Post-storm recovery assessment of urbanized versus natural sandy macro-tidal beaches and their geomorphic variability

Anne-Lise Clémence Montreuil, Margaret Chen, Evelien Brand, Toon Verwaest, Rik Houthuys

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

After an erosive event induced by storms, beach recovery occurs under fairweather conditions. The geomorphic
nature and rapidity of beach recovery following such high-energy events are, however, rather poorly
documented. Storm Dieter hit the Belgian coast on 14–15th January 2017 causing widespread and severe damage
to the coastal environment and infrastructures. This study focuses on two representative sandy macro-tidal
beaches, one characterized by environmental settings with a natural dune-beach system composed of multiple
intertidal bars at Groenendijk, and another by a nourished beachwith devoid of bars and backed by an urbanized
coastline at Mariakerke. Airborne LiDAR survey-based morphological changes were analyzed pre, post- and
4.5 months after the storm complemented by monthly topographic profiles to investigate and compare the
beach response and recovery at the study sites. Despite site-specific environmental settings, sediment was
removed from the backshore in both sites at a relatively similar net rate of −0.03 m3/m2/month equivalent to
−0.001 m3/m2/day, and erosion also dominated in the intertidal zone during the storm. Deposition and erosion
alternated on both the backshore and intertidal zones in the 4.5 month following the storm. However, the
initiation of beach rebuilding was evident from 1.1 month after the storm. The beaches were largely recovered
over the 4.5 months after the storm at a rate 2 to 3 times lower than that induced by the storm. The results
showed a coherence in the accretional trend in the two sites, and especially the urbanized beach retained
some natural ability to rebuild without recourse to post-storm artificial nourishment. The fast return to reequilibriumin
thismacro-tidal environmentmay be partly explained by the fact that the eroded sediment caused
by the stormwas still locally present in the systemand returned to the beach under low-moderate onshore-wave
conditions during the post-stormperiod. A number of distinctmorphological features such as the intertidal bars,
embryo dunes and a backshore berm appeared in the course of net accretion. They participated in rapid beach
recovery through efficient sediment redistribution with relatively low magnitude elevation changes occurring
within, and across the backshore as well as the intertidal zone.
Original languageEnglish
Article number107096
Pages (from-to)1-6
Number of pages6
JournalGeomorphology
Volume356
DOIs
Publication statusPublished - 1 May 2020

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