[管理学]CaseStudyClimateChangeandCoastalManagementinPractice–Acost-benefitassessmentintheHum.doc

Case Study Climate Change and Coastal Management in Practice A cost-benefit assessment in the Humber UK.Emma Coombes, Diane Burgess, Nina Jackson, Kerry Turner and Sarah CornellIn 1995, the Intergovernmental Panel on Climate Change (IPCC) concluded that human intervention is increasing the rate of atmospheric temperature rise and that this is affecting global sea levels due to thermal expansion of the sea and melting of ice on land. Over the last 100 years, the world has experienced an increase in mean temperature of about 0.5C and sea level has risen by 10-20cm (Gornitz, 1993). Although there is much uncertainty over the precise impacts of climate change, it seems likely that this general rise in temperature and sea level will continue for the foreseeable future (Wigley and Raper, 1993). In the face of such a change in sea level, this case study of a cost-benefit analysis is undertaken of coastal flood management in the Humber catchment of the UK, presenting generic guidelines that enable the methodology to be transferable between countries. In the UK, there are currently nearly 2 million properties lying in floodplains along rivers, estuaries and coasts that are at risk from flooding, with an average annual damage costs of over 1000 million with over 450 million being spent on flood management costs in 2003-2004 (DEFRA, 2002, Foresight, 2004). Foresight (2004) estimate that given flood management policies and expenditure remain unchanged, annual flood losses would increase between 1 billion to 27 billion by the 2080s. The traditional method of flood management has been to construct structural or hard defences, such as sea walls to protect land and also to reclaim land for development. Intensive construction periods occurred around the time of the First and Second World Wars (1914-1918, 1939-1945) when the need for agricultural self-sufficiency was paramount. Although the contemporary belief was that this was best practice, it is now recognised that hard defences are unsustainable both from an environmental and economic perspective given recent understanding of coastal dynamics (Crooks et al., 2001b). Not only do these hard defences provide a false sense of security and encourage development immediately behind the defences, they show little regard for natural processes (Crooks et al, 2001b). Where sea walls or other hard flood defences have been constructed, a natural response to sea level rise cannot occur. The erosional response in which the intertidal boundary exhibits a landward transgression is observed, but migration of the landward boundary is prevented by the flood embankments, resulting in coastal squeeze (Pethick, 2001). Coastal squeeze is illustrated in Figure 1 and refers to the forcing of intertidal habitats between the rising sea and fixed hard defences that results in their overall area being reduced. In severe cases intertidal habitats may be lost completely (ORiordan et al., 2000). The loss of intertidal habitats may actually increase the potential for a flood to be hazardous as these habitats provide the mainland with natural protection from the sea by absorbing energy and water.Figure 1. Coastal Squeeze (Environment Agency, 1998). Evidence of where adaptation to sea level rise has been prevented by hard defences can be seen along the Essex coastline, UK. Medieval to 19th century embankments have led to the loss of 40,000ha of saltmarsh. These embankments have restricted the landward migration of intertidal habitat and have resulted in high-level saltmarsh and natural transition zones between the sea and the mainland becoming very restricted (Dixon et al., 1998). Of all the coastal environments, estuaries are likely to be the most vulnerable to sea level changes due to the diversity of pressures on them. Although most estuaries are drowned river valleys and were created by sea level rise following the last ice age, the problem now is that sea level rise appears to be accelerating. This not only causes difficulties in terms of an increased risk of flooding for property in coastal areas, but there is also uncertainty regarding how estuaries will physically adjust to the accelerated rate of sea level rise. First-order effects may include increased frequency of flooding, changes in wave climates, rearrangement of unconsolidated sediment, accelerated dune and beach erosion, upstream intrusion of saltwater wedges, and land-based retreat of the fresh/brackish water boundary. To these, second-order impacts may be added, including changes in bottom profiles, sediment and nutrient fluxes, and primary production (McIntyre, 1998). These effects will cause estuaries to migrate landwards and upwards as a unit. In the outer estuary the deeper water as a result of the sea level rise will lead to an increase in the energy of waves propagating from the open sea, due to reduced friction with the estuary bed. The increased energy and height of these waves will cause upper intertidal sediments to erode, resulting in retreat of the intertidal boundary to further inland. The eroded sediments will move landwards to the inner estuary where they will be redeposited on the upper intertidal zone, raising the mudflat and saltmarsh surfaces and resulting in transgression of the landward edge of the intertidal area. The loss of intertidal habitats has great significance as they are important in terms of providing natural flood defence, the flora and fauna they support, their ability to improve water quality, recreation, education and science, and in their own right. In particular relating to climate change, intertidal habitats act as stores of carbon.Current SituationMany of the hard defences are reaching the end of their design life and are in need of repair or replacing, while rising sea level and increased storminess resulting from climate change exacerbates the problem of eroding sea-defence lines (Mller et al., 2001). The institutional response to the threat of climate change in the UK has included an on-going re-assessment of sea defence and coastal protection strategies.It is possible to discern a re-orientation in thinking about response strategies which is leading to an abandonment of “coastal armouring” (i.e. the building and maintenance of hard engineering structures and works) in favour of a mixed approach which will include substantial elements of more flexible “soft engineering” measures such as set back or managed realignment linking in with Integrated Coastal Zone Management (see Box 1). Box 1.Integrated Costal Zone Management One of the central objectives of coastal zone management is to find the balance between satisfying competing present-day demands, without compromising the potential for future users of coastal resources to maintain their well-being (Bower and Turner, 1998; Von. Bodungen and Turner, 2001; Brown et al., 2002). Integrated Coastal Zone Management (ICZM) promotes the management of coastal zones by taking into account the natural processes occurring in ecosystems, the complexity and interaction between ecosystems, the linkages between human activity and ecosystem health, and the need to reduce the stress imposed by humans on the coastal zone (Tompkins, 2001; Coombes, 2003). The House of Commons Environment Committees report on Coastal Zone Protection and Planning (1992) outlined the main objectives of ICZM “to promote sustainable use of the coast, balance demands for coastal zone resources, resolve conflicts of use, promote environmentally sensitive use of the coastal zone, and promote strategic planning of the coast”. European parliament has recently recommended that all member states should adopt National ICZM strategies (Ledoux et al., forthcoming). DEFRA, the UK Governments Department for the Environment, Food and Rural Affairs, currently holds responsibility for flood and coastal management in England (and Wales). It provides policy guidance, and gives consent and funding through its grants-in-aid to programmes of action, under the terms of the Environmental Protection Act 1990. At the operational level, the situation is more complicated. Box 2 shows the organisations with specific formal responsibilities for flood and coastal management.Box 2. Responsibilities for Flood and Coastal ManagementOperating AuthorityResponsibilitiesLegal FrameworkEnvironment Agency (EA)Supervision of flood defence, sea defences, and main rivers Bringing all coastal and inland waters to good statusEnvironment Act 1995Water Resources Act 1991Water Act 2003Water Framework Directive 2000Internal Drainage Boards (IDBs)Maintenance of ordinary watercourses within Internal Drainage DistrictsLand Drainage Act 1991Local Planning Authorities (LAs)Coastal protection, flood defences (not covered by IDBs)Coast Protection Act 1949This appears to be a pragmatic three-way division of responsibility, but the real situation is rather more complex. Water resource management also comes under the remit of the privatised water companies (regulated by OFWAT, the Drinking Water Inspectorate, and the EA), and individual owners of riparian and coastal lands. Further complexity, in governance terms (see Box 3), arises from the fact that flood defence and protection against coastal erosion are not sought after in isolation. Box 3. GovernanceGovernance is the encompassing term given to the institutional, regulatory and political framework for making and implementing policy decisions (EC, 2001; CGG, 1995). Under conditions of strong central state control, governance is more or less a synonym for government (the forms and functions of the state). Increasingly however, the term governance refers more broadly to the many possible ways in which society is steered. It is widely argued that the ability of central governments to steer society has declined (several discussions are brought together in Jordan and Liefferink, 2004), as their powers have been shifted upwards (e.g., to the EU), downwards (through devolution of power to the regions), and indeed outwards to other bodies (corporate interests, NGOs, and other quasi-private organisations). One of the tenets of sustainability (UK Government, 1999) is that government interacts with civil society in reaching mutually acceptable decisions about societys direction: although the trend is a move away from the Strong State, we have not reached the opposite extreme of a self-governing network of societal actors. In this context, new governing styles have emerged (Jordan et al., 2003), with increasingly blurred boundaries between public and private sectors. In the UK environmental sphere, there is still some financial control and regulation implemented top down by the state, but there are also various forms of bottom up delivery of policy, such as voluntary agreements for self-regulation, and initiatives such as corporate responsibility schemes which harness market forces.The operating authorities also have obligations to manage the water supply and quality, deal with waste water and sewage, and protect (and enhance) the natural environment. Furthermore, the relationship between flood and coastal management and planning and development control is very complex. Flood risk is a material consideration for local authorities in determining development planning applications, but local authorities are often faced with conflicting aims; for instance, the governments planning guidance (in particular, PPGs 20, 25, 7 and 3) sits uneasily with the targets for new housing development. In other words, there are many actors in this particular network, constrained and directed by many different regulatory instruments. As a result, the UK is now endowed with an assortment of Plans relating to water management and flood protection (in addition to local and regional spatial and structural planning for economic development), each of which has been devised as a policy response to one or more of the multiple obligations mentioned above. These are shown in Box 4 (compiled from DEFRA, 2002), with the plans ranked in approximate order of significance to managed realignment implementation. Box 4. Plans relating to water management and flood protection in the UKPlanAgenciesPurposeShoreline Management Plans (SMPs)DEFRA (and National Assembly for Wales), Coastal LAs, EAStrategic coastal planning (defences)Estuary Management PlansEnglish Nature (and Countryside Council for Wales), EA and stakeholder partnersLinking conservation needs of estuaries with other usesIntegrated Coastal Zone Management Plans LAs as lead partners, EA and many stakeholder partnersBalancing defence needs with multiple coastal activitiesCoastal Habitat Management Plans EA, English Nature (and CCW), DEFRA, NERC, stakeholder partnersBalancing defence needs with conservation (Habitats) objectives Habitats Directive Management SchemesEnglish Nature (and CCW), EA and stakeholder partnersManagement of European Marine SitesBiodiversity Action Plans Many Implementing Rio Convention and UK Biodiversity Action PlanLocal Agenda 21 Plans ManyImplementing Rio Convention society and environmentCatchment Flood Management Plans (CFMPs)EA as lead partnerHolistic flood managementLocal Environment Agency Plans (very soon to be superseded) EA plus its key stakeholdersConsultation on local environmental improvementsWater Resources Strategy for England and WalesEA and many stakeholder partnersNational longer-term framework for water resource planningCatchment Abstraction Management StrategiesEA, water companies, and other abstractorsSustainable water resource useWater Resource Management Plans Water companies, OFWAT, EAMeeting long term water needsDrought Plans EA, water companiesMaintaining water supplies in severe drought eventsIn the UKs progression towards its sustainability aims for flood and coastal management policy, two trends are particularly clear: there is a transition towards holistic, catchment-scale systems thinking, a response to the recognition that piecemeal, reactive action leads to unsustainable situations; and there is an expectation and obligation of broader societal engagement in catchment and coastal planning and management. What are the implications of this context for managed realignment? Catchment-scale thinking: Flooding and erosion, and their consequences, are the outcome of complex interactions between natural systems (the hydrological cycle, topographical and geological factors, the ecology, and so on) and social systems (e.g., land-use patterns, the value of activities in flood-threatened land, flood response measures). In the UK, a relatively small and densely populated island, managed realignment is essentially a conscious intervention in both systems. The twin challenge is to develop a more integrated view of how these natural and social systems work and interact, and to provide policy approaches that match the scale of these systems. Europes Habitats and Birds Directives are instruments to halt and reverse the damage caused by society to the natural environment, and they have had very significant impacts on river and coastal zone management. Recent past experience suggests that they are both compelling reasons for managed realignment in the UK and also obstacles to its implementation (Ledoux et al., 2004). The regulatory power of these Directives has the potential to trigger social conflicts in areas where realignment is proposed as part of strategic shoreline or catchment planning (e.g., Lee, 2001; Jackson et al., 2001). Some uncertainty still remains about the interpretation of the European regulations following their transposition into UK national law, with the effect that all sides operatives in coastal management, local communities, conservation bodies have explored all possible legal loopholes or hurdles (DfT (2004) gives an example of the tensions, in the context of a proposed port development with compensatory habitat creation). As a consequence, the implementation of managed realignment programmes has tended to become a longer process, more costly, and smaller in scale. It is likely that the Water Framework and Strategic Environmental Assessment Directives will have a similar process of testing, but their explicit inclusion of participatory engagement in priority-setting from the outset may mean that some tensions of the last decade in coastal zone management would be attenuated. There is some positive progress in integrated policy approaches. Funding and flood management action are more streamlined than before, and some public-private partnership initiatives allow more flexibility and systemic implementation (for example, Norfolks Broadland; EA, 2003). However, flood planning (CFMPs and SMPs) is still not linked with Regional Spatial Strategies and land use planning, giving an imbalance in statutory weight, and is not automatically subject to public consultation. Engagement, responsibility and accountability: The legacy of dispersed power and complexity in the UKs flood and coastal management can be considered in a positive light. Partnerships across different geographical scales have raised expectations of multi-stakeholder buy-in, and there is evidence of the satisfactory emergence of negotiated responsibilities and pooled resources for managed realignment projects (ORiordan, 2002). Coastal forums bring together local planning authorities, community representatives, and technical and scientific expertise, and while the different contributory bodies involved have different degrees of community engagement, democratic participation and public responsibility, the level of accountability afforded by the partnership approach of