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I I I I , 1'ABLE-7 I I PEAK FLOWS AT SELECTED LOCATIO~S , LOCATION REFERENCE DRAINAGE " '" '" Q100 LINE STATION AREAS (Acres) d. ," d. d. Kennett Drainage COutltyRoadLJ6 41-+50 81.0 94 '" 50' '41 Oetention Re.ervoir 29+15 156.5 "0 '50 m '" Inflow Detention Reservoir 28+45 156.5 , , " '" Oueflo'" Alley Between Poplar 21+00 165.5 " " 94 m and ElmStreeta Elm-Elbert Street 18+00 213.9 " 94 '59 '50 Intersection Concrete Box Culvert 10+00 222.6 78 Inlet at Banner St. '" 177 '" "<ldKiowaAvenue Intersection . Downstream from Con- 9+00 225.3 W 20 " '" crete Box Culvert (68) (S1) (iOn (liS) InLet Pine Rid!>:" Draina~e Elm~Mobile Street 9+50 25.2 " 54 " '" Intersection UpstteamFrom Elm- 1+00 33.7 49 " 99 ", Elbert Street Inter- section CHAPTER X HYDRAULIC ANALYSIS The hydraulic analysis entailed computation of water .urface profiles along the study reachea of the major dtainage..."ys ...ithin the Town of ELi~a- beth for the 5-, 10-, 50-. and lOO-year frequency flows. The topo~r,,~hic ",apping, "ith a scale of l-inch equal to lOO-feet and 2-foot contour intervals. "as provided by Elbert County in cooperation with the Town of Elizabeth. The rnapping waa prepared in 1976 and does ootreflect current developmcnt in town. Ho"ever,recentaerialphotographyandfield surveys "ere used to revise the maps aa necessary along tbe stream study reaches. Extensive revision "as necessary in the detention rescrvoir area and in the southwestern portion of town whete new residences are currently under construction. Channel cross sections were field surveyed at .pecified interval. along the study reach. Waur "urfsce profiles were detennined using the field s"r- veyed ctOss sections. the roughness coefficients of the drainagcw"y., and the conveyance characteristic. of culvert. and street overflow sections. The hydraulic characteristics of the study reach =re determined on a nmIlber of field investigations" Photographs of typical areas are presented on P~ges 38 through 40. Esch of the drain~ge conduits and struct~res "ere measured and the capacity WB~ d~t~nni""d. At most street crossings. flood flows ate conveyed bY;J com- bination of culvert flow and street overflow. Rating curveS ~re developed for each crossing to determine flo" depth assuming that e~istlng drainsge SHuet".cs "ere operatingeffldently. Detailed hydraulic analysis of the stonn sewer On Kio..." Avenue waa also performed. Theratingcurveforthestormaewer allo". the ov~dand Ho... On Kio\<ls Av<<nue to be detennined. The \<later sudace elevations for the 5-, 10-, 50-, and IOO-year frequency floods were computed u.ing the Corps of Engineers HEC-l Step Backwater Compu- terprogra... The tapsbilitiesof this program src explained in the Running Cr.'ek floodplain study part of thi" repon. ....ddit;ona! coml"utHioll" at "atn * Th" Ill",bc"r l.n parenthesis is the e.timate-l flo" '" llL" sl'Hm """''t. -4'- -48-