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FLOOD00703
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Last modified
11/23/2009 1:21:34 PM
Creation date
10/4/2006 9:25:41 PM
Metadata
Fields
Template:
Floodplain Documents
County
Boulder
Community
Boulder County
Stream Name
Lefthand Creek
Title
Floodplain Information Report
Date
1/1/1969
Prepared For
Denver Regional Council of Governments
Prepared By
US Army Corps of Engineers
Contract/PO #
&&
Floodplain - Doc Type
Floodplain Report/Masterplan
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<br />PAST FLOODS <br /> <br />TABLE 3 <br />STREAM ~GING RECORDS LEFT-HAND CREEK <br /> <br />This section pr~sents the flood histories ~nd stor~ C~3r- <br />acteristics of tne Left-~and Creek Casino <br /> <br />Gage <br />Location <br /> I92Q 19}Q 1940 1950 1960 1970 <br /> , , , , , <br />Hwy.287 , , H <br /> 3/27 9/42 8/5312/55 <br /> , , , . <br /> 6121 9/38 6/498/51 <br />Near , 10/55 <br />&lulder ,-, 1-11-1 <br /> 5/29 9/31 10/49 12/53 I 9/57 <br /> <br />"Iood Records <br />SCilttered data from unofficial sourcos and I imited records <br />irldic<ltcsignifiCi.lntfloodlngoccurred in 1864, 1876, 1894, 1921,1938, <br />1949, Jnd 1951. ~inor flooding may have occurred in other years but <br />w3snotrecorded. The first stream gaging station was estabJish<'XJ by <br />the State of Colorado in March 1927 just downstream from U.S. HiGhway <br />287. In May 1929, a second gage wasostablished in the mountains <br />approximately 2 1/2 miles above State Highway 7. This gage was later <br />reestablished approximately 0.9 miles downstream, but both locations <br />ar<>referred to as "Near Boulder". The peak discharges for the last <br />three major floods were estimated by extrapolating the 9ago rating <br />curves or by taking slope aroa measurements. The largest dlschargo <br />recorded at U.S. Highway 287 was 812 cubiC' feet per second ir,Septemb<>r <br />1938. The l"rgostflood rocordod lItthcg:!gO near Rouldor was 785 <br />cuoie feet per second j n .~ugust 19~1, however, " di seharg" of 1,140 <br />CUbic f<>et per second waS recorded at a location upstream of the qago <br />for The June 19>19 f 1000. Tablo 3 shOWS gr<~rhically the perlmh of <br />Op~ration fOr e~Ch 91lge ~nd the d~Tes of recenT major floods. <br /> <br />Major floods occurred at times indicated by asteriSk. <br /> <br />Rainfall Reeords <br />Rainfall records data for these floods are moagor sinc" <br />no U.S. woatherElureau preclplt<ltlon stations are located within <br />tlwl>d5in. Theavallablodataarofrornuhofflcidl reoortsondtrom <br />recordS tor the nearby Bould<>r and Longmont stations. <br /> <br />Duration and Rate of RIse <br />Left-Hand Creek floods are most frequently produced by <br />Intense rainfall during thunderstorms. Snowmelt runoff combined with <br />runoff from spring rains of long duration also produce high streamflows. <br />The for_r are characterized by a high pe<ll<. dlSCMrge of short duration, <br />The latter usually have Ill'lsor p....l<.dischargas and are of longer dura- <br />tion. Because of the steep stream slopes, the flood peaks travel down <br />the vdlley with such rapidity that littlet!me is aVdilable to "a rn <br />or evacuate residents. <br /> <br />FIQOdOescriptions <br />^ goneral oescription of the last tour major floods occur. <br />...1 ~8 o~ Left-H~!'!d Cr~ek I s p~ov I ded tC' i! I uS+~l!+e The 'Iood po+enTl a I . <br />Heavy damages were not rocorded for theso floods since the flood <br />plain was rural [nnature. <br /> <br />u <br /> <br />" <br />
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