My WebLink
|
Help
|
About
|
Sign Out
Home
Browse
Search
FLOOD08899
CWCB
>
Floodplain Documents
>
Backfile
>
8001-9000
>
FLOOD08899
Metadata
Thumbnails
Annotations
Entry Properties
Last modified
1/26/2010 10:07:04 AM
Creation date
10/5/2006 3:58:22 AM
Metadata
Fields
Template:
Floodplain Documents
County
Boulder
Community
Longmont
Stream Name
Lefthand Creek (mouth to Foothills HWY)
Basin
South Platte
Title
Floodplain Information Report
Date
12/1/1981
Prepared For
Boulder County
Prepared By
Gingery Associates, Inc.
Contract/PO #
&&
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.
/
48
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 /> <br />5 May 1973 ~ Rainhll amounts ranging to as much as 6 inches fell on <br /> <br />HYDROLOGIC AND HYDRAULIC DETERMINATIONS <br /> <br />tile plains east of the Rocky Mountains beginning on 5 May. The lefthand <br /> <br />Creek basin received amounts ranging from 2 to J inches. Runoff from <br />this general storm contributed to considerable flooding on the South <br /> <br />Flood Characteristics <br /> <br />[ <br />I <br />[ <br />I <br /> <br />PhtteRjver. <br /> <br />Floodflows on Lefthimd Creek result from heavy rainfall associated <br />with cloudburst thunderstOmlS during the spring and sumer months. This <br />rainf;tl! mdY occasionally be augmented by melting snows. These rainfall <br /> <br />flood events are characterized by high peak flows of relatively short <br /> <br />duration. <br /> <br />Hydrologic AnalysiS <br />Discharge values for the 10-,50-,100-, and SOD-year floods were <br />developed for Lefthand Creek by the U.S. Army Corps of Engineers, Omaha <br /> <br />District using the Environmental Protection Agency's Storm Water <br /> <br />Management Model (SWMM) (Reference 2). Rainfall values for the 10-, 50-,' <br /> <br />a.ndlOO-yea.r; 1_, 3-, a.nd 6-hour events wereobta.lned from "Precipita.tion <br />Frequency Atlas of the Western United States, Volume II!, ColoradO" <br /> <br />(ReferenceS). The peak discha.rge values on Leftha.nd Creek below James <br />Creek were computed by applying the 6-hour rainfall to the entire basin. <br /> <br />Rainfall depths for the 10-, 50-, 100-, and 5DD-yea.rstorms are shown in <br /> <br />Tables 2 thru 5. <br /> <br />Table 2 <br /> <br />Rainfall Oepths for l-Hour Storm Duration <br />at Various Frequencies _ lefthand Creek <br />Reach - Upstream of Spring Gulch <br /> <br />Frequency <br /> <br />.Depth(lnches) <br />1.3 <br />1.8 <br />2.J <br />2.8 <br /> <br />la-year <br />50-year <br />laO-year <br />SOD-year <br /> <br />I <br />\ <br /> <br />5 <br />
The URL can be used to link to this page
Your browser does not support the video tag.