Contents

Executive Summary

1. Introduction

2. Climate Change and Coastal Hazards

3. The Legislative and Planning Context

4. Risk assessment

5. Integrating Coastal Hazard Assessment and Climate Change into Council Planning and Decisions

6. Monitoring and review

7. Relevant case law

Glossary and abbreviations

References and bibliography

Web sites

Appendix 1: Relevant legislation

Appendix 2: Hazard drivers and the effects of climate change

Appendix 3: The response of different coastline types to coastal hazards

4. Risk assessment

This chapter describes:

• the fundamental concepts of the risk assessment process;
• a framework for applying risk assessment to coastal hazards and climate change within the decision making process;
• a method for summarising and documenting the risk appraisal.

4.1 Introduction

A sound risk assessment process is fundamental to ensure that climate change is appropriately taken into account in local authorities' planning and decision-making processes.

The purpose of the risk assessment is to identify risks and hazards in the coastal area that may be induced or exacerbated by climate change, and to evaluate their effects and likelihood. This allows the risks and the responses to those risks to be prioritised and compared equitably with other risks, resource availability and cost issues.

This document recommends Risk Management standard AS/NZS 4360 as the under-girding standard for all risk assessment procedures and processes relating to coastal hazards in a changing climate.

It is important that your council decides and works within a pre-selected planning or response period before evaluating climate change-related risk. That is to say, it matters whether your council is considering a 50-year return period hazard or a 100-year return period event, and this needs to be consistent across all hazards under consideration.

Risk assessment can be appropriately commenced with an initial screening process. This can show whether climate change impacts are likely to be material for a particular council function, activity or service. Table 4.1 contains a list of questions which may ascertain whether adopting a risk based approach to incorporate coastal hazards and / or climate change is required. If the answer to any of the questions in Table 4.1 is 'yes' or 'maybe', then it is likely that the procedures outlined within this Guidance Manual may be of use.

Table 4.1: Screening assessment for coastal hazards

Characteristics	Issue	Yes	Maybe	No
Current driver	Is there an existing problem (e.g., erosion or inundation) that could be exacerbated by climate change?
Future driver	Is there a foreseeable problem that may be caused or exacerbated by climate change?
Complexity	Is this a complex issue (e.g., many different stakeholders, new suburb vs one house)?
Location	Could the location be sensitive to coastal hazards and / or the effects of climate change?
Duration	Does the decision involve a long-term, permanent change?
Extent	Does the decision involve substantial infrastructure or public services

How to undertake a suitable risk assessment process is briefly summarised below. A more detailed description is provided in the companion guidance manual "Climate Change Effects and Impacts Assessment".

4.2 Terminology

For the purpose of this Guidance Manual, the following definitions apply:

Risk:

the chance or likelihood (probability) of an event, such as a coastal hazard, occurring that will have an impact (or consequence) on something of value to the present and/or future community.

Hazard:

a source of potential harm to people and/or property. Examples are erosion or inundation.

Event:

a coastal hazard incident that occurs in a particular place during a particular interval of time. This is distinct from merely a 'storm event', for example; it is an event that perhaps occurs during a storm (e.g., erosion that occurs which results in loss of private property).

Consequence (or impact):

the outcome of an event, expressed qualitatively in terms of the level of impact. Consequences can be measured in terms of economic, social, environmental or other impacts.

Uncertainty:

exists where there is a lack of knowledge concerning outcomes. It may result from imprecise knowledge of risk (i.e., the hazards and / or the consequences), or where the 'relationship' between the hazards and the consequences is imprecisely known.

Probability:

the chance or likelihood of a particular event occurring (in relation to all other events within the same dataset). It is dimensionless and is normally expressed as a decimal or percentage (e.g., 1% of the time). Probability can refer to a specific time frame. For example Annual Exceedance Probability (AEP) refers to the chance of a particular threshold being equalled or exceeded in any one year. AEP is expressed usually as a percentage. For example, an AEP of 1% means there is a 1% chance that a particular threshold is equalled or exceeded in any one year. This terminology is now preferred over the use of the "return period" concept, which can be confusing when, for example, two 100-year return period events occur in successive years.

Event probability:

refers to the probability of a particular threshold (e.g., an extreme sea level of XX m above datum) being equalled or exceeded.

Return period:

can be approximated to the reciprocal of the AEP (e.g., a 2% AEP, in decimal form 0.02, would give a return period of 50 years). This terminology is not recommended - rather, the use of AEP is encouraged.

4.3 Fundamental concepts for the risk assessment process

There are several fundamental concepts that should be borne in mind in a risk assessment process. These are:

1. Risk varies over time. This reflects both the changing probability of the risk occurring, and the changing scale of consequence should the risk occur. For example, the factors below are likely to increase risk probability and impact over time:

• changing climate (both natural variability and longer term climate change);
• changing (usually intensifying) land use, sub-division or development;
• changing (usually increasing) value of human assets at risk; and
• changing natural defences, e.g., beach or dune width.

Consequently, a fundamental consideration when incorporating the risks associated with coastal hazards and climate change into the planning process is the notion of time. A risk may not exist at present but may evolve, for example due to climate change, over the duration of a particular decision. The time/horizon that must be considered (and how the risks may change within this timeframe) is, at a minimum, the lifetime of the development, service or infrastructure (this is discussed further in Section 5).

2. Risk varies spatially (again in terms of both probability and consequence), even over relatively small distances. For example:

• changing coastal morphology along a coast (e.g., open coast/estuary; sand beach/shingle beach), resulting in differing erosion rates, storm response etc;
• differing hinterland elevations, e.g., variation in inundation risk;
• varying land use, sub-division density, value of human assets; and
• cultural and environmental assets.

3. Risk assessment needs to be appropriate. It needs to be:

• conducted at a level of detail appropriate to the scale of the decision;
• consistent with the level of data or information available.

A tiered approach is normally adopted, as shown in Table 4.2.

Table 4.2: The tiered approach to determining the level of detail for the risk assessment

Tier	Description	Scope	Nature	Scale
1	Risk screening	Broad	Qualitative	Policy, national, regional, local, project
2	Qualitative & semi-quantitative risk estimation	Specific	Qualitative + quantitative	Policy, regional, local, project
3	Quantitative risk assessment	Specific, detailed	Quantitative	Local, project

This Guidance Manual is aimed primarily at performing a Tier 1 risk-screening assessment. The Tier 1 assessment should be able to be conducted chiefly by local authority personnel, but some input from coastal hazard specialists is desirable - as a minimum, regional council coastal hazard personnel should be consulted.

The risk-assessment procedure is also amenable to a more detailed Tier 2 assessment, where sufficient data or information is available to make informed choices on the likelihood and consequences. Some input from a suitably qualified and experienced coastal hazard specialist (possibly available from the regional council) is strongly recommended for a Tier 2 assessment.

Although the framework provided here should still be appropriate for a Tier 3 assessment, Tier 3 will require more detailed risk assessment methodologies than are described in this Guidance Manual, and specialist coastal hazard assistance will be required.

4. Risk needs to be communicated. The purpose of the risk assessment process is to aid decision-making,so the process needs to be communicated in clear and concise language. Within all risk assessments there is a need to:

• define the overall approach;
• clearly define all key assumptions made;
• identify all uncertainties and their potential impact of the overall decision;
• outline the scope and impact of any sensitivity testing;
• be accountable and transparent; and
• report in a way that the non-specialist can understand the significance of the results.

5. Uncertainty and the need for more detailed analysis of specific areas should be assessed.Many areas of risk assessment can only be partly covered by the approach detailed in the following sections. In any assessment of the occurrence and impact of coastal hazards and the influence of climate change, uncertainty will be a significant issue. Such uncertainty can be categorised under two headings:

• Natural variability, which refers to the randomness and longer-term "cycles" observed in nature. For example it is not possible to predict when the next 50-year return period storm-tide level will occur. A time period of 100 years could pass without observing such and event, but then two could occur within the space of a year; and
• Knowledge uncertainty, which refers to the state of knowledge of a physical system and our ability to measure it and reproduce the significant features within a model. For example not all the physics are understood of how climate change will affect future coastal erosion hazards and hence some assumptions need to be made to account for such effects.

A full assessment of uncertainty is beyond the scope of this Guidance Manual. However, it is important to be aware of where major uncertainty exists within the risk assessment process, and where such uncertainty could be reduced, for example by:

• more rigorous (or quantitative) risk assessment process (e.g., Tier 2 or Tier 3 type assessment);
• using a range of climate change scenarios (refer to the companion manual to this document "Climate Change Effects and Impacts Assessment") to better understand sources and range of uncertainties;
• use and interpretation of available datasets, e.g., sea-level data or beach-profile surveys, to provide quantitative predictions of extreme conditions;
• collection of additional data through a monitoring programme (see Section 6);
• use of numerical modelling tools (e.g., wave modelling) to simulate and extend existing measured datasets or to simulate hazard processes, e.g., inundation or coastal erosion; and
• use of scenario techniques where, based on the degree of uncertainty, a range of different scenarios are used to assess the range of possible outcomes. An example could be to assess the potential magnitude of future coastal erosion due to changes in the wave climate by assuming potential (but realistic) shifts in the wave climate.

It is important to clearly define where uncertainty exists and the possible steps that could be taken to reduce it. It may be that the scale of the decision does not warrant detailed investigation to reduce such uncertainty, or that adopting a precautionary approach is appropriate. Within the context of the Guidance Manual, adopting a simple rating system is often sufficient to communicate uncertainty, e.g.:

Low: Little uncertainty, confident that change / hazard / impact will occur.

Moderate: Some uncertainty.

High: Major uncertainty.

It is also important to identify which uncertainties have the most impact on the decision to be made. For example there may be high uncertainty on a particular issue, but if the issue is minor then the high uncertainty may not be particularly important.

4.4 Applying the risk assessment process

Figure 4.1 provides a format for conducting a risk assessment, concentrating on qualitative approaches to assessing risk. The remainder of this section introduces the various steps within the risk assessment process.

4.4.1 Step 1: Define the problem and establish the context

This step 'sets the scene' within which the risk assessment process takes place and the context within which coastal hazards and climate change effects fit. It involves defining what the local authority is responsible for, what it owns, what services it provides, its structure, and its objectives in relation to coastal hazards, and which of those may be affected by climate change, as well as those other facilities and structures that are essential to a community's functioning (e.g., schools, ports, lifelines etc).

It should take into account:

• mechanisms available (e.g., district, community, strategic plans etc);
• assets, functions and services provided; physical environment; stakeholders; organisational context (e.g., the staffing, locations, resources and systems availability, and goals/objectives).

It also should involve:

• defining the current or foreseen problem or activity to be undertaken (including assessment of the planning or response period (or "period of concern" - see Table 4.4)
• the climate change variables and climate change variability
• specifying the outcomes anticipated from the risk assessment process and how they will be used in planning and decision making.

Depending on the scale of the issue, the process may involve only one person (e.g. local authority planner), a few people, or all key personnel (e.g., local authority planners, chief building inspector, engineers, and emergency management co-ordinator, with input from regional council planners and scientists, and possibly other stakeholders such as tangata whenua, business people, local residents, and lifeline utilities managers such as Transit New Zealand).

Typical techniques that can be applied at this stage include:

• brainstorming;
• consultation exercises; and
• focus groups

This is a vital stage in the risk assessment process, as it is against these considerations that the significance of the risk and the appropriateness of the adaptation measures can be judged.

4.4.2 Step 2: Identify the relevant coastal hazards and climate change risks

The components of Step 2 could also be conducted by one person with a good overall knowledge of the area and issue, but preferably should include personnel with specialist technical or local knowledge.

Step 2.1: Identify the potential extent of the built and human environment within the coastal margin likely to be impacted by the development or issue under consideration and how this may change over time.

Step 2.2: Identify the coastal morphology and how it varies spatially over the area

This step involves characterising the coast in terms of its physical form (e.g. sandy beaches, cliffs, estuaries etc). (See also Appendix 3 for considering the response of different coastline types to coastal hazards).

Step 2.3: Identify the hazard types based on current and historical information

This step involves identifying the coastal hazards that could presently affect the existing coastal margin identified in Step 2.1 and identifying where different hazards may occur due to variations in the coastal morphology (Step 2.2).

In general the hazards will be categorised as:

• coastal erosion caused by storms and/or long term processes;
• coastal inundation caused by storms or gradual inundation from sea level rise; and
• coastal inundation caused by tsunami.

Step 2.4: Identify the long-term changes in coastal hazards due to climate change

This step involves identifying the particular drivers of the coastal hazards identified in Step 2.3 and the potential effects climate change could have on that hazard. It should take into account the planning horizon or timeframe over which the particular decision is to be applied (see Section 5). For example over a 100 year planning timeframe the potential for a particular magnitude of coastal hazard event occurring could increase substantially.

Step 2.3 should be re-visited to re-assess the hazard types in response to the potential effects of climate change.

Use a range of scenarios if drivers other than sea-level rise are important (e.g., sediment supply). Refer to the Guidance Manual on Climate Change Effects and Impacts Assessment for quantitative input.

4.4.3 Step 3: Analyse the risks

As with previous steps, this part of the risk assessment process should be undertaken in conjunction with people with specialist coastal knowledge (e.g., regional council or specialist consultants) or detailed analysis of historic data.

Step 3.1: Assess the consequences of the hazard occurring

The level of the impact (consequence) on the land, built environment, and people for each hazard scenario should be assessed. This can be achieved by assigning a level of impact, on a relative or scaling basis as outlined in Table 4.3. It may be appropriate also to use actual consequences (e.g., monetary values).

Table 4.3 Level of impact for locality/hazard scenario

Designation	Impact	Examples
1	Catastrophic	Huge financial losses involving many people and/or corporations and/or local government; large long-term loss of services; permanent loss of many people's homes; large-scale loss of employment
2	Major	Major financial losses for many individuals and/or a few corporations; some long-term impacts on services; some homes permanently lost; complete loss of an important natural environment
3	Moderate	High financial losses, probably for multiple owners; disruption of services for several days; people displaced from their homes for several weeks; major impacts on valued natural environment
4	Minor	Moderate financial losses for small number of owners; disruption of services for a day or two; moderate distress to some individuals; some impacts on significant natural environment
5	Insignificant	Minimal financial losses; short term inconvenience

The choice of the appropriate impact designation is somewhat subjective. However, as long as the approach is applied consistently for each locality or feature, the choice of the relative level of impact should be consistent.

Step 3.2: Assess the likelihood (or probability) of a particular hazard occurring

Having identified the potential hazards and the consequences if they occurred, the next step is to identify the likelihood (or the probability) of the particular hazard occurring and impacting on a particular feature (e.g., a road) or location (e.g., area to be subdivided). In doing this, the nature of the hazard is important. For example, inundation and tsunami hazards tend to be episodic events whereas coastal erosion can be episodic, periodic and/or continuous.

Information or data on hazard probabilities for a particular location should be used wherever it is available. However, for situations where it is not available, an assessment for each location could be made based on judgement of a knowledgeable individual or group. A suggested five-point scale for initial probability is given in Table 4.4.

When carrying out the likelihood assessment, the following questions should be considered:

• is there a history of hazard experience at this site? Can this history be objectively assessed to determine the likelihood of future impacts?
• are certain parts of the locality more exposed than others to specific hazards such as predominant winds/storm directions?
• is local knowledge based on an adequately long timeframe (e.g., how long ago was the last major storm and how large was it)?
• do other organisations have any relevant information?
• is the planning horizon sufficiently long (say >30 years) that climate change effects will increase the likelihood of the event?
• how will climate change affect the hazard?

Table 4.4: Probability scale for hazard event scenario

Designation	Likelihood	Description	Frequency of occurrence (IPCC definition)1
			Virtually certain (>99% chance that a result is true)
A	Almost certain	Is expected to happen, perhaps more than once during the period of concern	Very likely (90-99%)
B	Likely	Will probably happen during the period of concern	Likely (66-99%)
C	Possible	Might occur some time during the period of concern (50/50 chance)	Medium (33-66%)
D	Unlikely	Unlikely to occur, but possible (e.g., one in ten times the duration of concern)	Unlikely (10-33%)
E	Rare	Highly unlikely, but conceivable	Very unlikely (1-10%)
			Exceptionally unlikely (<1%)

Note 1: The IPCC definitions of likelihood are included for comparison - they are very similar to the scale recommended in this Manual.

To investigate the relative potential impact of climate change, it is suggested that this process be conducted firstly by assessing risks while ignoring climate change effects, and secondly, assessing risks while allowing for climate change effects. Use a range of scenarios if drivers other than sea-level rise are important (e.g., sediment supply). Refer to the companion guidance manual "Climate Change Effects and Impacts Assessment".

4.4.4 Step 4: Evaluate the risks

Based on the assessment of the potential consequence of a hazard occurring (Step 3.1), and the likelihood of it occurring (Step 3.2), the degree of risk can be determined. Use the results from Tables 4.3 and 4.4 to position the activity in Table 4.5 to give the risk of each hazard scenario. For example, an activity with moderate (3) consequence but which is likely to occur (D) has a moderate risk (M) - it should be included in the response planning but at a lower priority. Note that this is an example only, and each local authority may wish to independently decide the risk classifications and which squares are H, M, or L.

Table 4.5: Risk Table

	Consequence
Likelihood	1 (Catastrophic)	2 (Major)	3 (Moderate)	4 (Minor)	5 (Insignificant)
A. Almost certain	E	E	E	H	M
B. Likely	E	E	H	H	M
C. Possible	E	E	H	M	L
D. Unlikely	E	H	M	L	L
E. Rare	H		M	L	None

Legend:

E: Extreme risk; immediate action required.

H: High risk; high priority for action, begin planning as soon as practicable.

M: Moderate risk; include in response planning, but lower priority.

L: Low risk; minimal action likely to be required; monitor the situation.

None: Negligible risk; no response required.

It is important to stress that "no climate change" is purely hypothetical because climate change will occur - it is a question of "how much", not "if".

Again, the risk evaluation process should be carried out in two phases; firstly, ignoring the effects of climate change, then again, taking into account the effects of climate change. This may result in a different risk rating for the climate change and non-climate change scenarios. Using this approach, risks can be prioritised and different risks compared. Note also that the risks will change depending on how far the risk assessment looks into the future. Planning decisions need to be based on the risk over the entire expected lifetime of the development. New residential subdivisions are composed of houses with individually limited lifetimes, but are essentially there forever when the subdivision as a whole is considered.

There may also be a different risk rating assigned for different timeframes. For example, a risk may a have a consequence of 4 (minor), a present likelihood of D (unlikely), but will become possible (C) in the next 30 years, and B (Likely) in 100 years. As a result the risk rating will go from low to high in the next 100 years.

4.4.5 Step 5 - Assess appropriate response options to treat the risk

Steps 1-4 should result in a good understanding of the implications and risk of climate change impact on coastal areas. The next step is to assess how these risks should be responded to, and treat the risk. The options are addressed in Section 5 of this Manual.

4.4.6 Step 6 - Document and communicate risk and uncertainty

The hazard identification and the information about the risks identified should be documented in some way, as risks that may not be important at the outset may become significant at a later stage (e.g., as our understanding of particular issues related to climate change increases). A common method of documentation is in the form of a risk register. An example of a simplified risk register is provided in Table 4.6.

Table 4.6: Example of simplified 'risk register'

View an example of the simplified 'risk register' (large table)

4.5 Best Practice guidance - Risk Assessment

• It is recommended that a coastal hazard risk assessment incorporate the effects of climate change if the lifetime of the development, asset, infrastructure, or service function exceeds 30 years. Climate change effects should not be limited to sea-level rise, but include the potential effects of other climate changes outlined in this Manual and in the companion Climate Change Effects and Impacts Assessment.
• To evaluate climate change risks, use at least the most likely mid-range scenario for sea-level rise (it is recommended that council staff use a figure of 20cm by 2050 and 50cm by 2100). If a mid-range scenario indicates the potential for noticeable negative impacts, evaluate the sensitivity of this result by assuming both high-end and low-end scenarios for a range of climate and sea-level rise parameters and check the change in the resulting impacts.
• Climate change risks evolve over time, so note that your response options may become locked in if you delay decisions because a risk is low initially but will increase (due to existing use rights, or increasing costs of responses due to increasing development).
• Climate change risk assessment is most effective and presents the lowest costs if it is done in the context of an overarching plan review, asset or infrastructure upgrade or redesign.
• Use expert help to assess coastal hazards where the costs or significance of the development, asset or service in question is significant.

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