Articles | Volume 16, issue 11
Nat. Hazards Earth Syst. Sci., 16, 2433–2442, 2016
https://doi.org/10.5194/nhess-16-2433-2016
Nat. Hazards Earth Syst. Sci., 16, 2433–2442, 2016
https://doi.org/10.5194/nhess-16-2433-2016

Research article 28 Nov 2016

Research article | 28 Nov 2016

Effects of Y-type spillway lateral contraction ratios on debris-flowpatterns and scour features downriver of a check dam

Huayong Chen1,2, Jinfeng Liu1,2, and Wanyu Zhao1,2 Huayong Chen et al.
  • 1Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of Sciences (CAS), Chengdu, 610041, China
  • 2Institute of Mountain Hazards and Environment, CAS, Chengdu, 610041, China

Abstract. Debris flows often cause devastating damage to property and can injure or kill residents in mountainous areas. The construction of check dams in debris-flow valleys is considered a useful strategy for mitigating the damages downstream. In this paper, a new type of spillway structure with lateral contraction was proposed to distribute debris flows after the check dam storage filled up. Four different lateral contraction ratios of the spillway were considered in experiments that investigated debris-flow patterns, scour characteristics, and energy dissipation rates when debris flows passed through the spillway. The results indicated that lateral contraction considerably influenced the extension of debris-flow nappes. The drop length of the nappe at η  =  0.7 (η means lateral contraction ratio) was approximately 1.4 times larger than at η  =  0.4. The collision, friction, and mixing forces between the debris-flow nappes and debris flows in downstream plunge pools dissipated much of the debris-flow kinetic energy, ranging from 42.03 to 78.08 % at different contraction ratios. Additionally, based on a dimensionless analysis, an empirical model was proposed to predict the maximum scour depth downriver of a check dam. It indicated that the results calculated by the model exhibited good agreement with the experimental results.

Download
Short summary
A new type of spillway structure with lateral contraction was proposed to distribute debris flows after the check dam storage filled up. Experiments were performed to investigate debris flow movement, the scour feature, and some related hydraulic characteristics of debris flows under this new structure. The results indicate that this type of structure can help extend debris-flow nappe, dissipate flow energy, and reduce the scour depth downriver of a check dam.
Altmetrics
Final-revised paper
Preprint