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. . Flooding on the south side in this section is generally restricted to flow in the street. at reference points along the channel. The water surface profile, channel thalweg profile, and flood plain are graphically shown on the drawings, are shown in the drawings are based on the two-foot contour mapping on which they appear and are limited to the accuracy of the mapping. First floor elevations of structures within the flood plain should be checked against the 100-year flood elevations on an individual basis, ( 4) Holly - Monaco Area . The inability of the Goldsmith Gulch chan- nel to contain the 100-year flood due to development constrictions, and the building of residences in low areas SUbject to flooding, illustrate the importance of flood plain zoning and building restrictions in minimizing flood damages, Overbank areas are lower than the channel throughout most of the length of Cherry Creek from the Platte River to the Dam, When floodwaters overtop the banks they are carried in the overbank, which acts as a separate channel, until the topography forces the waters to return to the Cherry Creek channel. The flow carried in the overbank areas is related to the water surface profile of the channel only at the upstream point of departure and down- stream point of re-entry, Water surface profiles for overbank areas of unrelated flow were determined and plotted separately using upstream and downstream water surface elevations for the Cherry Creek channel and the estimated flow in the overbank, Where overbank flow is not related to the channel profile, water surface elevations are marked by wavy water surface contour lines on the plan views of the drawings, In Reach 1, from the Platte River to Colfax Avenue, a situation exists which requires a modified approach to depicting the 100-year flood plain and floodway. Large amounts of water leave the inade- quate channel between 11th and 14th Avenues and are carried in the overbanks, Downstream from 14th A venue, the water carried by the south overbank will never re-enter Cherry Creek but will descend directly to the Platte River through Auraria and the railroad yards, Water carried by the north overbank will flow from 11th Avenue through portions of downtown Denver before re-entering Cherry Creek between Arapahoe and Larimer Streets, Floodwaters overtop- ping either bank downstream from Wazee Street will flow to the Platte River without returning to Cherry Creek, . Flooding occurs on the north side of the channel in this section from overtopping at Monaco. Generally, the flooding occurs through Garland Park, . . Floodwater originating from Goldsmith Gulch will flow along Monaco Blvd, and Minnesota Drive, south to Cherry Creek, between Monaco Blvd. and Holly St. flood- ing the residences located along Cherry Creek. . FLOOD PLAIN AND FLOODWAY DATA The low lying overbank areas along Cherry Creek are all presently occupied and although the Cherry Creek channel will handle the greatest percentage of the 100-year flood, any overflow from Cherry Creek will be destructive. In these developed areas, flood- waters are conveyed mostly by streets, But as water surface elevations rise in the streets, areas of standing or slow moving water develop between buildings and other areas adjacent to the streets. The islands which In this situation, the 100-year flood was modeled by calculating water surface profiles for only the channel (cross-sections extended vertically at the banks) for flows ranging from 7,000 cfs up to the 100- year flood flow. Then, beginning at 11th Avenue and working downstream, flows into overbank areas were calculated by assuming a broad crested weir from the channel over Speer Boulevard. This flow was then . . The flood plain limits of the 100-year storm are shown on the drawings and tabulated in Table 3. The table lists the 100-year flood discharge, stream bed elevation, water surface elevation and flooding width . 7 ~