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TABLE 1. SUMMARY OF DISCHARGES Flooding Source and Location Drainage Area (SQ. miles) Peak Discharge (cubic feet per second) 10-Year 50-Year 100-Year 500-Year South Platte River At Crook, Colorado 19,23B 17,000 46,500 68,000 152,000 South Platte River At Ju1esburg, Colorado 23,13B 16 ,000* 42,5001' 61,0001' 129,0001' *Decrease in Discharge is Due to the Effects of Valley Storage Along the South Platte River. 3.2 Hydraulic Analyses An analysis of the hydraulic characteristics of flooding from the riverine source studied was carried out to provide estimates of the elevations of floods of the selected recurrence interval. Locations of selected cross sections used in the hydraulic analysis are shown on the Flood Profiles (Exhibit 1) and the Flood Insurance Rate Map (FIRM) (Exhibit 2). Flood profiles were drawn showing the computed water-surface elevation for the flood of the selected recurrence interval. The hydraulic analysis for this study are based on unobstructed flow. The flood elevations shown on the profiles are thus considered valid only if hydraulic structures remain unob- structed, operate properly, and do not fail. All elevations are referenced to the National Geodetic Vertical Datum of 1929 (NGVD). 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS The NFIP encourages State and local governments to adopt sound floodplain management programs. Therefore, each Flood Insurance Study includes a flood boundary map designed to assist communities In developing sound floodplain management measures. 4.1 Floodplain Boundaries To provide a national standard without regional discrimination, the l-percent annual chance (lOO-year) flood has been adopted by FEMA as the base flood for floodplain management purposes. For each stream studied by detailed methods, the boundaries of the laO-year floodplain boundary have been delineated using the flood elevation determined at each cross section. 5