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1. Introduction

This chapter:

  • explains the key role that local authorities play in coastal hazard management;
  • sets out the objectives, scope and structure of the Guidance Manual;
  • introduces a risk-based approach to managing coastal hazards.

1.1 The role of local authorities

A good proportion of New Zealand's development has occurred in coastal areas, some of which are vulnerable to erosion and inundation. As coastline development intensifies and property values increase, the potential impacts of coastal hazards also increase.

Climate change will not introduce any new types of coastal hazards, but it will affect existing coastal hazards by changing some hazard drivers.

The effects of climate change will increase coastal erosion and inundation in many areas, and will thus further increase the impacts of coastal hazards.

In attempting to achieve sustainable management of the coast (as required under Section 6 of the Resource Management Act), local authorities face increasing pressures and difficulties, such as:

  • the need to provide for the natural character and the ecological, landscape, amenity, and cultural and spiritual values of the coast;
  • the increasing social, economic and political pressures to intensify use and development of coastal areas, particularly with respect to redevelopment and sub-division;
  • the lack of regional or nationwide strategic planning processes to manage the long-term risks associated with coastal hazards in a sustainable manner;
  • the public's perceptions of existing use rights, permanence of property, and local government responsibilities for protection from impacts of coastal hazards;
  • the lack of guidance on the range of land-use management options available and how to apply them effectively over longer planning horizons; and
  • the complex nature of assessing risks associated with coastal hazards and climate change, and the lack of a decision-making framework using uncertain knowledge.

Figure 1.1: Effects of coastal erosion adjacent to a tidal inlet. (Note railway-iron stakes offshore - an earlier attempt to protect shoreline.)

Coastal erosion can result in coastal dwellings being undermined and falling into the sea. In this case railway-iron stakes had been driven vertically into the shore, but they failed to halt the erosion. [Source: R.K. Smith].

Figure 1.2: Coastal inundation from a high storm-tide.

Showing coastal flooding of a road in Southland. [Source: Southland Times].

Climate-change effects are very gradual. However, land-use planning decisions usually have long-term horizons because of the permanency of structures (e.g., buildings, roads, network utilities etc). Climate-change effects will therefore eventually have major implications for those decisions. It is vital that planning begins now for climate change effects, particularly where decisions are being made on issues and developments that have planning horizons and life expectancies of 50 years or more.

Territorial authorities' role in addressing the effects of climate change on coastal hazards (and managing coastal hazards in general) stems from:

  • land-use planning, subdivision consenting and building permitting functions (including the need to take natural hazards into account in these processes);
  • infrastructure planning, construction and maintenance; and
  • natural hazards management, education and response.

Regional councils' role stems from:

  • responsibilities for the avoidance and mitigation of natural hazards; and
  • responsibilities (in conjunction with the Minister of Conservation) for controlling the effects of the use of land and water in and adjacent to the coastal marine area.

Accordingly, coastal hazards should be taken into account by:

  • considering coastal hazards and climate variability and change in the preparation of district and regional plans, and when considering individual proposals for development and subdivision;
  • recognising that the natural coastal margin (beach, dunes, cliffs and immediate hinterland) has a natural role of defence against the sea;
  • consulting with the community when sustainable response options need to be considered to protect, adapt or retreat from worsening coastal hazard impacts;
  • applying the precautionary principle to the decision-making process where uncertainty exists, so that risk is minimised with 'no regrets'; and
  • providing information to the public about the risks of development within the coastal margin.

1.2 Aims and objectives of the Guidance Manual

This Guidance Manual aims to strengthen the integration of coastal hazards and climate change within the land-use planning process. The key audience is local authority staff (policy and planning staff, consents staff and engineers), but it will also assist consultants, policy analysts, and other interested individuals.

The primary objectives of the Guidance Manual are to:

  • provide regional and territorial authorities with information on the key effects of climate change on coastal hazards;
  • provide a decision-making framework to assess the associated risks;
  • provide criteria to appraise and decide on appropriate responses to the risks.

The main purpose of the Guidance Manual is to address the effects of climate change on coastal hazards. However, it also aims to help local authorities identify, assess and respond to coastal hazards generally.

This document is a companion to the "Overview of climate change effects and impacts assessment" Guidance Manual (NZCCO, 2004). The Overview Guidance Manual is an 'umbrella' document that addresses the range of effects of climate change on the whole range of local authority functions. Readers of the Coastal Hazards Guidance Manual should also refer to the Overview Guidance Manual. [Note that the term 'Guidance Manual' in this document always refers to this Coastal Hazards Guidance Manual rather than the Overview Guidance Manual, unless stated otherwise].

The Guidance Manual addresses the three main types of coastal hazards:

  • 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.

1.3 Managing coastal hazards: a risk-based approach

The overall process recommended for managing coastal hazards, including climate change effects on those hazards, is summarised in Figure 1.3. The steps highlighted in blue comprise a risk assessment process, which has been adopted in this Guidance Manual to assist local authorities in decision-making by addressing the following questions:

  1. What coastal hazards and climate-change risks are important to the decision?
  2. What are the possible consequences and impacts of "doing nothing", and should climate change influence the decision?
  3. What and where are the most vulnerable localities in the district or region?
  4. What response options are available?
  5. Within the wider community or region, what response options are most appropriate to manage the risks?

Figure 1.3: The process of managing coastal hazards, including climate-change effects

Thumbnail of image. See figure at its full size (including text description).

A key feature of coastal hazards and associated risks is that they are not constant, but change over time. Risk management decisions therefore need to be based not only on the current risks, but incorporate changes over the lifetime of the infrastructure or building in question. The effects of climate change typically become relevant whenever the lifetime of the development exceeds 50 years.

As part of the risk assessment process, guidance is provided on assessing numerical values for various coastal hazards, but this is intended purely to assist with prioritising hazards. The methods suggested must not be used for design purposes, which require more detailed and site-specific assessments.

1.4 Structure of the Manual

This Guidance Manual is set out as follows:

  • Section 2 covers what is known about climate change, the main causes of coastal hazards, and the likely effects of climate change on those coastal hazards.
  • Section 3 summarises the legislation that is relevant and/or requires the assessment of coastal hazards and climate change. It also sets out the key values and significance of the coastal environment, which need to be borne in mind in any decision-making process.
  • Section 4 sets out the appropriate process of how to go about assessing risks in the coastal area from climate change-induced hazards.
  • Section 5 is the critical part of this Manual. After identifying the hazards (Section 2) and determining the risk (Section 4), Section 5 provides a range of options of how local authorities can respond to those risks and hazards. Specifically it identifies:
    • the range of functions local authorities undertake that may need to take climate change-induced effects into account;
    • the range of planning options available to local authorities as a means of responding to the climate change and coastal hazard issues (e.g., set-back areas, relocation, retro-fitting etc). These are provided both for undeveloped ('greenfield') areas, and for areas where development is already in place;
    • the mechanisms available to put the above response options into place (e.g., plans, policy documents, resource consent decisions etc).
  • Section 6 outlines the basic requirements of a monitoring programme, given that the effectiveness of any planning response must be able to be monitored and reviewed in an ongoing and iterative process.
  • Section 7 incorporates the most relevant case law about responding to climate change effects.

Note that although considerable technical detail is provided in the Guidance Manual, coastal hazard processes are often complex and site-specific, so any detailed assessment must involve an experienced coastal hazards practitioner.