An investigation on the root system of mangroves and its influence on current flow

Abstract

An investigation into the geometrical and material characteristics of mangrove roots, including pneumatophores and prop roots was performed to improve our understanding of physical processes in mangrove ecosystems. It was found that for both roots in a normal tidal environment, they can be regarded as rigid structures under riverine hydrodynamic loadings. An experimental study of current flow over mangrove roots was conducted in laboratories. Different submergences were performed in flume tests to simulate the tidal current under the quasi-steady assumption. Mean flow and turbulent structures were investigated and the roots induced flow resistances were also deduced from both indirect and direct force measurements. The experimental data were further used to validate numerical simulations. In the course of the experiments with emergent pneumatophores, vortex induced transverse standing waves were encountered and the phase averaging method was adopted to filter out the periodic component, which was hardly reported in the literature.