Sediment dynamics on intertidal mudflats: A study based on in situ measurements and numerical modelling

Tidal flats provide essential ecosystem services (e.g. coastal protection and function as habitats sustaining coastal food webs). They are also under pressure due to climate change and human interventions. To investigate the sediment dynamic processes on tidal flats for a better understanding of the morphological development, in situ measurements were carried out on three tidal flats in the Yangtze Estuary (China) and in the Westerschelde Estuary (the Netherlands). The results show that erosion and deposition stages alternate due to the competition between hydrodynamic forces and bed strength, and due to variability of suspended sediment concentration. A bed-level change (BLC) model has been developed based on this understanding. Sediment dynamic processes on tidal flats are governed by tidal forcing exhibiting neap-spring variation, as well as by random wind events. The impacts from wind events were investigated by an integrated approach based on in situ measurements and the BLC model. This integrated approach also helped to reveal the spatial variability of bed erosional characteristics of tidal flats under influence of diatoms. This work not only improves the prediction of morphological changes of tidal flats, but also has implications for coastal engineering and for studies of coastal ecology and the coastal environment.