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<br /> <br />~ <br /> <br />The Corps of Engineers Hydrology Appendix for Chatfield Dam has. <br /> <br />graphs of the June 16-17, 1965 inflow to Cherry Creek Reservoir .and <br /> <br />the June 16-17, 1965 flood ~t the Littleton gage on the South Platte. <br /> <br />These floods resulted from the intense storm of June 16, 1965, <br /> <br />centered over the Plum Cree~ drainage basin. The Corps developed <br /> <br />1-hour unitgraphs for each contributing area of the above floods by <br /> <br />the Clark method using paraweters indicated by the recess~on limb <br /> <br />of each hydrograph. Snyder's constants of Ct"O.51 and 640C ,,537 were <br />. p <br />developed from the 1-hour unitgraphs and used for determining synthetic <br /> <br />unitgraphs for subareas above Chatfield Dam, These constants were <br /> <br />also used in another study for developing a sYnthetic.unitgraph for <br /> <br />the area above Mount Carbon damsite. Consideration was given to con- <br /> <br />verting Corps synthetic unitgraphs to our dimensionless graph form <br /> <br />for use in this study; but after trials, this approach was rejected' <br /> <br />because HI time of peak and recession slope of.the converted graphs were <br /> <br />not believed sufficiently representative of flood runoff from the <br /> <br />mountainous subareas delineated for this study. The two observed <br /> <br />flood hydrographs were not converted directly to dimensionless <br /> <br />graph form because: <br /> <br />a. The Cherry Creek hydrograph has a "hump" on the rising limb <br /> <br />apparently .caused by one of two differently timed bursts of <br /> <br />rainfall at different points in the watershed. <br /> <br />b. The hydro graph for tbe flood at the Littleton gage was esti- <br /> <br />mated from f100dmar~s and once daily staff gage readings as <br /> <br />3 <br /> <br />.;. . ~. .....:"...__.. <br /> <br />'1IIlIr1 <br /> <br />. <br />