Integrating Sea-Level Rise Adaptation into Planning Policies in the Coastal Zone

Isaac BOATENG, United Kingdom

1. INTRODUCTION

There is increased scientific understanding and a very high confidence of the dangers and impacts of climate change on natural ecosystem, managed and human systems and the capacity of these systems to adapt to their vulnerability. The biggest danger, many experts warn, is that climate change will cause sea levels to rise increasingly rapidly. The Inter- governmental Panel on Climate Change (IPCC) Fourth Assessment Report, published in 2007, has the following projections: temperature is likely to rise between 1.1oC and 6.4oC by 2099 and sea level likely to rise between 0.18m – 0.59m by 2099. Arctic summer sea ice may disappear by the second half of the century; increase in heatwaves is very likely and increase in tropical storm intensity likely, the latter being likely to cause severe problems for tropical developing countries. Walsh et al (2004) indicated that although scientific evidence for future sea-level rise seems convincing, the available estimates of future sea-level rise are not sufficient for planning purposes because of high uncertainties. However, the IPCC, (2007) report concluded that there is a greater certainty (at least 90% certain) that human emissions of greenhouse gases rather than natural variations are warming the planet’s surface and most likely to cause sea level to rise.

Nicholls, et al (2007) acknowledged that since the IPCC Third Assessment Report (TAR), our understanding of the implications of the climate change for coastal systems and low-lying areas has increased substantially and the level of uncertainty has reduced considerably. Six highly confident coastal planning policy-related facts that emerged from the IPCC 2007 report are:

• –  Coasts are experiencing the adverse consequences of hazards related to climate and sea-level rise.
• –  Coasts will be exposed to increasing risks, including coastal erosion, over coming decades due to climate and sea-level rise.
• –  The impact of climate change on coasts is exacerbated by increasing human-induced pressures.
• –  Adaptation for the coasts of developing countries will be more challenging than for coasts of developed countries, due to constraints on adaptive capacity.
• –  Adaptation costs for vulnerable coasts are much less than the cost of inaction.
• –  The unavoidability of sea-level rise, even in the long-term, frequently conflicts with

  present-day human development pattern and trends.

  0. Rising sea-levels is particular problems in the world because a majority of the world’s population lives in coastal areas and hence many of the world’s built assets are located in the coastal zone. Sixty percent of the world’s 39 metropolises with a population of over 5 million are located within 100km of the coast, including 12 of the world’s 16 cities with populations

  

  TS 3F – Coastal Zone Administration
  Isaac Boateng
  Integrating Sea-Level Rise Adaptation into Planning Policies in the Coastal Zone

  Integrating Generations
  FIG Working Week 2008 Stockholm, Sweden 14-19 June 2008

  2/22

  The possible impacts of sea-level rise on the coastal zone include:

  • –  Increased inundation (flooding) of coastal land, which may cause loss of life and property;
  • –  More frequent storm-surge flooding, which may cause destruction of life, property and beaches and severe shoreline erosion e.g Hurricane Katrina;
  • –  Accelerated coastal erosion, which may also cause destruction of coastal properties and possibly loss of life;
  • –  Seawater intrusion into fresh and groundwater sources thus reducing the supply of fresh water in coastal towns;
  • –  Altered tidal range in estuaries and tidal river systems which may destroy estuarine ecosystems; and
  • –  Change in sedimentation patterns.

    These impacts coupled with increased temperature, rainfall and storm associated with climate change could cause severe impacts to coastal developments, resources and the coastal economies. Such impact on coastal economies will go a long way to affect the global economy, since every country, including landlocked countries, depend on the coast in some form. It must be noted, that the extent of the impact of sea-level rise on countries depends on many factors including:

  • –  the nature of the coastline and the level of exposure (delta, marsh, estuary lowlands/uplands, soft geology/hard geology etc);
  • –  the nature and value of developments on vulnerable coastal lands;
  • –  the capacity and affordability to build defence and protection schemes;
  • –  the natural adaptive capacity of the coast;
  • –  adaptation planning and mitigation and
  • –  availability of cost effective sources of alternative supply of goods and services to the

    hinterland, landlocked countries in times of climate hazards.

    3.1 Climate change adaptation strategies

    McCulloch, et al (2002) categorised climate change adaptation strategies as follows:

    • –  Prevent the loss – adopt measures that reduce vulnerability to climate change;
    • –  Tolerate the loss – do nothing to reduce the vulnerability, and absorb the cost of the

      losses as they occur;

    • –  Spread or share the loss – do not reduce vulnerability, but spread the burden of the

      losses over different systems or populations (this is how insurance works);

    • –  Change the affected activity – stop doing things that cannot cope with changes in

      climate, and substitute other activities; and

    • –  Change the location of the activity – move the activity or system to a more favourable

      location.

      0. The Protection policy aimed at protecting the land from the sea so that existing land uses can continue, by constructing hard structures as well as using soft engineering measures. The first shortfall of protection policy is that it is generally costly and has limited or finite long term effectiveness. It may me toppled by storm surge and other extreme weather conditions associated with climate change (e.g. Hurricane Katrina in New Orleans, 2006). It tends to overly control or operate against natural processes and can trigger effects detrimental to long- term sustainability. For instance seawalls may be effective as flood protection, but in an open coast with long wave fetch, wave reflection and scour at the base of a seawall can cause loss of beach in front of the seawall (Krauss and McDougall, 2006). Even in a sheltered coastline, local waves in a storm surge may lead to the failure of a protection structure. Groynes are effective where there is significant longshore drift, but they can be subject to bypassing, and do not address crosshore transport losses. Hard structures usually require regular maintenance to achieve full longevity and this is not always adhered to leading to earlier than anticipated failures.

         One negative impact of protective structures is the “knock-on effect”. Seawalls for instance almost always cause terminal scour (out flanking) downdrift. Groynes also may succeed in trapping sediment updrift and cause starvation (erosion) of sediment downdrift and possibly lead to the continuous construction of expensive groynes or other forms of protective structure along the entire coastline.

         “Soft” engineering methods such a beach replenishment or artificial breakwaters are used increasingly amongst developed countries and offer opportunities to avoid some of the problems associated with hard structures (e.g. Hamm et al. 2002). However, these techniques do require better technical knowledge and continued monitoring for effective performance. However, in spite of the short-comings of the protection policy, it may still be the best sea level rise adaptation policy depending on the values of properties along the coastline, the cultural heritage of the local people as well as the contribution of the vulnerable coastal resources to the local and national economy.

         The Accommodation policy implies that people continue to occupy the land but make some adjustments to properties and activities. The policy involves: redesigning of structures (e.g. elevating buildings and strengthening foundations) to minimise impact of flooding and; zoning and proper land use policy to encourage only low capital investments on vulnerable lands; soft approaches like dyke opening, wetland renewal, dune rehabilitation and beach re- feeding to enhance natural resilience; drainage modifications for built up areas that might become inundated; growing flood or salt-tolerant crops; and storm warning, preparedness and evacuation schemes.

         Accommodation allows wetlands and other natural coastal features to migrate inland through wash-over and tends not to result in the environmental problems that can occur with protection. It reduces risks without the expense of full protection, but it does not completely reduce risk. Indeed, substantial risks can remain if measures are not implemented carefully (e.g. storm warnings available, but communications with rural areas are poor and without education of local populations) appropriate reactions may not be made. Because of the problem of significant residual risks these methods alone may not be suitable for densely populated cities and centres of economic activity. However, the measures can be implemented at community level and may be suited to developing countries supported by appropriate technical guidance.

         Retreat involves either only a partial, or perhaps no attempt to protect the land from the sea. In an extreme case, the coastal area is abandoned and coastal landforms and ecosystems are allowed to shift landwards. This policy option is recommended for highly vulnerable coastlines, where the market cost and/or technical difficulty of protecting the coast far exceeds the benefits of providing protection. To be effective, vulnerable populations and infrastructure need to be shifted away from hazardous zones. The potential benefits of this policy include savings on cost of defences, habitat and wetland conservation and maintain aesthetic value of the coast. The opportunity cost of obtaining these benefits includes loss of land, properties, heritage and payment of high compensations.

         Effective organised retreat, rather than simply doing nothing, does require planning and organisation within a strong governmental framework and does assume that land is available to support displaced populations. Implementation requires legislation and regulations that prevent development and possibly settlement on vulnerable coastal lands and properties. It may involve public education, taxation, insurance and zoning policies. In fact, in areas where reliable data on historical rate of shoreline recession are available, a setback distance may be fixed based on predicted rate of recession into the future. The success of this policy depends on the ease with which vulnerable communities can be resettled inland which in developed countries appears conditional on the willingness of government and local authorities to pay compensation. In developing countries this may not be possible due to inadequate funding to provide housing and the payment of compensation.

         3.3 The Process of Coastal Adaptation

         Klein and Nicholls (1999) argue, that the adaptation polices proposed by Biljsma et al.(1996) have not necessarily been effective in assessing the wide range of technical, institutional, economic, and cultural elements in different localities. Indeed, they observed that the methodology could be limited by a protection-oriented response rather than consideration of the full range of adaptation options. Klein et al. (2000) argued that successful coastal adaptation embraces more than just selecting one of the technical options to respond to sea- level rise; it is a more complex and iterative process, with a series of policy cycles. They identified four steps which can be distinguished in the process of coastal adaptation. The four steps are:

         • –  Information collection and awareness creation
         • –  Planning and design
         • –  Implementation
         • –  Monitoring and
         • –  Evaluation.

          

         0. According to Klein et al (2000) if the four steps of coastal adaptation process above are adhered to before and after the selection of the coastal adaptation policy option and implementation of the selected policy option, positive results can be achieved. The reason is that following the first two steps should significantly improve knowledge, and participation, which will in turn; enable a much better informed selection of coastal adaptation policy that would be suited to both natural and human conditions and also acceptable to the local population. These last three steps are equally important since the selected adaptation policy option needs to be implemented and also monitored after implementation of the policy, so as to identify any uncertainties, gaps in coverage and allowing amendments where necessary (see figure 2). Evaluation is also required to enable policy makers to assess how the policy is achieving its objectives.

            Another sea level rise adaptation policy that has gained much attention in the UK and perhaps other coastal countries is the Shoreline Management Plan (SMP). It is a plan that identifies one coastal defence strategy for a specific length of coastline (a “management Unit”) and for a defined period of time, typically up to 50 years. The first plans were prepared to cover the coast of England and Wales in 1993. The guidance for SMP has been extensively reviewed since 1993. The latest SMP guidance was published by Department for Environment Food and Rural Affairs (DEFRA) in 2006. DEFRA, (2006) SMP guidance outlined four strategic coastal defence/adaptation policy options to deal with effects of sea-level rise. They are:

            • –  Hold the line: protect the economic assets of the frontage and backing flood risk areas.
            • –  Advance the line: reclaim land lost to the sea where no environmental impacts would result from seaward movement of defences.

              – Managed Realignment: where there is a potential long-term technical and environmental benefit.

            – No active intervention: vast flood risk areas where there is limited potential benefit from controlled inundation.

            It must be noted here that the key to successful application of DEFRA strategic coastal defence options is based on sound understanding of coastal processes and the involvement of stakeholders to ascertain potential hazards, vulnerability, resilience and risk to the environmental and economic resources of a given coastal system. The duration for the application of a strategic coastal defence option to an area could be a short-term (20years), a medium-term (30years) and a long term (50years) period. DEFRA believe that to minimise future risk is to encourage fully engagement of local people and planning authorities to ensure that the adaptation plan is link to and inform Regional Spatial Planning Strategies and Local Development Frameworks. This will help to ensure that inappropriate development does not take place in areas that are at risk of flooding or erosion either now or in the future.