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

requires establishing flood routing criteria (initial reservoir levels,

reservoir constraints, and operation requirements) and freeboard require-

ments. Dam appurtenances (spillways and outlet works) should be selected

and designed to safely convey reservoir outflow from the IOF to a discharge

point downstream from the toe without endangering the dam.

2. Flood Routinq Criteria

Site-specific considerations should be used to establish flood routing

criteria for each dam and reservoir. The criteria for routing the IOF

should be consistent with the reservoir regulation procedure that is to be

followed in actual operation. General guidelines to be used in establish-

ing criteria follow:

a. Initial reservoir elevation. - Initial pool levels for routing

runoff through reservoirs should be basec on hydrologic characteristics

of the basin and project operational considerations. The assumed

initial levels should be reasonable for the season when the IOF may

occur and generally should be based on reservoir system regulation

studies which reflect basin runoff conditions and releases for specific

project purposes. In some cases, it may be necessary to examine

seasonal variations in pool levels and the IOF series to determine

maximum reservoir levels. Regulating rule curves and forecasting

procedures established for the forecastable components of the IOF

(usually only the snowmelt portion) may be considered when establishing

initial reservoir elevation. Hydrologic characteristics and reservoir

regulation objectives will vary significantly from one reservoir or

reservoir system to the next.

14