FLOOD01659

• County: Statewide
• Title: Floodplain Management Handbook
• Date: 9/1/1981
• Prepared By: Flood Loss Reduction Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

. Reducing the danger and suscepti-
bility to damages from flooding by
keeping people and developments
subject to damage out of the flood
hazard area or by making such develop-
ments more resistant to damage.

financial and social
flooding through such
insurance and post-flood

. Reducing the
impact of
measures as
assistance.

Table 1 lists the principal
measures that can be used in carrying
out each of the three strategies. A
program combining at least some of the
measures from each strategy is usually
required for the greatest and most
cost-effective reduction of losses.

TABLE 1
STRATEGIES AND HEASURES
FOR
FLOOD LOSS REDUCTION

Modify Flooding
dams and reservoirs
levees and walls
channel alterations
diversions
land treatment
onsite detention

Modify Susceptibility to Flooding
floodplain regulations
development and redevelopment
warning and preparedness
floodproofing

Modify Impact of Flooding
flood insurance
relief and recovery

The principal
each measure are
following sections.

characteristics of
described in the

Measures Modifying Flooding

Each of the measures for reducing
flooding is intended to protect an area
rather than a particular property or
person. Most--but not all--involve

heavy construction and a high capital
cost. As a result, most measures in
this category are usually undertaken as
public projects.

The measures that require signi-
ficant amounts of construction also
share several disadvantages including:

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. Lengthy and complex planning and
design.

. Potential for making flood damages
outside the project area more severe.

. Potential for major losses if design
levels are exceeded.

. Potential for creating a
of security about the
protection provided.

false sense
extent of

. Need for careful and costly routine
inspection, operation and maintenance.

. Possible detrimental effects to the
natural environment.

The main attraction for these
measures is that they require rela-
tively little disruption to homes,
businesses and life styles for most
floodplain occupants.

Dams and Reservoirs

Reservoirs capture and
temporarily hold floodwaters upstream
of flood-prone areas. Excess water is
gradually released after the flood
threat has passed. Use of dams requires
sites capable of storing sufficient
amounts of water which are upstream but
fair ly close to the area to be protec-
ted. In addition, the location must
normally be "available" in the sense
that it does not contain significant
urban development or sites warranting
preservation for historical or other
reasons.

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Reservoirs have the potential for
reducing flooding in several downstream
communities rather than protecting
single areas as with some flood-modify-
ing measures. Another advantage lS
their potential for serving other uses,

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