Water for people.pdf - WHO Thailand Digital Repository

M I T I G A T I N G R I S K A N D C O P I N G W I T H U N C E R T A I N T Y / 2 8 1Hazard mappingThe World Meteorological Organization (WMO) and the Scientific andTechnical Committee of the IDNDR (WMO, 1999), have initiated ajoint assessment of risk from a variety of natural hazards –especially meteorological, hydrological, seismic and volcanicdisasters. They found the need for standard methodology indifferent sectors where composite hazard maps are generallyrecognized as an important tool for joint assessment. Mitigation ofrisks from natural hazards depends on the implementation of riskmanagement measures and political will. Risk management requiresa long-term view, while governments operate more on short-termobjectives and limited annual budgets, and are sometimes reluctantto commit expenditure for proactive risk management measures thatare based on weak indications of possible future risks. Governmentsare, however, generally responsive to short-term emergency reliefrequirements.An iterative processFigure 11.3 shows that risk assessment and risk management areiterative processes wherein various options are assessed and anoptimal solution with acceptable risk is attained, for which thepossible measures and the cost are defined. It requires anassessment of what level of risk is acceptable, given that it is notgenerally possible to reduce risk to zero. The acceptability of certainrisks may vary both in different countries and in time.The economic groundsDecisions on risk management may be taken on economic grounds. Thecosts and benefits associated with managing the risk from a particularhazard can be compared to the returns from other investments, bothwithin the water sector and other public health and safety areas, tomaximize the effectiveness of public funding. It is also important tonote that social acceptability is a contributing factor in making gooddecisions. It should be recognized that decisions about allocation of riskare often made more as part of political economic processes thanthrough public consultation or participation (Rees, 2001). Establishingeffective mitigation of risk and uncertainty therefore depends on thelevel and the strength of the political economy (see box 11.4).While the impact of water disasters (mainly from flooding, droughtand pollution) is apparent, there is an even greater impact in terms offuture social costs. Appropriate investment strategies and a redirectionof resources into prevention offer the potential for significantFigure 11.3: Framework for risk assessmentNatural system observationsInventoryAccountingDataThematic event mapsHazard potentialSector domainIntensity or magnitudeProbability of occurrenceVulnerabilityValue (material, people)InjuriesResiliencyRisk AssessmentRisk = function (hazard, vulnerability, value)Protection goals/risk acceptanceUnacceptable risk Acceptable riskPlanning measuresMinimization of risk through best possiblemanagement policiesImplementationandperiodic reviewLand use planningStructural measures (building codes)Early warning systemsRisk assessment and risk management are iterative processes.Source: Adapted from WMO, 1999.