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Cities with the highest flood risk in every state

  • Cities with the highest flood risk in every state

    Floods accounted for three of the 14 natural disasters that caused at least $1 billion in damage in the United States in 2019. In total, flooding impacted 14 million Americans last year and put another 200 million at risk—and that doesn’t even take into account hurricanes and other extreme weather events that often lead to flooding.

    The most common natural disaster in the United States, floods can occur anywhere in the country at any time of year—and like all natural disasters, global warming is making them more frequent and more severe. They’re often the result of heavy rainfall, but snowmelt can cause destructive flooding, too, as can ice jams in rivers, storm surges, and overwhelmed drainage systems.

    Standard homeowners insurance does not cover flood damage. In order to determine which businesses and homes must be covered by supplementary flood insurance, the Federal Emergency Management Agency (FEMA) created maps that classify areas based on the likelihood that they’ll experience a flood. Zones with a 1% chance of flooding every single year are considered to be at-risk. Since 1% represents one in 100, this formula sometimes refers to “100-year floods.” That language does not indicate flooding so severe that it happens only once in a century. It’s important to understand this because the 1%/100-year flood benchmark is the standard for determining which regions are most vulnerable.

    As readers will see with several states on this list, recent studies have shown that FEMA’s mapping is often wildly inaccurate in terms of how many structures are truly at risk in each state. Among the most credible is a report issued by a nonprofit called The First Street Foundation.

    To find the cities with the highest flood risk in every state, Stacker analyzed the First Street Foundation’s National Flood Risk Assessment Report released June 29, 2020. The First Street model identifies any property at risk of flooding one centimeter or more over the next 30 years. Using a broader definition than FEMA, the First Street model identified 23.5 million properties as at risk, with 3.6 million categorized as facing almost certain risk. Regrettably, data from Alaska and Hawaii were not available. Any ties in the proportion of properties under threat were broken using the city with the higher number of properties at threat.

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  • Alabama

    - Most properties at risk: Mobile (24,070 properties at risk; 29% of all properties)
    - Highest share of properties at risk: Dauphin Island (88% of all properties; 3,071 properties at risk)
    - Highest projected increase: Satsuma
    --- Properties at risk in 2020: 772 (25% of all properties)
    --- Properties at risk in 2050: 1,778 (57% of all properties)

    Both floods and hurricanes have become more frequent and more severe in recent years in Alabama, according to the Pew Charitable Trusts. Flooding, the second most common natural disaster in the state, occurs every 12 days on average there. Coastal counties like Baldwin and Mobile are especially vulnerable to flooding induced by storm surges.

  • Arizona

    - Most properties at risk: Phoenix (62,351 properties at risk; 13% of all properties)
    - Highest share of properties at risk: Wilcox (65% of all properties; 2,728 properties at risk)
    - Highest projected increase: Somerton
    --- Properties at risk in 2020: 375 (9% of all properties)
    --- Properties at risk in 2050: 431 (11% of all properties)

    Like the United States as a whole, flooding is the most common natural hazard in Arizona. The state experiences between 40 and 100 floods a year, and residents have suffered from 116 severe floods in the last decade. Flooding is most common there in the wake of winter storms and monsoon storms, particularly in fire-damaged areas.

  • Arkansas

    - Most properties at risk: North Little Rock (9,140 properties at risk; 33% of all properties)
    - Highest share of properties at risk: Rockwell (46% of all properties; 1,004 properties at risk)
    - Highest projected increase: Dermott
    --- Properties at risk in 2020: 123 (5% of all properties)
    --- Properties at risk in 2050: 141 (6% of all properties)

    From the Great Floods of 1915 and 1927 to the April 1945 Flood and the Albert Pike Flood of June 11, 2010, Arkansans have grappled with rising waters since Arkansas was still a territory. Flash floods are common to the state, as are river flooding, coastal flooding from tropical storms, and floods resulting from failed dams or levees. Snowmelt, ice jams, and water-repelling burn scars all contribute to or cause floods, as well.

  • California

    - Most properties at risk: Los Angeles (132,046 properties at risk; 20% of all properties)
    - Highest share of properties at risk: Yuba City (100% of all properties; 19,174 properties at risk)
    - Highest projected increase: Coronado
    --- Properties at risk in 2020: 103 (2% of all properties)
    --- Properties at risk in 2050: 1,142 (24% of all properties)

    Every single county in California has been declared a flood disaster area several times. While virtually all of the state is vulnerable, the most at-risk areas are those that suffered burn scars from California’s notorious annual wildfires, urban areas with poor drainage systems, low-lying coastal areas, and the state’s many valleys. According to the Public Policy Institute of California, the risk of floods has dramatically outpaced funding for flood mitigation and management.

  • Colorado

    - Most properties at risk: Colorado Springs (15,440 properties at risk; 10% of all properties)
    - Highest share of properties at risk: Lamar (46% of all properties; 1,621 properties at risk)
    - Highest projected increase: Edgewater
    --- Properties at risk in 2020: 1,626 (15% of all properties)
    --- Properties at risk in 2050: 1,700 (18% of all properties)

    In 2013, unprecedented flooding destroyed thousands of homes and hundreds of miles of roadways in Colorado—the state is just now finishing rebuilding and repairing several years later. The silver lining is that the trauma forced a dramatic shift in thinking among state officials. The roads, homes, infrastructure, and natural environments that were destroyed were largely built back stronger and more resistant to future flooding.

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  • Connecticut

    - Most properties at risk: Bridgeport (5,836 properties at risk; 21% of all properties)
    - Highest share of properties at risk: Old Greenwich (31% of all properties; 725 properties at risk)
    - Highest projected increase: West Haven
    --- Properties at risk in 2020: 1,824 (13% of all properties)
    --- Properties at risk in 2050: 2,971 (21% of all properties)

    Connecticut officials have conducted assessments, ordered widespread tree-trimming programs around utility lines, improved drainage systems, and ordered hundreds of shoreline homes to be raised. Those efforts, however, seem like temporary fixes to officials who understand just how vulnerable the state is to severe, long-term, and widespread flooding. Global warming has increased the frequency and severity of major storms so significantly that catastrophic shoreline erosion has put Connecticut just one big storm away from a statewide flood crisis.

  • Delaware

    - Most properties at risk: Bethany Beach (2,135 properties at risk; 97% of all properties)
    - Highest share of properties at risk: Bethany Beach (97% of all properties; 2,135 properties at risk)
    - Highest projected increase: Rehoboth Beach
    --- Properties at risk in 2020: 33 (2% of all properties)
    --- Properties at risk in 2050: 247 (11% of all properties)

    According to States at Risk, climate change has caused more nuisance flooding in Delaware and between 2005 and 2014, 67% of the state’s 214 total floods were classified as “human-caused.” Thanks mostly to an increase in Atlantic hurricanes, 22,000 people are at risk of flooding, and rising sea levels are expected to add 9,000 more to that tally by 2050.

  • Florida

    - Most properties at risk: Cape Coral (111,237 properties at risk; 86% of all properties)
    - Highest share of properties at risk: Warm Mineral Springs (100% of all properties; 5,097 properties at risk)
    - Highest projected increase: Golden Gate
    --- Properties at risk in 2020: 153 (3% of all properties)
    --- Properties at risk in 2050: 4,000 (76% of all properties)

    Surrounded on three sides by rising seas, Florida is home to America’s longest sea coast and is defined by flat terrain, low elevation, and a high water table—few states are more likely to lose cities to water in the coming decades. Cities like Miami have invested hundreds of millions of dollars in stormwater projects, but the state’s geography, its location in the heart of hurricane country, and the onslaught of global warming make Florida’s long-term outlook bleak.

  • Georgia

    - Most properties at risk: Atlanta (14,227 properties at risk; 11% of all properties)
    - Highest share of properties at risk: Brunswick (100% of all properties; 6,815 properties at risk)
    - Highest projected increase: Adel
    --- Properties at risk in 2020: 80 (3% of all properties)
    --- Properties at risk in 2050: 146 (5% of all properties)

    North of Florida is Georgia, which suffered 500-year floods in 2009—three out of four Georgia counties were declared federal disaster areas due to severe flooding over the last 15 years. The main cause is thunderstorms, but increasingly strong and frequent hurricanes and tropical storms, as well as rising sea levels, aggressive erosion, and greater overall rainfall, are taking their toll, as well.

  • Idaho

    - Most properties at risk: Boise City (15,529 properties at risk; 19% of all properties)
    - Highest share of properties at risk: Blackfoot (81% of all properties; 3,881 properties at risk)
    - Highest projected increase: Fruitland
    --- Properties at risk in 2020: 77 (4% of all properties)
    --- Properties at risk in 2050: 103 (5% of all properties)

    In Idaho, the annual rituals of spring snowmelt and mountain runoff are part of life—the phenomenon is both a blessing and a curse. Too little and the state is at risk of drought and low reservoirs. Too much and the result is gorged rivers and widespread flooding.

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