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HomeMy WebLinkAboutArmy Corp Debris (Line N)US Army Corp Debris Method Eng:HT Los Angeles District Date:12/7/2006 published (2000)Project:Lakeland Village MDP Line N-2 (A)=Drainage Area (miles^2 )=0.504 =322.56 acres Calculate the dervation equation for watersheds (.1 to 3 miles^2) max elevation (ft) =3575 min elevation (ft) =1560 =3 total stream length (miles) =1.67 Log Dy=.65 (Log(P))+.62 (Log(RR))+.18(Log(A))+.12(FF) Slope (ft/miles) =(max elev.-min elev)/(total stream length)Log Dy=1.44 +1.91 +0.45 +0.36 (RR)=1206.6 Log Dy=4.16 Solve for Dy 100yr 1hour Rainfall (in)=1.65 x 100 Dy=14570.71 (CY/mile^2) (P)=165 Multiply A-T Factor =14570.71 x 0.67 Fire Factor =9762.38 (CY/mile^2) 1(FF)=3 Debris from watershed 2(FF)=4.5 =9762.38 x 0.504 3(FF)=6.5 =4920.24 (CY) =3.05 (acre*ft) Adjustment-Transposition =4.5 (A-T)=0.67 Log Dy=.65 (Log(P))+.62 (Log(RR))+.18(Log(A))+.12(FF) Log Dy=1.44 +1.91 +0.45 +0.54 Calculate the Log base 10 of the factors P, A, RR Log Dy=4.34 Solve for Dy Log (P)=2.22 Dy=22053.67 (CY/mile^2) Log (A)=2.51 Multiply A-T Factor Log (RR)=3.08 =22053.67 x 0.67 =14775.96 (CY/mile^2) Debris from watershed =14775.96 x 0.504 =7447.08 (CY) =4.62 (acre*ft) =6.5 Log Dy=.65 (Log(P))+.62 (Log(RR))+.18(Log(A))+.12(FF) Log Dy=1.44 +1.91 +0.45 +0.78 Log Dy=4.58 Solve for Dy Dy=38324.88 (CY/mile^2) Multiply A-T Factor =38324.88 x 0.67 =25677.67 (CY/mile^2) Debris from watershed =25677.67 x 0.504 =12941.54 (CY) =8.02 (acre*ft) Fire Factor = 1(FF) Fire Factor = 2(FF) Fire Factor = 3(FF)