FLOOD04090

• County: Pueblo
• Community: Pueblo
• Stream Name: Dry Creek
• Basin: Arkansas
• Title: Dry Creek Flood Review
• Date: 7/1/1997
• Prepared For: State of Colorado
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Documentation Report

surveyed two channel and floodplain cross sections, From the field data, CWCB staff computed a
flood discharge from the July 9, 1996. flood event using the slop-area method, The estimated
discharges are 3,100 cfs and 3, 600 cfs respectively (See Attachment C-I and C-2),

Hydraulic characteristics for the Flood InsuraI1ce Study were computt:d using the Corp's HEC-2
program, Flood profiles were drawn showing the computed water surface elevations for floods of
the selected recurrence intervals (See Attachment D), The water surface elevations and inundation
areas for the 1 DO-year flood event are shown on Attachment E,

Study Findings

The Board staff finds that the July 9,1996 flood event was greater than the 1 DO-year flood event.
The roadway crossing of the stream immediately downstream of the Missouri-Pacific Railroad is a
concrete "ford," otherwise known as a 'Texas Crossing," It appears that the stream crossing does
not have enough capacity to contain the 1 DO-year flood flow, During the July 9, 1996 flood, high
water overtopped the right overbank and flooded Booth Street, causing a flood condition in areas not
identified on the FEMA floodplain map (Attachment E),

Recommended Flood Mitigation Measures - Structural

The Board staffs flood mitigation recommendations are shown on Attachment F, The structural
flood mitigation measures are:

1) Construct a deflective jetty upstream of the county road on the right bank.

2) Extend the "ford" (Texas Crossing) of the county roadway into the left overbank,

3) Add rip-rap material to the existing right bank rip-rap to lower the roughness and friction
coefficient, which would help create a smoother flow regime,

,

4) Widen the channel cross-section downstream of the Missouri-Pacific Railroad to a point 500 feet
downstream of the county road,

;-..~

5) Add freeboard to the overall project design.

Non-Structural Mitigation

Non-structural flood mitigation measures include:

1) Purchase of flood insurance by residents,

2) Implementation of flood-proofing measures by residents_

3) Relocation of residents in flood prone areas,

4) Informing the area residents that floods larger than the 1 DO-year event can ~md do occur.