Riverine Flooding

Hazard in Flooding

A slow-rising, often forecastable hazard where rivers leave their banks for days, inundating the floodplain and everything built in it.

Plans also call it: riverine flood, river flooding, flood, flooding, inland flooding, overbank flooding, atmospheric river, ice jam

Talk to us about Riverine FloodingAll 73 hazards →

What you’d hand your council

The first page of a Riverine Flooding evidence brief: likelihood, impact and readiness on your own scale, every figure sourced.

Evidence brief for Cedar Ridge County (example)

September 14, 2026

Riverine Flooding

Hazard in Flooding, on the established threats & hazards list

Impact
5432112345

Likelihood

Likelihood
4

Likely — Expected within the decade — roughly once in 1 to 10 years (10–100% chance in any year).

Impact
4

Major — Severe effects — casualties possible, serious damage across a significant share of the jurisdiction, essential services disrupted for weeks, outside assistance needed.

Readiness
2

Low — Some elements of capability are in place, but important gaps remain that could significantly limit the organization's ability to perform effectively. Additional development is needed before the capability can be relied upon.

  • 2source documents
  • 58verified mentions
  • 2federal declarations
  • 91.6NRI score, relatively high
Worked example: Cedar Ridge County is fictional. The scores illustrate the format and are nobody's decision. Open a full sample brief →

The national record

FEMA National Risk Index: Inland Flooding

$65.3B
expected loss a year, nationally
212
counties rated high or very high

Your county’s own rating is the first thing we pull.

How it maps

The same hazard in the vocabularies your plan and FEMA already use.

FEMA National Risk Index
Inland Flooding (IFLD)one of the 18 hazards NRI scores per county
FEMA declaration incident type
Flood926 declarations on record
NOAA Storm Events type
Flood
Hazzard category
Flooding, natural hazards

How it connects

The national record

What the federal data says about Riverine Flooding

The same national sources a Hazzard brief starts from. For your jurisdiction we narrow each one to your county and its neighbors.

Where Riverine Flooding is rated high

Share of each state's counties FEMA rates Relatively High or Very High

Alabama: 4 of 67 counties rated high (6%) · $1.1B expected loss a yearAlaska: 0 of 26 counties rated high (0%) · $30M expected loss a yearArizona: 7 of 15 counties rated high (47%) · $2.0B expected loss a yearArkansas: 1 of 75 counties rated high (1%) · $628M expected loss a yearCalifornia: 33 of 58 counties rated high (57%) · $11.7B expected loss a yearColorado: 3 of 64 counties rated high (5%) · $960M expected loss a yearConnecticut: 5 of 9 counties rated high (56%) · $858M expected loss a yearDelaware: 1 of 3 counties rated high (33%) · $217M expected loss a yearDistrict of Columbia: 1 of 1 counties rated high (100%) · $130M expected loss a yearFlorida: 15 of 67 counties rated high (22%) · $2.8B expected loss a yearGeorgia: 4 of 159 counties rated high (3%) · $1.6B expected loss a yearHawaii: 3 of 5 counties rated high (60%) · $622M expected loss a yearIdaho: 0 of 44 counties rated high (0%) · $383M expected loss a yearIllinois: 7 of 102 counties rated high (7%) · $2.9B expected loss a yearIndiana: 3 of 92 counties rated high (3%) · $1.2B expected loss a yearIowa: 0 of 99 counties rated high (0%) · $725M expected loss a yearKansas: 2 of 105 counties rated high (2%) · $634M expected loss a yearKentucky: 3 of 120 counties rated high (3%) · $1.3B expected loss a yearLouisiana: 6 of 64 counties rated high (9%) · $911M expected loss a yearMaine: 0 of 16 counties rated high (0%) · $181M expected loss a yearMaryland: 4 of 24 counties rated high (17%) · $492M expected loss a yearMassachusetts: 7 of 14 counties rated high (50%) · $943M expected loss a yearMichigan: 4 of 83 counties rated high (5%) · $1.5B expected loss a yearMinnesota: 2 of 87 counties rated high (2%) · $1.3B expected loss a yearMississippi: 1 of 82 counties rated high (1%) · $500M expected loss a yearMissouri: 4 of 115 counties rated high (3%) · $1.6B expected loss a yearMontana: 0 of 56 counties rated high (0%) · $277M expected loss a yearNebraska: 1 of 93 counties rated high (1%) · $401M expected loss a yearNevada: 2 of 17 counties rated high (12%) · $517M expected loss a yearNew Hampshire: 0 of 10 counties rated high (0%) · $314M expected loss a yearNew Jersey: 13 of 21 counties rated high (62%) · $2.0B expected loss a yearNew Mexico: 2 of 33 counties rated high (6%) · $641M expected loss a yearNew York: 11 of 62 counties rated high (18%) · $2.8B expected loss a yearNorth Carolina: 4 of 100 counties rated high (4%) · $2.1B expected loss a yearNorth Dakota: 0 of 53 counties rated high (0%) · $161M expected loss a yearOhio: 6 of 88 counties rated high (7%) · $1.9B expected loss a yearOklahoma: 2 of 77 counties rated high (3%) · $738M expected loss a yearOregon: 5 of 36 counties rated high (14%) · $852M expected loss a yearPennsylvania: 15 of 67 counties rated high (22%) · $2.7B expected loss a yearRhode Island: 1 of 5 counties rated high (20%) · $153M expected loss a yearSouth Carolina: 2 of 46 counties rated high (4%) · $785M expected loss a yearSouth Dakota: 0 of 66 counties rated high (0%) · $274M expected loss a yearTennessee: 4 of 95 counties rated high (4%) · $1.2B expected loss a yearTexas: 16 of 254 counties rated high (6%) · $4.9B expected loss a yearUtah: 1 of 29 counties rated high (3%) · $329M expected loss a yearVermont: 0 of 14 counties rated high (0%) · $162M expected loss a yearVirginia: 1 of 133 counties rated high (1%) · $1.1B expected loss a yearWashington: 3 of 39 counties rated high (8%) · $1.4B expected loss a yearWest Virginia: 1 of 55 counties rated high (2%) · $859M expected loss a yearWisconsin: 2 of 72 counties rated high (3%) · $1.1B expected loss a yearWyoming: 0 of 23 counties rated high (0%) · $147M expected loss a year
  • None
  • Up to 10%
  • 10–25%
  • 25–50%
  • Over 50%
  • Not rated
FEMA National Risk Index v1.20.0, county table

926 federal declarations since 1953

Declarations FEMA filed as “Flood”, by year (2026 to date)

025501953: 5 declarations1954: 7 declarations1955: 8 declarations1956: 7 declarations1957: 10 declarations1958: 5 declarations1959: 6 declarations1960: 3 declarations1961: 10 declarations1962: 17 declarations1963: 15 declarations1964: 15 declarations1965: 9 declarations1966: 9 declarations1967: 6 declarations1968: 10 declarations1969: 21 declarations1970: 12 declarations1971: 10 declarations1972: 43 declarations1973: 34 declarations1974: 33 declarations1975: 25 declarations1976: 19 declarations1977: 16 declarations1978: 21 declarations1979: 29 declarations1980: 12 declarations1981: 7 declarations1982: 19 declarations1983: 14 declarations1984: 20 declarations1985: 10 declarations1986: 23 declarations1987: 10 declarations1988: 2 declarations1989: 17 declarations1990: 16 declarations1991: 13 declarations1992: 18 declarations1993: 15 declarations1994: 4 declarations1995: 5 declarations1996: 27 declarations1997: 11 declarations1998: 6 declarations1999: 3 declarations2000: 2 declarations2001: 5 declarations2002: 4 declarations2004: 1 declaration2005: 2 declarations2006: 2 declarations2007: 1 declaration2008: 3 declarations2009: 3 declarations2010: 9 declarations2011: 27 declarations2012: 3 declarations2013: 17 declarations2014: 10 declarations2015: 9 declarations2016: 18 declarations2017: 13 declarations2018: 17 declarations2019: 28 declarations2020: 6 declarations2021: 9 declarations2022: 11 declarations2023: 24 declarations2024: 20 declarations2025: 14 declarations2026 (to date): 11 declarations1972: 431960197019801990200020102020
OpenFEMA Disaster Declarations Summaries, as of 2026-09-27. Counts distinct disasters; major, emergency and fire-management declarations.

In your plan

What a Riverine Flooding profile needs, and where each part comes from

A local hazard mitigation plan profiles each hazard the same way (44 CFR 201.6). Here is how Hazzard fills each part for Riverine Flooding.

  1. Location

    44 CFR 201.6(c)(2)(i)

    National data

    FEMA's National Risk Index rates Riverine Flooding for every county. We place yours against its neighbors and the state, then add what your plans map in more detail.

  2. Extent

    44 CFR 201.6(c)(2)(i)

    Your documents

    The magnitude your plans use for Riverine Flooding (a scale, a depth, an acreage, a duration), read from your documents and cited, so the profile states the strength you plan for.

  3. Previous occurrences

    44 CFR 201.6(c)(2)(i)

    National data

    Every FEMA declaration filed as Flood that included your county, back to 1953, alongside the events your own records and after-action reports describe.

  4. Probability of future events

    44 CFR 201.6(c)(2)(i)

    National data

    NRI's annualized frequency for your county, and the declaration history, drafted into a likelihood on your own scale for your team to accept or change.

  5. Vulnerability and impacts

    44 CFR 201.6(c)(2)(ii)

    National data

    NRI's expected annual loss and social vulnerability for your county, the Census population profile and HHS emPOWER counts, with the impacts your plans already describe.

  6. The assessment itself

    Your team decides

    Likelihood, impact and readiness for Riverine Flooding are drafted with every source attached, and a person on your team accepts each one. Hazzard never records a score on its own.

How we can help

How we’d help you prepare for Riverine Flooding

  1. 1

    We pull your flood history

    Federal declarations, NRI's inland and coastal flooding ratings, and the mitigation projects FEMA has already funded in your county.

  2. 2

    We read your plans for each cause

    Mitigation plan, floodplain and dam safety material, so Riverine Flooding is profiled as its own thing instead of folded into “flooding”.

  3. 3

    You leave with a cited brief

    Likelihood, impact and readiness for Riverine Flooding on your own scale, every figure tied to its source, ready for the planning team or the council.

Also in Flooding

Preparing for Riverine Flooding

Show where Riverine Flooding actually reaches, not just that it can.

Flooding is the most common declaration in the country, and each cause plans differently. We separate them in your evidence so the mitigation that follows is aimed at the right water. A person replies within one business day.

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