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Inland Flooding

Changing rain and snowfall patterns, combined with other environmental and socio-economic factors could alter inland flooding risk in many states. These floods put people at risk and can damage buildings and infrastructure, especially those in low-lying areas. Our analysis assesses each state’s threat from inland flooding based on the severity of high runoff events and the number of people living in areas at risk of a 100-year flood (which has a 1 percent chance of occurring every year).

Key Findings

  • Florida has the most people living in the FEMA 100-year floodplain, with 1.5 million, California is next with 1.3 million, followed by Georgia with 570,000.

  • Maine has only 132,000 people at risk, but that represents 10 percent of the state’s population, the greatest percentage of any state.

  • States are generally well prepared for the current threat level, but far less prepared for the future climate driven increases in risk. Seventeen of the 32 states have taken no action to plan for future changes in inland flooding risks or implemented strategies to address them.

Threat/Action Plot