Laserfiche WebLink
<br />Cross sections for Sand Creek, Sand Creek East Fork, Sand Creek <br />Center Tributary, Spring Creek, Kettle Creek, Pine Creek and its <br />tributaries, Mesa Basin, Douglas Creek South, Douglas Creek North, <br />Templeton Gap Floodway, Rockrimmon Basin and Peterson Field Drainage <br />were obtained from aerial topographic maps compiled by Landmark <br />Mapping between 1981 and 1983 (Reference 21). <br /> <br />Cross sections for Cottonwood Creek below Woodman Road were obtained <br />from the Landmark Mapping maps (Reference 21). Above WOodman Road, <br />cross sections were obtained from COE topographic maps (Reference <br />22) . <br /> <br />Cross sections for Templeton Gap Lower Tributary were obtained <br />from "as constructed" channelization plans from the Colorado State <br />Division of Highways (Reference 23). <br /> <br />Locations of selected cross sections used in the hydraulic analyses <br />are shown on the Flood Profiles (Exhibit 1). FOr stream segments <br />for which a floodway was computed (Section 4.2), selected cross <br />section locations are also shown on the Flood Insurance Rate Map <br />(Exhibit 2). <br /> <br />Roughness factors (Manning's WnW) for these computations were assigned <br />on the basis of field inspections of flood plain areas. Roughness <br />values used for the stream channels and overbank areas varied from <br />0.013 to 0.080, which correspond to concrete channels and densely <br />vegetated overbanks, respectively. Photographs also aided in the <br />documentation of channel and overbank roughness coefficients. <br /> <br />Starting water-surface elevations were either based on coincident <br />condition elevations, slope-area method or elevations of an adjacent <br />study. <br /> <br />The hydraulic analyses for this study were based on unobstructed <br />flow. The flood elevations shown on the profiles are thus con- <br />sidered valid only if hydraulic structures remain unobstructed, <br />operate properly, and do not fail. <br /> <br />-. .. <br /> <br />All elevations are referenced to the National Geodetic Vertical <br />Datum of 1929 (NGVD). Elevation reference marks used in this study <br />are shown on the maps. <br /> <br />4.0 <br /> <br />FLOOD PlAIN MANAGEMENT APPLICATIONS <br /> <br />The NFIP encourages State and local governments to adopt sound flood <br />plain management programs. Therefore, each Flood Insurance Study provides <br />lOa-year flood elevations and delineations of the 100- and SOO-year flood <br />plain boundaries and lOa-year floodway to assist communities in developing <br />flood plain management measures. <br /> <br />21 <br />