Hydrodynamics

Few studies in the literature compare the sediment stability of depositional habits across marine, freshwater and brackish ecosystems. This is partly because there is conceptual difficulty in comparing different erosional devices but also because scientist often focus on specific habitats. In addition, many field devices generate shear stresses over the 0–1 N m^-2 range, with few capable of generating erosive forces beyond this level (Tolhurst et al. 2000). However, habitats such as intertidal deposits and salt marshes are often quite resistant to hydrodynamic forcing and are considered to provide an “ecosystem service” of coastal protection. Most existing measurements have been made within a “measurement comfort zone” (Fig. 3.1), usually where a bed shear stress between approximately 0.1 and 1 N m^-2 surpasses the critical threshold. However, the study of a wider range of habitats is fundamental to the understanding of ecosystem dynamics in aquatic environments.