Laserfiche WebLink
Straight Drop Basin Design <br />Submergence Coef from USBR Weir Measurement Manual Table 13 <br />Consider that submergence coefficients are related to submergence based on water levels, not total head <br />Channel tailwater below lower weir from HEC -RAS <br />Reference for Design Basis - Design of Small Dams, Figure 9-53 <br />r <br />PMF <br />Sefected <br />Upper Weir Elev <br />ft. <br />8562.5 <br />8562.5 <br />Crest Length= <br />ft. <br />15 <br />15 <br />Q total= <br />cfs <br />792 <br />1522 <br />Uppwer Weir Q openings= <br />cfs <br />123 <br />134 <br />Q= Qtotal - Q openings <br />cfs <br />669 <br />1388 <br />Y (drop height) <br />ft. <br />8.5 <br />8.5 <br />Weir Coefficient - upper weir <br />3.19 <br />2.70 <br />q= <br />cfs <br />44.6 <br />92.5 <br />He (head over Weir) <br />ft. <br />5.81 <br />10.54 <br />WS above Upstream Weir Elev <br />ft. <br />8568.31 <br />8573.04 <br />Upstream Depth <br />ft. <br />14.31 <br />19.04 <br />Dc (critical depth above weir) <br />ft. <br />3.95 <br />6.43 <br />Drop Number (D)= <br />0.101 <br />0.433 <br />Lower Weir Q openings <br />cfs <br />100 <br />128 <br />Q total lower weir <br />cfs <br />692 <br />1394 <br />Weir Coefficient - lower weir <br />2.53 <br />2.53 <br />h1 (include velocity head) lower weir <br />ft. <br />6.92 <br />11.05 <br />Lower Weir Height <br />ft. <br />3.00 <br />3.00 <br />TailWater above lower weir with Velocity Head <br />ft. <br />9.92 <br />14.05 <br />Approach Velocity Head Estimate <br />ft. <br />0.44 <br />0.81 <br />Tailwater Observed (w/o V head) <br />ft. <br />9.48 <br />13.24 <br />h1 observed lower weir (w/o velocity head) <br />ft. <br />6.48 <br />10.24 <br />Channel tailwater below weir <br />ft. <br />7.04 <br />9.37 <br />h2 (downstream depth above crest) <br />4.04 <br />6.37 <br />Weir Submergence (d/H=h2/h1) <br />0.623 <br />0.622 <br />Submergence Coefficient factor <br />0.761 <br />0.760 <br />Velocity of Approach Above Weir <br />5.57 <br />7.66 <br />Adjusted Velocity Head <br />0.48 <br />0.91 <br />Adjusted Tailwater Observed above lower Weir <br />9.44 <br />13.14 <br />Tailwater/Dc <br />2.39 <br />2.04 <br />Target is Greater than 2.15 <br />Hd (drop from Upstream WS to TW) <br />ft. <br />4.87 <br />5.90 <br />Hd/He <br />0.84 <br />0.56 <br />Lp/Y <br />1.85 <br />3.15 <br />DSD Fig 9-53 <br />Lp <br />15.7 <br />26.8 <br />Distance to Baffle Block = Lp+.BDc <br />18.9 <br />31.9 <br />20.0 <br />Basin Length = LP+2.55 Dc <br />25.8 <br />43.2 <br />27.5 <br />Baffle Block Height <br />ft. <br />3.16 <br />5.14 <br />4.0 <br />Baffle Block Width and Spacing <br />ft. <br />1.616 <br />2.548 <br />2.5 <br />End Sill Height <br />ft. <br />1.616 <br />2.548 <br />3.0 <br />Submergence Coef from USBR Weir Measurement Manual Table 13 <br />Consider that submergence coefficients are related to submergence based on water levels, not total head <br />Channel tailwater below lower weir from HEC -RAS <br />Reference for Design Basis - Design of Small Dams, Figure 9-53 <br />