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<br />TABLE 1. SUMMARY OF 100-YEAR DISCHARGES <br /> <br />FLOODING SOURCE <br />AND LOCATION <br /> <br />DRAINAGE ~EA <br />(SO MILES) <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 />N/A <br />N/A <br />N/A <br />N/A <br /> <br />3.2 Hydraulic Analyses <br /> <br />PEAK DISCHARGE (cfs) <br />100-YEAR <br /> <br />1,075 <br /> <br />1,000 <br /> <br />820 <br /> <br />670 <br /> <br />350 <br /> <br />Analyses of the hydraulic characte~istics of flooding from the <br />riverine sources studied were carried out to provide estimates of <br />the elevations of floods of the selec'ted recurrence intervals. <br /> <br />The drainageway between Depew Stree,t and Sheridan Boulevard was <br />studied to provide estimates of tQe elevation of the 100-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 Progr~m. For the program, current <br />topographic data were taken from al. topographic map with .i-foot <br />contour intervals prepared by Grein~r Engineering Sciences, Inc., <br />and checked to ensure conformance w~th national mapping standards <br />(Reference 6), Field surveying was *lso conducted by Wright Water <br />Engineers. From this topographic milp, 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 ion the Manning Equation to <br />estimate normal depth. A step back~ater analysis was used where <br />necessary to reflect obstructions, such as culverts. Where bends <br />occur in the channel, superelevatiion of the flow has been <br />calculated and included in the waterTsurface elevations. Culverts <br />have been analyzed to determine the' control condition, inlet or <br />outlet control. <br /> <br />Because of irregular and poorly def,ined <br />overland flows in the area upstream of <br />Avenue, the resulting 100-year flood~lain <br />well defined. Updated aerial ma~ping <br />"channel" cross sections and water-surface <br />I <br /> <br />6 <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 />