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Lakewood Gulch and Lakewood Gulch Overflow Cross-section data, Manning's "n" values, and starting water- surface elevations were obtained from the 1979 UDFCD Flood Hazard Area Delineation report for Lakewood Gulch (Reference 53). The starting WSELs for Lakewood Gulch were established using the elevation of a 10-percent-alll1ual-chance flood on the South Platte River at its confluence with Lakewood Gulch. The starting WSELs for Lakewood Gulch Overflow were taken from the Lakewood Gulch profile at the confluence with.To Lakewood Gulch Overflow. Values of Manning's "n" on Lakewood Gulch were selected in order to model the roughness of the streambed and overbank areas. Each cross section or group of cross sections was evaluated and assigned a Manning's "n" value for the left overbank, the channel, and the right overbank. Selected Manning's "n" values ranged from as low as 0.02 for street crossings and parking lots to as high as 0.08 for overbank areas restricted by buildings or debris. At a typical channel section, consisting of a natural channel with natural overbank areas, the generally selected Manning's "n" values were between 0.030 and 0.035 in the main challl1el, and between 0.045 and 0.050 in the overbank areas. In overbank areas that were restricted by buildings, Manning's "n" values of 0.08 were used when it was felt that a flow of water could occur through the developed area. Dry Gulch (Lakewood Gulch Tributary) Cross-section data, Manning's "n" values, and starting water- surface elevations were obtained from the 1977 UDFCD Flood Hazard Area Delineation report for Dry Gulch and its tributaries (Reference 12). Values of Manning's "n" used in that report ranged from as low as 0.017 for streets and parking lots to as high as 0.100 for overbank areas restricted by buildings. In general, areas of natural chalUlel section with natural overbanks were assigned Manning's "n" values of approximately 0.045 and 0.080. Where buildings represented significant obstructions to the chalUlel flow, they were represented in the ~ross sections as total blockages. Starting WSELs were determined from the Lakewood Gulch flood profiles. Harvard Gulch'l Harvard Gulch Overflow 'I West Harvard Gulch'l and Dry Gulch (Harvard Gulch Tributary) Cross-section data, Manning's "n" values, and starting water- surface elevations were developed for use in the 1979 UDFCD Flood Hazard Area Delineation report for Harvard Gulch, West Harvard Gulch, and Dry Gulch (Harvard Gulch Tributary) (Reference 14). Cross-section information was obtained photogrammetrically by digitizing cross sections marked on aerial photographs of the stream challl1el and floodplain (Reference 54). The digitized cross-section information was supplemented with cross sections taken from topographic mapping (Reference 55) developed from the aerial photography. All cross sections at bridges were obtained from field measurement. Estimates of channel and overbank roughness coefficients were made after field investigation of the study areas. MalUling's "n" values ranged from 0.015 to 0.040 in the channel and from 0.035 to 0.120 in the overbank areas. 21