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Show Certainly after very short initial distances the maximum velocity is nearly reached. Defense structures are destroyed, as will be shown from a study of the thrust effects, sooner from sliding snow than from its creep pressure. If in Equation ( 4) the very small values y/ yand ^ are neglected and sinl/ ~ tamV is set equal to the gradient, J, Equation ( 4), with [ g] 1/ 2 = c and h' = F/ U ( the hydraulic radius R of wide rectangular channels), leads to the well- known formula of Chezy: v = c[ RJ ] 1 ^ 2 The flow velocity, v, is larger or smaller than the speed of propagation of surface waves, according to Equation ( 1), accordingly as J is larger or smaller than g/ g + It is approximately true that for: J > g/ 5 + ii : shooting J < g/ £ + p, : streaming that is, for £ - 500 shooting flow certainly can occur on small gradients ( > 2%). Since snow set in motion behaves very similar to a liquid it is to be expected that the co- , N ?^ * , y ^* Mf efficient f - c2 also ^^,- e* *! corresponds approximately with the determinations of hydraulics, according to AH which the roughness value, c, for surfaces as rough as natural ones varies between 20 and 25 and correspondingly the velocity coefficient^ between 400 and 600. In the flow of avalanches thru forest the value of £ can fall below Fig> 22. House in Vals- Platz, of which one half was the lower boundary value, cut off s h a r p l y by an avalanche in 1951. on the other hand, in ground avalanches which run in a gully smoothed out with snow by preceding avalanches significantly higher values of "£ can occur. The assumption g = 500 m/ sec2shows a satisfactory agreement with the existing observations, which refer mostly to grassy slopes. The integral of the motion equation neglecting the sliding resistance 1 / 9 v =[ 2 s g ( 1 - YL/ Y> s i n^ ] 24 is |