Road closed sign in front of flooded road with swollen river on both sides of the road.
  1. Learn More
  2. Determining Risk
  3. Expected Annual Loss
  4. Riverine Flooding

Riverine Flooding

Riverine Flooding is when streams and rivers exceed the capacity of their natural or constructed channels to accommodate water flow and water overflows the banks, spilling out into adjacent low-lying, dry land.

In the National Risk Index, a Riverine Flooding Risk Index score and rating represent a community's relative risk for Riverine Flooding when compared to the rest of the United States. A Riverine Flooding Expected Annual Loss score and rating represent a community's relative level of expected building, population, and agriculture loss each year due to Riverine Flooding when compared to the rest of the United States.

A map of the United States colored by Riverine Flooding Risk Index ratings. Riverine Flooding risk is possible across the United States with concentrated risk in southern Texas and along the Mississippi River and its tributaries. For full results, see the National Risk Index Map webpage.

Riverine Flooding Exposure

A Riverine Flooding exposure value represents a community's building value (in dollars), population (in both people and population equivalence), and agriculture value (in dollars) exposed to Riverine Flooding.

Riverine Flooding Annualized Frequency

A Riverine Flooding annualized frequency value represents the average number of recorded Riverine Flooding hazard occurrences (event-days) per year over the period of record (24 years).

Riverine Flooding Historic Loss Ratio

A Riverine Flooding historic loss ratio is the representative percentage of the exposed consequence type value (building, population, or agriculture) expected to be lost due to a Riverine Flooding hazard occurrence.

Riverine Flooding Processing Methodology

For comprehensive details about the Riverine Flooding processing methodology, see the National Risk Index Technical Documentation.

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