Modeling of suspended particulate matter transport in coastal areas

A three-dimensional suspended particulate matter (SPM) transport model, developed for North Sea scales (6 nm horizontal resolution), was improved and applied for a part of the North Frisian Wadden Sea with 100 m horizontal and 0.5 m vertical resolution. Satellite data were used to separate different SPM exchange processes and to derive appropriate model parameters. The model calculates distributions of three SPM fractions with different settling velocities in the water column and of the corresponding fine sediment fractions in the upper 20 cm of the bottom. The local shear stress velocities, derived from currents and waves control the processes of sedimentation, resuspension and erosion. In extreme shallow water during storms, waves generate additional currents up to 1 m/s over sand banks and long-shore currents of about 20-40 cm/s. This is an important contribution to the transport of eroded sediments in tidal basins. Therefore the forcing wave and current fields necessary for SPM modeling were generated by an interactively coupled model system. Results of the SPM simulations in the Wadden Sea area will be presented and compared with independent observations.