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Delft University of Technology

1. Garcia Triana, I.D.T.F. Towards a data assimilation system for morphodynamic modeling.

Degree: 2014, Delft University of Technology

Currently, available models are not able to accurately predict the temporal evolution of coastal morphodynamic processes. The main reason for this, is that essential components governing this evolution are neither fully identified nor understood. Additionally, there is high uncertainty in some of the parameterizations and their input parameters. A proper management of coastal systems depends on a thorough understanding of their present and future state. Regarding the present state of the system, detailed analyses that take into account the inference of human activities and interactions with other natural process may provide the required information to the decision makers. The evaluation of future states, on the other hand, is not possible without the use of data assimilation, i.e. integration of measurements and predictions in the context of formal uncertainty analysis. Despite the need to implement data assimilation, only recently the necessary coastal observations became available. Since then, the integration of data assimilation methods and coastal morphodynamic models have become the focus of ongoing research. Unfortunately, the implementation of these methods is not straightforward. Sequential data assimilation methods, such as ensemble Kalman filter, are practical to implement but their update usually breaks conservation laws and may easily result in model instabilities. Variational (adjoint based) schemes, on the other hand, preserve the physical integrity but require the implementation of an adjoint model which commonly matches in complexity the forward model. This thesis is concerned with the implementation of a variational data assimilation method to improve the predictive skills of a commercial model by estimating its input parameters. Model reduced 4DVar was used to address the problem. This method is an adjoint-free variational method that uses a truncated first order Taylor approximation of the morphodynamic model to implement the data assimilation process. The construction of the Taylor approximation is considerably simpler than the development of a full adjoint model. Additionally, the method provides the sensitivity of the morphodynamic model with respect to the state and/or input parameter vector. Regarding the commercial morphodynamic model, on the other hand, the Delft3D suite was selected. Delft3D is a module based simulator that merges a wave module and a flow and morphodynamic module to produce a fully coupled wave, flow and morphodynamic model. To gain a better understanding of the method and the potential challenges of its implementation on a real application, the technique is first applied to a small study case with synthetic observations (twin experiment). In this \emph{proof of concept}, three wave properties were estimated by assimilating observations of bathymetry. Different reduction strategies were implemented to characterize the method's performance and to assess the effects of uncertain observations on the results. The data assimilation method is able to improve the performance of… Advisors/Committee Members: Heemink, A.W., Schuttelaars, H.M..

Subjects/Keywords: data assimilation; EnMOR; 4DVar; model order reduction; reduced order model; model reduced 4DVar; morphodynamic

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APA (6th Edition):

Garcia Triana, I. D. T. F. (2014). Towards a data assimilation system for morphodynamic modeling. (Doctoral Dissertation). Delft University of Technology. Retrieved from ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ;

Chicago Manual of Style (16th Edition):

Garcia Triana, I D T F. “Towards a data assimilation system for morphodynamic modeling.” 2014. Doctoral Dissertation, Delft University of Technology. Accessed January 19, 2021. ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ;

MLA Handbook (7th Edition):

Garcia Triana, I D T F. “Towards a data assimilation system for morphodynamic modeling.” 2014. Web. 19 Jan 2021.


Garcia Triana IDTF. Towards a data assimilation system for morphodynamic modeling. [Internet] [Doctoral dissertation]. Delft University of Technology; 2014. [cited 2021 Jan 19]. Available from: ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ;

Council of Science Editors:

Garcia Triana IDTF. Towards a data assimilation system for morphodynamic modeling. [Doctoral Dissertation]. Delft University of Technology; 2014. Available from: ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ; urn:NBN:nl:ui:24-uuid:894ef142-80f6-4378-b0cb-6fdc932435ce ;