WSP02645 - Laserfiche WebLink

Home Browse Search

OOlOiJ8 I I I I I I I I I I I I I I I I I I I There is one sizable tributary, Happy Canyon Creek, which enters Cherry Creek about midway in the study reach. On the October 1983 aerial phot09raph, the channel of thi s I eft bank tri butary is shown where it crosses the flood- plain of Cherry Creek. Also, where the tributary had previously entered Cherry Creek, there was a head cut working its way back up the channel fill. The former bed profile of Happy Canyon Creek is shown on the 1977 Flood Hazard Area Oelineation Map (Howard, Needles, Tammen and Bergendorf, 1977). From County Line to Arapahoe Road, the low-flow channel of Cherry Creek is 3,3 miles long. The valley length is 2.2 miles making the sinuosity 1.5, There are 13 bends of various shapes. . These are described in detail later in this report. 2. Profile The profile of the thalweg and banks of Cherry Creek in the study reach are shown in Figure-6. The thalwe9 elevations were obtained from the 1983 1-foot and 2-foot contour topographic maps. The river bend drops 64 feet in its 3.3 mile meander length making the average slope 19.4 feet per mile. At Arapahoe Road, the riverbed elevation is 5631 feet above mean sea level, Locally, there are flatter and steeper reaches. Another 1.6 miles downstream, Cherry Creek meanders into Cherry Creek Lake with a maximum flood pool elevation of 5596 feet. The normal pool level is 5548 feet which is maintained for recreational purposes. The Cherry Creek Lake creates a backwater effect on flow in Cherry Creek upstream. The effect is to decrease the velocity of the flow and results in the deposit of sediment on the streambed. The July 1978 aerial photograph indicates deposits had not yet occurred beyond the maximum pool elevation. According to the vegetation pattern on the photograph, deposits extended upstream 1.4 miles from the normal pool level. The valley distance from Arapahoe Road to the normal pool level at the delta is 3.2 miles. -16-