A new water–sediment separation structure for debris flow defense and its model test

Abstract

Structural measures, such as the commonly used open dam with a water-sediment separation function, are important in the mitigation of debris flow hazards and disasters. However, the existing open dams often lose their water-sediment separation function over time and/or during a debris flow event because of blockage by sediment and other debris. To resolve this problem, this paper describes a new debris flow water-sediment separation structure. This structure causes the separated sediment to leave the structure automatically and move to a deposit field. In this way, it maintains its water-sediment separation function in a debris flow event. To test the effectiveness of the new structure, model experiments were developed and tested in the laboratory. These showed that the water-sediment separation function was maintained. More than 80 % of the sediment larger than the design sediment was separated, and most of it left the structure automatically with the water-sediment separation functioning throughout the debris flow process.