MORPHODYNAMIC COUPLING OF BOTTOM ROUGHNESS ANDFLUID MUD FOR MODELLING TIDAL PROPAGATION IN THE LOIREESTUARY (FRANCE)

摘要

Hydrodynamic simulations of tide propagation in the macro-tidal estuary of the Loireriver at two different dates (1947 and 2002) led to difficulties in calibrating roughnesscoefficient maps against tidal measurements especially to reproduce low water levels aNantes located 55 km upstream. A careful analysis showed that this was due to a strongcoupling between bed roughness and the presence (or not) of fluid mud in the innernavigation channel whose position is closely linked to the dynamics of the maximumturbidity. A comprehensive 3D estuarine model including computation of salinity,turbidity and bed evolution was built to correctly reproduce the data including a newalgorithm coupling at each time-step the computation of the roughness coefficients as afunction of the position of the fluid mud in the estuary. Such an improvement madepossible the use of this model to simulate the impact of future developments in theestuary with enough confidence.