When the available data and information point towards a potential problem
  justifying action, the next stage is to decide which action to take and where
  and when to take it. The answers to these questions depend on prevailing criteria
  that guide local, national or regional policy preparation, as well as on existing
  coastal-development and management plans that form the broader context for any
  adaptation initiative. Important policy criteria that could influence adaptation
  decisions include cost-effectiveness, environmental sustainability, cultural
  compatibility and social acceptability. In addition, countries may choose to
  take a precautionary approach when postponing action would involve substantial
  risks, even though uncertainty may still be considerable (CEC, 1999).
  
  Coastal planners will always face a certain degree of uncertainty, not only
  because the future is by definition uncertain, but also because knowledge of
  natural and socio-economic coastal processes is and always will remain incomplete.
  Limits to predictability require planners to assess the environmental and societal
  risks of climate change with and without adaptation (Carter et al., 1994). The
  information thus obtained can help to determine the optimal adaptation strategy
  (which action?) and timing of implementation (when?) (e.g., Chao
  and Hobbs, 1997; Yohe and Neumann, 1997). There are a number of decision tools
  available to assist in this process. Examples of these tools include cost-benefit
  analysis, cost-effectiveness analysis, risk-effectiveness analysis and multicriteria
  analysis (Turner and Adger, 1996). The latter technique is particularly relevant
  when great significance is attached to values that cannot be easily expressed
  in monetary terms.
  
  Geographical information systems (GIS) are an important technology for spatial
  planning (where?), while they can also contribute to the other adaptation steps
  described in this Section and indeed to all aspects of coastal management 
  (Box 15.1). 
| Box 15.1 The role of GIS (Geographical Information Systems) in coastal adaptation and management | 
| 
       GIS combines computer mapping and visualisation techniques with spatial
	databases and statistical, modelling and analytical tools. It offers powerful
	methods to collect, manage, retrieve, integrate, manipulate, combine,
	visualise and analyse spatial data and to derive information from these
	data (Burrough and McDonnell, 1998; Longley et al., 1999; Wright and Bartlett,
	1999). One simple, first-order application of GIS in coastal adaptation
	would be overlaying scenarios of sea-level rise with elevation and coastal-development
	data to define impact zones. More sophisticated applications may include
	morphodynamic modelling (e.g., Capobianco et al., 1999). GIS technology
	is evolving rapidly and is increasingly used for sophisticated modelling.
	Hence, GIS can provide excellent support to coastal managers for making
	decisions about adaptation. 
 The rapid ongoing developments of all aspects of GIS may remove some of these concerns. There is no doubt that GIS presents great potential for societies wishing to anticipate and understand the consequences of climate change and develop adaptation strategies to cope with the potential impacts.  | 
  
 The modelling of potential futures based on plausible scenarios is particularly
  pertinent for the planning and design of adaptation technologies when relevant
  impacts are quantified, alternative adaptation options are evaluated and one
  course of action is selected. Modelling capabilities are increasing rapidly,
  leading, for example, to better morphodynamic models (De Vriend et al., 1993;
  Stive and De Vriend, 1995), dynamic biogeophysical models (e.g., Capobianco
  et al., 1999) and integrated models (e.g., Engelen et al., 1993). The rapid
  developments in information technology are facilitating the transfer of these
  tools. However, the limitations inherent in all models (i.e., they are representations
  of a part of reality for a specific purpose) must not be overlooked. Human expertise
  remains essential for the intelligent use of models.
  
  The quality and effectiveness of the planning and design process is affected
  by the context in which the decision is made. Coastal management in many countries
  used to be top-down by nature, but as public interest and involvement in coastal
  issues has grown, so has resistance to top-down decision-making (e.g., Taiepa
  et al., 1997). The successful implementation of many coastal policies, including
  adaptation to climate change, is now increasingly dependent on public acceptance
  at the community level (King, 1999). Hence, in addition to informing the public
  to raise their awareness of the issues at stake (Section 15.3.1),
  it is also important to involve them throughout the planning process to inform
  decision makers (CEC, 1999). Gaining public acceptance, for example by two-way
  interaction and partnerships, is an important prerequisite for finding and transferring
  appropriate adaptation technologies. Furthermore, local expertise will be required
  for technology implementation, application, maintenance and enforcement.
  
  In some settings, however, public involvement can be difficult to accomplish.
  In situations where there is little truly private land, coastal inhabitants
  may have little long-term stake and therefore interest in the land they occupy
  (e.g., in parts of Tonga; Nunn and Waddell, 1992). Moreover, governments may
  have neither the resources to address country-wide coastal management (particularly
  in archipelagic nations) nor, compared to long-resident inhabitants, the local
  knowledge or experience that are essential for effective management (e.g., in
  parts of Fiji; Nunn et al., 1994a).
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