Debris flow velocity can be calculated through the dynamic and potential energy or the relationship between line speed and radius as the debris flow moving in a bend channel. A practical formula of super elevation in bend based on the theory of unequal angle speeds and hydromechanics was put forwars. The bend bed roughness parameter can be gotten through velocities and experiential theories. The velocities of straight channels also can be gotten by the roughness parameter. The calculation of Tonggeding debris flow velocity and its distribution showed that the results by two models above are very close. Indeed for the “unequal velocity model”, the calculated mud line distributed with a parabola shape, which is more close to the reality. The velocity from “unequal velocity model” is a little lower than that of calculated by “equal velocity model”
