Laserfiche WebLink
<br />Ii'!:LRODUCTJ ON. <br /> <br />Th i 5 pr-e I irni nar-y matet- j a I j 5 one e I ernent elf a p~-oposed <br />report for the Cripple Creek Flood Plain Management Study. <br />It is irltended to be reviewed for purposes of getting <br />concurrance by interested parties before proceeding with <br />other elements of ttlE study. <br /> <br />A full outl ine of the pr-oposed study and t-epot-t is avai lable <br />in the fot"rn of a Plan of Wot-k develc,ped in June, 1991. <br /> <br />HYDROLOGY <br /> <br />The watersheds that produce runoff to channels in and around <br />C,-ipple C,-eek a'-e ,-elatively srnall in size and at high <br />elevation. These two characteristics are very significant <br />to the hydrology of the area. High elevation watersheds do <br />not r-eceive the depth of t~ainfall EHper-ienced at lower <br />elevations. <br /> <br />The small contt-ibuting dr-ainage at-eas dc. nClt j:H-oduce set.ious <br />runoff from snowmelt. The U.S. Army Corps of Engineers <br />computer program HEC-l was used to test the contribution <br />snowmelt makes to peak discharges. It appears that snowrnelt <br />is not significant for flood frequencies of 10 year and <br />greater, which is the prirnary concern of this study. This <br />im",lies that signiflcar,t flooding is most likely to t,e f,-orn <br />t.ainfall events. As a consequence, only t-ainfall genet-ated <br />runoff was considered in developing peak discharge-frequency <br />values included herein. <br /> <br />NOAA Atlas for Colorado was used as a reference for 24 hour <br />,-alnfall depths initially. Histo,-ical station p,'ecipitation <br />data was also analysed as a possible alternative to using <br />NOAA Data. It was deterrnlned that historical station <br />precipitation data was more appropriate and therefore was <br />use,j in th i s stu,jy. No Ae,- i al a.jjustrnents were rnade because <br />of the small dt.a.inage at-eas involved. The Soi I Conset-vatiorl <br />Se,.vice (SCS) 24 hou,- type II ,-ainfa.11 dist,-ibution wa.s <br />selected for use in the TR-20 computer model to generate <br />peak discharge - frequency values. <br /> <br />Hydrologic runoff curve numbers were developed from very <br />limited soi I and land use info,-rnation and field <br />(lbservations. The Soi I (:onset-vation Service S(lj I scientist <br />from Canon City was consulted to obtain the best information <br />avai lable fo,- the C,-I"'ple C,-eek area. Better data is not <br />avai lable at this tirne. <br /> <br />1 <br />