Fricke, Benjamin

Malcherek, Andreas

English

Hydraulic Engineering Repository

Conference Paper, Published VersionFricke, Benjamin; Malcherek, AndreasA Stratigraphic Soil Model for Coastal MorphodynamicsZur Verfügung gestellt in Kooperation mit/Provided in Cooperation with:Kuratorium für Forschung im Küsteningenieurwesen (KFKI)Verfügbar unter/Available at: https://hdl.handle.net/20.500.11970/99475Vorgeschlagene Zitierweise/Suggested citation:Fricke, Benjamin; Malcherek, Andreas (2014): A Stratigraphic Soil Model for CoastalMorphodynamics. In: Lehfeldt, Rainer; Kopmann, Rebekka (Hg.): ICHE 2014. Proceedings ofthe 11th International Conference on Hydroscience & Engineering. Karlsruhe: Bundesanstaltfür Wasserbau. S. 553-560.Standardnutzungsbedingungen/Terms of Use:Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichendenNutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, dieWeiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung derNamensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigenNutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte.Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license isapplicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the materialof the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms ofthe restrictive license will be binding. 1 INTRODUCTION 1.1 Characteristics of sediment transport in coastal areas Morphodynamics in coastal areas is to a large part driven by the energy of the tide. Under the tidal influ-ence current velocities in the estuaries are changing constantly, interrupted by brief periods of very low, near zero velocities. Maximum velocities can go up to 2 m/s in the fairway, while being considerably lower in shallow water regions like tidal flats or side arms. Since the hydrodynamic conditions are the main driving force for sediment transport and morphodynamic processes, a periodic alternation of erosion and deposition is common in tidally influenced coastal areas. Therefore estuaries are a very dynamic and diverse system with regards to sediment distribution and movement. In coastal areas and tidal flats fine sands are quite common and bedload transport plays an important role (Albers, 2012). Inside the estuaries finer sediments transported in suspension are more dominant. A common feature of most estuaries is the existence of a turbidity zone with sediment concen-trations ranging from a few hundred mg/l up to a few g/l. These sediments are to a large part settling dur-ing slack water and are then resuspended. In all German estuaries this sequence happens twice a day. Meanwhile tidal flats and side arms tend to be depositional zones due to the lower current velocities. Sed-iment is transported there in suspension but once it has settled in these areas, there is not sufficient energy available to resuspend the full amount which leads to net deposition. 1.2 Development of a stratigraphy due to tidal forcing This behaviour can lead to characteristic depositional patterns in areas with low currents and a high sedi-ment supply. These patterns are called tidal rhythmites and have been found in many geological studies in areas that still are or were under tidal influence. They are caused by different sediment distributions and amounts being transported during different phases of the tidal cycle. Sediment cores with such a stratigra-phy can provide information about the tidal characteristics during the time of deposition (Mazumder 2005).  A Stratigraphic Soil Model for Coastal Morphodynamics  B. Fricke Federal Waterways Engineering and Research Institute, Hamburg, Germany A. Malcherek Universität der Bundeswehr München, München, Germany  ABSTRACT: Morphodynamic processes in coastal areas are strongly influenced by tidal forcing. The constant change in current velocities leads to a regular alternation of erosion and deposition of sediments. To model the transport of these sediments under tidal conditions, it is important to describe the spatial and temporal variation of the sediment with the appropriate level of detail. The soil model presented here classifes the soil according to differences in sediment distribution. It is grouped in soil textures, which de-scribe the sediment distribution according to the amounts of e.g. sand, silt and clay. In contrast to com-mon morphodynamic models, an exchange layer is not used to describe transport processes, because the information is stored in the layer stratigraphy. First results for a 1D-Z model with a depositional setting are shown.  Keywords: Coastal morphodynamics, Stratigraphy, Sediment transport ICHE 2014, Hamburg - Lehfeldt & Kopmann (eds) - © 2014 Bundesanstalt für Wasserbau ISBN 978-3-939230-32-8553A  area of grid element [m²] rhos  grain density [kg/m³] n  porosity [/] Nsed  maximum number of sediment fractions [/] Nlayer  maximum number of layers [/] ztop  top elevation [m] z0  non-erodible horizon [m] REFERENCES Albers, T. (2012). Messung und Analyse morphologischer Änderungen von Ästuarwatten, Untersuchungen im Neufelder Watt in der Elbmündung. Hamburger Wasserbau-Schriften. TuTech Verlag, Vol. 15. Choi, K.S., Park, Y.A. (2000). Late Pleistocene silty tidal rhythmites in the macrotidal flat between Youngjong and Yongjou Islands, west coast of Korea. Marine Geology, Elsevier, Vol. 167, pp. 231-241. Malcherek, A., Piechotta, F., Knoch, D. (2005). Morphodynamical Module SediMorph – Validation Document, Version 1.1. Federal Waterways Engineering and Research Institute (BAW). Mazumder, R., Arima, M. (2005). Tidal rhythmites and their implication. Earth-Science Reviews, Elsevier, Vol. 65, pp 79-95. Sanford, L.P. (2008). Modeling a dynamically varying mixed sediment bed with erosion, deposition, bioturbation, consolida-tion, and armoring. Computers & Geosciences. Elsevier, Vol. 34, pp. 1263-1283. Warner, J.C., Sherwood, C.R., Signell, R.P., Harris, C.K., Arango, H.G. (2008). Development of a three-dimensional, regional, coupled wave, current, and sediment-transport model. Computers & Geosciences. Elsevier, Vol. 34, pp. 1284-1306. Villaret, C., Hervouet, J.-M., Kopmann, R., Merkel, U., Davies, A.G. (2013). Morphodynamic modeling using the Telemac fi-nite-element system. Computers & Geosciences. Elsevier, Vol. 53, pp. 105-113. 559

A Stratigraphic Soil Model for Coastal Morphodynamics

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A Stratigraphic Soil Model for Coastal Morphodynamics

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