Numerical simulations of hydrodynamics and dredging operations in a South-Eastern Italian harbor

Nowadays, dredging operations are ever more needed in ports and internal waterways, as well as in superficial water bodies, such as rivers, natural and artificial basins, in order to both improve and increase their navigability. On these special operations, part of the finer material that is got again in suspension could be a nuisance source for the underwater environment, as the produced cloudiness and the possible toxic substances that are associated to it can interact with the aquatic ecosystem. Therefore, during the dredging activities, phenomena like the increase of cloudiness, concentration of material in suspension, chemical oxygen demand, nutrients spreading and the decrease of the dissolved oxygen occur, with negative consequences on the benthonic fauna and on the organisms of the water column. In order to minimize these environmental impacts, it is important to define the dredging operational modes. They are correlated to the bathymetric and hydrodynamic conditions of the water body, to the chemical-physical characteristics of the sediment, to the distance and the characteristics of the settling area and eventually to the kind of treatment to which the sediment will be subjected. A practical application about the environmental implications related to dredging operations is dealt with in the present study, whose purpose is firstly the modeling of the hydrodynamics inside the harbor of a city located in the Southern Italy and then the simulation of dredged sediments in the same area. The dredging operation of the port area was hypothesized with the use of both hydraulic and mechanical dredges and the consequent sediment transport was studied, so that the impact of the operations on the aquatic environment could be considered. Results show that the modeling of such complex technical operations is an important tool for their best planning.