The Egmond Model - Calibration, validation and evaluation of Delft3D-MOR with field measurements

Coastal management and engineering rely increasingly on predictions made by computational numerical models of hydrodynamic and morphodynamic processes. However due to the lack of real data from coastal field measurements the models used, are rarely tested. With the COAST3D measuring campaign at a site near the town of Egmond a data set is available with detailed measurements, not only a dense spatial coverage of the modelled area is obtained, but also detailed measurements of boundary conditions, like the wind field and deep water wave height are made. Delft3D-MOR was used to construct a model for the Egmond site. This EGMOND model is validated and calibrated using the data base available from the pilot measuring campaign (data available from April 30 to May 6 1998). Comparison of the model results with measured data show that the model is capable of reproducing the measurements. The validation runs have been carried out using standard parameter settings. These settings enable the hindcasting of measured data but also enables the model to be used for making predictions of future situations. In general the model results give a good approximation of the measurements. For deeper water, where waves have little influence, the results are very good. For the surf-zone, where the details of wave transformations have large influence, the results show less agreement with the measurements. With modifications in the Delft3D-WAVE program and wave schematisations these results could be improved. In the current version of Delft3D-WAVE the Battjes-Janssen theory to take wave breaking into account is applied, including the roller formulation (the roller is defined as a turbulent bore-like mass of water representing a forward momentum flux, which can be seen as an additional sink term in the Battjes-Janssen formulation) could improve the results in the surf zone.Hydraulic EngineeringCivil Engineering and Geoscience

Morphodynamics of Texel Inlet

Abstract not availableCivil Engineering and Geoscience

Waterbouwkundige kunstwerken: Bijzondere Onderwerpen

Civil Engineering and GeosciencesHydraulic Engineerin

Morphodynamic development and sediment budget of the Dutch Wadden Sea over the last century

The availability of nearly 100 years of bathymetric measurements allows the analysis of the morphodynamic evolution of the Dutch Wadden Sea under rising sea level and increasing human constraint. The historically observed roll-over mechanisms of landward barrier and coastline retreat cannot be sustained naturally due to numerous erosion control measures that have fixed the tidal basin and barrier dimensions. Nevertheless, the large continuous sedimentation in the tidal basins (nearly 600 million m3), the retained inlets and the similar channel-shoal characteristics of the basins during the observation period indicate that the Wadden Sea is resilient to anthropogenic influence, and can import sediment volumes even larger than those needed to compensate the present rate of sea-level rise. The largest sedimentation occurs in the Western Wadden Sea, where the influence of human intervention is dominant. The large infilling rates in closed-off channels, and along the basin shoreline, rather than a gradual increase in channel flat heights, render it likely that this sedimentation is primarily a response to the closure of the Zuiderzee and not an adaptation to sea-level rise. Most of the sediments were supplied by the ebb-tidal deltas. It is, however, unlikely that the sediment volume needed to reach a new equilibrium morphology in the Western Wadden Sea can be delivered by the remaining ebb-tidal deltas alone.Hydraulic EngineeringCivil Engineering and Geoscience

Lagrangian sediment transport modelling as a tool for investigating coastal connectivity

Estuaries and coasts can be conceptualized as connected networks of water and sediment fluxes. These dynamic geomorphic systems are governed by waves, tides, wind, and river input, and evolve according to complex nonlinear transport processes. To predict their evolution, we need to better understand the pathways that sediment takes from source through temporary storage areas to sink. Knowledge of these pathways is essential for predicting the response of such systems to climate change impacts or human interventions (e.g., dredging and nourishment). The conceptual framework of sediment connectivity has the potential to expand our system understanding and address practical coastal management problems (Pearson et al., 2020). Connectivity provides a structured framework for analyzing these sediment pathways, schematizing the system as a series of geomorphic cells or nodes, and the sediment fluxes between those nodes as links (Heckmann et al., 2015). Once organized in this fashion, the resulting network can be expressed algebraically as an adjacency matrix: sediment moving from a given source to different receptors. There is a wealth of pre-existing statistical tools and techniques that can be used to interpret the data once it is in this form, drawing on developments in other scientific disciplines (Newman, 2018; Rubinov & Sporns, 2010). Lagrangian flow networks have been increasingly used to analyze flow and transport pathways in oceanographic and geophysical applications (Padberg-Gehle & Schneide, 2017; Reijnders et al., 2021; Ser-Giacomi et al., 2015). However, this approach has not yet been adopted to analyze coastal or estuarine sediment transport, and requires a multitude of field measurements or numerical model simulations. Lagrangian particle tracking has been widely used to assess connectivity in the context of oceanography and marine ecology (Hufnagl et al., 2016; van Sebille et al., 2018), because the models record the complete history of a particle’s trajectory, not only its start and end points. Particle tracking models are also relatively fast and lend themselves well to parallel computing (Paris et al., 2013). This approach thus permits a faster and more detailed analysis of sediment connectivity than existing Eulerian approaches (e.g., Pearson et al., (2020)). Although several Lagrangian sediment transport models have been developed (e.g., (MacDonald & Davies, 2007; Soulsby et al., 2011)), they have not been used to support connectivity studies. Hence, there is a need for Lagrangian sediment particle tracking tools tailored to predicting sediment transport pathways and determining connectivity of complex coastal systems. To meet this need, we developed a Lagrangian sediment transport model, SedTRAILS (Sediment TRAnsport vIsualization & Lagrangian Simulator) and used it to develop a sediment connectivity network. Our approach provides new analytical techniques for distilling relevant patterns from the chaotic, spaghetti-like network of sediment pathways that often characterize estuarine and coastal systems. We demonstrate a proof of concept for our approach by applying it to a case using these tools.Environmental Fluid MechanicsGeo-engineeringCoastal Engineerin