Laserfiche WebLink
<br />TABLE 1. SUMMARY OF 100-YEAR DISCHARGES <br /> <br />FLOODING SOURCE <br />AND LOCATION <br /> <br />DRAINAGE AREA <br />(SO MILES) <br /> <br />PEAK DISCHARGE (cfs) <br />100-YEAR <br /> <br />Sloans Lake Basin Drainage <br />West 18th Avenue at <br />Sheridan Boulevard <br />West 20th Avenue <br />at Ingalls Street <br />West 20th Avenue <br />at Kendall Street <br />West 20th Avenue <br />at Newland Street <br />25th Avenue at Pierce <br />Street <br />N/A - Not Available <br /> <br />2.07 <br /> <br />1,075 <br /> <br />N/A <br /> <br />1,000 <br /> <br />N/A <br /> <br />820 <br /> <br />N/A <br /> <br />670 <br /> <br />N/A <br /> <br />350 <br /> <br />3.2 Hydraulic Analyses <br /> <br />Analyses of the hydraulic characteristics of flooding from the <br />ri verine sources studied were carried out to provide estimates of <br />the elevations of floods of the selected recurrence intervals. <br /> <br />The drainageway between Depew Street and Sheridan Boulevard was <br />studied to provide estimates of the elevation of the lOa-year <br />flood. For these flooding sources, other than shallow flooding <br />areas, water-surface elevations for floods of selected recurrence <br />intervals were computed through use of the U.S. Army Corps of <br />Engineers HEC-2 Step-backwater Program. For the program, current <br />topographic data were taken from a topographic map with I-foot <br />contour intervals prepared by Greiner Engineering Sciences, Inc., <br />and checked to ensure conformance with national mapping standards <br />(Reference 6). Field surveying was also conducted by Wright Water <br />Engineers. From this topographic map, a total of fifteen cross <br />sections were digitized and used as data for the computer analysis. <br />An analysis of flow in the stormwater channel between Ingalls <br />Street and Depew Street is based on the Manning Equation to <br />estimate normal depth. A step backwater analysis was used where <br />necessary to reflect obstructions, such as culverts. Where bends <br />occur in the channel, superelevation of the flow has been <br />calculated and included in the water-surface elevations. Culverts <br />have been analyzed to determine the control condition, inlet or <br />outlet control. <br /> <br />Because of irregular and poorly defined <br />overland flows in the area upstream of <br />Avenue, the resulting 100-year floodplain <br />well defined. Updated aerial mapping <br />"channel" cross sections and water-surface <br /> <br />channels for street and <br />Ingalls Street and 20th <br />for this area is not as <br />was used to determine <br />elevations in this area. <br /> <br />6 <br />