FLOOD07643

• County: Statewide
• Basin: Statewide
• Title: Physical and Economic Feasibility of Nonstructural Flood Plain Management Measures
• Date: 3/1/1978
• Prepared For: US
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Educational/Technical/Reference Information

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CHAPTER 8
FLOOD FORECAST, WARNING, AND EVACUATION

Description
Flood forecast, warning, and evacuation is a strategy to reduce flood losses by charting out a
plan of action to respond to 'a flood threat. The strategy includes,

. A system for early recognition and evaluation of potential floods.

. Procedures for issuance and dissemination of a flood warning.

. Arrangements for temporary evacuation of people and property.

. Provisions for installation of temporary protective measures,

. A means to maintain vital services.

. A plan for post-flood reoccupation and economic recovery of the flooded area.

Figure 8-1 illustrates the basic interaction between components of this strategy. Each covers a
broad spectrum of actions and reactions varying from responding to a visual flood threat to
sophisticated flood forecast, warning, and evacuation systems. The more sophisticated systems
require coordinated assistance from local, state and federal agencies.

Systems for early recognition and evaluation of potential floods are generally of two types:
Those for flooding of major stream systems and those related to flash floods. The National
Weather Service (NWS) has 13 River Forecasting Centers and 82 River District offices located
throughout the United States. Generally their forecasts predict stages on major river systems.
Flash flood systems are of many different types(3,4). These include,

. Self-contained community or county forecasting systems.

. Automatic flash flood alarm systems.

. NWS forecasting charts.

. Weather warning broadcasts.

. Manual observations.

Flood warning is the critical link between forecast and response. An effective warningprocess
will communicate the current and projected flood threat, reach all persons affected, account for
the activities of the community at the time of the threat (day, night, weekday, weekend), and
motivate persons to action. The decision to warn must be made by responsible agencies and
officials in a competent manner to maintain credibility of future warnings.

An effective warning needs to be followed by an effective response. This means effective and
orderly evacuation of people and property. Actions which can facilitate this include,

. Establishment of rescue, medical and fire squads.

. Identification of rescue and emergency equipment which can be utilized during a flood.

. Identification of priorities for evacuation.

. Surveillance of evacuation to insure safety and protect property.

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