FLOOD05706

• County: Statewide
• Community: State of Colorado
• Basin: Statewide
• Title: DAMCAL - Damage Reach Stage-Damage Calculation - Users Manual
• Date: 2/1/1979
• Prepared For: State of Colorado
• Prepared By: Hydrologic Engineering Center
• Floodplain - Doc Type: Educational/Technical/Reference Information

and the difference is added to the reference flood elevation of the ~rjd

cell. The computed elevation is the protection level water surface eleva-

tion. The amount of protection required for the grid cell is the protpction

elevation less the topographic (or ground) elevation. If the grid cell

requires flood protection, the computer program truncates the elevation-damage

curve at the protection level elevation. The process is repeated for each

grid cell assigned to the damage reach.

Figure 4-8 illustrates the preceding computational procedure. The sample

grid cell used has a ground elevation of 420.0 feet (see Figure 4-8b). The

damage reach index location has a reference flood water surface elevation

of 427.0 feet and a desired target protection level of 425.5 feet. The dif-

ference in water surface elevations at the index location is a minus 1.5

feet (425.5 - 427.0). The difference is added to the reference flood elev-

ation of the grid cell to yield a corresponding target protection elevation

(424.5 - 1.5 ~ 423.0 feet) for the cell (see Figure 4-8c). The elevation

damage function is then truncated as shown in Figure 4-8d and aggregated to

the index location in the usual manner. The option of flood proofing se-

lected land Use categories within a damage reach to various frequency flood

events can be done for 1) existing conditions, 2) alternative land use con-

ditions, and 3) alternative land use conditions considering the flood proof-

ing of new development only.

I
~

Response to Flood Warning Dissemination. The temporary evacuation of

facilities within a damage reach is a component of the implementation of a

flood warning system. This type of option is difficult to evaluate, not

because of theory, but because it requires the estimation of the effect of

a flood warning system on the stage-damage functions (for each land use

category) as temporary protection measures are implemented. To evaluate

the option, the stage-damage functions which are input to the DAMCAL program

are modified (based on a percentage of the existing damage associated with

each stage) for each damageable land use category that is affected. The

modification in the stage-damage functions should include damage reduction

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