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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Location <br /> <br />Antelope Creek <br /> <br />uls study limit <br />County line <br />Piney Cr. confI. <br /> <br />Saddle Rock <br />Ranches Gulch <br /> <br />uls study limit <br />County line <br />Piney Cr. confI. <br /> <br />South Saddle <br />Rock Gulch <br /> <br />at mouth <br /> <br />Sampson Gulch <br /> <br />Piney Lake Rd. <br />dls Otero Dr. <br />uls Robinson Gulch <br />Piney Cr. confI. <br /> <br />Tenderfoot Gulch <br /> <br />uls study limit <br />Spring Cr. Rd. <br />Piney Cr. confl. <br /> <br />Table 6 <br /> <br />SUMMARY OF DISCHARGES <br /> <br />Drainage <br />Area <br /> <br />10-year <br />(cfs) <br /> <br />50-year <br />(cfs) <br /> <br />100-year <br />(cfs) <br /> <br />HYDRAULIC ANALYSES <br />Water surface profiles were computed for each of the streams under <br />study using the U.S. Army Corps of Engineer's HEC-2 computer model. <br />Elevation data for channel cross sections were obtained from <br />digitized cross sections taken from the new topographic mapping <br />developed for the study. <br /> <br />0.19 <br />0.86 <br />2.63 <br /> <br />70 <br />200 <br />310 <br /> <br />160 <br />490 <br />790 <br /> <br />210 <br />650 <br />1050 <br /> <br />Geometric measurements and invert elevations for culvert crossings <br />were provided by Landmark Aerial Mapping and supplemented where <br />necessary by additional field measurements. Photographs were <br />taken of each crossing and a sketch of each was prepared showing <br />appropriate dimensions. Additional photographs were taken to <br />document the existing channel and overbank conditions for <br />determining the roughness coefficients for use in the hydraulic <br />analyses. This material is on file at the Urban Drainage & Flood <br />Control District as backup information to the project in the <br />Technical Addendum. The Manning's un U values utilized in the <br />hydraulic analyses ranged from .035 to .080 in the channel and <br />from .030 to .060 for the overbank areas. <br /> <br />0.25 <br />0.71 <br />1. 83 <br /> <br />220 <br />420 <br />700 <br /> <br />280 <br />540 <br />930 <br /> <br />100 <br />180 <br />280 <br /> <br />0.21 <br /> <br />50 <br /> <br />130 <br /> <br />170 <br /> <br />0.17 <br />0.68 <br />2.21 <br />2.67 <br /> <br />50 <br />140 <br />560 <br />1170 <br /> <br />120 <br />370 <br />1290 <br />2410 <br /> <br />160 <br />480 <br />1670 <br />3040 <br /> <br />Water surface profiles were computed for the 10-, 50-, and 100- <br />year events for each stream under study. In addition, a floodway <br />was calculated for all reaches where the 100-year floodplain was <br />not confined within the channel banks. This floodway was based on <br />a total increase of not more than 0.5 feet in the energy grade <br />line due to an approximately equal reduction in conveyance on both <br />sides of the floodplain. The floodway data is summarized in <br />tabular form and referenced to the channel stationing in Floodplain <br />and Floodway Reference Data Tables 8 through 12. Pertinent data <br />for the 10-, 50-, and 100-year floodplain is also included in <br />these tables. <br /> <br />0.48 <br />0.87 <br />1. 72 <br /> <br />90 <br />180 <br />220 <br /> <br />230 <br />470 <br />600 <br /> <br />300 <br />630 <br />820 <br /> <br />15 <br /> <br />