Hurrican Katrina flooding

Source: Jocelyn Augustino - Aug 29, 2005 | FEMA

Not all floods are alike; they happen on different scales of space and time.

  • Flash Floods - Flash floods can occur within a few minutes or hours of heavy rainfall or from a dam or levee failure. These floods can destroy structures, down trees, roll boulders, and create new waterways.
  • Urban Floods - Floods can be magnified in urban areas. As land is converted from fields and woodlands to roads and parking lots, it loses it ability to absorb rainfall. During periods of urban flooding, streets can become swift moving rivers.
  • River Floods - Flat areas near rivers, streams, lakes and reservoirs are vulnerable to river floods. Some river floods occur when winter or spring rains fill river basins with too much water too quickly. Other floods can happen when storm systems move slow or from heavy rains from hurricanes or tropical systems.
  • Area Floods - Area floods are long-lived and do not usually threaten life. Standing water in flat areas, such as an open field, is just one example of an area flood. Area floods can cause damage to crops and cause livestock to become displaced. In addition, the standing water from this type of flooding can serve as a breeding ground for insects and diseases.