MODELING BIOGEOMORPHOLOGICAL INTERACTIONS IN UNDERWATER NOURISHMENTS

Bas Borsje, Maurits Kruijt, Jebbe van der Werf, Suzanne Hulscher, Peter Herman

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.

Keywords


Biogeomorphology; Nourishments; Dutch coast; Bio-engineers; Building with Nature

References


Austen, I., Andersen, T.J., Edelvang, K., 1999. The influence of benthic diatoms and invertebrates on the erodibility of an intertidal mudflat, the Danish Wadden Sea. Estuarine, Coastal and Shelf Science 49, 99-111. http://dx.doi.org/10.1006/ecss.1998.0491

Baptist, M.J., Tamis, J.E., Borsje, B.W., van der Werf, J.J., 2009. Review of the geomorphological, benthic ecological and biogeomorphological effects of nourishments on the shoreface and surf zone of the Dutch coast. IMARES Report C113/08, Deltares Report Z4582.50.

Borsje, B.W., De Vries, M.B., Bouma, T.J., Besio, G., Hulscher, S.J.M.H., Herman, P.M.J, 2009a. Modelling bio-geomorphological influences for offshore sandwaves. Continental Shelf Research 29, 1289-1301.http://dx.doi.org/10.1016/j.csr.2009.02.008

Borsje, B.W., Hulscher, S.J.M.H., Herman, P.M.J., de Vries, M.B., 2009b. On the parameterization of biological influences on offshore sand wave dynamics. Ocean Dynamics 59, 659-670.http://dx.doi.org/10.1007/s10236-009-0199-0

Bouma, T.J., van Duren, L.A., Temmerman, S., Claverie, T., Blanco-Garcia, A., Ysebaert, T., Herman, P.M.J., 2007. Spatial flow and sedimentation patterns within patch of epibenthic structures: combining field, flume and modeling experiments. Continental Shelf Research 27, 1020-1045. http://dx.doi.org/10.1016/j.csr.2005.12.019

De Ronde, J.G., Mulder, J.P.M., Spanhoff, R., 2003. Morphological developments and coastal zone management in the Netherlands. International conference on Estuaries and Coasts. Hangzhou, China, 46-56.

Degraer S., Verfaillie, E., Willems W., Adriaens, E., Vincx, M., Van Lancker, V., 2008. Habitat suitability modeling as a mapping tool for macro-benthic communities: an example from the Belgian part of the North Sea. Continental Shelf Research 28, 369-379.http://dx.doi.org/10.1016/j.csr.2007.09.001

Eckman, J.E., Nowell, A.R.M., Jumars, P.A., 1981. Sediment destabilization by animal tubes. Journal of Marine Research 39,361-374.

Friedrichs, M., Graf, G., Spring, B., 2000. Skimming flow induced over a simulated polychaete tube lawn at low population densities. Marine Ecology Progress Series 192, 219-228. http://dx.doi.org/10.3354/meps192219

Giardino, A., van der Werf, J., van Ormondt, M., Brière, C., Walstra, D.J., 2010. Detailed morphodynamic simulations of shoreface nourishment scenarios. In: Vionnet, C.A., Garcia, M.H., Latrubesse, E.M., Perillo, G.M.E. (Eds). Proceedings of the sixth IAHR Symposium on River, Coastal and Estuarine Morphodynamics (RCEM), Santa Fe, Argentina, pp 947-952.

Grunnet, N.M., Walstra, D.R., Ruessink, B.G., 2004. Process-based modeling of a shoreface nourishment. Coastal Engineering 51, 581-607. http://dx.doi.org/10.1016/j.coastaleng.2004.07.016

Grunnet, N.M., Ruessink, B.G., 2005. Morphodynamic response of nearshore bars to a shoreface nourishment. Coastal Engineering 52, 119-137. http://dx.doi.org/10.1016/j.coastaleng.2004.09.006

Hamm, L., Capobianco, M., Detee, H.H., Lechuga, A., Spanhoff, R., Stive, M.J.F., 2002. A summary of European experience with shore nourishment. Coastal Engineering 47, 237-264.http://dx.doi.org/10.1016/S0378-3839(02)00127-8

Hanson, H., Brampton, A., Capobianco, M., Dette, H.H., Hamm, L., Laustrup, C., Lechuga, A., Spanhoff, R., 2002. Beach nourishment projects, practices, and objectives – a European overview. Coastal Engineering 47, 81-111. http://dx.doi.org/10.1016/S0378-3839(02)00122-9

Janssen, G., Mulder, S., 2005, Zonation of macrofauna across sandy beaches and surf zones along the Dutch coast. Oceanologia 47, 265-282.

Lesser, G., Roelvink, J., van Kester, J., Stelling, G., 2004. Development and validation of a threedimensional morphological model. Coastal Engineering 51, 883-915. http://dx.doi.org/10.1016/j.coastaleng.2004.07.014

Muir, S. D., 2003. The biology of razor clams (Ensis spp.) and their emergent fishery on the West coast of Scotland. University Marine Biological Station. Millport, University of London: 1 - 280.

Murray, J.M.H., Meadows, A., Meadows, P.S., 2002. Biogeomorphological implications of microscale interactions between sediment geotechnics and marine benthos: a review. Geomorphologiy 47, 15-30. http://dx.doi.org/10.1016/S0169-555X(02)00138-1

Ojeda, E., Ruessink, B.G., Guillen, J., 2008. Morphodynamic response of two-barred beach to a shoreface nourishment. Coastal Engineering 55, 1185-1196.ttp://dx.doi.org/10.1016/j.coastaleng.2008.05.006

Rabaut, M., Guilini, K., Van Hoey, G., Vincx, M., Degraer, S., 2007. A bio-engineered soft-bottom environment: The impact of Lanice conchilega on the benthic species-specific densities and community structure. Estuarine, Coastal and Shelf Science 75, 525-536.http://dx.doi.org/10.1016/j.ecss.2007.05.041

Rabaut, M., Vincs, M., Degraer, S., 2008. Do Lanice conchilega (sandmason) aggregations classify as reefs? Quantifying habitat modifying effects. Helgoland Marine Research, 1-10.

Renschler, C.S., Doyle, M.W., Thoms, M., 2007. Geomorphology and ecosystems: Challenges and keys for success in bridging disciplines. Geomorphology 89, 1-8.http://dx.doi.org/10.1016/j.geomorph.2006.07.011

Riethmüller, R., Heineke, M., Kühl, H., Keuker-Rüdiger, R., 2000. Chlorophyll a concentration as an index of sediment surface stabilization by microphytobenthos? Continental Shelf Research 20, 1351-1372. http://dx.doi.org/10.1016/S0278-4343(00)00027-3

Uittenbogaard, R., 2003. Modelling turbulence in vegetated aquatic flows. In international workshop on riparian forest vegetated channels: hydraulic, morphological and ecological aspects, 20-22 February 2003, Trento, Italy, 2003.

Van Dalfsen, J.A., Essink, K., 1997. Risk analysis of coastal nourishment techniques (RIACON). Rijksinstituut voor Kust en Zee/RIKZ. Report RIKZ-97.022.

Van Dalfsen, J.A., 2006 Inventarisatie brandingszone zandige kust. TNO-rapport B&O-DHR2005/251.

Van der Werf, J.J., Giardino, A., van Ormondt, M., Walstra, D.J., Ramaekers, G., 2010. Detailed morphodynamic simulations of shoreface nourishment scenarios. In: Vionnet, C.A., Garcia, M.H., Latrubesse, E.M., Perillo, G.M.E. (Eds). Proceedings of the sixth IAHR Symposium on River, Coastal and Estuarine Morphodynamics (RCEM), Santa Fe, Argentina, pp 953-957.

Van Duin, M.J.P., Wiersma, N.R., Walstra, D.J.R., Van Rijn, L.C., Stive, M.J.F., 2004. Nourishing the shoreface: observations and hindcasting of the Egmond case, The Netherlands. Coastal Engineering 51, 813-837. http://dx.doi.org/10.1016/j.coastaleng.2004.07.011

Van Leeuwen, S., Dodd, N., Calvete, D., Falques, A., 2007. Linear evolution of a shoreface nourishment. Coastal Engineering 54, 417-431. http://dx.doi.org/10.1016/j.coastaleng.2006.11.006

Widdows, J., Brinsley, M.D., 2002. Impact of biotic and abiotic processes on sediment dynamics and the consequences to the structure and functioning of the intertidal zone. Journal of Sea Research 48, 143-156.http://dx.doi.org/10.1016/S1385-1101(02)00148-X


Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.