Seite - 289 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

12 IntegratedDisasterRiskManagementandAdaptation 289 Hazardis thenaturalevent, inthecaseoffloodingcharacterisedbyfrequencyand intensity (water depth, direction, and flowvelocity). Exposure is the set of assets, peopleand(economic)activitiesthatcanbehitbythehazard.Vulnerabilityindicates theextenttowhichtheseassets,peopleandactivitiescansufferdamagewhenahazard occurs.Vulnerability is typicallyexpressedas themean loss (or the fulldistribution of losses) for agiven intensityof thehazard. Climate change-related risks, such asweather-related natural disasters, are thus the result of a complex interplay of natural hazards, like storm and flood condi- tions, and exposure of assets and their vulnerability, i.e. susceptibility to damage (IPCC2012).While climatechangemay increase the frequencyor intensityof cer- tain natural hazards, exposure andvulnerability are determinedby socio-economic development andhumandecision-making. It is these latter processes, such as pop- ulation and economic growth in hazard-prone areas that have been the dominant driversof increases innaturaldisaster losses in thepast (Bouwer2011; IPCC2012; seealso introductionbyMechleretal.2018a).Naturalhazard riskmanagementcan steer thesevulnerabilityandexposurecomponentsof riskand traditionally includes allactivitiesaimedatminimisingimpactsofnaturalhazardsbefore,duringandafter an event (Botzen andvandenBergh2009). Thereby, actions related to anticipated increased risk levels, becauseofanthropogenicclimatechangeorotherdrivers, can address thepreventionof risk (throughadaptation), or theminimisationof impacts duringanevent(emergencymeasures),oraftertheevent(clean-up,repair,compensa- tionandrehabilitation).Climatechangeimpactscanbeavoidedbyriskmanagement policies that limit exposure to natural disaster risk, for example by steering devel- opment away from hazard-prone areas, by better protecting these developments, andlimitingvulnerabilityofexposedassets, forexample throughimplementingand enforcingbuildingcodepolicies that limitwindorflooddamages(AertsandBotzen 2011;Czajkowski andSimmons2014). Integrated riskmanagement takes a holistic view (in the sense that it considers variousdriversof risk,andpossiblemitigationoptions rangingfromstructuralmea- sures, to emergencymanagement and risk transfer suchas insurance).Moreover, it usesavarietyofapproachesfortheassessmentofriskandevaluationofoptions,bor- rowingmethods fromnatural sciences, engineering, economics, ecologyandsocial sciences.An important cornerstoneof successful riskmanagement lies in theappli- cation of an assessment of risk, and the analysis of costs (of actions) and benefits (reducedrisk)ofriskmanagementoptions inorder to identifyeconomicallyoptimal strategies.Theseanalysesshowthat itoftenpaysoff topreventdisastrousdamages, or at least prepare formanaging these damageswhen they occur (Mechler 2016). Inaddition toeconomicappraisalof riskmanagementoptions,otherconsiderations can come into playwhen deciding about the implementation of riskmanagement strategies, suchasequity, acceptable risk levels and impactson theenvironment.