Deltares - R&D Highlights 2009

Contact: marcel.marchand@deltares.nl +31 (0)88 335 8558 Modelling coastal vulnerability A cyclone shelter on the coast of Andhra Pradesh (India) This research focuses on the vulnerability of societies in low-lying coastal and delta environments to tropical cyclonic storms and fl oods. There are hardly any models that explore vulnerability in various planned and unplanned conditions. The Andhra Pradesh Cyclone Hazard Mitigation Project designed and implemented an Expert Decision Support System (EDSS) that links coastal vulnerability to integrated coastal zone management (ICZM). The interpretation and critical examination of the model generated new knowledge about the design of a model of this kind, and about the use of the results to reduce vulnerability through planning. Screenshot showing the application of the model to Andhra Pradesh (India) The fundamental idea underpinning the EDSS is that, in order to determine the impact of a cyclonic disaster on coastal society, the structure and functioning of this society needs to be modelled fi rst with ‘normal’ conditions. Only by understanding the dependencies between the use of land, its resources, socio-economy and environmental conditions, is it possible to simulate the impact of a disruption of these dependencies by a cyclone. The model therefore captures the annual economic and environmental conditions of a coastal area with and without a cyclone. Vulnerability is then calculated as the diff erence in assets and income in the area for the two years modelled. The model was applied to two diff erent deltas: the Godavari Delta in India and the Red River Delta in Vietnam. Both exercises showed how vulnerability changes as a function of physical and socio-economic conditions. The application of the model to the Godavari Delta confi rmed that reducing vulnerability to cyclonic storms requires a broader set of measures than is usually considered by disaster managers. The model illustrates not only the need for fl ood protection and early warning, but also the need for measures that reduce sensitivity and enhance the resilience of households, like diversifying cropping patterns and broadening the economic basis. Flood protection, early warning and evacuation measures do reduce the number of deaths, but 108

they cannot prevent wind damage, which still accounts for approximately half of total damage. This insight was possible due to the inclusion of wind hazard as an inextricable part of the cyclone hazard and due to the link with damage to household livelihoods. The research showed that the diff erential character of vulnerability originating from inequality in income is essential in order to link it to planning issues. The research proved that modelling coastal vulnerability is possible and useful for the mainstreaming of disaster management into sustainable coastal development. The model’s main contribution comprises three innovations: • the modelling of the entire impact chain, from hazards to consequences, including exposure, sensitivity and resilience; • the integration of hazards and the human-environment system, enabling explorative analyses of ‘typical’ disaster management measures, as well as land use planning and environmental management measures; • the model’s ability to quantify diff erential vulnerability at the household level, enabling the analysis of measures targeting critically vulnerable groups. 109 Further reading Marcel Marchand, Modelling coastal vulnerability – Design and evaluation of a vulnerability model for tropical storms and fl oods, PhD thesis TU Delſt 2009

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