Abstract

ACRIPREVISUB is a novel project for forecasting wave–induced flood hazards, such as wave runup and overtopping, that occur along coastal areas. The main scope of our project is the real time evaluation of emergency situations and the issue of warnings to the relevant coastal or port authorities and stake holders. Within the context of this study, we numerically investigated the propagation of directionally—spread short and infragravity waves towards the shore to predict runup heights and overtopping motions on structures and beaches. This novel methodology was applied in the coastal zone of Alpes Maritimes in France and was tested against laboratory experimental data.

INTRODUCTION

Coastal environment is a significant geographical area, since it gathers a wide range of human social activities. This complex system of natural variables is especially fragile and exposed to multiple risks, including flooding, shoreline erosion and infrastructural damages due to extreme hydro–meteorological events: storm surges, heavy precipitation and tides (Plomaritis et al., 2018; Mori et al., 2019). Coastal flooding phenomena are among the most damaging natural disasters affecting urban zones adjacent to the shorelines. Extreme coastal water levels may lead to considerable impacts in densely populated low–lying coastal areas, while anthropogenic unplanned infrastructures and poor governance are additional factors that increase flood risk. Flood hazard is rarely a function of one process alone but comprises multiple drivers, including energetic waves, extreme coastal water levels, heavy precipitation, and high river discharge (Ganguli and Merz, 2019).

Monitoring of two key mechanisms, wave overtopping and run–up, is necessary to estimate the results of coastal flooding, therefore significant efforts have been undertaken in recent years into their predicting (Tsoukala et al., 2016; Xie et al., 2019; Beer et al., 2021) The accurate prediction of wave runup (the maximum vertical extent of wave uprush on the beach), as well as its components, time–averaged setup and the time–varying swash, is an important element of coastal storm hazard assessments, as runup height controls the potential for flooding by wave overtopping. Moreover, the oscillatory component of runup (swash) transfers energy from the waves to the shore, playing a dominant role in nearshore sediment transport and morphology, as it can drive significant erosion during storms. In addition, in order to meet design requirements for the construction of seawalls and dikes the evaluation of wave overtopping phenomena is of high engineering interest.

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