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Input Parameters for Foothills Reservoir <br /> h =depth of water above breach invert at time of failure= 14.2 m 46.6 ft <br /> h b = height of breach = 15.5 m 50.9 ft <br /> h d = height of dam = 15.5 m 50.9 ft <br /> V, =volume of water stored above breach invert at time of failure= 5,104,951 m' 4138.5 ac-ft <br /> S = reservoir storage= 5,104,951 m3 4138.5 ac-ft <br /> Ko = 1.4 for overtopping, 1.0 for piping = 1 <br /> Z= breach side slope = 0.7 <br /> Breach Width Equations <br /> Froehlich (2008) <br /> B =0.27KOVwo.32hbo.oa = 42.2 m 138.5 ft <br /> bottom width = 31.4 m 102.9 ft <br /> Von Thun and Gillette (1990) <br /> Cb =function of reservoir size = 18.3 m 60.0 ft <br /> B=2.5hw + Cb = 53.8m 176.5 ft <br /> bottom width = 42.9 m 140.8 ft <br /> USBR(1988) <br /> B =3(h K,) = 42.6 m 139.7 ft <br /> bottom width = 31.7 m 104.1 ft <br /> Failure Time Equations <br /> Froehlich (2008) <br /> tf = 63.2(Vw/(g*hb2))°.5 = 0.82 hours <br /> Von Thun and Gillette(1990) <br /> t f =B/(4h w) (erosion resistant) = 0.95 hours <br /> USBR(1988) <br /> tf =0.011(B) = 0.47 hours <br /> B = average breach width <br /> Vet =volume of embankment material eroded <br /> tf =failure time <br /> Cb = 6.1 m for Vw< 1230000 m3 <br /> Cb = 18.3 m for 1230000 m3<Vw< 6170000 m3 <br /> Cb =42.7 m for 6170000 m3<VH,< 12300000 m3 <br /> Cb = 54.9 m for Vw> 12300000 m3 <br />