title: MOZES – Research on the Morphological Interaction between the Sea bottom and the Belgian Coastline: working year 1
Creators: name: Dujardin, Arvid
name: Houthuys, Rik
name: Nnafie, Abdel
name: Röbke, B.
name: Van Der Werf, J.
name: De Swart, Huibert E., H.E.
name: Biernaux, V.
name: De Maerschalck, Bart
name: Dan, Sebastian
name: Verwaest, Toon
Publisher: name: Flanders Hydraulics
Year: 2023

description: The MOZES‐project (MOrfolgische interactie kustnabije ZEebodem en Strand) focuses on the morphological interaction between the nearshore seabed (inner shelf) and the shoreline of the Belgian coast on time scales of months to centuries. The knowledge gained in this project aims to improve system understanding of the regional morphodynamics, which is essential for an efficient coastal management.This report describes the progress of four subtasks (called Work Packages, WP) of the first working year. WP1 involves data collection to expand the overall covering of the historic elevation dataset of the Belgian coast. WP2 addresses the coupled shelf-shoreline long-term morphodynamics (10-100 years) by developing new idealized morphodynamic models. WP3 investigates the hypothesis of natural feeding of the beach by sediment transport over shoreface-connected sand ridges (sfcr) using complex process-based numerical models (Delft3D Flexible-Mesh FlemCo model, openTELEMAC Scaldis-Coast model). Finally, WP4 addresses effects of the observed deepening of nearshore tidal channels on beach erosion and beach nourishments.WP1: Inner shelf, nearshore bathymetric and beach topographic maps of the mid-1980s have newly been vectorized and converted to DEMs, showing the situation just after the extension of the Zeebrugge harbour breakwaters. Another DEM was built for the year 1866: a coastline without harbour breakwaters and three sfcr (Trapegeer – Broersbank – Den Oever; Stroombank; and Wenduinebank – Paardenmarkt), as opposed to only the first one nowadays.WP2: A new idealized morphodynamic shelf model was developed, which is capable of reproducing ridges that resemble the sfcr observed on the Long-Island shelf (New York, USA), which were used to validate this new model. Furthermore, an existing shelf-shoreline coupled model, which was designed for the Long-Island micro-tidal coast, was modified so that it is more representative for the Belgium coast. Preliminary results are promising, but still many adjustments are needed in the two models (inclusion of tides, waves and sea-level rise, using more realistic bathymetry,…), which are suggested key topics for the next working year.WP3: Preliminary results from the complex morphological models for years 1866 and 2015 indicate landward sediment transport over the nearshore parts of sfcr towards the beaches. Further research is needed to examine whether this landward directed sediment indeed nourishes the beaches (called natural feeding). Moreover, the interaction of tide and waves relevant for this landward directed has to be investigated in more detail.WP4: Analysis of the large-scale morphological changes between 1984 – 1987 and 2022 showed a landwards and northeastwards movement of the sfcr and the tidal channels that separate these ridges from the coastline. A deepening of those channels is observed, although doubts on the vertical accuracy of the 1980’s map prohibited the execution of reliable volume balances. An analysis of beach and shoreface nourishment intensity showed that storm events, changes in (safety) policy or nourishment method and other human factors are the main drivers behind nourishment intensity and obscure a possible correlation with the deepening of nearshore tidal channels.
description: Title : FH reports. Flanders Hydraulics: Antwerp. Volume : 20_079_1 Issue : Pagination : XII, 155 + 6 p. app.