Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats
Abstract River cutoffs and oxbow lakes represent ubiquitous features in alluvial plains, shaped by unidirectional meandering flow. Extensive studies have been conducted on these features as their presence immediately decreases meander sinuosity and plays a significant role in the long‐term eco‐morph...
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| Format: | Article |
| Language: | English |
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Wiley
2024-06-01
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| Series: | Water Resources Research |
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| Online Access: | https://doi.org/10.1029/2024WR037129 |
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| author | Chao Gao Ya Ping Wang Zhiwei Li Cong‐Qiang Liu Shu Gao |
| author_facet | Chao Gao Ya Ping Wang Zhiwei Li Cong‐Qiang Liu Shu Gao |
| author_sort | Chao Gao |
| collection | DOAJ |
| description | Abstract River cutoffs and oxbow lakes represent ubiquitous features in alluvial plains, shaped by unidirectional meandering flow. Extensive studies have been conducted on these features as their presence immediately decreases meander sinuosity and plays a significant role in the long‐term eco‐morphodynamic and sedimentary evolution of landscapes they carved in. In contrast, limited attention has been given to meander cutoffs formed in tidal environments by bidirectional currents, and the corresponding hydrodynamical processes within these features are poorly understood. Here, we present new, first‐handed hydroacoustic data collected through a series of fixed‐point and cross‐sectional flow measurements along a chute cutoff located in the microtidal Diaokou Mudflat, the Yellow River Delta, China. The investigated cutoff bend displays higher hydrologically active than the newly‐formed chute channel at low tide, whereas the chute channel gradually become the main conduit for tidal flow propagation with water stage increasing. Specifically, poorly‐developed flow separation zones are compensated by widespread secondary circulation cells that are more pronounced under the influence of turbulences and complex bedforms rather than channel curvatures. Unlike fluvial cutoffs, which tend to be hydrologically disconnected to parent channels by coarse‐grained bed sediment plugging near the entrances, our study case is characterized by the absence of plug bars and widespread bank slumps instead. Consequently, our results support earlier suggestions that tidal cutoffs seldom disconnect from parent channels due to frequent overbank events and flow confluences, which can keep cutoffs active by flushing away fine‐grained, cohesive sediments, especially in mudflat systems. |
| format | Article |
| id | doaj-art-c530b2e567504b7ca7118d48804257d0 |
| institution | DOAJ |
| issn | 0043-1397 1944-7973 |
| language | English |
| publishDate | 2024-06-01 |
| publisher | Wiley |
| record_format | Article |
| series | Water Resources Research |
| spelling | doaj-art-c530b2e567504b7ca7118d48804257d02025-08-20T03:22:18ZengWileyWater Resources Research0043-13971944-79732024-06-01606n/an/a10.1029/2024WR037129Hydrodynamics of Meander Chute Cutoffs in Microtidal MudflatsChao Gao0Ya Ping Wang1Zhiwei Li2Cong‐Qiang Liu3Shu Gao4Ministry of Education Key Laboratory for Coast and Island Development School of Geographic and Oceanographic Sciences, Nanjing University Nanjing ChinaMinistry of Education Key Laboratory for Coast and Island Development School of Geographic and Oceanographic Sciences, Nanjing University Nanjing ChinaState Key Laboratory of Water Resources Engineering and Management Wuhan University Wuhan ChinaInstitute of Surface‐Earth System Science, School of Earth System Science Tianjin University Tianjin ChinaMinistry of Education Key Laboratory for Coast and Island Development School of Geographic and Oceanographic Sciences, Nanjing University Nanjing ChinaAbstract River cutoffs and oxbow lakes represent ubiquitous features in alluvial plains, shaped by unidirectional meandering flow. Extensive studies have been conducted on these features as their presence immediately decreases meander sinuosity and plays a significant role in the long‐term eco‐morphodynamic and sedimentary evolution of landscapes they carved in. In contrast, limited attention has been given to meander cutoffs formed in tidal environments by bidirectional currents, and the corresponding hydrodynamical processes within these features are poorly understood. Here, we present new, first‐handed hydroacoustic data collected through a series of fixed‐point and cross‐sectional flow measurements along a chute cutoff located in the microtidal Diaokou Mudflat, the Yellow River Delta, China. The investigated cutoff bend displays higher hydrologically active than the newly‐formed chute channel at low tide, whereas the chute channel gradually become the main conduit for tidal flow propagation with water stage increasing. Specifically, poorly‐developed flow separation zones are compensated by widespread secondary circulation cells that are more pronounced under the influence of turbulences and complex bedforms rather than channel curvatures. Unlike fluvial cutoffs, which tend to be hydrologically disconnected to parent channels by coarse‐grained bed sediment plugging near the entrances, our study case is characterized by the absence of plug bars and widespread bank slumps instead. Consequently, our results support earlier suggestions that tidal cutoffs seldom disconnect from parent channels due to frequent overbank events and flow confluences, which can keep cutoffs active by flushing away fine‐grained, cohesive sediments, especially in mudflat systems.https://doi.org/10.1029/2024WR037129chute cutofftidal mudflathydroacousticflow separationsecondary circulationplug bar |
| spellingShingle | Chao Gao Ya Ping Wang Zhiwei Li Cong‐Qiang Liu Shu Gao Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats Water Resources Research chute cutoff tidal mudflat hydroacoustic flow separation secondary circulation plug bar |
| title | Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats |
| title_full | Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats |
| title_fullStr | Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats |
| title_full_unstemmed | Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats |
| title_short | Hydrodynamics of Meander Chute Cutoffs in Microtidal Mudflats |
| title_sort | hydrodynamics of meander chute cutoffs in microtidal mudflats |
| topic | chute cutoff tidal mudflat hydroacoustic flow separation secondary circulation plug bar |
| url | https://doi.org/10.1029/2024WR037129 |
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