According to Montgomery, the study provides further evidence that natural hazards like flooding are complex, as areas at risk to flooding are often associated with environmental amenities such as beaches. "It is a double environmental injustice that neighbourhoods with low-income and racial/ ethnic minorities are exposed to inland flood hazards and have impeded access to desirable coastal beaches," Montgomery told environmentalresearchweb. "On the other hand, economically affluent residents at risk of coastal flooding have easy access to beaches."

Montgomery believes the study demonstrates the importance of treating areas exposed to coastal and inland flood risks separately while controlling for water-related amenities, and that this is a significant contribution to understanding environmental justice. "We also highlight the diversity within large Hispanic groups, since Colombians, Cubans, Mexicans, and Puerto Ricans in Miami have different levels of social vulnerability, their neighbourhoods are segregated from each other, and they have different access to resources in order to mitigate flood hazards," she said.

To come up with the findings, Montgomery and Chakraborty used data from the 2010 US Census, the 2007–2011 American Community Survey, and the 100-year flood risk zones from the US Federal Emergency Management Agency (FEMA), defined as areas that have a 1% chance of flooding every year. The models that estimated exposure to flood risks also included controls for water-related amenities, which were represented by proximity to public beach access sites and percentages of vacation homes.

"We investigated social vulnerability in exposure to coastal and inland 100-year flood risk zones in Miami by assessing neighbourhood racial and ethnic minority composition, as well as two social vulnerability indices – economic insecurity and instability," said Montgomery. "Since Miami's population is 41% Hispanic according to the 2010 US Census, we also examined contextually-relevant Hispanic subgroups of Colombians, Cubans, Mexicans, and Puerto Ricans."

Now the researchers plan to focus on the social equity and affordability concerns of the National Flood Insurance Program (NFIP), a FEMA scheme that provides flood insurance to homeowners. "The NFIP has a tremendous debt, partly because it does not charge premiums that accurately reflect risk," said Montgomery. "Changes in the NFIP have recently been implemented to increase premiums to risk-based rates, but some socially vulnerable households may not be able to afford the new rates."

Studies addressing affordability in the NFIP are emerging; Montgomery hopes to contribute to this research by identifying neighbourhoods with high social vulnerability that will be faced with higher flood insurance premiums. "This research could be used to target socially vulnerable households with public assistance programmes, to help them pay higher flood insurance premiums and make other improvements to their homes to mitigate flood hazards," she said. "Mitigating homes against flood damages can also reduce insurance premiums."

The study is published in Environmental Research Letters (ERL).

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