FLOOD06619

• County: Statewide
• Community: State of Colorado
• Basin: Statewide
• Title: Federal Guidelines for Selecting and Accommodating Inflow Design Floods for Dams
• Date: 2/1/1986
• Prepared For: State of Colorado
• Prepared By: FEMA
• Floodplain - Doc Type: Project

e. Both normal and minimlll1 freeboard requirements should be evaluated

in determining the elevation of the top of dClll. The resulting

higher top of dam elevation should be adopted for design.

e Freeboard allowances for wind-wave action should be based upon

the most reliable wind data available that are applicable to

the site. The significant wave should be the minimum used in

determining wave runup; and the sum of wind setup and wave runup

should be used for determining requirements for this component of

freeboard.

Computations of wind-generated wave height, setup, and runup
should incorporate selection of a reasonable combined occurrence of
pool level, wind velocity, wind direction, and wind durations

based on site-specific studies.

. It is highly unlikely that maximlll1 winds will occur when the
reservoir water surface is at its maximum elevation resulting
from routing the IDF, because maximum levels generally persist
only for relatively short periods of time (a few hours).
Consequently, winds selected for computing wave heights should
be appropriate for the short period the pool would reside at or
near maximum levels.

. Normal pool levels persist for long periods of time. Conse-
quently, maximlll1 winds should be used to compute wave heights,

e Freeboard allowance for settlement should be applied to account

for consolidation of foundation and embankment materials when

uncertainties exist in computational methods or data used yield

unreliable values for camber design. Freeboard allowance for

settlement should not be applied where an accurate determination

of settlement can be made and is included in the camber,

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