Modeling biogeomorphological interactions in underwater nourishments

Bas W. Borsje, Maurits A. Kruijt, Jebbe J. van der Werf, Suzanne J.M.H. Hulscher, Peter M.J. Herman

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Abstract

To prevent sandy coastlines from further erosion, nourishments are executed in which sand is usually put underwater at the foreshore. Waves and currents transport the sand on the beach and in this way stabilize the coastal profile. Little is known about the interactions of these so-called shoreface nourishments with the benthic populations inhabiting the coastal strip. Benthos is affected by the nourishments, but benthic populations could in turn affect the morphological evolution of the nourished coast. Monitoring has shown that the benthic community will mainly recovery after ca. 1 year. However, the impact of benthos on the sediment dynamics and hydrodynamics is unknown. In this paper we focus on tube building worms, which have a large abundance in the foreshore, live in patches of several square meters in diameter and protrude several centimeters from the sediment in the water column. Tube building worms are included in a numerical modeling tool (Delft3D), by explicitly accounting for the influence of cylindrical structures on drag and turbulence by an extra source term of friction force in the momentum equation and an extra source term of Total Kinetic Energy (TKE) and turbulent energy dissipation in the k-ε equations respectively. The model is validated against field and flume experiments and it shows a significant influence on flow velocities near the bed, bed shear stress and bed-load transport rates. Moreover, model results reveal that tube building worms are able to stabilize nourishments and slow down the migration of the outer breaker bar. Present model explorations indicate that future research should focus on the measurement of the patchy distribution of bio-engineers in the foreshore and their impact on the sediment dynamics and hydrodynamics. Such knowledge will enable process based modeling of the spatial and temporal variation in biological activity on the morphological development of the coastal profile and also it will lead to validation of the proposed model with field measurements.
Original languageEnglish
Title of host publicationProceedings of 32nd International Conference on Coastal Engineering (ICCE)
Subtitle of host publication30 June - 5 July 2010, Shanghai
EditorsJane McKee Smith, Patrick Lynett
PublisherCoastal Engineering Research Council
Pages1-11
ISBN (Print)978-0-9896611-0-2
DOIs
Publication statusPublished - 30 Jun 2011
Event32nd International Conference on Coastal Engineering, ICCE 2010 - Shanghai, China
Duration: 30 Jun 20105 Jul 2010
Conference number: 32

Publication series

NameCoastal Engineering Proceedings
PublisherCoastal Engineering Research Council
ISSN (Print)2156-1028

Conference

Conference32nd International Conference on Coastal Engineering, ICCE 2010
Abbreviated titleICCE
CountryChina
CityShanghai
Period30/06/105/07/10

Fingerprint

benthos
modeling
hydrodynamics
sediment
flume experiment
sand
bottom stress
coast
bedload
energy dissipation
flow velocity
kinetic energy
drag
shear stress
momentum
temporal variation
beach
friction
spatial variation
water column

Keywords

  • METIS-275183

Cite this

Borsje, B. W., Kruijt, M. A., van der Werf, J. J., Hulscher, S. J. M. H., & Herman, P. M. J. (2011). Modeling biogeomorphological interactions in underwater nourishments. In J. McKee Smith, & P. Lynett (Eds.), Proceedings of 32nd International Conference on Coastal Engineering (ICCE): 30 June - 5 July 2010, Shanghai (pp. 1-11). (Coastal Engineering Proceedings). Coastal Engineering Research Council. https://doi.org/10.9753/icce.v32.sediment.104
Borsje, Bas W. ; Kruijt, Maurits A. ; van der Werf, Jebbe J. ; Hulscher, Suzanne J.M.H. ; Herman, Peter M.J. / Modeling biogeomorphological interactions in underwater nourishments. Proceedings of 32nd International Conference on Coastal Engineering (ICCE): 30 June - 5 July 2010, Shanghai. editor / Jane McKee Smith ; Patrick Lynett. Coastal Engineering Research Council, 2011. pp. 1-11 (Coastal Engineering Proceedings).
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title = "Modeling biogeomorphological interactions in underwater nourishments",
abstract = "To prevent sandy coastlines from further erosion, nourishments are executed in which sand is usually put underwater at the foreshore. Waves and currents transport the sand on the beach and in this way stabilize the coastal profile. Little is known about the interactions of these so-called shoreface nourishments with the benthic populations inhabiting the coastal strip. Benthos is affected by the nourishments, but benthic populations could in turn affect the morphological evolution of the nourished coast. Monitoring has shown that the benthic community will mainly recovery after ca. 1 year. However, the impact of benthos on the sediment dynamics and hydrodynamics is unknown. In this paper we focus on tube building worms, which have a large abundance in the foreshore, live in patches of several square meters in diameter and protrude several centimeters from the sediment in the water column. Tube building worms are included in a numerical modeling tool (Delft3D), by explicitly accounting for the influence of cylindrical structures on drag and turbulence by an extra source term of friction force in the momentum equation and an extra source term of Total Kinetic Energy (TKE) and turbulent energy dissipation in the k-ε equations respectively. The model is validated against field and flume experiments and it shows a significant influence on flow velocities near the bed, bed shear stress and bed-load transport rates. Moreover, model results reveal that tube building worms are able to stabilize nourishments and slow down the migration of the outer breaker bar. Present model explorations indicate that future research should focus on the measurement of the patchy distribution of bio-engineers in the foreshore and their impact on the sediment dynamics and hydrodynamics. Such knowledge will enable process based modeling of the spatial and temporal variation in biological activity on the morphological development of the coastal profile and also it will lead to validation of the proposed model with field measurements.",
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year = "2011",
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}

Borsje, BW, Kruijt, MA, van der Werf, JJ, Hulscher, SJMH & Herman, PMJ 2011, Modeling biogeomorphological interactions in underwater nourishments. in J McKee Smith & P Lynett (eds), Proceedings of 32nd International Conference on Coastal Engineering (ICCE): 30 June - 5 July 2010, Shanghai. Coastal Engineering Proceedings, Coastal Engineering Research Council, pp. 1-11, 32nd International Conference on Coastal Engineering, ICCE 2010, Shanghai, China, 30/06/10. https://doi.org/10.9753/icce.v32.sediment.104

Modeling biogeomorphological interactions in underwater nourishments. / Borsje, Bas W.; Kruijt, Maurits A.; van der Werf, Jebbe J.; Hulscher, Suzanne J.M.H.; Herman, Peter M.J.

Proceedings of 32nd International Conference on Coastal Engineering (ICCE): 30 June - 5 July 2010, Shanghai. ed. / Jane McKee Smith; Patrick Lynett. Coastal Engineering Research Council, 2011. p. 1-11 (Coastal Engineering Proceedings).

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

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AU - Kruijt, Maurits A.

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AU - Hulscher, Suzanne J.M.H.

AU - Herman, Peter M.J.

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N2 - To prevent sandy coastlines from further erosion, nourishments are executed in which sand is usually put underwater at the foreshore. Waves and currents transport the sand on the beach and in this way stabilize the coastal profile. Little is known about the interactions of these so-called shoreface nourishments with the benthic populations inhabiting the coastal strip. Benthos is affected by the nourishments, but benthic populations could in turn affect the morphological evolution of the nourished coast. Monitoring has shown that the benthic community will mainly recovery after ca. 1 year. However, the impact of benthos on the sediment dynamics and hydrodynamics is unknown. In this paper we focus on tube building worms, which have a large abundance in the foreshore, live in patches of several square meters in diameter and protrude several centimeters from the sediment in the water column. Tube building worms are included in a numerical modeling tool (Delft3D), by explicitly accounting for the influence of cylindrical structures on drag and turbulence by an extra source term of friction force in the momentum equation and an extra source term of Total Kinetic Energy (TKE) and turbulent energy dissipation in the k-ε equations respectively. The model is validated against field and flume experiments and it shows a significant influence on flow velocities near the bed, bed shear stress and bed-load transport rates. Moreover, model results reveal that tube building worms are able to stabilize nourishments and slow down the migration of the outer breaker bar. Present model explorations indicate that future research should focus on the measurement of the patchy distribution of bio-engineers in the foreshore and their impact on the sediment dynamics and hydrodynamics. Such knowledge will enable process based modeling of the spatial and temporal variation in biological activity on the morphological development of the coastal profile and also it will lead to validation of the proposed model with field measurements.

AB - To prevent sandy coastlines from further erosion, nourishments are executed in which sand is usually put underwater at the foreshore. Waves and currents transport the sand on the beach and in this way stabilize the coastal profile. Little is known about the interactions of these so-called shoreface nourishments with the benthic populations inhabiting the coastal strip. Benthos is affected by the nourishments, but benthic populations could in turn affect the morphological evolution of the nourished coast. Monitoring has shown that the benthic community will mainly recovery after ca. 1 year. However, the impact of benthos on the sediment dynamics and hydrodynamics is unknown. In this paper we focus on tube building worms, which have a large abundance in the foreshore, live in patches of several square meters in diameter and protrude several centimeters from the sediment in the water column. Tube building worms are included in a numerical modeling tool (Delft3D), by explicitly accounting for the influence of cylindrical structures on drag and turbulence by an extra source term of friction force in the momentum equation and an extra source term of Total Kinetic Energy (TKE) and turbulent energy dissipation in the k-ε equations respectively. The model is validated against field and flume experiments and it shows a significant influence on flow velocities near the bed, bed shear stress and bed-load transport rates. Moreover, model results reveal that tube building worms are able to stabilize nourishments and slow down the migration of the outer breaker bar. Present model explorations indicate that future research should focus on the measurement of the patchy distribution of bio-engineers in the foreshore and their impact on the sediment dynamics and hydrodynamics. Such knowledge will enable process based modeling of the spatial and temporal variation in biological activity on the morphological development of the coastal profile and also it will lead to validation of the proposed model with field measurements.

KW - METIS-275183

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M3 - Conference contribution

SN - 978-0-9896611-0-2

T3 - Coastal Engineering Proceedings

SP - 1

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BT - Proceedings of 32nd International Conference on Coastal Engineering (ICCE)

A2 - McKee Smith, Jane

A2 - Lynett, Patrick

PB - Coastal Engineering Research Council

ER -

Borsje BW, Kruijt MA, van der Werf JJ, Hulscher SJMH, Herman PMJ. Modeling biogeomorphological interactions in underwater nourishments. In McKee Smith J, Lynett P, editors, Proceedings of 32nd International Conference on Coastal Engineering (ICCE): 30 June - 5 July 2010, Shanghai. Coastal Engineering Research Council. 2011. p. 1-11. (Coastal Engineering Proceedings). https://doi.org/10.9753/icce.v32.sediment.104