My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
FLOOD02373
CWCB
>
Floodplain Documents
>
Backfile
>
2001-3000
>
FLOOD02373
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
1/25/2010 6:24:15 PM
Creation date
10/4/2006 10:51:23 PM
Metadata
Fields
Template:
Floodplain Documents
County
Teller
Community
Teller County and Incorporated Areas
Basin
Arkansas
Title
FIS - Teller County and Incorporated Areas
Date
9/30/1988
Prepared For
Teller County
Prepared By
FEMA
Floodplain - Doc Type
Current FEMA Regulatory Floodplain Information
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
53
PDF
Print
Pages to print
Enter page numbers and/or page ranges separated by commas. For example, 1,3,5-12.
After downloading, print the document using a PDF reader (e.g. Adobe Reader).
Show annotations
View images
View plain text
<br />~- <br /> <br />Water-surface elevations for the different floodflows were <br />computed using the COE HEC-2 step-backwater computer program <br />(Reference 11). The channel cross section data were obtained <br />photogrammetrically using aerial photos taken in October 1984. <br />The cross sections at all but one of the hydraulic structures were <br />obtained from field data taken in the fall of 1984. The data for <br />the bridge over Loy Gulch at state Highway 67 were supplied by <br />engineering consultants for the City of Woodland Park <br />(Reference 12). <br /> <br />Locations of selected cross sections used in the hydraulic <br />analyses are shown on the Flood Profiles (Exhibit 1). For stream <br />segments for which a floodway was computed (Section 4.2), selected <br />cross section locations are also shown on the Flood Insurance Rate <br />Map (Exhibit 2). <br /> <br />Roughness factors (Manning's "nil) used in the hydraulic <br />computations were selected on the basis of field observations of <br />the streams and flood plain areas. Values were documented with <br />photographs and descriptions in Open-Channel Hydraulics <br />(Reference 13). Photographic documentation of channels and <br />overbanks was used extensively in this process. Roughness values <br />for the main channel of the streams ranged from 0.030 to 0.040., <br />values for the overbank areas ranged from 0.040 to 0.050. <br /> <br />Starting water-surface elevations were selected at critical depth, <br />as each stream slope was greater than critical slope at the start <br />of the reach. The majority of the stream reaches were of super- <br />critical slope. The HEC-2 computer program (Reference 11) was run <br />using the subcri tical flow option so that the water depths were <br />never less than critical depth. <br /> <br />The fact that there are many small culverts on the streams was <br />taken into account. In cases in which a culvert was expected to <br />be unobstructed and its capacity represented a minor portion of <br />the 100-year flood discharge, the section was treated as if it had <br />no culvert, and discharge equal to the flood discharge less the <br />culvert capacity was used. Culvert capacities were estimated <br />using standard nomographs of the Federal Highway Administration <br />(Reference 14). The small culverts on Fountain Creek that are <br />often obstructed with sediment: were considered to be inoperative. <br />A portion of Loy Gulch shares -a common 100-year flood plain with <br />Paint Pony. Although two dist;inct channels exist, they have been <br />considered as one flooding source for the reach above their <br />confluence. As a result, profiles for Loy Gulch include culverts <br />existing only on the Paint Pony channel. <br /> <br />Hydraulic analyses of Lovell Gulch, Paint Pony, and East Fork <br />Paint Pony indicated that water depths for the 100-year flood are <br />generally less than 3 feet. Exceptions occur when manmade <br />channels, such as road ditches, concentrate flow. The natural <br />channels on these streams are ,typically undefined, and overland <br />sheetflow is common. <br /> <br />12 <br />
The URL can be used to link to this page
Your browser does not support the video tag.