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exit losses, It was determined that the hydraulic grade line remains within the system and that the lOa-year flood is conveyed by the system. The Manning's "n" value used was 0.014 for this study reach (Reference 32), Sand Creel< Cross section data, Manning's "n" values, and starting water- surface elevations were obtained from the 1977 UDFCD Flood Hazard Area Delineation report for Sand Creel< (Reference 42). Cross section data were compiled from topographic maps (Reference 59), Manning's "n" values ranged from 0,036 to 0,044 in the channel and from 0.035 to 0,100 in the overbanl< areaS, Bacl<water computations for determination of the flood profiles were started at the Burlington Ditch Weir, located within the City of Commerce City, where critical depth was assumed. Between Quebec Street and Havana Street, shallow flooding extends north from Sand Creel<, inundating large areas of the Stapleton International Airport with depths averaging from less than 1 foot to 3 feet, - Downstream of Quebec Street, shallow flooding extends west from Sand Creel< with depths averaging less than 1 foot, Normal-depth calculations were used to determine depths and extent of shallow flooding areas. South Platte River Valley crOss sections for the South Platte River were developed using digitized cross sections from aerial photography flown April 16, 1983, Where appropriate, river cross sections were field surveyed and incorporated into the digitized cross sections (References 60, 61, 62, and 63). Manning's "n" values ranged from 0.030 to 0.035 in the main channel and from 0,040 to 0.070 in the overbanl< and split-flow areas. Starting water-surface elevations and channel stationing were obtained from the September 1977 UDFCD Flood Hazard Area Delineation report for the South Platte River in Adams County (Reference 7), Both normal and special bridge routines were used in the HEC-2 computer program to determine bridge losses. Special split-flow analyses were made for those floodplain reaches where a significant discharge leaves the main channel and flows parallel to the main channel as overland flow until it is forced back into the main channel by the natural topography or a man-made improvement. Separate spl it-flow profi les are presented for the left (west) banl< from 56th Avenue upstream to 47th Avenue, for the left (west) banl< from West Jewell Avenue upstream to West Iliff Avenue, and for the right (east) banl< from Lawrence Street upstream to 8th Avenue, A separate Profile Base Line was delineated for each split-flow area and is shown on the flood Insurance Rate Map. Westerly Creel< The approximate computed using 100-year the COE elevations along Westerly Creek were HEC-2 computer program (Reference 44), 25