Laserfiche WebLink
<br />IV. SCOUR EXAMPLE PROELEMS <br /> <br />A, Example Problems. <br /> <br />STEP 1. DETERMINE SCOlR ANALYSIS VARIABLES <br /> <br />Ql00 = 43,600 cfs. <br /> <br />Qsoo = 1,7 X 43,600 = 74,120 cfs. <br /> <br />QSankfull = 14,800 cfs <br /> <br />Upstream (500 ft, upstream). <br /> <br />Main Channel: <br />Dimensions <br />Bank height = 7 ft <br />Bottom width = 398 ft <br />Top width at bank elevation 400 ft <br /> <br />Ql00 <br />Average width = 400 ft, Average depth = 6,00 ft <br />Hydraulic radius = A/WP = 3593/416 = 8,64 ft <br />Slope = 0,00076, Manning n = 0,024 <br />Average velocity = 7,21 ft/s, Discharge = 25,390 crs, <br />Boring Results <br />Bed material: <br />D'6 0.18 mm, Dso 0,30 mm , . D~4 2,8 D::l <br />Dso of 0.30 mm. = 0,00098 ft '.nth <br />Fall velocity (w) = 0,13 rt/s, <br />Description: Be~ material is sand. <br />Foundation material is sand similar to the bed material <br />with some fine gravel lenses below 43 ft, Bed rock, which <br />is shale, is 1,760 ft below stream bed. <br />Bed Forms <br />Low flow = Dunes, Max, height 2,4 ft. Q = 2,400 or less <br />High flow = plane bed and antidunes. <br /> <br />Qbankfull <br />Average width = 400 ft, Average depth = 7.00 ft <br />Hydraulic radius = A/WP = 2793/412 = 6.78 ft <br />Slope = 0.00076, Manning n = 0,020 <br />Average velocity = 7.36 ft/s, Discharge = 20,560 cfs. <br /> <br />Right Overbank: <br />Dimensions <br />Top of bank above channel <br />Length of overbank area <br /> <br />Ql00 <br />Discharge <br />Average depth <br />Average velocity <br /> <br />bed <br /> <br />= <br /> <br />7 ft <br />= 52 ft <br /> <br />= 70 +/- cfs, <br />= 2,0 ft <br />1.22 ft/s <br /> <br />neglect, <br /> <br />60 <br />