Geophysical and social vulnerability to floods at municipal scale under climate change: The case of an inner-city suburb of Sydney

Assessments of vulnerability to flooding can generate useful data for planners and policy makers. To the best of the authors knowledge, no flood-vulnerability study has combined geophysical modelling of floods with socio-economic assessments of vulnerability at finer municipal or household scale. In addition, the extent to which vulnerability assessments actually feed into flood adaptation policies remains largely unknown. A new flood vulnerability index, and associated methodology, is proposed, combining high-resolution hydrological-hydraulic modelling with built-environment and socio-economic indicators at the smallest spatial scale at which socio-economic data is available. The main advantage of the methodology is its ability to incorporate place-specific data, hence yielding more refined simulations of floods and the capacity to make projections into climate futures at local scale. The index is built and applied to the inter-city suburb of Marrickville in Sydney and used to assess the effects of future climate change on vulnerability mapping in the suburb. Finally, the results of the assessment are presented to, and discussed with, the local government authority responsible for implementing flood adaptation policies for Marrickville. Locally specific modelling of floods, combined with socio-economic and built-environment mapping, has yielded a rich set of information on flood vulnerability and significant variability within a single suburb. Flood duration is projected to increase by more than 100% under some climate change scenarios, as a result of reduced drainage caused by sea level rise. Feedback from municipal council has highlighted the potential usefulness of the knowledge generated by the assessment, especially for emergency services.