Restoration of the maritime nature of Mont-Saint-Michel – Design and use of a numerical hydrosedimentary model

摘要

The Mont-Saint-Michel bay is subject to siltation which is gradually destroying the maritime nature of the Mont. Thernon-going project, which aims to control this trend, comprises the following assignments: construction of a dam on thernriver Couesnon to enable sediment flushing, increase of the storage capacity upstream of the dam, creation of channelrnfeeds downstream of the dam, and replacement of part of the causeway leading to Mont-Saint Michel by a pile bridge.rnA numerical model has been designed with a view to achieving better management of flows released from the new dam.rnThe model is able to compute hydrodynamics, sediment transport, and changes in bed configuration (deposition andrnerosion). Major developments were made on the sediment transport model for dealing with the transport of a mud-sandrnsediment mix.rnHydraulic and morpho-sedimentary calibration of the model has been performed, based on a one month-longrnmeasurement campaign. The model was then operated in order to assess the hydraulic, sedimentary and morphologicalrnimpact considering a forcing scenario (tides – Couesnon river flow) of the phased schedule of the works and potentialrnchanges to the new dam’s operating instructions.