Development of a Meandering Channel Caused by a Shape of the Alternate Bars

Nagata, Tomonori; Watanabe, Yasuharu; Yasuda, Hiroyasu; Ito, Akashi

doi:10.2208/jscejhe.69.i_1099

Cited by 6 publications

(4 citation statements)

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“…Note that, hereinafter, in order to achieve consistency with previous studies (e.g., Nagata et al, 2013), the analysis was conducted at 1 : 100 scale; however, in order to facilitate the comparison with the actual site, in this paper, the numerical values obtained in the calculation results are converted into actual measurement values.…”

Section: Watercourse Changementioning

confidence: 99%

“…That is to say, there is a possibility that the development of meandering flows in the flood occurred under the interrelated influence between the mechanism of sandbar development and the mechanism of meandering channel development operating in the low-water channel. Previous studies conducted by the authors (e.g., Nagata et al, 2013) addressed sandbar topography as a factor in the development of meandering flow. Experiments and analyses confirmed that the topography of alternating bars can be a factor in the development of meandering channels.…”

Section: Introductionmentioning

confidence: 99%

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Development of a meandering channel caused by the planform shape of the river bank

et al. 2014

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Abstract. Due to a typhoon and a stationary rain front, record amounts of rain fell in September 2011, and the largest class of discharge in recorded history was observed in the Otofuke River of eastern Hokkaido in Japan, and extensive bank erosion occurred in various parts of the river channel. Damages were especially serious in the middle reaches, where part of a dike was washed out. The results of a post-flood survey suggested that the direct cause of the dike breach was lateral advance of the bank erosion associated with the development of meandering channels. As the related development mechanism and predominant factors have not yet been clarified, this remains a priority from the viewpoint of disaster prevention. A past study on the development of meandering channels was reported by Shimizu et al. (1996). In this study, the meandering channel development process was reproduced using a slope failure model that linked bank erosion with bed changes. The study attempted to clarify the meandering development mechanism in the disaster and its predominant factors by using this model. The analysis properly reproduced the characteristics of the post-flood meandering waveforms. Therefore, it is suggested that the development of meandering during the flood attributed to the propagation of meandering downstream, which is triggered by the meandering flow from the meandering channel in the upstream, which also suggests that this propagated meandering then caused a gradual increase of meandering amplitude accompanied by bank erosion in the recession period of the flood.

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Section: Watercourse Changementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of a meandering channel caused by the planform shape of the river bank

et al. 2014

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“…Given the above, it was determined to be appropriate to perform the analysis at a model scale that was confirmed to be able to reproduce hydraulic and sediment transport phenomena, and then to convert the obtained results to those at actual scale and discuss the phenomena that occurred at the actual place. Note that, hereinafter, in order to achieve consistency with previous studies (e.g., Nagata et al, 2013), the analysis was conducted at 1 : 100 scale; however, in order to facilitate the comparison with the actual site, in this paper, the numerical values obtained in the calculation results are converted into actual measurement values.…”

Section: Watercourse Changementioning

confidence: 99%

“…Previous studies conducted by the authors (e.g., Nagata et al, 2013) addressed sandbar topography as a factor in the development of meandering flow. Experiments and analyses confirmed that the topography of alternating bars can be a factor in the development of meandering channels.…”

Section: Introductionmentioning

confidence: 99%

Development of a meandering channel caused by the plane shape of the river bank

Nagata¹,

Watanabe²,

Yasuda³

et al. 2013

Preprint

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Abstract. Due to a typhoon and a stationary rain front, record amounts of rain fell in September 2011, and the largest class of discharge in recorded history was observed in the Otofuke River of eastern Hokkaido in Japan, and extensive bank erosion occurred in various parts of the river channel. Damages were especially serious in the middle reaches, where part of a dike was washed out. The results of a post-flood survey suggested that the direct cause of the dike breach was lateral advance of the bank erosion associated with the development of meandering channels. As the related development mechanism and predominant factors have not yet been clarified, this remains a priority from the viewpoint of disaster prevention. A past study on the development of meandering channels was reported by Shimizu et al. In this study, the meandering channel development process was reproduced using a slope failure model that linked bank erosion with bed changes. The study attempted to clarify the meandering development mechanism in the disaster and it's predominant factors by using this model. The analysis properly reproduced the characteristics of the post-flood meandering waveforms. Therefore, it is suggested that the development of meandering during the flood attributed to the propagation of meandering to downstream, which is triggered by the meandering flow from the meandering channel in the upstream, and also suggested that this propagated meandering then caused a gradual increase of meandering amplitude accompanied by bank erosion in the recession period of the flood.

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Assessment of risks associated with development of river meandering under climate change using a physics-based free-meandering model

Masuya,

Inoue,

Iwasaki

et al. 2024

Environ Fluid Mech

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Recent increases in heavy rainfall events, which may have resulted from climate change, have caused various natural water- and sediment-related disasters. A typical sediment-related disaster in a steep gravel-bed river is extreme bank erosion and subsequent meander development, damaging residential areas and infrastructure along the river. Assessing the bank erosion rate and its future changes under climate change is essential to prevent such severe disasters. Here, we propose a simple but useful framework for this purpose using a physics-based numerical model of free meandering and a large dataset of flood hydrographs generated from climate and runoff models. First, numerical experiments on meandering development were conducted using a two-dimensional morphodynamic model of free meandering. The results indicate that meander dynamics could reach a dynamic equilibrium state under several hydraulic and channel geometry conditions, and the characteristics of the simulated meandering channel were reasonably consistent with the field data. The meander amplitude of this state was positively correlated with the steady discharge; therefore, the increase in flow discharge may have an important effect on river dynamics under climate change. To quantify this effect, we combined a simple predictor of meander amplitude derived from a numerical experiment with a flood hydrograph dataset for current and future climatic conditions. The results suggest that the meander amplitude increased significantly for the same probability of occurrence; therefore, the risk of riverbank erosion due to river meandering will increase significantly under future climate conditions.

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Development of a Meandering Channel Caused by a Shape of the Alternate Bars

Cited by 6 publications

References 0 publications

Development of a meandering channel caused by the planform shape of the river bank

Development of a meandering channel caused by the planform shape of the river bank

Development of a meandering channel caused by the plane shape of the river bank

Assessment of risks associated with development of river meandering under climate change using a physics-based free-meandering model

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