Flooding Hazards

Short Term Flooding Hazards

RISK LEVEL	HAZARD DESCRIPTION
Low	Small streams, creeks, canals, and drainage ditches may become swollen and overflow in a few places. In urban locations, ponding of water may occur at certain underpasses or poor drainage spots. Storm sewer drains and retention ponds may become near full and overflow in a few places. Flooding is expected to pose a low threat, mainly an inconvenience, likely only impacting a few buildings and roads, with few if any evacuations necessary, and causing only minor damage.
Moderate	Area rivers and tributaries may become swollen and start to overspill their banks in a few places. Small streams, creeks, canals, and drainage ditches will likely overflow. In flatter terrain, expanded areas of inundation may occur around low-lying spots covering several secondary roads. In urban areas, expanded areas of inundation may occur at several underpasses or poor drainage spots, with some streets and parking lots taking on moving water up to a foot deep. Storm sewer drains and retention pondswill likely fill and overflow. Flash flooding is expected to cause a moderate threat, more than just an inconvenience. Flooding will likely impact several buildings and roads with several evacuations necessary, and produce moderate damge.
High	Area rivers and tributaries may overflow their banks in several places. Small streams, creeks, canals, and drainage ditches may become fast flowing dangerous rivers. In flatter terrain, extensive inundation may occur covering both primary and secondary roads. In urban areas, widespread inundation is possible, with streets and parking lots becoming rivers of moving water. Flash flooding is expected to pose a high risk, and may significantly impact many buildings and roads, with many evacuations necessary, and produce major damage.

General Information

Short term flooding hazards can be classified into two types:

Flash floods are rapid rises in water that can begin within a few minutes or hours of heavy rainfall. Water rises rapidly, and moves swiftly, carrying cars, ripping trees from the ground, and even destroying roads and bridges.

Urban/Area floods are rapid events, although not quite as severe as flash floods. Still, streets can become swift moving rivers. This type of flooding can occur in urban areas where water cannot be aborbed into the ground, but instead into storm drains and sewers, and in flat low lying areas with poor drainage.

For additional information visit:

NWS Severe Weather Awareness

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Updated 4/19/2015