Mapping Flood Risk at a Hyper-Local Level: Using Census Data to Identify Cultural and Socioeconomic Factors Influencing Mitigation Efforts

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Monday, 5 January 2015
Erin Jordan, University of Arizona, Tucson, AZ

Handout (18.5 MB)

Communities are the first and last line of defense against the harmful impacts of natural disasters.  Using census block data to determine hyper-local areas of current and future risk, residents and city managers can make better-informed decisions regarding mitigation of that risk to themselves and the community as a whole.  But to effectively reduce risk, the information needs to be tailored to ensure that the population is engaged in mitigation activities.  Varying degrees of socioeconomic status as well as cultural factors can influence individual and collective behaviors.  Determining how these behaviors affect mitigation efforts before, during, and after a disaster allows governments and insurance companies to better direct resources intended to reduce loss. 

In the desert Southwest United States, arid land flood risk is especially challenging to pinpoint because drainage in many areas is from ephemeral streams.  People living in or near these normally dry waterways may have never seen high levels of water, if any at all.  Plus research shows extreme precipitation events, which increase the risk of localized arid land flooding, may become more common as the climate continues to shift.  Even during an economic downturn, the Southwest population has increased, resulting in cities and towns building into areas un-mapped for flood risk.  All of these factors can lead to increased risk and losses within the community.

This study focuses on flood risk in the Tucson Metropolitan Area (TMA) located in the semi-arid Southwest United States, where the local flood control district recently updated FEMA flood maps, plus expanded flood maps to areas of previously unknown risk.  Combining these maps with census block data will lead to insights about vulnerability within the community at a hyper-local level.  The resulting maps will show which race, cultural, and socioeconomic backgrounds are at greatest risk, plus which areas are most prepared for disasters through the use of mitigation options such as insurance and building regulations.  The objective is to use this data to conduct a residential survey about flood risk knowledge and how different parts of the community view factors that could mitigate that risk.  Results of the survey can then be used by local government agencies, insurance agents, and realtors to customize risk information to homeowners and homebuyers.  The intent is to better inform homeowners and homebuyers about hyper-local flood risk and how to protect their investment.  Ideally this would lead to loss reduction within the community through adaptive management, which aims to reduce current risk and future losses in the face of uncertainty.  The mapping and survey results also offer a base of knowledge by which to measure the impacts of future flood events and the losses, as well as changing attitudes based on education efforts.