Effects of mud supply on large-scale estuary morphology and development over centuries to millennia
Alluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-10-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://www.earth-surf-dynam.net/5/617/2017/esurf-5-617-2017.pdf |
| _version_ | 1818083547085275136 |
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| author | L. Braat T. van Kessel J. R. F. W. Leuven M. G. Kleinhans |
| author_facet | L. Braat T. van Kessel J. R. F. W. Leuven M. G. Kleinhans |
| author_sort | L. Braat |
| collection | DOAJ |
| description | Alluvial river estuaries consist largely of sand but are typically
flanked by mudflats and salt marshes. The analogy with meandering rivers
that are kept narrower than braided rivers by cohesive floodplain formation
raises the question of how large-scale estuarine morphology and the late Holocene
development of estuaries are affected by cohesive sediment. In this study we
combine sand and mud transport processes and study their interaction effects
on morphologically modelled estuaries on centennial to millennial
timescales. The numerical modelling package Delft3D was applied in 2-DH
starting from an idealised convergent estuary. The mixed sediment was
modelled with an active layer and storage module with fluxes predicted by the
Partheniades–Krone relations for mud and Engelund–Hansen for sand. The model
was subjected to a range of idealised boundary conditions of tidal range,
river discharge, waves and mud input. The model results show that mud is
predominantly stored in mudflats on the side of the estuary. Marine mud
supply only influences the mouth of the estuary, whereas fluvial mud is
distributed along the whole estuary. Coastal waves stir up mud and remove the
tendency to form muddy coastlines and the formation of mudflats in the
downstream part of the estuary. Widening continues in estuaries with only
sand, while mud supply leads to a narrower constant width and reduced channel
and bar dynamics. This self-confinement eventually leads to a dynamic
equilibrium in which lateral channel migration and mudflat expansion are balanced on
average. However, for higher mud concentrations, higher discharge
and low tidal amplitude, the estuary narrows and fills to become a tidal
delta. |
| first_indexed | 2024-12-10T19:39:43Z |
| format | Article |
| id | doaj.art-ba0eba3b3b0446bc8f2a3d24c821d58e |
| institution | Directory Open Access Journal |
| issn | 2196-6311 2196-632X |
| language | English |
| last_indexed | 2024-12-10T19:39:43Z |
| publishDate | 2017-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth Surface Dynamics |
| spelling | doaj.art-ba0eba3b3b0446bc8f2a3d24c821d58e2022-12-22T01:36:01ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2017-10-01561765210.5194/esurf-5-617-2017Effects of mud supply on large-scale estuary morphology and development over centuries to millenniaL. Braat0T. van Kessel1J. R. F. W. Leuven2M. G. Kleinhans3Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, the NetherlandsDeltares, Boussinesqweg 1, 2629 HV Delft, the NetherlandsUtrecht University, Heidelberglaan 2, 3584 CS Utrecht, the NetherlandsUtrecht University, Heidelberglaan 2, 3584 CS Utrecht, the NetherlandsAlluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene development of estuaries are affected by cohesive sediment. In this study we combine sand and mud transport processes and study their interaction effects on morphologically modelled estuaries on centennial to millennial timescales. The numerical modelling package Delft3D was applied in 2-DH starting from an idealised convergent estuary. The mixed sediment was modelled with an active layer and storage module with fluxes predicted by the Partheniades–Krone relations for mud and Engelund–Hansen for sand. The model was subjected to a range of idealised boundary conditions of tidal range, river discharge, waves and mud input. The model results show that mud is predominantly stored in mudflats on the side of the estuary. Marine mud supply only influences the mouth of the estuary, whereas fluvial mud is distributed along the whole estuary. Coastal waves stir up mud and remove the tendency to form muddy coastlines and the formation of mudflats in the downstream part of the estuary. Widening continues in estuaries with only sand, while mud supply leads to a narrower constant width and reduced channel and bar dynamics. This self-confinement eventually leads to a dynamic equilibrium in which lateral channel migration and mudflat expansion are balanced on average. However, for higher mud concentrations, higher discharge and low tidal amplitude, the estuary narrows and fills to become a tidal delta.https://www.earth-surf-dynam.net/5/617/2017/esurf-5-617-2017.pdf |
| spellingShingle | L. Braat T. van Kessel J. R. F. W. Leuven M. G. Kleinhans Effects of mud supply on large-scale estuary morphology and development over centuries to millennia Earth Surface Dynamics |
| title | Effects of mud supply on large-scale estuary morphology and development over centuries to millennia |
| title_full | Effects of mud supply on large-scale estuary morphology and development over centuries to millennia |
| title_fullStr | Effects of mud supply on large-scale estuary morphology and development over centuries to millennia |
| title_full_unstemmed | Effects of mud supply on large-scale estuary morphology and development over centuries to millennia |
| title_short | Effects of mud supply on large-scale estuary morphology and development over centuries to millennia |
| title_sort | effects of mud supply on large scale estuary morphology and development over centuries to millennia |
| url | https://www.earth-surf-dynam.net/5/617/2017/esurf-5-617-2017.pdf |
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