ORCID Profile
0000-0001-5865-3715
Current Organisation
Technische Universiteit Delft
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Publisher: MDPI AG
Date: 27-05-2021
DOI: 10.3390/JMSE9060582
Abstract: In this paper, a new approach to model wave-driven, cross-shore shoreline change incorporating multiple timescales is introduced. As a base, we use the equilibrium shoreline prediction model ShoreFor that accounts for a single timescale only. High-resolution shoreline data collected at three distinctly different study sites is used to train the new data-driven model. In addition to the direct forcing approach used in most models, here two additional terms are introduced: a time-upscaling and a time-downscaling term. The upscaling term accounts for the persistent effect of short-term events, such as storms, on the shoreline position. The downscaling term accounts for the effect of long-term shoreline modulations, caused by, for ex le, climate variability, on shorter event impacts. The multi-timescale model shows improvement compared to the original ShoreFor model (a normalized mean square error improvement during validation of 18 to 59%) at the three contrasted sandy beaches. Moreover, it gains insight in the various timescales (storms to inter-annual) and reveals their interactions that cause shoreline change. We find that extreme forcing events have a persistent shoreline impact and cause 57–73% of the shoreline variability at the three sites. Moreover, long-term shoreline trends affect short-term forcing event impacts and determine 20–27% of the shoreline variability.
Publisher: Wiley
Date: 12-2011
Publisher: Springer Science and Business Media LLC
Date: 17-06-2021
DOI: 10.1038/S41598-021-92150-X
Abstract: Sea level is rising due to climate change and is expected to influence the development and dynamics of coastal dunes. However, the anticipated changes to coastal dunes have not yet been demonstrated using field data. Here, we provide evidence of dune translation that is characterized by a linear increase of the dune toe elevation on the order of 13–15 mm/year during recent decades along the Dutch coast. This rate of increase is a remarkable 7–8 times greater than the measured sea level rise. The observed vertical dune toe translation coincides with seaward movement of the dune toe (i.e., progradation), which shows similarities to prograding coasts in the Holocene both along the Dutch coast and elsewhere. Thus, we suspect that other locations besides the Dutch coast might also show such large ratios between sea level rise and dune toe elevation increase. This phenomenon might significantly influence the expected impact of sea level rise and climate change adaptation measures.
Publisher: MDPI AG
Date: 16-05-2019
DOI: 10.3390/JMSE7050151
Abstract: In Africa, several new seaport developments are being considered. In sedimentary environments, such port developments can have adverse impacts on the evolution of adjacent coastlines. To learn from past port engineering practice, we created a unique database containing the coastline evolution and characteristics of 130 existing African seaports. Whereas the systematic mapping of coastal impacts was previously h ered by data availability, innovative automated satellite image processing techniques have enabled us to intercompare ports at an unprecedented continental scale. We found large geographical differences with respect to the beach evolution. The total detected changes in the beach area between 1984 and 2018 totaled 44 km2, of which ca. 23 km2 is accretion and ca. 21 km2 is erosion. The top 10% “hotspot” ports account for more than 65% of these changes. These hotspots exhibit common characteristics, namely: they are located on open coastlines, have large alongshore sediment transport potential, and have large cross-shore breakwaters. Although these driving characteristics are well established in coastal engineering theory, our results indicate that the beaches adjacent to the existing seaports have been and remain seriously affected by these drivers. Our results can be used to inform beach maintenance strategies for existing seaports and to support planners and engineers to minimize long-term coastal impacts of port expansions and new port developments in Africa in the future.
Publisher: Wiley
Date: 18-08-2022
DOI: 10.1002/ESP.5449
Abstract: Coastal aeolian sediment transport is influenced by supply‐limiting factors caused by sediment sorting by grain size. Sorting processes can lead to coarsening of the bed surface and influence the formation of aeolian ripples. However, the influence sorting processes and bedforms might have on the magnitude of the transport is not fully understood. This study explores sorting processes and their influence on the magnitude and mode of aeolian transport by using sediment tracers. Sand was painted in different colors according to particle size and placed on a supratidal beach in Noordwijk, the Netherlands. Several experiments were conducted with varying wind speeds. Surface s ling and cameras tracked the sand color movement on the bed surface, and wind velocity was measured. The tracer experiments showed that ripples developed in moderate wind conditions. Once the ripples had formed, the supply of finer tracer grains in the downwind direction decreased over time, while the supply of coarser grains remained constant. A linear relationship between ripple migration speed and wind speed was found. For higher wind speeds, no ripples or differences in transport of grain size fractions were observed. Instead, alternating phases of erosion and deposition of the bed surface were observed, which could not be related to local variations in wind velocity. Based on these results and literature, a conceptual model was developed for an active bed surface layer with two transport regimes corresponding to moderate (I) and high (II) wind speeds. The conceptual model is intended to guide the selection of aeolian sediment transport models as a function of wind speed, bed characteristics, and upwind sediment supply. For Regime I, transport could be modeled using a linear relationship between sediment transport and wind speed and for Regime II using a third power relationship in combination with a process‐based model accounting for supply limitations.
No related grants have been discovered for Sierd de Vries.