PLANNING FOR SUSTAINABLE COMMUNITIES RESILIENT TO NATURAL HAZARDS

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1 IPEWA Conference: 7 June 11 June 2015 PLANNING FOR SUSTAINABLE COMMUNITIES RESILIENT TO NATURAL HAZARDS Pathmanathan Brabhaharan Technical Principal, Geotechnical & Earthquake Engineering, Resilience Opus International Consultants, Wellington, New Zealand Dougal Mason Senior Engineering Geologist Opus International Consultants, Wellington, New Zealand Keywords: natural hazards, earthquake, planning, vulnerability, resilience, sustainability Abstract Sustainable communities need to be resilient to natural hazards. Recent natural hazard events such as the Canterbury earthquakes provide ample lessons and highlight the need for integrated planning for natural hazards. Planning with a long term view and a focus on resilience is fundamental to achieve resilience to natural hazards such as earthquakes, storms, tsunami, landslides, volcanic eruption. Such sustainable planning is required in a range of activities that are the responsibility of local authority planners and engineers. Planning for future urban growth taking into consideration the natural hazards etc, as well as guiding sustainable planning of development is important to achieve resilience. Local authorities have a major role in the planning of future communities including land use as well as infrastructure. Case studies illustrate how this could be achieved through best practice in planning for urban growth (land use considering liquefaction in Marlborough District), district planning (natural hazards in Queenstown) and development controls for future sustainability. In addition it is also important to understand the resilience of existing infrastructure and communities, and planning for toughening existing assets, emergency response and recovery, and integrated into strategic asset management and planning capital projects. Introduction Natural hazards such as earthquakes, tsunami and storms can cause extensive damage to the built and natural environment and loss of life. Recent earthquakes such as the Canterbury earthquakes in New Zealand, the 2008 Wenchuan earthquake in China, the 2011 Tohoku earthquake and tsunami in Japan, 2004 South Asian tsunami and the recent 2015 Nepal earthquake have all highlighted the devastation that can be caused by such natural hazard events. Sustainable communities need to be resilient to natural hazards that we are exposed to. Natural hazards themselves do not cause the extent of devastation. We contribute to the kind of destruction we experience, because of where we choose to locate our communities, how we locate and construct our infrastructure and how we plan and build our buildings. Local authorities and public works engineers, planners and managers have a huge influence in building sustainable communities. This is because of our responsibilities for planning where we locate our communities, planning much of our infrastructure and how the built environment is designed and built. In addition we can strongly influence major infrastructure and shape the resilience of our

2 communities. Local authorities exert this influence through town and country planning or urban planning, land use zoning, building control and resource consent processes, and through responsibility for water supplies, wastewater, local roads, flood defences, etc. Local authorities have a responsibility to ensure the resilience of our built environment and the sustainability of our communities that are exposed to natural hazards. Public works sector professionals need to take leadership and a proactive role in planning to ensure the resilience of communities to natural hazards. The Beichuan city in the Sichuan Province of China was devastated by the 2008 Wenchuan earthquake, see Figure 3. Beichuan city was located in a valley prone to landslides, flooding and amplified ground shaking (Yong et al, 2009). There were also large number of casualties in the event, and the city was deserted after the earthquake. It would have been impractical, if not extremely costly to design for the large landslides. Recent Natural Hazard Events In 2004, the South Asian tsunami devastated many coastal towns around the Indian Ocean in countries such as Indonesia, Thailand, India and Sri Lanka, causing major loss of life. Figure 3: Beichuan city after 2008 earthquake Figure 1: Devastation caused by 2004 tsunami In 2005, a storm event in Eastern Bay of Plenty caused debris flows in Matata, which caused extensive damage to the local village, see Figure 2. The community had settled on an existing alluvial fan that was geologically prone to such debris flow hazards. The Canterbury earthquakes in New Zealand caused extensive damage to the built environment. In particular, buildings and infrastructure in areas prone to liquefaction and rock fall were severely affected. This included the recently developed residential areas in Bexley in the eastern suburbs, see Figure 4. The damage from landslides in the Port Hills area is shown on Figure 5. Figure 4: Liquefaction damage to houses Figure 5: Debris flow destruction in Matata

3 The sustainability of communities susceptible to such extensive damage and /or loss of life is poor and needs to be improved. Not only does this cause a lot of hardship and grief to society, but also substantial resources are required to rebuild these communities, not just financial, but also scarce material resources. Sustainable communities therefore need to be resilient to natural hazards. Figure 5: Landslide damage in the Canterbury earthquakes Lessons from Canterbury Earthquakes A number of important lessons can be drawn from past natural hazard events that have caused extensive damage in the past decade. In some areas natural hazard events caused extensive destruction that would have been impractical or extremely costly to mitigate or design for by suitable engineering measures. Most buildings in Christchurch, for example, did not collapse, and hence their design had served their life safety objectives. However, many buildings were damaged beyond repair or were uninhabitable, and were demolished. This included relatively new buildings. At the same time some buildings survived and remained functional or were able to be quickly restored for continued use. Natural hazards plans exist for a number of urban areas, and that did not prevent areas such as Bexley in eastern Christchurch to be developed relatively recently. The Canterbury earthquake sequence caused extensive damage to underground utilities, and lifelines such as roads and bridges, particularly in areas subject to liquefaction and lateral spreading. It is important to learn from these events, and the take on board lessons that they provide for planning and development in the context of built environments. Sustainability Resilience Resilience is the ability to readily recover and return to its original form from adversity. The Community and Regional Resilience Institute (2013) defines resilience as the capability to anticipate risk, limit impact, and bounce back rapidly through survival, adaptability, evolution, and growth in the face of turbulent change. In our context, the built environment needs to be planned, located, built and developed in a way that reduces damage and the consequent effects on the functionality of the community, and in a form that enhances the ability to recover quickly. Brabhaharan et al (2006) illustrate the concept for resilience for the built environment as illustrated in Figure 6. before event Loss or reduction of Functionality Time for Recovery after event Figure 6: Resilience of the built environment To achieve greater resilience, it is important to focus on two aspects: 1) Avoid or mitigate the effects of natural hazards to minimise the impact and loss of functionality of society. 2) The form of the built environment and emergency preparedness should be such that functionality is able to be restored quickly after an event.

4 This requires attention to resilience by a range of professionals involved in the local authority or public works sector. Natural Hazards Maps It is important to understand and map the natural hazards and their consequences. For example earthquakes cause effects such as ground shaking, liquefaction, landslides, tsunami etc, and storms cause effects such as flooding, landslides, storm surge, debris flows etc. Such maps provide a fundamental tool for understanding the consequences of natural hazards to our built environment and society. The natural hazard maps are useful to provide information to professionals working in the local authority and lifelines sectors, and also the community itself, so that informed decisions can be made. Unfortunately, as illustrated by the Bexley suburb example above (Figure 4), the hazard maps that have been developed by local authorities have not been used to their full potential. It is not uncommon to observe development of land subject to potential severe hazards. It is important that the hazard understanding is used in planning for natural hazards and the consequent risks to infrastructure and the community. Figure 7: Liquefaction Ground Damage Hazard Map for Western Bay of Plenty A typical liquefaction induced ground damage hazard map for the Western Bay Plenty is shown on Figure 7. Such maps are very useful because it shows the effects of earthquakes on the ground conditions in the area causing liquefaction, but also the severity of ground damage, rather than the hazard in subjective terms such as low, medium, high. The quantum of ground damage predicted can be directly used to assess the damage to infrastructure. Planning for Natural Hazards The planning function of local authorities has a very important role to play in mitigating the effects of natural hazards. This is because through appropriate land use planning and planning controls, such as through the District Plan, the land can be used in ways consistent with their exposure to natural hazards. Severity of Impacts of Natural Hazards It is important to understand the severity of the impact of natural hazards on land use and

5 development. Appendix A shows a range of natural hazards of a particular district, in this case Queenstown, and the broad scale impacts of these hazards on different types of land use. The table suggests combinations of hazards and land use with high damage or loss of life consequences can be better managed by avoidance. As discussed above, some natural hazards have such a catastrophic impact on land use, and they are best avoided, rather than impose the cost of developing such land on society. Developing such land involves increased development costs, leading to increases in the cost of housing and other buildings, as well as infrastructure to service them. Trying to develop such land also leads to poor sustainability as scarce resources are used to make such land suitable for development. This includes land prone to major landslides, liquefaction induced lateral spreading, debris flows or tsunami. Some hazards are difficult to avoid, and their effects may be able to be mitigated by design, for example earthquake shaking. These may be already addressed by building codes and standards, or can specifically be addressed by rules in the District Plan, for example. environments. Used proactively ahead of development pressures, it enables local authorities to plan for a resilient future and manage expectations of land owners and developers as to the use of land in a sustainable manner. An example of good land use planning is the urban growth strategy for Blenheim, where the town had the opportunity to expand to the east southeast alongside the Opawa River. The Marlborough District Council had the area investigated by Opus, through geotechnical investigations and assessment. The study found the land to be prone to liquefaction and lateral spreading, which had the potential to lead to severe damage to future development or impose very high development costs and poor sustainability (Mason and Brabhaharan, 2013). An alternate area to the west (green) was identified based on the geology, investigated and found to have a significantly lower level of liquefaction hazard that the east (red), and was adopted by the Council for urban growth with appropriate planning controls, see Figure 8 and Appendix B. Land Use Planning Land use planning therefore is key to minimise the risk to the future development and society, and move towards a more resilient built environment. Zoning land considering natural hazards as one of the key criteria will enable: 1) Zoning relatively lower natural hazard areas for higher intensity built urban environment where building codes and standards can easily address the risks, eg ground shaking from earthquakes; 2) Zoning moderate hazards areas, where the risk to the built environment can be economically mitigated, for moderate intensity land use, with appropriate building controls; 3) Zoning higher hazard areas where the hazards can have severe effects on the built environment for low intensity land use. Land use zoning is a long term measure to improve the resilience of the future urban Figure 8: Urban Growth strategy modified (green) to exclude liquefaction and lateral spreading prone land to the east of Blenheim (red)

6 Existing Urban Areas Managing the resilience of development in existing areas is also important, but requires a different approach. The properties have existing use rights. This requires the use of District Plan rules and building control measures to ensure that the land is developed, taking into consideration the natural hazard risks involved. Provision of information and education would play an important part. Mason et al (2015) present an example in Wanganui where development of properties require consideration of the level of slope failure hazard, categorised as Land Stability Assessment (LSA) areas. Type A areas comprise land that is steep and shows evidence of instability, with a high risk of further instability and damage to property or life. The Council is discouraging subdivision and new dwellings in these high risk areas. Type B areas have marginal slopes, which have shallower slope angles but are still prone to instability, where the Council requires geotechnical investigations and detailed assessment of the slope stability hazards prior to any development proposal being submitted for resource consent. The investigations and assessment will determine the risk to property from landsliding, and whether the land is suitable for development, with mitigation measures implemented, or whether it is unsuitable for further development. There are also existing areas where natural hazards pose a high risk to existing property, where the sources of hazard are outside the property. A good example of this are the rock fall hazards in the Port Hill area, where rock fall sources from outside the properties caused damage to many properties such as that shown in Figure 9. Figure 9: Severe damage to house by boulders originating from outside property In a pre-hazard situation, we need to evolve integrated approaches to evolve solutions to such issues. This requires the collaboration of different various professionals from inside and outside of local authorities to evolve solutions. Such solutions may be restricting further development, or physical measures such as netting or protection bunds to protect from rock fall, or bunds to protect against debris flows. One of the few hazards, for which we have established systems for intervention to mitigate the risk from hazards is the case of flood hazards, where regional council flood protection teams proactively address this hazard. It would be useful to learn how we can extend this to other hazards affecting us. Resilient Infrastructure Infrastructure is an important element of our built environment. It is important for us to understand the resilience of our existing infrastructure, particularly lifeline infrastructure that is critical to the well-being of our communities. This will allow us to plan to improve our infrastructure, and this should become an integral part of asset management for such infrastructure (Brabhaharan, 2006). Functionality and Recovery Resilience requires consideration of the functionality of development in the aftermath of natural hazard events. This will vary significantly depending on the purpose of the development or building. If damage is expected in hazard events it would be prudent to consider how this will affect functionality and the time taken to recover from a loss or reduction in functionality. This requires a change in thinking in our planning, control and implementation of development, to take into consideration functionality and recovery. Integrated Approach The Canterbury earthquakes have highlighted gaps in early integrated practice, whether in achieving good land use planning, a collective approach to mitigating natural hazards or

7 ensuring that buildings that are appropriately sited, or appropriate building forms. Early integrated practice between various professionals who are involved in planning, forming and protecting our built environment is important to achieve greater resilience. Professionals of diverse background should be involved from a very early stage to work together in an integrated manner to achieve greater resilience. This includes: 1) Geoscientists 2) Planners 3) Council hazard analysts 4) Asset managers 5) Emergency managers 6) Engineers The different professionals should work together in an integrated manner from an early stage of development planning as illustrated in Figure 9. Such early engagement is important to develop a resilient built environment. Geoscientists Emergency Managers Figure 9: Integrated relationships important to achieve resilient built environments. Conclusions Planners Resilience and Sustainability Building Control Officers Engineers Hazard Analysts Recent events indicate the severe destruction that can be caused by natural hazards to our built environments. It also shows that some hazards are so destructive that in some instances it may be impractical or uneconomic to design or mitigate the risk to development. These events also show that resilience of our built environment is important to build sustainable communities. The concept of sustainability is important when we address these natural hazards not only from the perspective of survival and functionality of society, but also considering the use of scarce resources to mitigate such hazards. Land use planning becomes a very critical tool to enhance future resilience of our built environment subject to severe impacts from natural hazards, while ensuring that the development is sustainable. The paper illustrates an example where the urban growth strategy for Blenheim took into consideration resilience in earthquakes and sustainability, and avoided land subject to lateral spreading. Managing the resilience of existing built environments is more challenging, and requires a variety of measures such as District Plan rules, similar to that adopted to manage slope hazards in Wanganui, and building control. Managing the risk to the existing built environment from some hazards requires fresh thinking by different professionals working together, so that we can address hazards such as rock fall or debris flows from a societal perspective. These hazards coming from outside properties cannot be effectively dealt with on a property by property basis. To achieve true resilience, we also need to consider functionality and recovery when planning, controlling and building our built environments, as we realise that resilience is a function of reducing loss of functionality and the ability to recover quickly and readily. We also need to understand the resilience of our infrastructure, and proactively enhance resilience by incorporating resilience initiatives into our asset management planning. Achieving sustainable and resilient built environments requires different professionals and disciplines from within and outside local authorities to work together to consider natural hazard issues from an early stage planning to development and operation.

8 References Brabhaharan, P (2006). Recent Advances in Improving the Resilience of Road Networks. Annual Conf. NZ Society for Earthquake Engineering. Napier, March Mason, D and Brabhaharan, P (2013). Land use planning for Blenheim, considering earthquake geotechnical hazards. Proc 19th NZ Geotechnical Society Symposium, Queenstown, November Mason, D, Brabhaharan, P and Frampton, M (2015). Land Use Planning for Slope Instability Hazards in Wanganui. ANZ Conf. Wellington.

9 Appendix A Impacts of Hazards in Land Use Planning Table 1 Natural Hazard Consequences to Different Land Uses LAND USE Effects RURAL RESIDENTI AL COMMERCIA INDUSTRIAL L RESIDENTI AL CRITICAL INFRASTRUC TURE EDUCATI ON Very Low Minor Damage Flooding Fault Rupture. Liquefaction Flooding Flooding CONTRO L RULES TO Medium Property Damage Landslides EQ induced Landslides? Lateral spread Flooding Liquefaction Flooding Fault Rupture Liquefaction Liquefaction AVOID High Structural Damage v. High Loss of Life Erosion River/ Alluvial Fan Debris Flows Fault Rupture Landslides Liquefaction/ Lateral Spread Erosion/Alluvial Fan EQ Landslide. Debris Fault Rupture Landslides Liquefaction/ Lateral Spread Erosion/Alluvial Fan EQ Landslides. Debris Liquefaction Lateral Spread Erosion/Alluv ial Fan Landslides EQ Landslides. Debris Fault rupture landslides Erosion/alluvial fan EQ Landslides. Debris Appendix B Urban Growth Strategy for Blenheim

10 Author Biography Brabhaharan is a Technical Principal at Opus, specialising in Geotechnical and Earthquake Engineering and Resilience, and provides technical direction to professionals operating these areas from across New Zealand and globally. He has a degree in civil engineering, a masters degree in geotechnical engineering and a MBA in technology management. Brabha has over 32 years experience, including 26 years based in New Zealand. He has been involved in the development of a variety of infrastructure and buildings across all sectors, and has been involved in the assessment and mapping of natural hazards, understanding the risks to the built environment, and developing and implementing strategies to enhance resilience. P Brabhaharan Opus International Consultants Ltd PO Box Wellington Brabha@opus.co.nz