FLOOD07245 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I v. Since the time the original hydraulics were completed, new, more detailed mapping was completed for the study reach (1987). In addition, some channel modifications were completed in the reach downstream of Yosemite Street. Therefore, a new 'existing' hydraulic analysis is necessary to define the floodplain as it exists in its present condition. A HEC-2 analysis was completed using the 1987 topography and as-constructed data for the area downstream of Yosemite Street. The lOO-year and 500-year floodplains and floodway are shown on Maps FP-l, FP-2, and FP-5. The HEC-2 run is included in the Appendix. III. STUDY LIMITS Downstream of this project reach (Belleview Avenue), Goldsmith Gulch is in the City and County of Denver and is shown on the attached copy of the FIRM (Figure 1). Denver has recently submitted a LOMR which was approved for Goldsmith Gulch ending at Belleview Avenue. This is the beginning of our CLOMR. Our hydraulic analysis begins at Denver's Station 258+32, which is at the downstream face of Belleview Avenue. The starting water surface elevations for this project match the Denver LOMR at Station 258+32. The Denver LOMR extends past Belleview to Station 259+72, however, this portion of the reach is revised in our analysis to reflect the changes upstream of Belleview Avenue. Our upstream study limit ends at the FIRM Station F just upstream of Yosemite Street. The total reach length is approximately 3/4 of a mile. IV. HAPPING The hydraulics are based on topography from aerial photographs flown in January 1987. In addition, as-constructed information was used to reflect the recent development of the area just downstream of Yosemite Street. HYDROLOGY The flows used for this CLOMR are taken from the current FIRM and Denver LOMR. By way of summary, the flows we used are as follows: 2