Experimental study on discharge process regulation to debris flow with open-type check dams

Abstract

Open-type check dams are widely used to mitigate debris-flow hazards in mountainous areas. However, the regulation function of dams is a non-trivial and still open issue. With the aim to better understand the process regulation of open-type check dam against debris flow, in this study, a series of specially designed flume experiments are conducted as well as contrast tests of closed-type dam. The effects of the debris-flow bulk density, opening form, and dam size are considered. Analysis of the flow patterns, discharge process, peak discharge, and flow duration give an insight into regulating detail. Results reveal that the regulation characteristics depend on the blocking performance of open structure. There are differences in the debris-flow hydrography after passing through an open-type or closed-type dam, and the temporary blocking phenomenon is found to play an important role in regulating the discharge process. Moreover, open-type dams produce a reduction and time lag in the peak discharge, and more effectively regulate the travel time of debris flow downstream than closed-type dam. The reduction ratio of peak discharge for narrow openings is similar to that of closed-type dam and decreases as the relative opening becomes wider. Finally, based on these regulation characteristics, the application of open-type dams for a novel form of debris flow mitigation is discussed from the perspective of balancing interception and regulation of sediment.