Abstract
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Static and dynamic flood models differ substantially in their complexity and their ability to represent
environmental processes such as storm tide or riverine flooding. This study analysed spatial differences in flood extent
between static (bathtub) and dynamic flood models (Delft3D) in estuarine environments with different morphology and
hydrodynamics in order to investigate which approach is most suitable to map flooding due to storm surges and river
discharge in estuarine environments. Time series of observed water levels and river discharge measurements were used to
force model boundaries. Observational data, such as tidal gauge and water level logger measurements, satellite imagery
and aerial photography, were used to validate modelling results. Flood extents were calculated including and excluding
river discharge to quantify and investigate its effect on the mapping of flooding. Modelling results indicate that the mature
estuarine system, which has largely infilled broad flood plains, requires a consideration of bottom friction and riverine
discharge through dynamic modelling techniques, whereas static models may provide an alternative approach to map
flooding at low cost and low computational expense in young lake-like estuarine systems that have not been infilled with
sediments. Our results suggest that estuarine classifications based on geomorphological characteristics can potentially
guide flood risk assessments in estuarine environments.