APPLICATION OF NUMERICAL RIVER BED DEFORMATION MODEL TO SEDIMENT TRANSPORT AND TOPOGRAPHY CHANGE DUE TO TSUNAMI

Solid and liquid mixtures in river courses intensify in areas of river confluence, conditioned mainly by the angular opening of the junction. Knowledge of hydrosedimentological dynamics in bedrock junctions with different angular openings is essential for understanding morphological adjustment at confluences and for supporting actions for the preservation and conservation of river ecosystems. For this reason, this article presents the results of a hydrogeomorphologic study on a river confluence with an obtuse junction angle (>100º), in a plateau bedrock river, in the Serra Geral Formation. The research evaluated a fluvial segment upstream and downstream of the Pedras River and in the Pombas River tributary, in Guarapuava, Paraná, through observations and measurements of morphological and hydraulic characteristics, width, talweg depth, bed declivity and bankfull flow. Morphological adjustment in obtuse confluences is peculiar in that the fluvial junction angle conditions specific flow, erosion, sediment transport and deposition dynamics, mainly resulting from its association with the geological nature of the river bed and types of land use and management upstream of the confluence.

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ROLES OF FLOODS AND FINE SEDIMENT TRANSPORT TO WOOD LAND EXPANSION ON A GRAVEL RIVER-BED

PROCEEDINGS OF HYDRAULIC ENGINEERING ◽

10.2208/prohe.42.433 ◽

1998 ◽

Vol 42 ◽

pp. 433-438 ◽

Cited By ~ 3

Author(s):

Sam-hee LEE ◽

Koh-ichi FUJITA ◽

Takao TSUKAHARA ◽

Satoshi WATANABE ◽

Koichi YAMAMOTO ◽

...

Keyword(s):

Sediment Transport ◽

Fine Sediment ◽

River Bed

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Numerical Investigation of a Flash Flood Process that Occurred in Zhongdu River, Sichuan, China

Frontiers in Earth Science ◽

10.3389/feart.2021.686925 ◽

2021 ◽

Vol 9 ◽

Author(s):

Qingyuan Yang ◽

Tonghuan Liu ◽

Jingjing Zhai ◽

Xiekang Wang

Keyword(s):

Sediment Transport ◽

Water Level ◽

Flash Flood ◽

Peak Level ◽

Field Studies ◽

Bed Deformation ◽

Bed Erosion ◽

Set Up ◽

Discharge Profile ◽

The Impact

In 2018, a flash flood occurred in the Zhongdu river, which lies in Yibin, Sichuan province of China. The flood caused many casualties and significant damage to people living nearby. Due to the difficulty in predicting where and when flash floods will happen, it is nearly impossible to set up monitors in advance to detect the floods in detail. Field investigations are usually carried out to study the flood propagation and disaster-causing mechanism after the flood’s happening. The field studies take the relic left by the flash flood to deduce the peak level, peak discharge, bed erosion, etc. and further revel the mechanism between water and sediment transport during the flash flood This kind of relic-based study will generate bigger errors in regions with great bed deformation. In this study, we come up with numerical simulations to investigate the flash flood that happened in the Zhongdu river. The simulations are based on two-dimensional shallow water models coupled with sediment transport and bed deformation models. Based on the real water level and discharge profile measured by a hydrometric station nearby, the numerical simulation reproduced the flash flood in the valley. The results show the flood coverage, water level variation, and velocity distribution during the flood. The simulation offers great help in studying the damage-causing process. Furthermore, simulations without considering sediment transport are also carried out to study the impact of bed erosion and sedimentation. The study proved that, without considering bed deformation, the flood may be greatly underestimated, and the sediment lying in the valley has great impact on flood power.

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Morphological development of river widenings with variable sediment supply

E3S Web of Conferences ◽

10.1051/e3sconf/20184002007 ◽

2018 ◽

Vol 40 ◽

pp. 02007 ◽

Cited By ~ 1

Author(s):

Cristina Rachelly ◽

Volker Weitbrecht ◽

David F. Vetsch ◽

Robert M. Boes

Keyword(s):

Sediment Transport ◽

Adverse Effects ◽

Habitat Heterogeneity ◽

Field Studies ◽

Sediment Supply ◽

Morphological Development ◽

Regime Theory ◽

Channel Response ◽

River Bed ◽

Experimental Flume

River widening is a common restoration approach to mitigate the adverse effects of past stream alterations on infrastructure and the riparian ecosystem by stabilizing the river bed and enhancing habitat heterogeneity. In this study, two river widening approaches, excavated and dynamic, are described for the case of moderately steep gravel-bed rivers in the Alpine foothills, with a focus on dynamic river widening. As most channelized rivers exhibit ongoing degradation due to the lack of sediment supply and efforts to restore sediment transport are increasing, the consideration of the response of river widenings to variable sediment supply is important. For this purpose, insights from regime theory are applied to river widening and several experimental flume and field studies on channel response to variable sediment supply are reviewed. Dynamic river widenings are expected to be morphologically active in weakly degraded rivers with sufficient sediment supply, while they may not be an appropriate restoration approach for highly degraded rivers due to persistent impairment of morphological activity.

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Numerical modelling of sediment transport in a channel bend with floating units

10.5194/egusphere-egu21-16114 ◽

2021 ◽

Author(s):

Diwash Lal Maskey ◽

Nils Ruther

Keyword(s):

Transport Phenomenon ◽

Sediment Transport ◽

Numerical Modelling ◽

Velocity Distribution ◽

Three Dimensional ◽

Flow Distribution ◽

Deposition Pattern ◽

Bed Deformation ◽

Channel Bend ◽

Conceptual Study

<p>Floating units/booms are used to trap or guide floating debris in watercourses. In a relatively shallow depth, these floats could affect the velocity distribution, sediment transport and channel bed deformation. &#160;A three-dimensional non-hydrostatic numerical modelling was performed in a 180 degree channel bend with floats to see the effects in flow distribution and bed deformation as a conceptual study. Different configurations of the floats were simulated. The results showed that the flow velocity increased and deposition decreased at the inner bank of the bend. Use of floating units could be studied to alter sediment deposition pattern and sediment transport phenomenon in watercourses.</p>

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