FLOOD06631

• County: Statewide
• Basin: Statewide
• Title: Flood Mitigation and Recovery Annex
• Date: 1/1/1995
• Prepared For: New Hampshire
• Prepared By: NH Office of Emergency Management
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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FLOOD WARNING

Most floods arrive with some warning_ A well-prepared response to a flood warning can
save lives and prevenl property damage. Sometimes flooding can occur from rainfall
elsewhere in the watershed_ Personal observation will not tell you how much of the rain
will flow into the stream, when the flood will reach its peak, or how high it will be.

The National Weather Service has a system for issuing flood warnings which relies on
scientific observations of rainfall and runoff patterns_ The Weather Service notifies the
New Hampshire Office of Emergency Management when a flood could occur. This is
called a "flood watch". It also issues a "flood warning" when flooding is imminent or
already happening_ You may also receive notification directly from the Weather Service_

The National Weather Service has available, a form for an official flood warning. The
warning tells when and where flooding is expected_ Sometimes the warning predicts the
height of the expected flood in feet above "flood stage". Someone in your local
government should be designated to receive the warning and take appropriate actions_ It
may be the city or town manager, the police chief, the fire chief, or your local emergency
manager.

A first task is to warn people who may be in danger. There are inany ways to do this_ A
siren is effective if people know what it means and what to do when they hear it. Some
communities send policemen with bullhorns to vulnerable neighborhoods_ Sometimes,
emergency responders go door-to-door warning people. Regardless of how initial
warning is delivered, it must be accompanied by information telling people what to expect,
when, and what actions they need to take_ Planning ahead and educating citizens will
make this task easier_

Warnings are not useful unless areas subject to flooding are identified - usually low lying
areas adjacent to rivers and streams or other drainage channels_ These areas are called
floodplains_ A floodplain may be composed of a channel defined by the banks of a stream;
a flood way which carries the bulk of floodwaters, particularly the high velocity
floodwaters; and a flood fringe which carries low velocity floodwaters that are not as deep
as in the floodway_

Local officials must evaluate the information they receive above the severity of the
approaching flood, and plan for possible evacuation. When a flood is expected, it is very
important to direct traffic to high and dry roads. These routes should be identified and
documented ahead of time_

Individuals and business can use warning time to move important records, furniture and
other items to upper stories of buildings or to high ground. Local government can prepare
the Emergency Operations Center or relocate it if, like so many, it is in a basement subject
to flooding. Anything that can be done to prevent damage will make life easier in the
days, weeks. and months after the f1ood_

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