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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
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Volume 16, issue 7 | Copyright
Nat. Hazards Earth Syst. Sci., 16, 1541-1551, 2016
https://doi.org/10.5194/nhess-16-1541-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 04 Jul 2016

Research article | 04 Jul 2016

Overtopping breaching of river levees constructed with cohesive sediments

Hongyan Wei1, Minghui Yu1, Dangwei Wang2, and Yitian Li1 Hongyan Wei et al.
  • 1State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, 430072 Wuhan, People's Republic of China
  • 2State Key Laboratory of Simulation and Regulation of River Basin Water Cycle, China Institute of Water Resources and Hydropower Research, 100038 Beijing, People's Republic of China

Abstract. Experiments were conducted in a bend flume to study the overtopping breaching process and the corresponding overflow rates of river levees constructed with cohesive sediments. The river and land regions were separated by the constructed levee in the bend flume. Results showed that the levee breaching process can be subdivided into a slope erosion stage, a headcut retreat stage and a breach widening stage. Mechanisms such as flow shear erosion, impinging jet erosion, side slope erosion and cantilever collapse were discovered in the breaching process. The erosion characteristics were determined by both flow and soil properties. Finally, a depth-averaged 2-D flow model was used to simulate the levee breaching flow rates, which is well expressed by the broad-crested weir flow formula. The deduced discharge coefficient was smaller than that of common broad-crested rectangular weirs because of the shape and roughness of the breach.

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Mechanisms, such as flow shear erosion, impinging jet erosion, side slope erosion and cantilever collapse, were discovered in the overtopping breaching process of cohesive levees. The levee breaching flow rates were simulated by a depth-averaged 2-D flow model. The calculated overflow rates can be well expressed by the broad-crested weir flow formula. The deduced discharge coefficient was smaller than that of common broad-crested rectangular weirs.
Mechanisms, such as flow shear erosion, impinging jet erosion, side slope erosion and cantilever...
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