Exploring the relationship between urban morphology types and household-level flood vulnerability profiles in Ho Chi Minh City

There is rising discussion focused on the ways in which urban growth and expansion, often into flood-prone areas, takes effect on the exposure and vulnerability profiles of the respective households. In order to drive city-wide and regional analysis, remotely sensed urban structure types are increasingly being used as a proxy for socio-economic characteristics. However, whether and how urban structure types in fact match the nuanced realities of socio-economic exposure and vulnerability to floods remains largely unclear. Resolving this question is of particular relevance for improving flood risk assessments in rapidly growing coastal cities with a high hazard exposure. We therefore use Ho Chi Minh City in Vietnam as a case study to develop a detailed composite indicator index for measuring the exposure and vulnerability at household level in flood-affected parts of the city, based on household survey data. We then correlate this index to urban structure types to see whether morphology characteristics map against socio-economic vulnerability and exposure profiles. In order to allow for an assessment of temporal trends, data from a repeated survey (two years after the first) is used to examine dynamics in exposure, vulnerability and urban development.

Our research yields a number of key results (Tu et al., forthcoming): First, household vulnerability is not necessarily correlated to flood exposure. Second, the vulnerability and flood exposure levels of households are differ along an urban, peri-urban and rural gradient. Third, the exposure and vulnerability profiles only partly correlate with the urban structure types, but a certain mapping can be done with a reasonable uncertainty bandwidth in order to drive future modeling forward. These findings not only shed light onto spatial vulnerability patterns in HCMC but also on methodological advances in the field of city-wide risk and adaptation modeling. These lessons and their transferability to other coastal cities with similar adaptation pressures but different morphology and vulnerability profiling will be discussed.