Response of Lake Piediluco to the change of hydrodynamic conditions and nutrient load reductions

In order to verify and quantify the efficacy of management strategies utilised to improve the water quality of Lake Piediluco in the long and short term, a model was developed to represent the unsteady and three-dimensional form of eutrophication processes and water anoxia phenomena. Such a model, taking into account the hydrodynamic mean and turbulent characteristic of the lake, allows the simulation of the spatial and temporal evolution of the concentration fields of the following species: (a) in water, dissolved oxygen, algal organic carbon, particulate organic carbon, dissolved organic carbon, orthophosphate, hydrogen sulphide; and (b) in sediments, dissolved, oxygen, particulate organic carbon, dissolved organic carbon, orthophosphate, adsorbed phosphorus, hydrogen sulphide. This paper presents the simulation results using the following configurations characterised by: different hydraulic regimes of the lake; different external phosphorus loads introduced into the lake from discharges; different initial adsorbed phosphorus concentrations in sediments (obtainable by sediment reclaim) in certain critical areas of the lake. The simulations have detailed: (1) the characterisation of the lake's eutrophication behaviour in its present state and the vulnerability of the different areas of the lake to summer water anoxia; (2) the role of external and internal phosphorus loads on the eutrophication processes; and (3) the management options to improve the environmental conditions of the lake.