Regulation effectiveness of a window-check dam on debris flows

Abstract

Window-check dams are widely used to regulate sediment transport in debris-flow hazard mitigation. However, the effectiveness of window-check dams on modulating debris flows is still unclear. In this study, dimensional analyses combined with physical experiments were conducted to evaluate the sediment-trapping and particle-regulating functions of a window-check dam. Results showed that both of the attenuation ratio of unit weight and (the difference between upstream and downstream divided by upstream) the retention ratio of mass (upstream divided by downstream) decreased with an increase in openings area, drain holes width, and bottom slope. However, the increase in inflow unit weight of debris-flow led to larger retention ratio of mass. Besides, an optimal attention ratio corresponding to dimensionless unit weight of 1.8 was found. Also, the particle sizes sorted by the window-check dam were found to be associated with the median grain size of sediment. Furthermore, two improved expressions were obtained to assess the effectiveness of window-check dams on trapping sediments. The comparison between these expressions and laboratory data is in reasonable agreement, serving a useful reference for the optimal design of check dams.