Controlling of overtopping flow of embankment with vegetative barrier: A Flume study

For earth coastal dikes or river embankments, overtopping is one of the most damaging factors for the downstream (d/s) slope. Very little is known about the stability of d/s slope covered with grass during overflow. For an understanding the processes and properties of the overflow on the d/s slope of the embankment with vegetal cover, a small-scale laboratory flume experiment with an embankment using emerged vegetal cover (polypropylene Hechimaron with 80% porosity) on the d/s slope have been performed with three different unit discharges (0.018, 0.013 and 0.010 m3/s). The results of the small-scale flume experiment indicate that the vegetation markedly reduces the overtopping velocity (60–70%) and effective shear stress (31–75%) at the surface of the d/s slope due to water compared with the case without vegetation. This demonstrates that a significant reduction of damage from overtopping flows can be achieved by providing vegetation cover on the d/s slope of the embankment.