Accurate evaluation of wave run-up on beaches is a critical issue for coastal flooding studies. During extreme events, the maximum wave run-up, caused by very long (frequently non-breaking) waves, may exceed the crest of the coastal protection structures or dunes and inundate the protected inland area.
This event may be simulated by a flood propagation model, recently published by the authors, that solves a simplified form of the Shallow Water Equations (SWE). The simplification mainly consists of linearizing bottom friction and neglecting advection. This study investigates on the relevance of the latter terms and on the model ability in predicting wave run-up on impermeable beaches. Numerical simulations of run-up induced by solitary non-breaking waves on a gentle-sloping planar beach are compared to the results found by Synolakis (1987) on the basis of an experimental study. For the numerical simulations, only 21 tests of the 40 experiments carried out by Synolakis (i.e. all the non-breaking waves) are considered. A good agreement between the numerical and the experimental maximum runup was found for all the tested waves.
In order to verify the magnitude and the effects of the advection terms in the SWE, some simulations are repeated considering and neglecting this term. The hypothesis of neglecting convective terms is found appropriate.
Coastal flooding occurs in low-lying coastal areas when high water levels due to tides and storm surges, together with waves (e.g. wind waves, tsunamis), inundate the hinterland.
Under climate change, the sea level (Cazenave & Cozannet, 2014) and the storm surge intensity (Pomaro et al., 2017; Rahmstorf, 2017) are expected to increase, leading to a significantly higher occurrence probability of extreme marine flooding events. Moreover, the rates of population growth, the development and the urbanization of coastal zones have greatly increased during the recent decades and this trend is expected to continue in the future (Neumann et al. 2015). Consequently, the vulnerability connected to coastal hazards needs to be investigated in order to mitigate the risk for human health, economic activities, cultural heritage and environment.