Modeling of solitary breaking wave force absorption by coastal trees

Abstract

Tall vegetation in the form of green belt along the shorelines is considered an environmentally friendly and cost-effective strategy against large coastal wave damages. Comprehensive experiments were carried out to determine the effects of green belt on attenuation of solitary wave height and force. A novel technique based on momentum approach was used to measure direct wave force absorbed by simulated green belt. Using artificial trees with different densities, the simulated coastal forest was exposed to the breaking waves with different heights. The green belt was simulated on a movable section of a flume. The movable section with 1-m length was mounted on frictionless supports at the middle of the flume to allow direct transfer of the absorbed horizontal wave force to the load cell between moveable and stationary sections of the flume. Instantaneous wave height was measured using recorded video and pressure transducers in five points before and after the vegetation section. Results indicated a considerable effect of green belt on the reduction of the wave force and inundation depth. For example, inundation depth decreases 14%, 18%, and 29% in average for the coastal vegetation density of 30%, 50%, and 100%, respectively.