My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
FLOOD10157
CWCB
>
Floodplain Documents
>
Backfile
>
9001-10000
>
FLOOD10157
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
1/26/2010 10:12:09 AM
Creation date
10/5/2006 4:56:10 AM
Metadata
Fields
Template:
Floodplain Documents
Designation Number
74
County
Arapahoe
Community
Aurora
Stream Name
Granby and Sable Ditches
Basin
South Platte
Title
FHAD - Granby and Sable Ditches, Aurora, Colorado
Date
4/1/1977
Designation Date
7/27/1977
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.
/
37
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 />I <br />. <br />I <br />I <br />I <br />. <br />I <br />I <br />I <br />. <br />. <br />I <br />I <br />. <br />I <br />I <br />. <br />I <br /> <br />-10- <br /> <br />Canal passes through this reach and creates a dam causing <br />considerable backup to Laredo Street. Depths range from <br />6 to 12 feet in this area. The existing Laredo Street <br />crossing is also inundated by the lOa-year flood. <br /> <br />flow velocity in the channel would range generally between 4 <br />and 10 feet per second for a lOa-year event in the study <br />area. Overbank velocities range between 1 and 4 feet per <br />second. <br /> <br />Flood Plain and Floodway Data <br /> <br />Water flowing at a rate greater than 6 to B feet per second <br />will cause severe erosion of stream banks and is capable of <br />transporting large rocks. velocities in the range of 6 to 8 <br />feet per second could erode fill around bridge abutments. <br />Water flowing at about 2 feet per second or less will deposit <br />debris and silt. <br /> <br />The limits of future flooding for Granby and Sable Ditches <br />are graphically outlined on the Flood Hazard Area Delineation <br />maps and tabulated in Tables V! and VII, Flood Plain and <br />Floodway Reference Data. The tables list the potential <br />flood elevations, flood plain and floodway widths, floodway <br />location, floodway surcharge elevation and thalweg elevation <br />at each cross-section studied. <br /> <br />SUMMARY <br /> <br />A floodway represents a part of the flood plain which is required <br />to pass a lOa-year flood event without raising the flood <br />profile more than an acceptable amount and also represents <br />that part of the flood plain most hazardous to personal <br />safety and welfare. In this study, the floodway was <br />defined as being the limit of encroachment into the flood plain <br />where existing flood profiles are not increased more than <br />1.0 foot. Also, flood plain areas where average velocities <br />exceeded two to three feet per second were considered to be <br />within the floodway. Floodway widths, which represent the <br />maximum limits of encroachment into the flood plain, are <br />tabulated in Tables VI and VII. <br /> <br />This report has identified the probable flooding limits of <br />a potential lOa-year flood event in the Granby and Sable <br />Ditch drainage basins. <br /> <br />Flood Velocities <br /> <br />The flood plain limits are based on (1) planned, future <br />development in the basin, (2) existing and mapped flood plain <br />conditions, (3) no peak flood flow reduction or interception <br />by the Highline Canal, (4) no consideration of the proposed <br />detention pond near Sixth Avenue, and (5) no blockage at the <br />existing culvert and bridge structures. Even with these <br />assumptions, floods of greater magnitude can and will occur in <br />which the limits of flooding will exceed those shown in this <br />report. <br /> <br />Average flow velocities, characteristic of a lOa-year flood <br />event on Sable and Granby Ditches are shown on the profile <br />portion of the Flood Hazard Area Delineation drawings. The <br /> <br />Presently, Granby and Sable Ditches are considered to have a <br />high flood damage potential. The preservation of the flood <br />plain will serve, at least, to maintain the present level <br />
The URL can be used to link to this page
Your browser does not support the video tag.