Multiscale modeling of the Scheldt-North Sea continuum and atmospheric resolution's impact on Storm Surges

With the rise of global warming, the intensity of compound events involving storm
surges, tides, and river discharge is expected to increase, amplifying coastal damage
and flooding, especially in estuarine regions. The Scheldt river-estuary and the North
Sea are densely populated areas with significant economic interests, including
shipping, fisheries, and tourism. Given the economic importance of this region, it is
crucial to understand the interactions within the river-estuary-ocean continuum during
extreme events. However, this is a challenging task due to the complexity arising from
the interaction between river and seawater masses, which operate on diXerent temporal
and spatial scales. Detailed modeling is essential to capture these multiple behaviors
and dynamics. This knowledge is vital for developing eXective strategies to protect the
economic assets and communities in the region. This study assesses the impact of
small-scale changes in the Scheldt river-estuary and atmospheric conditions on the
dynamics of storm surges in the Northwestern Continental Shelf and Belgian Bight of the
North Sea during extreme weather events. We developed an unstructured-mesh
multiscale coastal ocean model to simulate storm surge events, successfully
replicating observed water elevations and tidal components. By incorporating
atmospheric forcings at various spatial resolutions and temporal resolutions, from 2 km
in a high-resolution regional model to 30 km in a global model and from hourly to 6-
hourly, we evaluate the sensitivity of storm surge simulations to these variations.
Additionally, we provide insights into the threats posed by North Sea storm surges
infiltrating the Scheldt, which could have severe implications for the region’s economic
activities. Our findings underscore the critical importance of precise and
comprehensive atmospheric forcing data for enhancing model accuracy in river-estuary
continuum. Improving these data is pivotal for robust coastal protection strategies and
informed decision-making in navigation, environmental hazard response, and
community resilience, safeguarding the vital economic interests of the Scheldt river-
estuary region.