Flood maps missing in climate era

What's happened

Flood risk maps are being challenged as climate change drives more extreme rainfall. New analyses show FEMA maps underestimate flood risk in less-populated areas, while private models indicate substantially higher exposure, prompting calls for updated nationwide mapping.

What's behind the headline?

Analysis

• FEMA maps have long set flood-insurance requirements, but new rainfall-based models show more properties are at risk than official maps reflect.
• The gulf between federal maps and private models suggests a broader vulnerability in regions with sparse populations where climate risks are rising.
• This shift will likely accelerate policy debates over how to price flood risk and where to target mitigation funds.

Context

• The trend aligns with observed increases in extreme rainfall across the Midwest and other non-coastal regions, challenging the adequacy of older flood-plains.
• Local planners may need to re-evaluate infrastructure resilience and zoning rules to manage risk more effectively.

How we got here

A look at how flood mapping has evolved shows FEMA maps were built on historic rainfall and river data. As extreme rainfall becomes more common, the gaps leave some communities exposed and underinsured. The debate now centers on whether to adopt updated methods that account for heavy rain and urban flooding.

Our analysis

AP News reports that flood maps have not kept pace with changing rainfall patterns. First Street’s analysis highlights discrepancies between FEMA maps and rainfall-driven models. The Guardian has covered related flood-preparedness concerns in midwestern states.

Go deeper

• How quickly will updated maps be rolled out?
• What will this mean for homeowners and insurers in non-coastal areas?
• Are there immediate steps communities can take to mitigate flood risk?

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