Numerical Investigation on a Flash Flood Disaster in Streams with Confluence and Bifurcation

4Citations
Citations of this article
12Readers
Mendeley users who have this article in their library.

Abstract

On 20 August 2019, a flash flood occurred in Sanjiang Town, Sichuan, China, and caused great damage to people living there. The town lies at the junction of five streams, with streams A, B, and C combining at the town and further dividing into streams D and E. The slope of streams A, B, and C is about 3~5%, while the slope of streams D and E is around 0.3%. The Sanjiang Town actually lies in the transition from supercritical slope to subcritical slope. During the flood, huge sediments were released to streams A, B, and C, and further transported to stream E. Due to the rapid change of velocity, only few sediments deposited at the supercritical slope parts of the stream, while plenty of them sedimented at the streams with subcritical slope. In order to simulate the flood with a hydrodynamic model, a field investigation was carried out to collect high DEM (digital elevation model) data, flood marks, sediment grading, etc., after the flood. The discharge curve of the flood was also obtained by the hydrometric station near Sanjiang Town. For the inlet sediment concentrations of streams A, B, and C, we made a series of assumptions and utilized the case which best fits the flood marks to set the inlet sediment concentration. Based on these data, we adopted a depth−averaged two−dimensional hydrodynamic model coupled with a sediment transport model to simulate the flash flood accident. The results revealed that the flash flood enlargement in confluence streams is mainly induced by the inflows, and the flash flood enlargement in bifurcation streams is largely affected by the sediment deposition. The bifurcation of flows can decrease the peak discharge of each branch, but may increase the flooded area near the streams. Flow in the supercritical slope runs at a very fast velocity, and seldom deposits sediment in the steep channel. Meanwhile, most sediment is transported to the streams with flat hydraulic slopes. Due to the func-tioning of the reservoir, the transition region from supercritical slope to subcritical slope has a much larger probability of being submerged during the flood.

References Powered by Scopus

Modelling dam-break flows over mobile beds using a 2D coupled approach

169Citations
N/AReaders
Get full text

Risk assessment and sensitivity analysis of flash floods in ungauged basins using coupled hydrologic and hydrodynamic models

117Citations
N/AReaders
Get full text

Quantifying the combined effects of multiple extreme floods on river channel geometry and on flood hazards

76Citations
N/AReaders
Get full text

Cited by Powered by Scopus

Flash Floods: Forecasting, Monitoring and Mitigation Strategies

7Citations
N/AReaders
Get full text

Confluence morphodynamics in mountain rivers in response to intense tributary bedload input

5Citations
N/AReaders
Get full text

Hydrometeorological-modeling-based analysis and risk assessment of a torrential rainfall flash flood in a data deficient area in Wenchuan County, Sichuan Province, China

2Citations
N/AReaders
Get full text

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Cite

CITATION STYLE

APA

Yang, Q., Wang, X., Sun, Y., Duan, W., & Xie, S. (2022). Numerical Investigation on a Flash Flood Disaster in Streams with Confluence and Bifurcation. Water (Switzerland), 14(10). https://doi.org/10.3390/w14101646

Readers over time

‘22‘23‘2402468

Readers' Seniority

Tooltip

PhD / Post grad / Masters / Doc 4

80%

Lecturer / Post doc 1

20%

Readers' Discipline

Tooltip

Earth and Planetary Sciences 4

80%

Business, Management and Accounting 1

20%

Save time finding and organizing research with Mendeley

Sign up for free
0