Laboratory Study On Wave Overtopping Across Coastal Dikes With A Vegetated Foreshore

Abstract

Coastal dikes are commonly engineered to safeguard coastal areas from various coastal hazards. When incoming waves interact with these coastal dikes, wave overtopping frequently occurs if the storm wave's runup exceeds the dike's freeboard. This wave overtopping can lead to natural disasters, such as coastal flooding and damage to the protective layers of the dikes. Consequently, extensive research has been conducted on this phenomenon, assuming the absence of vegetation, as documented in EurOtop (2018). However, in many tidal flat regions, like the Yangtze River Delta, vegetation is prevalent and forms a vegetated foreshore alongside coastal dikes. It is widely acknowledged that a vegetated foreshore not only dissipates waves more effectively than a natural beach, as demonstrated in studies by Suzuki et al. (2019), but also reduces flow velocities, resulting in sediment accumulation over the vegetated area, as observed in research by Chen et al. (2012) and Hu et al. (2018). While increased wave dissipation due to vegetation may lead to reduced wave overtopping, there is currently limited research available that addresses the influence of vegetation on wave overtopping across coastal dikes.