Impacts of Rigid Vegetation on Gravity Currents Propagating in a Stratified Environment

Abstract

In the stratified environment, systematic experiments are carried out to understand the impacts of rigid vegetation on the evolution of lock–release gravity currents, including the propagation process and entrainment characteristics. A theoretical model is developed to predict the gravity currents completely entering the vegetation-drag-dominated regime and verified by the experimental data. The adjustment of rigid vegetation on the current propagation is limited by the strongly stratified ambient fluid. With the coupling of the stratified ambient fluid and rigid vegetation, responses of current frontal velocity to the change of any single environmental factor are not monotonic. The phenomenon of finger-like intrusion, excited by the stratified environment and promoted by the rigid vegetation, provides a nonnegligible contribution to the current entrainment. In the homogeneous environment, the entrainment occurring in the current head caused by the wakes behind submerged patches is stronger than that of the Rayleigh–Taylor instability, while the situation is reversed when the ambient fluid is stratified.