The Belgian MSFD monitoring programme ‘Hydrographical changes’ aims at assessing the following ETs: • ET 29 – An impact demands consideration if one of the following conditions – related to the bottom stress on a 14 days spring tide/neap tide cycle as computed by validated mathematical models – is met: (i) there is an increase of more than 10% of the mean bottom shear stress (ii) the variation of the ratio between the duration of sedimentation and the duration of erosion is outside the “- 5%, + 5%” range • ET 30 – This consideration demanding impact remains within a distance equal to the root square of the surface occupied by this activity and taken from its external limit One sub-programmes can be discerned: • ANSBE-D7 Hydrography- SP16 (delivering data to assess ET29 and 30), targeting change in elevation, 3D currents, bottom shear stress using a validated numerical model. This programme will be performed during each licensing procedure regarding human construction at sea