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, " B. Flood Elevation Water surface elevations for the 10-, 25-, 50-, and IOO-year floods, as determined at each cross section, may be found in Table:> "Flood Frequency-Elevation illnct Discharge Data". The flood profile data (sheets 1-13) show a graphical relationship of water surface elevations along the stream reaches for the given frequencies. Selected typical cross sections from different reaches within the study area are shown on sheets 1 thru 6. Hvdroloqy The watersheds that produce runoff to channels in and around Cripple Creek are relatively small in size and at high elevation. These t~o characteristics are very significant to the hydrology of the area. High elevation watersheds do not receive the depth of rainfall experienced at lower elevations. The flood profiles may be used in areas where controversy arises over the lOO-year flood boundary shown on the Flood Plain Maps. Since the flood profile exhibits give the water surface elevation at a specific point on the reference line, the flood elevations can be surveyed on the ground to alleviate any discrepancies on the base map. C. Flooded Areas The small contributing drainage areas do not produce serious runoff from snowmelt. The U.S. Army Corps of Engineers computer program HEC-l was used to test the contribution snowmelt makes to peak discharges. It appears that snowmelt is not significant for flood frequencies of 10 year and greater, whiCh is the primary concern of this study. This implies that significant flooding is most likely to be from rainfall events. As a consequence, only rainfall generated runoff was considered in developing peak discharge-frequency values included herein. Flood plain maps, sheets I and 2, show the boundary of the 100-year flood plain. The flood plain boundary was plotted using flood contour elevations and stationing from the plotted flood profiles. This was done at elevation intervals compatible with the map contour intervals. Flood contours are shown as wiggly lines at 5-ft intervals perpendicular to the direction of flow. Peak discharge values developed by GMS, Inc. Consulting Engineers for the "Drainage Master Plan for The city of Cripple Creek, April 1992", for future conditions, will be used in conjunction with the HEC-2 hydraulic model to develop water surface elevations, profiles, and flood plain maps included in this report. GMS, Inc. Consulting Engineers used the Rational Formula supported by a TR-20 analysis fo~ calibration purposes in the preparation of the "Drainage Master Plan for Cripple Creek, April, 1992. NOAA Atlas for Colorado was used as a reference for 24 hour rainfall depths initially. Ilistorical station precipitation data was also ana lysed as a possible alternative to using NOAA Data. It was determined that historical station precipitation data was more representative and therefore was used in this study. No Aerial adjustments were made because of the small drainage areas involved. The Soil Conservation Service (SCS) 24 hour type II rainfall distribution was selected for use in the TR-20 computer model to generate peak discharge - frequency values. Hydrologic runoff curve numbers were developed from very limited soil and land use information and field observations. The Soil Conservation service soil scientist from Canon City was consulteu to obtain the best information available for the Cripple Creek ar~a. Better data is not available at this time.