River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method
Riverbanks vary considerably in anti-scourability and consequently take various profiles. By using an isosceles trapezoid as the generalized form of river channel cross-sections and then incorporating the effects of bank angle into the variational analytical approach developed by Huang and Nanson (2...
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MDPI AG
2020-04-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/12/5/1250 |
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| author | Jinsheng Fan Heqing Huang Guoan Yu Teng Su |
| author_facet | Jinsheng Fan Heqing Huang Guoan Yu Teng Su |
| author_sort | Jinsheng Fan |
| collection | DOAJ |
| description | Riverbanks vary considerably in anti-scourability and consequently take various profiles. By using an isosceles trapezoid as the generalized form of river channel cross-sections and then incorporating the effects of bank angle into the variational analytical approach developed by Huang and Nanson (2000), this study presents a detailed theoretical investigation of the self-adjustment of alluvial channel forms. It is demonstrated that when alluvial channel flow achieves stable equilibrium, a significant decrease in riverbank steepness leads to a slight decrease in maximum sediment (bedload) discharge, and yet results in a significant increase in optimal channel width and a considerable decrease in optimal channel depth. The hydraulic geometry relations, theoretically derived for bank steepness to vary across a wide range, show that among the multivariant controls, the roles of bed sediment size, channel roughness, flow discharge and sediment (bedload) discharge are independent of bank steepness. While the effects of bank steepness illustrated in the theoretically derived hydraulic geometry relations are highly consistent with the results of threshold theory and previous empirical studies, limitations on using bank angle to reflect the anti-scourability of natural riverbanks are also highlighted. |
| first_indexed | 2024-03-10T20:11:47Z |
| format | Article |
| id | doaj.art-c577aede1a9d4695b5d6d09f29c179a8 |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-10T20:11:47Z |
| publishDate | 2020-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-c577aede1a9d4695b5d6d09f29c179a82023-11-19T22:54:53ZengMDPI AGWater2073-44412020-04-01125125010.3390/w12051250River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical MethodJinsheng Fan0Heqing Huang1Guoan Yu2Teng Su3Key Lab. of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaKey Lab. of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaKey Lab. of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaKey Lab. of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaRiverbanks vary considerably in anti-scourability and consequently take various profiles. By using an isosceles trapezoid as the generalized form of river channel cross-sections and then incorporating the effects of bank angle into the variational analytical approach developed by Huang and Nanson (2000), this study presents a detailed theoretical investigation of the self-adjustment of alluvial channel forms. It is demonstrated that when alluvial channel flow achieves stable equilibrium, a significant decrease in riverbank steepness leads to a slight decrease in maximum sediment (bedload) discharge, and yet results in a significant increase in optimal channel width and a considerable decrease in optimal channel depth. The hydraulic geometry relations, theoretically derived for bank steepness to vary across a wide range, show that among the multivariant controls, the roles of bed sediment size, channel roughness, flow discharge and sediment (bedload) discharge are independent of bank steepness. While the effects of bank steepness illustrated in the theoretically derived hydraulic geometry relations are highly consistent with the results of threshold theory and previous empirical studies, limitations on using bank angle to reflect the anti-scourability of natural riverbanks are also highlighted.https://www.mdpi.com/2073-4441/12/5/1250alluvial riversriverbank anti-scourabilityvariational methodequilibriumriver channel forms |
| spellingShingle | Jinsheng Fan Heqing Huang Guoan Yu Teng Su River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method Water alluvial rivers riverbank anti-scourability variational method equilibrium river channel forms |
| title | River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method |
| title_full | River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method |
| title_fullStr | River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method |
| title_full_unstemmed | River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method |
| title_short | River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method |
| title_sort | river channel forms in relation to bank steepness a theoretical investigation using a variational analytical method |
| topic | alluvial rivers riverbank anti-scourability variational method equilibrium river channel forms |
| url | https://www.mdpi.com/2073-4441/12/5/1250 |
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