Page - 294 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

294 W.J.WouterBotzenet al. Fig.12.3 Conceptual frameworkof thefloodriskassessmentofHoChiMinhCity.Yellowboxes indicate thepoints in themodellingwhereadaptationmeasuresare implemented. SourceModified fromScussolini et al. (2017) Thenextstepis themodellingoftwomainimpact indicators: thedirecteconomic losses, and the likely casualties. Direct losses include damage to different types of buildings, infrastructure and crops, and are calculatedwith theDamagescanner model, by combining floodmaps and land usemaps (for the present and for the future) through the use of vulnerability curves. Casualties aremodelled based on thefieldoffloodvelocities anddepths that isproducedby thehydraulicmodel, and applyingempirical relationships to local informationon thenumberpeoplepresent inHoChiMinhCity. The following step is the integrationof the impacts offloodsof eachmagnitude acrossfourreturnperiods,toquantitytherisk,intermsofaverageannualimpacts.As canbeseen inFig.12.4 thealready largeexpectedannualdamageand thepotential casualties increase substantially until the year 2050 and 2100, depending on the scenarioand if adaptationmeasuresarenot taken. TheHoChiMinhCitycasestudygoesonestep further than theJakarta studyby analysingtheriskreducingpotentialof(combinationsof)fourfloodriskmanagement measures. Thesemeasures are: the construction of a ring dike around the central districts, theelevationof land in thedistrictswhere risk ishigher, the retrofittingof residential andcommercial buildingsbydry-proofing, and spatial reorganisationof landuse.These are incorporated in thefloodhazard and impactmodelling (yellow boxes inFig.12.3).