Longitudinal and vertical evolution of wave-induced turbulence within vegetation

Abstract

Salt marsh vegetation provides essential morphodynamic and ecological benefits in coastal environments, yet the dynamics of wave-induced turbulence within vegetation remain poorly understood. Laboratory experiments are carried out to reveal the longitudinal and vertical evolution of wave-induced turbulence within vegetation for both non-breaking and breaking waves. Data from non-breaking intermediate waves highlights a nonlinear behavior of the longitudinal turbulent intensity across the vegetation, especially with high stem densities. A modified model is developed to account for the competition between increased turbulence scaling and reduced local wave orbital velocity at the leading edge of vegetation. For breaking waves, bubble clouds in video records and measured turbulence intensity together quantify vegetation's crucial role in buffering the vertical evolution of wave-induced turbulence and consequently reducing near-bed turbulence. Findings are crucial for understanding vegetation's role in shaping coastal morphodynamics and maintaining ecosystem health, with broad implications for coastal management and restoration efforts.