Hydrological model and management of a natural catchment: the case of Trasimeno lake

This paper will show the main features of a mathematical model developed for the simulation of the daily water level of Trasimeno lake. This model, witch introduces a stochastic noise, simulates many fundamental hydrological processes such as: distributed rainfalls over the catchment; distributed rainfalls over the lake; direct, lateral sub-surface and base flow; evaporation from the lake; evapo-transpiration from the catchment; loss due to the seepage from the lake bottom. This procedure can be assumed as an instrument useful to evaluate the effectiveness of the different solutions proposed to increase water inflow towards the lake, in relation to the possible trend scenarios of the hydro-meteorological features of the area (rainfall and air temperature trends). The model can also be used to manage water contributions directed to the lake, when an optimized multiple use of the water resource of the whole system is concerned (upper basin of Tevere river, middle basin of Chiascio river ) and when the multiple use itself is meant to control both the lowest and highest water levels that are effected by strong rainfalls. As a study case, the model has been used to evaluate the effects of the addition of other middle-hill basins of Esse, Vallaccia, and Formanuova torrents, each one of these having a drainage basin external to the lake itself. The results obtained make this method an operative instrument useful to plan possible hydraulic works in order to optimize the regime of the lake water levels.