Print Email Facebook Twitter Long-term modelling with XBeach Title Long-term modelling with XBeach: combining stationary and surfbeat mode in an integrated approach Author Bart, L.J.C. Contributor Aarninkhof, S.G.J. (mentor) Bodde, W.P. (mentor) McCall, R.T. (mentor) Luijendijk, A.P. (mentor) Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Programme Coastal Engineering Date 2017-07-13 Abstract XBeach is a process-based morphological model that has been used for modelling short term behaviour of beaches and dunes. In the past years interest has been shown by researchers and engineers to use XBeach for longer simulation periods (multiple years). XBeach has multiple modules: stationary mode is often used during calm conditions and surfbeat mode is often used during storm conditions. In this study was investigated whether the coupling of the two modes can increase the performance of long-term models compared to the separate models, while focusing on the cross-shore processes. Also the added value of (quasi-)2D models was studied. The high frequency bathymetryic data of Vlugtenburg, an alongshore uniform beach in The Netherlands, was used for creating 1D models for a period of 1 year. To compare the difference between singular and coupled models, first the potential performance of the stationary and surfbeat modules was investigated separately by optimising the settings for asymmetry, skewness and groundwater flow. It was found that the skill of the stationary and surfbeat models with default settings was negative. Erosion was overestimated (especially in surfbeat mode) and the models showed no seasonal effects. Settings for asymmetry and skewness proved to be effective measures to improve the model performance and were able to introduce seasonal effects. The optimised stationary model was able to predict the profile development reasonably well. The groundwater flow module did not affect the model stability as much as was found in the studies of Zimmermann et al. (2015) and Pender (2013). In order to validate whether a coupling between stationary and surfbeat mode would benefit the model performance, it was investigated whether stationary mode was able to restore the dune and beach erosion of the surfbeat model. Therefore surfbeat was run during the first 100 days of the year (during more extreme conditions) and stationary mode during the remainder of the year (more mild conditions). Stationary mode appeared not to be able to restore the eroded surfbeat profile. The performance of the coupled model was better than the surfbeat model, but the stationary mode was found to perform better than the coupled model for long-term modelling on the most criteria. It was found that a deficiency in XBeach is the ability to transport sediment from the intertidal zone (and just above) further up the beach and dunes. The erosion volumes in the dunes in stationary mode were in the same order of magnitude as the onshore directed aeolian transport. Therefore is expected that the results of long-term models can be improved by coupling XBeach with a wind model. The quasi-2D model was found to have a better performance than 1D models due to the spreading of infra-gravity waves in 2D; in both the separate and coupled models the erosion volumes were not overestimated as much as in the 1D models. Subject XBeachlong-term modellingcoupled modelsstationarysurfbeatVlugtenburginfra-gravity wavesasymmetryskewness To reference this document use: http://resolver.tudelft.nl/uuid:e2550e26-36c5-4a30-afa1-169e82b4b811 Coordinates 52.00675, 4.13156 Part of collection Student theses Document type master thesis Rights (c) 2017 Bart, L.J.C. Files PDF Bart (2017) Long-term mod ... proach.pdf 7.84 MB Close viewer /islandora/object/uuid:e2550e26-36c5-4a30-afa1-169e82b4b811/datastream/OBJ/view