My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
FLOOD08945
CWCB
>
Floodplain Documents
>
Backfile
>
8001-9000
>
FLOOD08945
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
1/26/2010 10:07:17 AM
Creation date
10/5/2006 3:59:51 AM
Metadata
Fields
Template:
Floodplain Documents
County
Larimer
Community
Fort Collins
Stream Name
Dry Creek
Basin
South Platte
Title
Hydrologic Analysis Major Drainageway Planning Dry Creek
Date
7/1/1979
Prepared For
Larimer County
Prepared By
Gingery Associates, Inc.
Floodplain - Doc Type
Floodplain Report/Masterplan
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
Laserfiche.
All rights reserved.
/
32
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 />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />, <br /> <br />- DISCUSSION OF RESULTS - <br /> <br />The comparison of the discharges determined in this study and <br />those determined in the Flood Insurance Study are shown in Table VII. <br /> <br />TABLE VII <br /> <br />Discharge Comparison <br /> <br />Location <br /> <br />QIO (efs) <br />Present FIA <br />Study Study <br /> <br />QIOO (efs) <br />Present FIA <br />Study Study <br /> <br />Q50 (cfs) <br />Present FIA <br />Study Study <br /> <br />u.s. Highway <br />287 <br /> <br />Confluence <br />with Poudre <br />River <br /> <br />660 <br /> <br />1190 <br /> <br />1950 <br /> <br />2230 <br /> <br />2820 <br /> <br />2650 <br /> <br />660 <br /> <br />1610 <br /> <br />2930 <br /> <br />1900 <br /> <br />2700 <br /> <br />3480 <br /> <br />A first observation from this discharge comparison is that the <br />discharge throughout the study reach is constant or decreases slightly <br />downstream using the SWMM model. This result would be expected where <br />a large basin narrows into a small bottleneck at its downstream end. <br />By the time the peak reaches the bottleneck, the lower area is con- <br />tributing very little to the overall basin flow. Therefore, a physi- <br />cal interpretation of the basin would suggest that discharges should <br />not increase sharply through this reach. At the upstream end of the <br />study, the discharge comparison for the 50-year and 100-year events <br />is very good, as should be expected at this point. <br />The 10-year event at the upstream end of the study reach does <br />not compare favorably. Since the model was calibrated for as-year <br />event, and because recent history would dictate a 10-year event of <br />fairly low magnitude, the results from the SWMM model are more <br />realistic. <br />Further information available through the SWMM model shows that <br />the effect of channel storage is to produce a constant peak through- <br />out a major part of this basin. Hence, not only is the peak constant <br />through the study reach because of the bottleneck, but it is also <br />constant up to Douglas Reservoir because of channel storage. <br />Also, in the lower developed reaches of the basin, the immediate <br />response of the impervious areas is shown in Figure 7 for the 100- <br />year event. The first peak of Figure 7 is the flow generated from <br />the urbanized area. <br /> <br />-12- <br />
The URL can be used to link to this page
Your browser does not support the video tag.