Roshanka Ranasinghe, Cilia Swinkels, Arjen Luijendijk, Judith Bosboom, Dano Roelvink, Marcel Stive, Dirkjan Walstra


The Morphological Acceleration Factor (MORFAC) approach for morphodynamic upscaling enables the simulation of long term coastal evolution. However the general validity of the MORFAC concept for coastal applications has not yet been comprehensively investigated. Furthermore, a robust and objective method for the a priori determination of the highest MORFAC that is suitable for a given simulation (i.e. critical MORFAC) does not currently exist. This paper presents some initial results of an ongoing, long-term study that attempts to rigorously and methodically investigate the limitations and strengths of the MORFAC approach. Based on the results of a numerical modelling exercise using the morphodynamic model Delft3D, the main dependencies and sensitivities of the MORFAC approach are investigated. A criterion (based on the CFL condition for bed form migration) for the a priori determination of the critical MORFAC is also proposed.


Morphodynamic modelling; MORFAC; Delft3D; long term coastal evolution

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Engelund, F. and E. Hansen. 1967. A monograph on Sediment Transport in Alluvial Streams. Teknisk Forlag, Copenhagen, Denmark.

Jones, O. P., O.S. Petersen, and H. Kofoed-Hansen. 2007. Modelling of complex coastal environments: Some considerations for best practice. Coastal Engineering, 54: 717-733.

Lesser, G. 2009. An approach to medium-term coastal morphological modeling, PhD-thesis. Delft University of Technology, ISBN 978-0-415-55668-2.

Lesser, G., J.A. Roelvink, J.A.T.M. Van Kester, and G.S. Stelling. 2004. Development and validation of a three-dimensional morphological model. Coastal Engineering, 51: 883–915.

Roelvink, J.A., 2006. Coastal morphodynamic evolution techniques. Coastal Engineering, 53: 277–287.

Tonnon, P.K., L.C. Van Rijn, and D.J.R. Walstra, D. J. R. 2007. Morphodynamic modelling of tidal sand waves on the shoreface. Coastal Engineering, 54: 279-296.

Dissanayake, D.M.P.K., R. Ranasinghe, and J.A. Roelvink. 2009. Effect of sea level rise on tidal inlet evolution, J. Coastal Research, SI 56(2): 942-946.

Dissanayake, D.M.P.K., J.A. Roelvink, and M. Van der Wegen. 2009. Modelled channel patterns in a schematized tidal inlet. Coastal Engineering, 56: 1069-1083.

Van der Wegen, M., and J.A. Roelvink. 2008. Long-term morphodynamic evolution of a tidal embayment using a two-dimensional, process-based model. J. Geophysical Research, 113, C03016. doi:10.1029/2006JC003983.

Van der Wegen, M., Z.B. Wang, H.H.G. Savenije, and J.A. Roelvink. 2008. Long-term morphodynamic evolution and energy dissipation in a coastal plain, tidal embayment, J. Geophysical. Research, 113, F03001, doi:10.1029/2007JF000898.

Van Rijn, L.C., D.J.R. Walstra, B. Grasmeijer, J. Sutherland, S. Pan, and J.P. Sierra. 2003. The predictability of cross-shore bed evolution of sandy beaches at the time scale of storms and seasons using process-based profile models. Coastal Engineering, 47: 295-327.