Natural Hazards: Causes and Effects - Disaster Management Center ...

Acquisition
Remedial acquisition consists of the acquisition and relocation or demolition of high-risk
structures in the floodplain. The cost of this alternative is high because full value must be paid
for the structure and the land. Occasionally some money can be recouped by selling the
structure to someone willing to move it or salvage materials from it. Acquisition can be better
justified if the land can be put to some beneficial public use compatible with the flood hazard. In
these cases funding assistance from a source such as an open space or recreation fund may be
available. Following a flood disaster, funding assistance for acquisition of damaged properties
may be available through disaster response agencies.
Public Awareness Programs
Appropriate public awareness programs should be implemented for the following purposes:
• to make floodplain occupants and/or owners aware of identified flood hazards;
• to encourage individuals to take actions such as floodproofing and developing escape plans,
to mitigate their flood potential;
• to make individuals aware of the existence and operation of flood warning plans;
• to encourage individuals to keep drainageways clean and to report potential maintenance
problems.
Master Plans
The basic guide, or road map, that provides local community officials, land owners, and
developers with the information necessary to manage the floodplain is the master plan. The
master plan documents the floodplain, floodway, discharges and proposed preventive and
remedial actions to be taken to reduce the flood damage potential.
Each drainageway should be master planned for its entire length through the urban area as well
as adjacent areas where future urbanization is anticipated. All local jurisdictions affected by the
drainageway should be actively involved in the planning process, and the final product should
be one that is acceptable to all jurisdictions. A regional agency can be very helpful in
coordinating the formulation of a multijurisdictional master plan.
• The master planning process consists of the following steps:
• Obtain good mapping of the study area.
• Develop hydrology for several frequencies including the 100-year (the other frequencies are
used in the benefit-cost analysis).
• Delineate floodplains for the frequencies for which hydrology was developed, using existing
channel and floodplain conditions.
• Estimate flood damages for the various frequencies and develop flood damage-frequency
curves and average annual damages (assume that floodplain regulations will prevent new
flood damage potential from being introduced into the floodplain).
• Conduct a review of all possible flood damage reduction alternatives, such as dams,
channels, conduits, floodproofing, acquisition, etc., to attempt to eliminate from
consideration those alternatives that are obviously inappropriate.
• Prepare preliminary designs and cost estimates for the remaining alternatives and delineate
residual floodplains for the frequencies being used.
• Determine residual flood damages for each alternative.
• Complete a benefit-cost analysis for each alternative.
• Review each alternative for other factors such as political considerations, multiple-use
opportunities, environmental factors, etc.
• Select an alternative or combination of alternatives acceptable to each affected jurisdiction.