Physical and sedimentological characterisation of dredged sediments.

Port dredging operations inevitably create a turbid plume around the dredge and it is necessary to follow the movement of this to impede its diffusion into the surrounding environment and reduce any negative impacts. To characterise the extension and concentration of the plume induced by dredging it is necessary to study the physical properties of the water, the residence time of the sediments in the water column and the diffusion velocity of the water and sediments. It is also essential to characterise the area and determine the specifics of the port environment under so-called normal maritime-traffic conditions. During the initial stage of such a study it is necessary to obtain measurements under diverse wind-wave conditions to characterise the physical features of the water column of the port area, the turbidity, the quantity and dimension of the suspended particulate matter and the current dynamics. In this article we present a series of physico-sedimentological operations to characterise a zone to be dredged based upon our experience during pre-dredging work in the Port of Genoa (Italy).