Modelling of hyperconcentrated flood routing and channel evolution in the lower Weihe River
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ORIGINAL PAPER
Modelling of hyperconcentrated flood routing and channel evolution in the lower Weihe River Jie Li 1 & Junqiang Xia 2 Received: 6 November 2019 / Accepted: 15 September 2020 # Saudi Society for Geosciences 2020
Abstract Hyperconcentrated floods with sediment concentrations higher than 300 kg/m3 often occur in the lower Weihe River. These floods result in extremely high water levels and severe channel evolution and may pose a threat to people and property in certain reaches. Therefore, it is necessary to accurately simulate hyperconcentrated flood routing processes and the associated channel evolution in the lower Weihe River. A one-dimensional (1D) coupled morphodynamic model was developed to simulate the 1978 hyperconcentrated flood in the lower reach between Lintong and Huayin, and the effects of sediment concentration and bed evolution on flood routing were considered in this model. The calculated hydrographs of the discharge and sediment concentration agreed well with the data observed at hydrometric sections, with corresponding correlation coefficients higher than 0.93. The calculated channel evolution amount in the lower Weihe River was 0.14 × 108 t based on the 1D numerical model, which was lower than the observed value (0.22 × 108 t). In addition, we investigated the effects of the thickness of the active layer and the size distribution of the incoming suspended load on the model results. The maximum sediment concentrations at hydrometric sections and the cumulative channel evolution volume of the study reach increased with an increasing active layer thickness, and with a decreasing mean median diameter of the suspended load. Two metres is a reasonable active layer thickness for simulations of hyperconcentrated flood events in the lower Weihe River. Keywords Hyperconcentrated flood . Channel evolution . One-dimensional numerical model . Lower Weihe River
Introduction Hyperconcentrated floods have been observed during flood seasons in various large alluvial rivers and their tributaries; these floods can lead to a variety of unique fluvial processes (Englund and Wan 1984; Wan 1985; Xu 2010; Li et al. 2014; Zhang et al. 2015; Wang and Ta 2016). The Weihe River, the largest tributary of the Yellow River, is well known for its high sediment concentrations. Severe sediment deposition has raised the riverbed in the Weihe River, and frequent hyperconcentrated floods have caused severe damage to the Responsible Editor: Stefan Grab * Junqiang Xia [email protected] 1
College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225009, China
2
State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
Guanzhong region in Shanxi Province (Li et al. 1998; Zhang et al. 1999). The large amount of sediment carried by hyperconcentrated floods in the Weihe River can also cause severe sedimentation in the Sanmenxia Reservoir (Guo et al. 2008). The characteristics of hyperconcentrated floods in the Yellow River have been investigated usin
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