FLOOD00076

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Title: Floodplain Study Review and Designation program - SOQ
• Date: 4/1/2000
• Prepared For: State of Colorado
• Prepared By: Sear-Brown Group
• Floodplain - Doc Type: Miscellaneous

FLOODPLAIN STUDY REVIEW AND DESIGNATION PROGRAM

PROJECT EXPERIENCE

Project Approach
Consistent with the process followed by CWCB staff, our approach to this project is built around:
(1) communication with the affected communities and the Colorado Water Conservation Board;
(2) research and accumulation of available pertinent floodplain information; and (3) consistent
methodical technical review of all gathered data. For each review, we anticipate the following
approach:

Communication
In cooperation with CWCB staff, identify each affected community and appropriate
community staff contacts. In writing and by telephone, contact the community with
notification of the pending floodplain review; to request input and background information;
and to discuss FEMA and CWCB regulatory standards.

Research
In cooperation with CWCB staff visits to the affected community, obtain and compile
available floodplain maps, Flood Insurance Studies (FIS), floodplain information reports
(FIR), community flood-level experience, and any other available supporting information.

Technical Review
Our technical review process will generally follow the approximate floodplain delineation
procedures outlined in the CWCB Rules and Regulations for the Designation and Approval
of Floodplains and of Storm or Floodwater Runoff Channels in Colorado. This would
include:

Mapping
Floodplain maps and current USGS quadnmgle maps will be used as a basis for this
analysis and compared for topographic consistency.

Hydrology
Available IOO-year runoff values will be compared against CWCB regional
regression equations to confirm suitable runoff values have been used in the basin.
In the absence of any hydrologic information, the IOO-year runoff will be estimated
using CWCB regional regression equations.

Hydraulic Analysis
Floodplain boundaries on the provided jJoodplain maps will be verified with a
variety of methods suitable to each particular case. These methods could include
regional regression analysis of depth-frequency relations, normal depth/slope-area

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