Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching
Managed dyke realignment is a method of creating more coastal wetland environments, by breaching constructed dykes (levees) to allow seawater driven by tides to flood the land surface and enable re-establishment of salt marshes over time. However, coastal land regions that are protected by dykes exp...
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| Language: | English |
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Elsevier
2025-06-01
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| Series: | Nature-Based Solutions |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2772411525000084 |
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| author | Rachel A. Burns Ryan P. Mulligan Megan Elliott Danika van Proosdij Enda Murphy |
| author_facet | Rachel A. Burns Ryan P. Mulligan Megan Elliott Danika van Proosdij Enda Murphy |
| author_sort | Rachel A. Burns |
| collection | DOAJ |
| description | Managed dyke realignment is a method of creating more coastal wetland environments, by breaching constructed dykes (levees) to allow seawater driven by tides to flood the land surface and enable re-establishment of salt marshes over time. However, coastal land regions that are protected by dykes experience major hydrodynamic changes after breaching. To investigate these dynamics, a dyke in Atlantic Canada was purposefully breached and the adjacent land surface allowed to flood with the tides. Field measurements pre- and post-breach provide a rare opportunity to model the hydrodynamics of early dyke realignment in a hypertidal estuary in the Bay of Fundy. These include measurements of water levels and current velocities at spring tide collected across of field site. A numerical model with an unstructured flexible mesh (Delft3D-FM) was applied to examine the impacts of tidal flooding from a river channel, through the dyke breach and across the previously agricultural landscape that was historically a salt marsh. The model was used to simulate the hydrodynamics inside and around the breach before and after seawater flooding during spring tides, to evaluate the initial impacts of this nature-based method of managed dyke realignment. The results indicate that the breach was not wide enough to influence water levels within the Missaguash River. The depth-averaged current speeds can exceed 1 m s−1 within the breach and are typically <0.3 m s−1 across the flooded area with an average depth of 0.66 m over the simulation period with six tidal cycles. The model results also highlight the importance of high-resolution computational grids and variable bottom roughness for simulating the hydrodynamics of small-scale salt marsh restoration projects. Overall, the results may provide insight to researchers and practitioners in applying nature-based solutions to improve coastal resilience. |
| format | Article |
| id | doaj-art-88c92fb4fb3f4027b993bd3ee4c24d25 |
| institution | Kabale University |
| issn | 2772-4115 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nature-Based Solutions |
| spelling | doaj-art-88c92fb4fb3f4027b993bd3ee4c24d252025-01-31T05:12:43ZengElsevierNature-Based Solutions2772-41152025-06-017100218Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breachingRachel A. Burns0Ryan P. Mulligan1Megan Elliott2Danika van Proosdij3Enda Murphy4Department of Civil Engineering, Queen's University, Kingston ON, CanadaDepartment of Civil Engineering, Queen's University, Kingston ON, Canada; Corresponding author.Department of Geography and Environmental Studies, Saint Mary's University, Halifax NS, CanadaDepartment of Geography and Environmental Studies, Saint Mary's University, Halifax NS, CanadaDepartment of Civil Engineering, University of British Columbia, Vancouver BC, CanadaManaged dyke realignment is a method of creating more coastal wetland environments, by breaching constructed dykes (levees) to allow seawater driven by tides to flood the land surface and enable re-establishment of salt marshes over time. However, coastal land regions that are protected by dykes experience major hydrodynamic changes after breaching. To investigate these dynamics, a dyke in Atlantic Canada was purposefully breached and the adjacent land surface allowed to flood with the tides. Field measurements pre- and post-breach provide a rare opportunity to model the hydrodynamics of early dyke realignment in a hypertidal estuary in the Bay of Fundy. These include measurements of water levels and current velocities at spring tide collected across of field site. A numerical model with an unstructured flexible mesh (Delft3D-FM) was applied to examine the impacts of tidal flooding from a river channel, through the dyke breach and across the previously agricultural landscape that was historically a salt marsh. The model was used to simulate the hydrodynamics inside and around the breach before and after seawater flooding during spring tides, to evaluate the initial impacts of this nature-based method of managed dyke realignment. The results indicate that the breach was not wide enough to influence water levels within the Missaguash River. The depth-averaged current speeds can exceed 1 m s−1 within the breach and are typically <0.3 m s−1 across the flooded area with an average depth of 0.66 m over the simulation period with six tidal cycles. The model results also highlight the importance of high-resolution computational grids and variable bottom roughness for simulating the hydrodynamics of small-scale salt marsh restoration projects. Overall, the results may provide insight to researchers and practitioners in applying nature-based solutions to improve coastal resilience.http://www.sciencedirect.com/science/article/pii/S2772411525000084Coastal environmentsTidal circulationDelft3D modelFlexible meshEstuariesSalt marshes |
| spellingShingle | Rachel A. Burns Ryan P. Mulligan Megan Elliott Danika van Proosdij Enda Murphy Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching Nature-Based Solutions Coastal environments Tidal circulation Delft3D model Flexible mesh Estuaries Salt marshes |
| title | Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching |
| title_full | Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching |
| title_fullStr | Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching |
| title_full_unstemmed | Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching |
| title_short | Numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching |
| title_sort | numerical modelling of the hydrodynamics driven by tidal flooding of the land surface after dyke breaching |
| topic | Coastal environments Tidal circulation Delft3D model Flexible mesh Estuaries Salt marshes |
| url | http://www.sciencedirect.com/science/article/pii/S2772411525000084 |
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