Seepage Effect on Channel Bank Stability

Canal side slope stability is related to ground water hydraulic gradient, channel flow velocity and initial side slope angle. A quantitative, as well as qualitative, investigation of channel side slope stability is based on an experimental investigation of a trapezoidal channel in a laboratory flume. Various combinations of the aforementioned variables were tested to determine the effect of seepage on channel side slope stability with various hydraulic and geometric conditions in the channel. An empirical relationship is developed for side slope seepage expressing the erosion of the side slope as a function of hydraulic gradient and flow velocity in the channel. At relatively low velocities (V 1 ft per sec) the erosion of the side slope is due primarily to the hydraulic gradient. At higher channel velocities, the side slope erosion is a function of channel flow velocity as well as the ground water hydraulic gradient.