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Show 10 Starting Zone Measured Values: '° = avg. slope o avg. thickness = smax = map area cos ipQ lomputed Values » 0 ( v average) tt Qo ( Q average) Gulleys: d depends on the form of the gulley cross- section and the discharge of flowing snow, Q a) determination of the snow discharge, Qo from the starting zone v = ^£ d o ( sin ^ o - y cos \ bo ) Q = _ 6^ ( m / s) At where volume of moving snow, K , is K = d F ( nr) TF = map area of avalanche in starting o o ° ' ° / ,1 zone/ cos y J and time difference, At is At = _ o_ ( sec.) v b) Graphic determination of d^ for a given gulley cross-section: GUIIET CROSS- SECTTCN d d d, - i f - F U v2=. ( sin ^-/ J- COSIJ/^- P v- F= G a. Qt < ls Assume different values of d ( d]_... 1dn). Use these to calculate different flow quantities Q .... Q 7 using the hydraulic radius. The value of Qj_ which corresponds to Q0 gives the sougnt value of d, as well as v-, . F = cross- section area of gulley [ often referred to as .. U = circumference of ground surface affected by avalanche R = hydraulic radius Q = snow quantity ( discharge quantity) l^ = mean avalanche width |