Evaluation of the functions of a grid-type sabo dam and sediment routing management in a basin

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Recently, many grid-type sabo dams have been constructed. These dams have functions to pass through sediment transported during normal floods and to store hazardous big boulders transported by a debris flow. In this study, firstly, we pay attention to the sedimentation processes of debris flow by a grid-type sabo dam, and flume experiments and numerical simulations are carried out using stochastic model of blocking by a planer grid-type dam. The model is expanded into the three-dimensional model and processes of the debris flow generation, development and sedimentation by a grid-type sabo dam are expressed by the model. This model is found to be very useful to clarify the function of the grid-type sabo dam. Secondary, by using this simulation model, the method to find the optimal site of the grid-type sabo dam along the steep channel is investigated. By using both the calculated flow characteristics such as solid concentration of the debris flow, flow depth, composition of the sediment diameter in the flow, flow velocity, and etc. and stochastic model of blocking we can evaluate the suitable position of the dam construction. As we checked this method only in the imaginary channel, we want to apply it to the actual river basin in future.