MODELLING ANTHROPOGENIC EFFECT OF A TIDAL BASIN EVOLUTION

Pushpa Kumara Dissanayake, Andreas Wurpts, Marco Miani, Heiko Knaack

Abstract


A numerical approach was undertaken to investigate an anthropogenic effect (i.e., construction of a peninsula in 1984) on the tidal basin evolution of the Ley Bay in the East Frisian Wadden Sea. Coupled hydro-morphodynamic model runs span from 1975 to 1990 applying both tidal and wave boundary forcings with a multiple-sediment bed. The offshore tidal force was transformed to the study area applying a cascade modeling approach while a highly schematised wave climate was adopted in this simulation. Two bathymetries (i.e., 1975 and 1990) were available for this study and therefore the peninsula was implemented based on the 1984 predicted bed. Resulting morphodynamic evolution indicates that the deeper areas (channels) are well reproduced by the model rather than the shallow areas (inter-tidal areas). In addition to the peninsula construction, the human interference by dredging and dumping appears to have influenced the Ley Bay evolution. Due to the lack of data availability, such information was not incorporated in this study. Comparisons of predicted and measured 1990 topographies in terms of qualitative and quantitative parameters show that the predicted bathymetry sufficiently resembles with the data. Application of a highly schematised wave climate affects on the bed evolution. Further investigation on the wave schematization could help to optimize the model prediction. On-going work uses this model set-up in order to forecast the Ley Bay evolution under future sea level rise scenarios.

Keywords


anthropogenic effect; morphological evolution; wave schematization; Ley Bay

References


Dissanayake, D.M.P.K. 2011. Modelling morphological response of large tidal inlet systems to sea level rise, CRC Press, Taylor & Francis Group, ISBN 978-0-415-62100-7.

Dissanayake, D.M.P.K., R. Ranasinghe, J.A. Roelvink. 2012b. The morphological response of large tidal inlet/basin systems to Relative Sea Level Rise. Climatic Change, DOI: 10.1007/s10584-012-0402-zhttp://dx.doi.org/10.1007/s10584-012-0402-z

Dissanayake, D.M.P.K., J.A. Roelvink, M. Van der Wegen. 2009. Modelled channel pattern in schematised tidal inlet. Coastal Engineering 56, 1069 – 1083.http://dx.doi.org/10.1016/j.coastaleng.2009.08.008

Dissanayake, D.M.P.K., A. Wurpts, M. Miani, H. Knaack, H.D. Niemeyer, J.A. Roelvink.2012a. Modelling morphodynamic response of a tidal basin to an anthropogenic effect: Ley Bay, East Frisian Wadden Sea – applying tidal boundary only and different sediment fractions Coastal Engineering, 67, 14 – 28.http://dx.doi.org/10.1016/j.coastaleng.2012.04.001

Elias, E., M.J.F. Stive, J.G. Bonekamp, J. Cleveringa. 2003. Tidal inlet dynamics in response to human intervention, Coastal Engineering 45(4), 629-658.http://dx.doi.org/10.1142/S0578563403000932

Hartung, W. 1983. Die Leybucht (Ostfriesland) – Probleme ihrer Erhaltung als Naturschutzgebiet, Neues Archiv f. Niedersachsen, Bd. 32, H. 4, Göttingen, S. 355-387.

Homeier, H., H.J. Stephan, H.D. Niemeyer. 2010. Historisches Kartenwerk Niedersächsische Küste der Forschungsstelle Küste, Niedersächsischer Landesbetrieb für Wasserwirtschaft, Küsten- und Naturschutz (NLWKN), Geschäftsbereich Gewässerbewirtschaftung und Flussgebietsmanagement.

Knaack, H., R. Kaiser, H.D. Niemeyer. 2003. Mathematische Modellierung von Tiden in der Leybucht, Dienstbericht, Niedersächsisches Landesamt für Ökologie, Forschungsstelle Küste, Norderney (in Deutsch).

PMid:14633059

Knaack, H., H.D. Niemeyer. 2001. Morphodynamische Gleichgewichtszustände in der Leybucht zwischen 1960 und 1999, Dienstbericht, Niedersächsisches Landesamt für Ökologie, Forschungsstelle Küste, Norderney (in Deutsch).

Lesser, G.R., J.A. Roelvink, J.A.T.M. Van Kester, G.S. Stelling. 2004. Development and validation of a three-dimensional morphological model, Coastal Engineering 51, 883-915.http://dx.doi.org/10.1016/j.coastaleng.2004.07.014

Niemeyer, H.D. 1984. Hydrographische Untersuchungen in der Leybucht zum Bauvorhaben Leyhörn, Jahresbericht 1983 Forschungsstelle f. Insel- u. Küstenschutz, Bd. 35, Norderney, S. 61-98 (in Deutsch).

Roelvink, D., A. Reniers, A.Van Dongeren, J.V.T. De Vries, R. McCall, J. Lescinski. 2009. Modelling storm impacts on beaches, dunes and barrier islands, Coastal Engineering 56, 1133-1156.http://dx.doi.org/10.1016/j.coastaleng.2009.08.006

Ruggiero, P., D.J.R. Walstra, G. Gelfenbaum, M. Van Ormondt. 2009. Seasonal-scale nearshore morphological evolution: Field observations and numerical modelling, Coastal Engineering 56, 1153-1172.http://dx.doi.org/10.1016/j.coastaleng.2009.08.003

Sutherland, J., A.H. Peet, R.L. Soulsby. 2004. Evaluating the performance of morphological models, Costal Engineering 51, 917-939.http://dx.doi.org/10.1016/j.coastaleng.2004.07.015

Thijsse, J.T. 1972. Een halve Zuider Zeewerken 1920-1970, Tjeenk Willink, Groningen.

Verboom, G.K., J.G. De Ronde, R.P. Van Dijk. 1992. A Fine Grid Tidal Flow and Storm Surge Model of the North Sea, Continental Shelf Research, Vol. 12.http://dx.doi.org/10.1016/0278-4343(92)90030-N


Full Text: PDF

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