Flood flow at the confluence of compound river channels

Numerical Simulation of Effects of River Reconstruction on Flooding: A Case Study of the Ba River, China

Advances in Materials Science and Engineering ◽

10.1155/2021/5538059 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Haixiao Jing ◽

Yongbiao Lang ◽

Xinhong Wang ◽

Mingyang Yang ◽

Zongxiao Zhang

Keyword(s):

Flow Velocity ◽

Eddy Currents ◽

Human Life ◽

River Channel ◽

Computational Domain ◽

River Channels ◽

One Dimensional ◽

Local Reconstruction ◽

Before And After ◽

Flood Flow

The local reconstruction of river channels may pose obstacles of flood flow, local eddy currents, or high flow velocity which pose potential threats to human life and infrastructures nearby. In the design of such projects, the effects of local reconstruction of the river channel on flooding are often evaluated by the one-dimensional method, which is based on the formula of one-dimensional nonuniform flow. In this study, a two-dimensional hydrodynamic model based on shallow water equations is employed to investigate the impacts of river reconstruction on flooding in the Ba River, China. The finite volume method and an unstructured triangular mesh are used to solve the governing equations numerically. The numerical model is validated by comparison with the results of a physical model of 1 : 120 scale. The backwater effects and impacts of flood flow fields under two flood frequencies are analyzed by comparing the numerical results before and after local reconstruction. The results show that the backwater length under both 10-year and 100-year floods can be reached up to the upstream boundary of the computational domain. However, the maximum water level rises are limited, and the levees in this river channel are safe enough. The flow velocity fields under both floods are changed obviously after local reconstruction in the Ba River. Areas with the potential for scour and deposition of the river bed are also pointed out. The findings of this study are helpful for the evaluation of flood risks of the river.

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Ancient River Channels

Scientific American ◽

10.1038/scientificamerican06091877-1184bsupp ◽

1877 ◽

Vol 3 (75supp) ◽

pp. 1184-1184

Keyword(s):

River Channels

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ASSESSMENT OF HYDROLOGICAL CHANGES IN THE ŠUŠVĖ RIVER

Proceedings of the 7th International Scientific Conference Rural Development 2015 ◽

10.15544/rd.2015.035 ◽

2015 ◽

Author(s):

Gražina ŽIBIENĖ ◽

Alvydas ŽIBAS ◽

Goda BLAŽAITYTĖ

Keyword(s):

Hydrological Regime ◽

Maximum Flow ◽

Environmental Flow ◽

Physical Structure ◽

River Channels ◽

Hydrologic Alteration ◽

Water Conditions ◽

Flow Components ◽

The Impact ◽

Large Floods

The construction of dams in rivers negatively affects ecosystems because dams violate the continuity of rivers, transform the biological and physical structure of the river channels, and the most importantly – alter the hydrological regime. The impact on the hydrology of the river can occur through reducing or increasing flows, altering seasonality of flows, changing the frequency, duration and timing of flow events, etc. In order to determine the extent of the mentioned changes, The Indicators of Hydrologic Alteration (IHA) software was used in this paper. The results showed that after the construction of Angiriai dam, such changes occurred in IHA Parameters group as: the water conditions of April month decreased by 31 %; 1-day, 3-days, 7-days and 30-days maximum flow decreased; the date of minimum flow occurred 21 days later; duration of high and low pulses and the frequency of low pulses decreased, but the frequency of high pulses increased, etc. The analysis of the Environmental Flow Components showed, that the essential differences were recorded in groups of the small and large floods, when, after the establishment of the Šušvė Reservoir, the large floods no longer took place and the probability of frequency of the small floods didn’t exceed 1 time per year.

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