beach to be used for dune nourishment that would not have adverse effects on the bio-diversity and the beach amenity. Council commissioned a number of additional assessments and reports for the following: Bio-diversity assessment of inter-tidal zone; Sand profile assessment; and Off-shore sand source and bio-diversity assessment. Due to costs involved it was decided to focus on Roches Beach only, to be followed with a similar assessment of Ocean Beach once funds become available. The bio-diversity assessment, undertaken by Aquenal Pty Ltd, identified a high level of macrofaunal communities in the sand and made the following recommendations: Avoid top section of inter-tidal zone occupied by the highest percentage of macrofauna;
Adopt a mosaic approach to scraping, buffer zones around control points; and Undertake regular monitoring in subsequent years to determine the effect on sand recovery and macrofauna numbers. Aquenal Pty Ltd also undertook to assess the sand profile along the beach with the following findings: Sand depth is variable over the beach, therefore the scraping option becomes more difficult; Sand depth increases further north along the beach. The greatest depth of sand is found in the lower inter-tidal zone and therefore more difficult to obtain due to tidal influences. Both these assessments proved that obtaining sufficient sand from the beach by using beach scraping techniques was going to be difficult. An alternate source of sand was considered, it was known that a large amount of sand (60 000e90 000 m3) passed by Roches Beach heading north in the littoral drift, so possibly there could be large sand deposits off-shore that could be easily obtained. Council again engaged Aquenal Pty Ltd to undertake an assessment of the sand source off-shore and bio-diversity. The assessment area was determined by the parameters for pumping methods provided by a sand pumping contractor. A sufficient quantity of sand was located within the identified assessment area. This option is the most cost effective method to successfully nourish the dune system at Roches Beach. Discussion was had around the possibility of the construction of a trial groyne to not only trap sand from the littoral drift but to support the retention of sand on the dunes from the pumping source off-shore by bulking of the beach sand. WRL were engaged to undertake modelling of a trial groyne and the resultant recommendation was a single groyne of 45m in length to be located between Hadlow Road and Epping Park at the northern end of Roches Beach. 4.3. Legal advice and land management Land Management along the Roches Beach was becoming a thorny issue. The State Government has land management responsibilities at the southern and northern ends of Roches Beach, whilst Council manages the foreshore reserve in between. This issue has caused much angst amongst Council staff and local residents because the State Government has a different approach to the impacts of climate change than Council. Council is committed to respond to future storm impacts on the dune system whilst the State Government is reluctant to intervene with natural forces and therefore are not responding in any way to damage that occurs to the dunes. Local residents are frustrated at the differing responses to storm damage and are encouraging both Council and the State Government to resolve this impasse. The State Government’s response has been to offer ownership of the Crown Land to Council so that the entire coastal reserve is managed by a single authority, Council. Council has decided to request further considerations by the State Government before it will consider this offer, they being: How the State would protect Council from any legal liability, including known and uninsurable risks, in relation to the land or events arising from or contributing to by works Council may undertaken on the land, and How the State would compensate Council for the transfer of an additional, (an unquantifiable) cost burden which is currently the responsibility of the State.
I. Preece / Ocean & Coastal Management 86 (2013) 119e123
Council obtained a legal research report to guide it through the issues of potential liability associated with undertaking protective works along its coastline. The findings of this research are:
123
12 additional stepped accesses onto both Roches Beach and Ocean Beach. This has been at a cost of approximately $250,000 to achieve. 5. What does the future hold?
When undertaking development approvals, Council must ensure that its decision does not place new or existing properties at risk. Council is in a position to make well informed decisions about development applications due to the investigations and assessments that Council have undertaken. A cautious approach is recommended. Section 41 of the Civil Liabilities Act 2002 (Tas) make it possible that Council could elect to take no action to protect its coastline from natural forces and would incur no liability for that decision. Council has regularly informed the public and made available all information on the Council website regarding its intention and response to storm events. Once Council responds to damage with appropriate works then residents and prospective purchasers will rely upon the adequacy of those works. Council will need to ensure that the works are designed and constructed in a way that guarantees performance in accordance with design standards. Various reforms to the Land Use Planning and Approvals Act 1993 (Tas) LUPPA, are required to provide local authorities scope to place conditions on approvals to account for e Imposing time restrictions on a permit; e Developer to provide indemnity or financial guarantee against future legal liability; and e Require local authorities to provide consistent information about hazards associated with land within their jurisdiction.
5.1. Report recommendations Council plans to progress through the recommendations contained in the “Climate Change Impacts on Clarence Coastal Areas e 2008” report with the emphasis on investigation, assessment and community consultation on options for the medium to long term adaptive actions within its available resources. This approach will develop a pathway to the desired outcome and any immediate actions will have focus on the agreed medium to long term actions. 5.2. Ongoing monitoring Council will continue to survey the dune systems at Roches Beach and Ocean Beach. It will broaden this work to other vulnerable locations such as Bellerive Beach and Howrah Beach. Council is working with University of Tasmania to look at more accurate aerial photography that will provide a more visual outcome for communication purposes. This monitoring will provide 3D images showing the changes in the coast over a timescale and become a valuable tool to assist with the communication of the impacts of storm events along the beaches. 5.3. Community information Council will continue to make all relevant information available to the community via Council’s website www.ccc.tas.gov.au.
4.4. Storm event July 2011 Reference A storm event occurred in July 2011 that resulted in significant damage to the beaches in Clarence. At Roches Beach there was an average of 4.5 m eroded from the face of the dune. The event left a steep escarpment and coastal vegetation clung tenuously to the remaining dune. Council undertook to rehabilitate the dune face to provide stability to the dune and also support the remaining vegetation. This was achieved by pushing sand from above the inter-tidal zone onto the face of the dune. Council has also reinstated a long term stone revetment wall at the southern end of Roches Beach and installed
SGS Economics and Planning, UNSW Water Research Laboratory, 2009. Climate Change Impacts on Clarence Coastal Areas.
Further readings McDonald, J., 2011. Legal Issues for Local Government in Addressing Coastal Erosion Risks e a Research Report for Clarence City Council. Stevens, J., 2009. Climate Change Impacts on Coastal Areas (Submission for Tasmanian Engineering Excellence Awards). Watson, P., 2011. Integrated Social, Economic and Impact Spatial Mapping Case Study e Community Consultation and Cost Benefit Analysis.
Contents lists available at ScienceDirect
Ocean & Coastal Management journal homepage: www.elsevier.com/locate/ocecoaman
Clarence’s adaptation journey Ian Preece Environment and Sustainability, Clarence City Council, Rosny Park, Tasmania 7018, Australia
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 19 November 2013
The coastal communities of Clarence were increasingly concerned at the continual foreshore erosion and flooding which was occurring in their communities. Uncertainty surrounding the impacts of climate change through rising sea levels and severe storm events was of most concern to local residents. Council embarked on a program to assess these vulnerable locations and the resultant Integrated Assessment Report has provided Council with direction to act upon these concerns. Erosion hazard mapping based on 5 scenarios (present day, 2050 high & low and 2 100 high &low) and inundation mapping indicating the impact of rising sea levels for present day, 2050 and 2100 have been embedded into Council’s Planning Scheme. This provides a framework for developers and Council to account for potential impacts of climate change when planning development. The Integrated Assessment Report also provides recommended adaptive actions for Council to assess and consider for implementation. The Report identified 4 highly vulnerable locations and these have been Council’s focus over past years when implementing the recommendations. This paper describes the journey taken by Clarence City Council from the initial community concerns through to implementation of adaptation treatments. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction The City of Clarence is situated on the eastern shore of the River Derwent in Hobart, Tasmania, Australia. There is 191 km of coastline, with many coastal communities that are low lying and built on soft sediment foreshores. The coastal communities have experienced frequent inundation and storm surge events in recent decades. Clarence City Council received community concerns about the erosion of beaches and flooding events in these coastal communities. Uncertainty about the impacts of sea level rise and sustainable coastal management led Council to seek funding to undertake an assessment of its coastline to address these community concerns. In 2007 the Clarence City Council received funding from the Integrated Assessment of Human Settlements Sub-Program of the Australian Greenhouse Office (AGO) now Department of Climate Change and Energy Efficiency (DCCEE) Climate Change Adaption Program to undertake a coastal vulnerability assessment of its coastline. Council also received funding from the Tasmanian Risk Mitigation Fund through the State Emergency Service. The purpose of the vulnerability assessment was to provide an integrated assessment of risks derived from the impacts of climate change and to begin the process of selecting and implementing
E-mail address: [email protected]. 0964-5691/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ocecoaman.2013.10.008
effective adaptation strategies for priority areas of Clarence’s most vulnerable coastal locations. 2. The Integrated Assessment Report The Integrated Assessment Report began in mid 2007, this project was one of 5 climate change impact assessments funded through the AGO/DCCEE Climate Change Adaptation Program: Integrated Assessment of Human Settlements Sub-Program. Approximately $130,000 was awarded in grants from the AGO/ DCCEE and the Tasmanian Risk Mitigation Fund for the Integrated Assessment. The Council itself contributed approximately $300,000 and a further in-kind contribution of $200,000 bringing a total project cost of approximately $630,000. The purpose of the study was to provide an integrated assessment of climate change risk on coastal areas, which included; An investigation into community concerns at present day vulnerability to storm events at the beginning of the project; Consultation with community groups, real estate and insurance institutions and State Government agencies concerning their awareness and response to climate change issues; A review of literature covering experiences of similar issues relating to the impacts of climate change elsewhere throughout the world; An assessment of 18 localities and infrastructure within the City of Clarence which may be vulnerable to coastal hazards both at
120
I. Preece / Ocean & Coastal Management 86 (2013) 119e123
present and due to sea level rise and climate change into the future. Coastal hazards were assessed for the present day scenario, mid-range of 20 cm by 2050 and 50 cm by 2 100 scenarios and high range of 30 cm by 2050 and 90 cm by 2 100 scenarios; Investigation of adaptive management options in response to present and future coastal hazards; and Preparation of a communication plan to inform the community of the findings; initiate discussion about the preferred response and report on the community response. The Integrated Assessment Report consisted of 2 components, one being a socio-economic component and the other being a technical component. Project briefs were developed and tenders called for both components of the Integrated Assessment Report. The Water Research Laboratory (WRL) from the University of New South Wales was awarded the technical component and SGS Economics and Planning was awarded the socio-economic component of the Integrated Assessment Report. Both a Steering Committee and a Technical Reference Group were appointed to oversee the project. The Steering Committee comprised of representatives from Clarence City Council, WRL, SGS Economics and Planning, AGO/DCCEE, the Local Government Association of Tasmania (LGAT), and the Tasmanian Government’s Department of Primary Industries Parks, Water and the Environment (DPIPWE) and the State Emergency Service. The benefits of the technical reference group and peer review panel provided assurance to the integrity, robustness and legitimacy of the research and created strong branding to build community confidence in the project. This aspect of the project has been again utilised when implementing the recommendations of the report.
Table 1 Preferred outcomes and goals (SGS, 2007). Rank
Type
Measure
Yes %a
No %a
1
Mitig.
94
2
2
I
91
3
3/4/5
A
87
5
3/4/5
P
86
6
3/4/5
A
87
8
6
R
81
8
7
A/R
57
29
8
A
47
26
9
Anti- R
48
34
10 11
R A
Take further action to reduce the rate of sea level rise by attempting to cut greenhouse gas emissioins Publish and promote maps etc. showing areas at risk from storm surges and flooding Set up warning systems to alert residentes about potential storm events, including evacuation plans Put shoreline protection in vulnerable areas Introduce additional planning controls to protect property from the effects of storm surgers and flooding Limit housing development in areas at risk from sea level rise Make development in risk areas at the owner’s risk e with limited community liability Compensate house owners for property damage or loss due to sea level rise Continue to develop services, such as roads, water, sewage, in areas that are at risk Remove existing housing in high risk areas Compensate house owners for property depreciation to being located in defined risk areas
37 35
38 38
I e Inform, A e Accommodate, P e Protect, R e Retreat (all are adaptation measures). a The values do not add up to 100 because some respondents provided a response of ‘don’t know’.
2.1. Socio-economic component
2.2. Technical component
The initial community consultation was based on two principles. Firstly early engagement with the community was seen as essential to create ownership and involvement in the project whilst the second principle focused on what was the community’s knowledge and interests in climate change. The main tools used were 3 focus groups with key stakeholders, being Clarence residents living in coastal areas, Clarence residents living in non-coastal areas and local business owners in coastal areas and a phone survey for the broader community. The focus groups and key stakeholder interviews were conducted first and their responses helped form the questions for the phone survey. The phone survey participants were categorised by the proximity of their house to the coast, to provide differentiation between those that will be potentially more or less affected by the impacts of Climate Change. The phone survey obtained responses from 150 coastal residents and 150 non-coastal residents, with a further 20 local business owners interviewed. A key output of the Socio-economic component was the communities preferred outcomes and goals as can be seen in Table 1. In response to the survey question What do you think Council should do to address the issue of sea level rise and its likely impacts? Residents provided responses over a range from 5-yes definitely to 0 e don’t know for 11 prompted questions covering issues such as future development/planning controls, shoreline protection, information, compensation and cutting greenhouse gas emissions. The above results have guided Council in responding to climate change events in the foreshore areas. The strong community support (>80%) identified the top 6 outcomes and goals to be mitigate greenhouse gas emissions, provide information (maps), provide shoreline protection, introduce planning controls that protect from the impacts of climate change and limit development in high risk areas.
The study identified the various coastal processes that were impacting on the Clarence Coastline: Astronomical tides; Tidal anomalies caused by barometric setup, wind setup and coastal trapped waves; Ocean swell waves; Local wind waves; Wave setup; Wave run up and overtopping; Long shore sand transportation; and On shore and off shore sand transport. As a result of those processes, the following coastal hazards were considered:
Beach erosion and dune stability; Shoreline recession; Beach rotation; Unstable creek or lake entrances; Wind blown sand; Coastal inundation; Stormwater erosion; Climate change including sea level rise, changes to waves, wind and rainfall; and Sea water increasing into ground water table causing displacement of fresh water. A scientific and technical analysis of the above coastal hazards found that the majority of these did not pose a significant risk and as such, the majority of the report focused on 3 main hazards;
I. Preece / Ocean & Coastal Management 86 (2013) 119e123
coastal inundation, storm erosion and climate change including sea level rise, changes to waves, wind and rainfall. Based on IPCC (2007, 2011) and NCCOE (2004) estimates for global sea level rise the assessment modelled impacts using 5 scenarios: present day scenario, mid range of 20 cm by 2050 and 50 cm by 2 100 scenarios and high range of 30 cm by 2050 and 90 cm by 2 100 scenarios. Hazards were considered using a 100 year Average Recurrence Interval (ARI)/1% Annual Exceedance Probability (AEP) events. Key outputs from the assessment were an analysis of the impacts to properties due to coastal erosion, recession and inundation and were expressed in mapping, number of houses/buildings at risk and the value of houses/buildings at risk. Estimated costing for protection strategies were another key output. Table 2 shows the impacts to properties for inundation only. One of the planning scheme initiatives was to include a 0.3 m freeboard above the present day sea level as a component of the minimum floor level for developments. This was to provide an indication on how many current dwellings would be impacted by not including the 0.3 m freeboard allowance. Modelling to analyse the extent of inundation for each scenario was first applied using existing 2 m contours which were further refined with higher resolution LIDAR data (0.25 m contours) (Fig. 1). This accuracy enabled superior modelling of the potential effects of events such as storm surge and inundation and consequently more accurate hazard assessments. As a result of these hazard assessments, adaptive management options were recommended in the draft integrated report “Climate Change Impacts on Clarence Coastal Areas e 2008”. This report deals with issues over a 100 year timeframe, so whilst the maps indicate indicative levels of inundation and erosion hazards, this will not occur in the immediate future but over several decades. The initial adaptive management options to be dealt with first are; Planning controls: - Development applications to be assessed as “discretionary”; - Performance based assessment for the life of the structure; - Assessments at the cost of the developer by suitably qualified engineer; - Ensure access to and from the coast; - Ensure no off-site built and environmental impacts; - Adopting minimum floor levels; - Erosion setback distances; and - Erosion risk management plan. Physical works: - Sand nourishment; - Groynes; or - Rock revetment walls. Table 2 Indicative houses/buildings at risk due to inundation (WRL 2008). Indicative Houses/Buildings at risk due to inundation
Kangaroo Bay Bellerive Howrah Seven Mile Beach Roche’s Beach Cremorne Beach Clifton Beach South Arm Beach Glenvar Beach Opossum Bay Total Number Potential Improved Value ($M)
Present day depth>0.3 m
Present day all depths
2 100 High SLR all depths
0 2 0 0 101 15 9 2 0 0 129 65
8 13 2 0 161 95 21 5 0 0 305 153
23 61 9 84 491 118 26 8 0 0 820 410
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Fig. 1. Lauderdale, inundation areas, from Ralphs Bay, north section (WRL 2008).
Ongoing monitoring; and 5 year reviews. The report identified 4 high priority locations having significant present day vulnerability, they being Roches Beach, Lauderdale, Ralphs Bay, Lauderdale, Ocean Beach, Cremorne and Pipe Clay Lagoon, Clifton Beach. A series of triggers form part of Council’s adaptive management process to raise awareness and response to risk issues before the risk becomes excessive, so Council can manage the risk as it develops. Council monitors its beaches for change which triggers action before the risk become excessive. 3. Project release The draft integrated report was released at a well attended press conference and was launched concurrently on Council’s website. Letters were sent to all the residents in the 18 vulnerable locations inviting them to comment on the draft report and attend public meetings to discuss issues of concern with Council and the consultants. The public meetings were well attended with considered and well informed issues raised. The Council was thanked for the initiative and the way it has communicated the information to the community. 4. Implementation of integrated report recommendations 4.1. Planning scheme amendment Derived from the “Climate Change Impacts on Clarence Coastal Areas e 2008 Report”, Council’s planning scheme was submitted to
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the Tasmanian Planning Commission to amend one existing overlay (1) and add 1 new overlay (2), these being; Subject to Inundation Overlay; and Coastal Erosion Hazard Overlay. The amendment provides Council with the statutory authority to condition development applications that fall within the above overlay areas requesting developers to meet planning scheme requirements with respect to the impacts of sea level rise and coastal erosion. These requirements include building setbacks, minimum floor levels, appropriate engineering assessments and appropriate construction techniques. After a lengthy period of consideration and legal debate, the planning scheme amendment was approved by the Tasmanian Planning Commission in September 2011. Council will now be required to regularly assess and amend relevant information that will influence development applications as its coastlines continually change. The first of these was to reassess the hazard line along Roches Beach based on photogrammetry from the 1950’s to present day. This is a far more detailed analysis than contained in the original report and will require a further amendment to Council’s Planning Scheme. 4.2. Dune nourishment using beach scraping techniques One recommendation from the Integrated Assessment Report was to nourish the dunes to the extent of its availability and cost effectiveness. Council engaged WRL to assess and provide advice on the possibility of gaining sand by using beach scraping techniques to nourish the dune systems at Roches Beach, Lauderdale and Ocean Beach, Cremorne. The report “Dune Building using Beach Scraping Techniques” was presented to Council and adopted in February 2010. The main implications arising from the report were;
Level of dune to be present day 1% ARI; Increase dune volume to buffer against storm erosion; Sand quantity required to be 13 500 m3; and Estimated cost of $250,000 for both beaches.
Council has and continues to undertake bi-annual land surveys of Roches Beach and Ocean Beach and this has formed a continual picture of the impacts of storm events on the dune system. As the report used a survey from 2008, by the time the report was to be implemented there were further erosive storm events that altered the volumes required to nourish the dunes. There needed to be confirmation that there was sufficient sand present on the beach to be used for dune nourishment that would not have adverse effects on the bio-diversity and the beach amenity. Council commissioned a number of additional assessments and reports for the following: Bio-diversity assessment of inter-tidal zone; Sand profile assessment; and Off-shore sand source and bio-diversity assessment. Due to costs involved it was decided to focus on Roches Beach only, to be followed with a similar assessment of Ocean Beach once funds become available. The bio-diversity assessment, undertaken by Aquenal Pty Ltd, identified a high level of macrofaunal communities in the sand and made the following recommendations: Avoid top section of inter-tidal zone occupied by the highest percentage of macrofauna;
Adopt a mosaic approach to scraping, buffer zones around control points; and Undertake regular monitoring in subsequent years to determine the effect on sand recovery and macrofauna numbers. Aquenal Pty Ltd also undertook to assess the sand profile along the beach with the following findings: Sand depth is variable over the beach, therefore the scraping option becomes more difficult; Sand depth increases further north along the beach. The greatest depth of sand is found in the lower inter-tidal zone and therefore more difficult to obtain due to tidal influences. Both these assessments proved that obtaining sufficient sand from the beach by using beach scraping techniques was going to be difficult. An alternate source of sand was considered, it was known that a large amount of sand (60 000e90 000 m3) passed by Roches Beach heading north in the littoral drift, so possibly there could be large sand deposits off-shore that could be easily obtained. Council again engaged Aquenal Pty Ltd to undertake an assessment of the sand source off-shore and bio-diversity. The assessment area was determined by the parameters for pumping methods provided by a sand pumping contractor. A sufficient quantity of sand was located within the identified assessment area. This option is the most cost effective method to successfully nourish the dune system at Roches Beach. Discussion was had around the possibility of the construction of a trial groyne to not only trap sand from the littoral drift but to support the retention of sand on the dunes from the pumping source off-shore by bulking of the beach sand. WRL were engaged to undertake modelling of a trial groyne and the resultant recommendation was a single groyne of 45m in length to be located between Hadlow Road and Epping Park at the northern end of Roches Beach. 4.3. Legal advice and land management Land Management along the Roches Beach was becoming a thorny issue. The State Government has land management responsibilities at the southern and northern ends of Roches Beach, whilst Council manages the foreshore reserve in between. This issue has caused much angst amongst Council staff and local residents because the State Government has a different approach to the impacts of climate change than Council. Council is committed to respond to future storm impacts on the dune system whilst the State Government is reluctant to intervene with natural forces and therefore are not responding in any way to damage that occurs to the dunes. Local residents are frustrated at the differing responses to storm damage and are encouraging both Council and the State Government to resolve this impasse. The State Government’s response has been to offer ownership of the Crown Land to Council so that the entire coastal reserve is managed by a single authority, Council. Council has decided to request further considerations by the State Government before it will consider this offer, they being: How the State would protect Council from any legal liability, including known and uninsurable risks, in relation to the land or events arising from or contributing to by works Council may undertaken on the land, and How the State would compensate Council for the transfer of an additional, (an unquantifiable) cost burden which is currently the responsibility of the State.
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Council obtained a legal research report to guide it through the issues of potential liability associated with undertaking protective works along its coastline. The findings of this research are:
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12 additional stepped accesses onto both Roches Beach and Ocean Beach. This has been at a cost of approximately $250,000 to achieve. 5. What does the future hold?
When undertaking development approvals, Council must ensure that its decision does not place new or existing properties at risk. Council is in a position to make well informed decisions about development applications due to the investigations and assessments that Council have undertaken. A cautious approach is recommended. Section 41 of the Civil Liabilities Act 2002 (Tas) make it possible that Council could elect to take no action to protect its coastline from natural forces and would incur no liability for that decision. Council has regularly informed the public and made available all information on the Council website regarding its intention and response to storm events. Once Council responds to damage with appropriate works then residents and prospective purchasers will rely upon the adequacy of those works. Council will need to ensure that the works are designed and constructed in a way that guarantees performance in accordance with design standards. Various reforms to the Land Use Planning and Approvals Act 1993 (Tas) LUPPA, are required to provide local authorities scope to place conditions on approvals to account for e Imposing time restrictions on a permit; e Developer to provide indemnity or financial guarantee against future legal liability; and e Require local authorities to provide consistent information about hazards associated with land within their jurisdiction.
5.1. Report recommendations Council plans to progress through the recommendations contained in the “Climate Change Impacts on Clarence Coastal Areas e 2008” report with the emphasis on investigation, assessment and community consultation on options for the medium to long term adaptive actions within its available resources. This approach will develop a pathway to the desired outcome and any immediate actions will have focus on the agreed medium to long term actions. 5.2. Ongoing monitoring Council will continue to survey the dune systems at Roches Beach and Ocean Beach. It will broaden this work to other vulnerable locations such as Bellerive Beach and Howrah Beach. Council is working with University of Tasmania to look at more accurate aerial photography that will provide a more visual outcome for communication purposes. This monitoring will provide 3D images showing the changes in the coast over a timescale and become a valuable tool to assist with the communication of the impacts of storm events along the beaches. 5.3. Community information Council will continue to make all relevant information available to the community via Council’s website www.ccc.tas.gov.au.
4.4. Storm event July 2011 Reference A storm event occurred in July 2011 that resulted in significant damage to the beaches in Clarence. At Roches Beach there was an average of 4.5 m eroded from the face of the dune. The event left a steep escarpment and coastal vegetation clung tenuously to the remaining dune. Council undertook to rehabilitate the dune face to provide stability to the dune and also support the remaining vegetation. This was achieved by pushing sand from above the inter-tidal zone onto the face of the dune. Council has also reinstated a long term stone revetment wall at the southern end of Roches Beach and installed
SGS Economics and Planning, UNSW Water Research Laboratory, 2009. Climate Change Impacts on Clarence Coastal Areas.
Further readings McDonald, J., 2011. Legal Issues for Local Government in Addressing Coastal Erosion Risks e a Research Report for Clarence City Council. Stevens, J., 2009. Climate Change Impacts on Coastal Areas (Submission for Tasmanian Engineering Excellence Awards). Watson, P., 2011. Integrated Social, Economic and Impact Spatial Mapping Case Study e Community Consultation and Cost Benefit Analysis.