Skip to main content.

Archived publication

This publication is no longer current or has been superseded.

6. Monitoring and review

This chapter identifies:

  • the types and scope of coastal hazard monitoring;
  • the need for reviews of the risk and response options at agreed milestones.

6.1 Introduction

With the onset of climate change, effects on coastal hazards are likely to accelerate with time. As a result, any response strategy needs to be adjustable. As vulnerability may change with time, it is essential that appropriate monitoring is undertaken, interspersed with regular reviews or audits of the adaptation measures, and adjustments made where necessary.

Many monitoring and review programmes have foundered because the initial conceptual design of a tailored programme was not adequate. It is essential that a tight set of specific objectives is agreed on before designing a monitoring and review programme. Generic guidance on the conceptual design of monitoring and review programmes is available in publications such as NZWERF (2002) [Although this document relates to wastewater discharge monitoring, the monitoring principles are generic and can be applied to coastal hazards.].

Definitions

  • Monitoring is the regular gathering and analysis of information and data to detect any specific change. It can cover coastal "drivers", coastal environmental response, performance of response options, and societal perceptions of the risk or response options.
  • Reviews are agreed milestones where the coastal hazard risk, response options, adaptation needs and monitoring programme are re-assessed on the basis of updated monitoring information, and adjustments made where necessary.

With climate change likely to exacerbate coastal hazards, the risk assessment process provided by this Guidance Manual will help local authorities prioritise the effort on monitoring and reviews. Where there is a high degree of uncertainty of the risk, monitoring might be instituted as the first stage of a "response option", enabling a better chance of avoidance, before committing the community to a more expensive option in the future.

6.2 Designing monitoring programmes

Comprehensive monitoring of coastal environments is difficult and expensive, since the timescales of responses to natural "drivers" can vary from hours (e.g., storms) to decades (e.g., IPO cycles). The key is to provide sufficient resolution (time interval and distance) to be in a position to differentiate a "change" from "natural variability". This means that both the natural variability and the anticipated change need to be detectable and quantified before they can be separately identified. The "change" that requires monitoring can be:

  • the effect of climate change on a beach, shoreline or cliff e.g., possible alteration in long-term erosion due to an accelerating sea-level rise;
  • the effect of climate-change and sea-level rise on a selected response option that is implemented;
  • the effect of the selected response option on the environment e.g., the impact of a rock wall on natural character and public access, and the potential to exacerbate erosion via "edge" effects, downstream effects or beach loss in front of the structure;
  • the effect of a response option or the change of a beach or cliff system on the ability of communities to access, use and enjoy the coastal environment.

A well-designed coastal monitoring programme needs to address:

  • who should do monitoring? - specialist coastal hazards practitioners, local authority staff, a surveyor, the local community, iwi groups etc.
  • what should be monitored? - beach profile, beach width and volume, scour depths around protection structures, upper bluff, dune or cliff retreat, sand size and colour, sediment supply, wave climate, etc.
  • why should measurements be taken? - determine long-term change, judge effectiveness, etc.
  • when should monitoring occur? - monthly, annually, seasonally, etc.
  • where should monitoring occur? - specific locations, general areas, on-site, off-site, etc.
  • how should monitoring be done? - follow specified guidelines or procedures, visual inspections, etc.
  • so what? - results of monitoring; how are they presented; triggers for maintenance or reviews; evaluation of performance, etc.

It is recommended that a specialist coastal engineer or scientist be involved in setting the objectives for any monitoring programme and (depending on the scale and importance of the issues) determining the details of the programme. In some cases existing historical data owned by the council or other agencies may provide a valuable baseline, including the effects of natural climate variability, against which future changes can be compared.

Short Example 1 - Monitoring coastal erosion at Windy Cove

The objective is to assess, in the future, the risk of coastal erosion of the shoreline or to establish or revise a coastal erosion hazard zone (CEHZ). The main interest for territorial authorities is the vulnerability of the coastal-margin land above MHWS, but there is a strong link between the health of the beach and the degree of vulnerability to storm cut-back or long-term erosion. To monitor this situation, sufficient measurements of both the beach and backshore/dune at Windy Cove are required to establish the characteristic range of short-term fluctuations (at days to month timescales) and long-term trends (years to decades, and including sea-level rise).

The findings of Smith & Benson (2001) indicate that beach-profile surveying should be undertaken at least bi-monthly to render a true picture of short-term fluctuations, particularly to capture cut-back from large storm events and seasonal cycles. Long-term trends in shoreline movement can be obtained from annual beach-profile surveys, and can be complemented by historic rectified aerial photographs, longitudinal shoreline survey traverses, cadastral maps, and more expensive approaches such as remote-camera monitoring, aerial photogrammetry or LiDAR surveys, and ground-based GPS surveys.

Short Example 2 - Monitoring beach re-nourishment response option at Sandy Bay

A one-off beach re-nourishment scheme has been implemented as the initial response option to cope with an increasing coastal erosion problem at the well-established coastal resort of Sandy Bay. The ongoing impact and success of the scheme needs to be able to be assessed. The General Objective therefore is to measure the state before and after the commencement of the scheme (baseline monitoring), and relies on prior monitoring information for the locality. To achieve this, the monitoring programme for Sandy Bay needs to have a very Specific Objective. For example-"To determine, after the beach re-nourishment, if the state of the beach profile and dune-crest position recovers to the March 1998 benchmark situation and for how long, by monitoring profiles at two sites (X and Y)".

The detailed design of the monitoring programme to meet the specific objective would then specify details of sampling frequency, methodology, accuracy, repeatability, compliance conditions for an environmental monitoring plan, how the data is presented, triggers to determine when the March 1998 situation is re-gained, and what should be done next if it does not happen e.g., a review process.

Communities can be involved in the effects monitoring process in a variety of ways, such as:

  • involvement of community or iwi representatives in the actual monitoring activities, including data gathering and recording visual observations (perhaps as part of a beach or dune-care programme);
  • evaluation by the community of the monitoring results, and involvement in reviews;
  • monitoring the impacts of coastal hazards, climate change and "side-effects" of any adaptation option on people's perceptions of the risks and their usage and enjoyment of the coast.

6.3 Monitoring techniques

Table 6.1 outlines some of the types of coastal or estuary environmental monitoring that can be carried out to provide background information (e.g., to support a risk assessment) or to detect change. For more technical details on monitoring techniques, consult articles such as Gorman et al. (1998) and Morang et al. (1997).

Table 6.1: Summary of types and methods of coastal monitoring, with possible alternative sources of that information and a relative rating of cost.

View summary of types and methods of coastal monitoring, with possible alternative sources of that information and a relative rating of cost (large table)

6.4 Guidance on reviews and audits

Reviews or audits of a monitoring programme should be planned at pre-determined milestones or when pre-set trigger levels are reached. Review mechanisms should be built into a monitoring plan and any response strategy right from the beginning - at the stage of conceptual design and setting of objectives.

Reviews or audits are undertaken for a variety of reasons, such as:

  • checking compliance for the impacts of a response option;
  • peer-review of results, analysis and interpretation;
  • possible re-design of the scope, objectives or design of a monitoring programme;
  • being required as part of statutory consents;
  • checking the cost-effectiveness of the monitoring approach.

Objectives also need to be set for the review or audits of various components of a monitoring programme and should involve a specialist practitioner. Some examples based on NZWERF, 2002 are:

  • interim monitoring could be put in place with a dated review clause to cover the uncertainties in the impacts that may arise from a response option;
  • establishing milestones for a review of monitoring plan objectives and how well they are being met; asking questions such as "is the sampling frequency or number of sites sufficient to resolve any changes or impacts occurring?";
  • periodic technical reviews, analysing trends and variability in monitoring data or before versus after differences where adaptation measures have been implemented;
  • occasional reviews of data analysis techniques, software and reporting format. However, any mid-course change in statistical or survey techniques or software will mean previous results may be different (e.g., calculation of beach profile volumes or change of datum). Consequently, entire datasets may need to be re-analysed;
  • community surveys on best methods and media for dissemination of monitoring information (e.g., web-based, newsletter, poster), which can be combined with steps to raise public awareness of the level of impacts from climate change and adaptation options.