### Abstract

The asymmetrical distribution of debris-flow velocity in a cross-section has long been observed and is currently regarded as one of the most essential issues in debrisflow research. Due to a lack of quantitative models for the velocity distributions of debris flows, most studies consider only the mean velocity. However, to optimize countermeasure structures, to estimate the erosion rate, or to evaluate the constitutive equations for shear behavior, it is beneficial to know the velocity profile in a cross-section. In this paper, a generalized model of typical channel geometries (e.g., rectangular, trapezoid, or V-shape) is proposed. A description of the velocity distribution that optimizes the Manning–Strickler velocity equation for transverse distribution and Egashira’s velocity equation for vertical distribution is presented; thus, the debris-flow velocity at any point in the cross-section can be calculated and the distribution profile therefore obtained. A well-documented debrisflow reference case and the Jiasikou debris flow in the high-seismic-intensity zone of the Wenchuan earthquake are selected as case studies to demonstrate the model. Analyses of both cases confirm the asymmetrical distribution of debris-flow velocity in cross-section, as originally expected. This shows that the velocity at the top surface in the middle of the channel is much larger than that at each sidewall and than the mean value calculated by former equations. The obtained velocity distribution profile is a better approximation of the observed field profiles.

Original language | English |
---|---|

Pages (from-to) | 2053-2070 |

Number of pages | 18 |

Journal | Natural Hazards |

Volume | 74 |

Issue number | 3 |

DOIs | |

Publication status | Published - Nov 1 2014 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Water Science and Technology
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)

### Cite this

*Natural Hazards*,

*74*(3), 2053-2070. https://doi.org/10.1007/s11069-014-1276-3

**A new approach for analyzing the velocity distribution of debris flows at typical cross-sections.** / Han, Zheng; Chen, Guangqi; Li, Yange; Xu, Linrong; Zheng, Lu; Zhang, Yingbing.

Research output: Contribution to journal › Article

*Natural Hazards*, vol. 74, no. 3, pp. 2053-2070. https://doi.org/10.1007/s11069-014-1276-3

}

TY - JOUR

T1 - A new approach for analyzing the velocity distribution of debris flows at typical cross-sections

AU - Han, Zheng

AU - Chen, Guangqi

AU - Li, Yange

AU - Xu, Linrong

AU - Zheng, Lu

AU - Zhang, Yingbing

PY - 2014/11/1

Y1 - 2014/11/1

N2 - The asymmetrical distribution of debris-flow velocity in a cross-section has long been observed and is currently regarded as one of the most essential issues in debrisflow research. Due to a lack of quantitative models for the velocity distributions of debris flows, most studies consider only the mean velocity. However, to optimize countermeasure structures, to estimate the erosion rate, or to evaluate the constitutive equations for shear behavior, it is beneficial to know the velocity profile in a cross-section. In this paper, a generalized model of typical channel geometries (e.g., rectangular, trapezoid, or V-shape) is proposed. A description of the velocity distribution that optimizes the Manning–Strickler velocity equation for transverse distribution and Egashira’s velocity equation for vertical distribution is presented; thus, the debris-flow velocity at any point in the cross-section can be calculated and the distribution profile therefore obtained. A well-documented debrisflow reference case and the Jiasikou debris flow in the high-seismic-intensity zone of the Wenchuan earthquake are selected as case studies to demonstrate the model. Analyses of both cases confirm the asymmetrical distribution of debris-flow velocity in cross-section, as originally expected. This shows that the velocity at the top surface in the middle of the channel is much larger than that at each sidewall and than the mean value calculated by former equations. The obtained velocity distribution profile is a better approximation of the observed field profiles.

AB - The asymmetrical distribution of debris-flow velocity in a cross-section has long been observed and is currently regarded as one of the most essential issues in debrisflow research. Due to a lack of quantitative models for the velocity distributions of debris flows, most studies consider only the mean velocity. However, to optimize countermeasure structures, to estimate the erosion rate, or to evaluate the constitutive equations for shear behavior, it is beneficial to know the velocity profile in a cross-section. In this paper, a generalized model of typical channel geometries (e.g., rectangular, trapezoid, or V-shape) is proposed. A description of the velocity distribution that optimizes the Manning–Strickler velocity equation for transverse distribution and Egashira’s velocity equation for vertical distribution is presented; thus, the debris-flow velocity at any point in the cross-section can be calculated and the distribution profile therefore obtained. A well-documented debrisflow reference case and the Jiasikou debris flow in the high-seismic-intensity zone of the Wenchuan earthquake are selected as case studies to demonstrate the model. Analyses of both cases confirm the asymmetrical distribution of debris-flow velocity in cross-section, as originally expected. This shows that the velocity at the top surface in the middle of the channel is much larger than that at each sidewall and than the mean value calculated by former equations. The obtained velocity distribution profile is a better approximation of the observed field profiles.

UR - http://www.scopus.com/inward/record.url?scp=84918591913&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84918591913&partnerID=8YFLogxK

U2 - 10.1007/s11069-014-1276-3

DO - 10.1007/s11069-014-1276-3

M3 - Article

VL - 74

SP - 2053

EP - 2070

JO - Natural Hazards

JF - Natural Hazards

SN - 0921-030X

IS - 3

ER -