FLOOD04753 - Laserfiche WebLink

Home Browse Search

Tab Ie I shows a large variance In the pea~ discharges for each flood from gage to gage. In 1933, 1934 and 1938 the storm was IlPparently con- centrated In the mountelns end the flood llttenUllted whi Ie trllvellng from the Morrison gage to the Sheridan gage. for the remaining floodS shown In tllble I the runoff WllS from the aree downstream from Morrison. pro- ducIng the highest flow at the Sheridan gege. Turkey Creek was undoubtedly a large contributor to the Increased flows between the two 9ages. fortu- nately, past floods were produced by flows originating either llbove or below Morrison but never from both drelnage arees at the same time. FloodS on Bear Creek, of whIch little InformatIon Is available, occurred In May, IS76, May end June of 1894, llnd In July of 1896. The peak dlscherge for the 1896 flood was estImated to be 8,600 c.f.s. at the Morrison gage, about 2 m1tes upstream of the study reach. High, sustelne<.! flows through the study reach on 9 May 1957 alused severe bank erosion and damagetoa brIdge under construction etWadsworth Avenue as well as to residentIal lots abutlngthe stream. Mlnorflood- Ingoccurred In the study reach on 23 and 24 July 1965 and 25 families were evacuated, 15 basements and a tourist court were flooded, and several brIdges were damaged. Heavy rains from 4 through S May 1969, with a total storm ralnfell of 11.27 Inches at Morrison, caused the greatest flOOd of record In the study reach. Many poop Ie were evacuated from houses and traIlers rlear Bear Cree~ from Lowell Boulevard to the mouth. Many homes sustained basemerlt and first floor damage. Potential floods Two large potential floods are used to study flood he~llrds In the Bear Creek study reach. The IntermedIate RegIonal flood, commonly called the 100 year flood, has a I perCElnT chance of occurring In arlY year and Is generallyeccepted by the public liS a minimum Ilmltfo r IIppI Ici!ltlonof IOall regulations. Bi!lseduponllprobllbllltyarlalysls of Bear Creek gi!lglng records and records of other typical Front Range streams, pellk dlschllrge for the Irltermedlate Regional Flood lit vllrlous points In the study reach werll computerl and are presented In table 2. TheStllndardProjectFloodlspresentedaSllprllctlcal upper limit of flooding. It Is dIfficult to assign frequencies of occurrence for 6 such a flood, but their magnitude carl be llpproxlmated by the floods that occurred on severlll streams In the Denvllr area In 1965. The peak discharge for thll Standard Project Flood OIl Bear Creek In the study reach would be 76,500c.f.s. floods smaller than the Intermediate RegIonal Flood are much more cOIIYllOn,asevldencedbypeakdlschi!lrgesofhlstorlcal floods In Table I, but can ci!luse damagellnd hardships. Floods lergerthantheSti!lrldard Project flOOd are possible, but the combination of factors to produce suchfloodswoutdbeextromelyri!lro. TIIble 2 INTERMEDIATE REGIC*lAL FLOOD DISCHARGES BEAR CREEK Location Upstream lImIt of study reach Kipling Street Wadsworth Aven..,e West Hampden Mouth reak DIscharge c.f.s. 30,000 27,000 25,000 22,500 19,500 Hllzardsof Large Floods The areas flooded by The IntermedIate Regional and Standard Project floods are shown On plaTes 2, 3 and 4. Profiles and cross sections, on pllltes 5 through lO,shO'wlflooddepthslnrelatlontochllnnel features and grourld levels on The flood 1'111 In. Reference points are showrl on these drawings to corrolate Them with deta presented I~ Table 3. The data In table 3 Includes distance from the mouth, strellmbed elevation, and the wllter surfllC8 elevations for the Intermediate Regional and Standllrd Project Floods. The flood outlines were prOduced by projecting the computed wllter surface elevlltlons onto U. S. Geological SurvllY quadrangle maps IInd surveyed cross sections. The outlInes lire reasoneble raTher th"npreclse. Wherellccuri!lcylsneeded, It wIll be necessary toti!lke the approprllltc floodelevlltlon from the refererlce table or profiles and find by survey the correspondlrlg loci!ltlon on the flood plain. 7