Laserfiche WebLink
<br />elevations for tile 10-. 50-, 100-, and500-year flood events at selected <br />reference points, for the reach of the Arkansas River from the upstream <br />Canon City corporate limits to Minnequa Dam (Appendix II). <br /> <br />elevations and general location of thebencmarks and control mark ersare <br />listed in Table 6. Additional survey notes and monument descriptions are <br />available for review at the Colorado Water Conservation Board. <br /> <br />Flooded Areas <br /> <br />As indicated, the IOO-year frequency flood has been selected by the State <br />of Colorado as the flood event to be used for floodplain delineation and <br />regulation. The flooded area plates show the boundary of the toO-year <br />floodplain. Since the base map for the flooded area plates isa two-foot <br />contour map, the outl ines of the other fl ood events, 10~, 50-, and <br />SOO-year, can be readily plotted using the information in Tables 5-1 and <br />5-11, <br /> <br />The flood elevations have been estimated by using surveyed channel cross- <br />sections and detailed topographic mapping. The hydraulfcmodel (HEC-2l, <br />assumes that the hydraulic sections such as the natural channel, channels <br />fOmledby dikes or levees, bridges, culverts and dams will not change due <br />to effects of erosion, sedimentation or debris blockage. Assumptionsmade <br />in this study are presented in the Technical Addendum of this report. <br />The area delineated on the flooded area plates as thel00-year floodplain <br />meets the requirements of H.B. 1041 as an arE!a of state interest. Also, <br />upon official approval by the Colorado Water Conservation Board, the area <br />outlined by the 100-year flood boundary will be designated as floodplain <br />area and may be regulated accordingly by the local officials. <br /> <br />Flood Elevations <br /> <br />Flood crest elevations for the 10-, 50-, 100-, and500-year floods may be <br />found in Tables 5-1 and 5-11 of this report (the Flood Frequency-El evation <br />and Oischarge Data tables). The flooded area maps presented in Appendices <br />I and lI,give the plan viI''' nf thf' flOOded area on a contour base map and <br />the hiqhwaterelevations for the lOO-year flool1can be intf'rpolatl'l1 from <br />thi s. The flood pro files, show the streambed 1'1 eva ti on sand 1'1 e~ations for <br />thelO-,50_, 100-, and500-year frequency floods. <br />The flood profiles may be used in areas where contro~ersy ari ses over the <br />lOO-yearfloodboundary shown on the flooded area plates. Since the flood <br />profile plates give the elevations and distance, or stationing, from a <br />knO\<;ll point, the high water elevations can be sur~eyed on the ground to <br />alleviate any discrepancies on the hase map. <br /> <br />Ijnd~ontal control us~1 f<;or ",appi~g is bHed cr. Cclcr~dc State ~1~~C' <br />Coordinate System South Zone 1929 USC&GS Sea Level DatlJlll. <br /> <br />Control Markers <br /> <br />In order to locate points on the ground relatjng to information given in <br />this report, fourbencmarks set by federal agencies have been identified <br />in the study area. These bencmarks are tied to United Stated Coast and <br />Geodetic Survey Ljne 25. The Fremont County control markers are brass caps <br />Sl't in concrete. The location of all benc~arks and control markers are <br />shown on the topographic maps prepared for this study. The coordinates. <br /> <br />23 <br /> <br />14 <br />