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ESTIMATION OF DAM BREACH PARAMETERS <br /> USING THE MACDONALD&LANGRIDGE-MONOPOLIS OR WASHINGTON STATE METHODS <br /> WITH ALL FAILURE TIMES ESTIMATED BY WASHINGTON STATE METHOD <br /> PROJECT: Walker Reservoir-North <br /> BREACH INPUT PARAMETERS: <br /> Select Embankment Type From Drop-Down Menu: EARTHEN(NON-COHESIVE) <br /> Height of water over base elevation of breach(H.)= 4.0 Feet <br /> Volume of water stored in reservoir at time of failure(V.)= 137.0 Acre-Feet <br /> Reservoir Surface Area at H.(As)= 35.1 Acres <br /> Crest width of dam(C)= 40.0 Feet <br /> Height of breach from dam crest to base elevation of breach(Hb)= 5.0 Feet <br /> Slope of upstream dam face(Z.)= 3.0 Z(H):1(V) <br /> Slope of downstream dam face(Zd)= 3.0 Z(H):1(V) <br /> Breach side-slope ratio(Zb)= 1.0 Z(H):1(V) <br /> Piping Orifice Coefficient(Cp)= 0.61 Used To Calculate Peak Discharge Through Piping Hole <br /> Dam Size Class: Small Assumes Full Reservoir At Time of Breach <br /> CALCULATED BREACH CHARACTERISTICS: <br /> Breach Formation Factor(BFF)= 547.96 <br /> Embankment Volume Eroded(VA= 481.8 Cubic Yards <br /> Average Dam Width(W...)= 55.0 Feet(In Direction of Flow) <br /> Average Breach Width(Bag)= 47.3 Feet <br /> Bottom Width of Breach(Bb)= 42.3 Feet <br /> Breach Formation Time(T,)= 0.18 Hours <br /> Storage Intensity(SI)= 34.2 Acre Feet/Foot <br /> Peak Breach Discharge(Q,)= 1101 Cubic Feet per Second <br /> RESULTS CHECK: <br /> Average Breach Width Divided by Height of Breach(Bavg/Hb)= 9.46 If(Bavg/Hb)>0.6,Full Breach Development is Anticipated <br /> Erosion Rate(ER),Calculated as(Bavg/Tf)= 255.9 <br /> Erosion Rate Divided by Height of Water Over Base of Breach(ER/Hw)= 64.0 If 1.6<(ERIHw)<21,Erosion Rate is Assumed Reasonable <br /> T <br /> ZB Z, <br /> r y= I I —W <br /> Figure I-Breach Variable Definition Sketch <br /> Zn Zd <br /> FSp � it <br /> D <br /> D F <br /> Figure _' - Piping Hole Variable Definition Sketch <br /> DWR 3567011-North.xlsm <br />