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L'analisi delle precipitazioni per la regione subalpina, condotta dagli anni '70 ad oggi, mette in evidenza un incremento della durata e dell'intensità degli eventi meteorici nel corso dell'anno. Diversi studi hanno messo in evidenza come la variazione della distribuzione delle precipitazioni può essere considerata causa naturale responsabile di modifiche dello stato trofico dei laghi. L'analisi si fonda sull'ipotesi che questo fenomeno, inducendo un cambiamento nel regime idrologico dei fiumi, determini un aumento delle portate in grado di innescare processi erosivi nel bacino responsabili di un incremento del carico di fosforo. Attraverso l'implementazione di un modello idrologico sul bacino del Lago di Pusiano, supponendo costanti i fattori di pressione antropica, sono state esaminate le variazioni del regime delle portate e il conseguente aumento del carico di fosforo a seguito dei processi erosivi. Tale incremento, risultato dell'ordine del 50%, è in controtendenza rispetto alla diminuzione dovuta all'ampliamento della rete di collettamento degli scarichi civili e giustificherebbe il raggiungimento di condizioni trofiche costanti nel lago negli ultimi anni. Lo studio evidenzia quindi la necessità di non trascurare le variazioni climatiche come causa naturale in grado di influenzare lo stato trofico dei laghi

In this poster the applied Geographic Information System (GIS) technology to watershed modelling is presented. The Pusiano Lake watershed is located in North Italy, at southern boundary of Alps, on a substratum prevalently calcareous. The main aim of the modelling framework is a basin-scale nutrients modelling, estimation of loads from the catchment and resulting water quality. A preliminary hydrological study was conducted using HEC-HMS model, which allows to understand the complex dynamics of the catchment. Soil and Water Assessment Tool (SWAT) was choose to study water quality aspects in the watershed. The model requires spatial data on elevation, hydrography, land use, soil characteristics etc. It leads to implementation of GIS as integral part of database. The GIS interface for SWAT allows to examine the available spatial data and provides a strong integrated tool for Lake Pusiano watershed modelling.

Lake Pusiano is a Northern Italian sub-alpine lake, with a depth around 24 m and a residence time of 0.8 yr. The lake surface and the catchment area are nearly 5 and 95 km$^2$ respectively. Despite a steady reduction of the nutrient concentration in the last 15 years (198 ?gP/l as TP during 1984 winter overturn against 74 ?gP/l in 2003), since 1994 the Pusiano has been affected by cyanobacteria's blooms. More recently the lake has been dominated by the cyanobacterium {\it Planktothrix rubescens} (more than 70 % of the phytoplankton population). The explanation for this dominance may have a number of reasons, such as a very efficient utilization of light gradients and nutrients patches and a low sensitivity to grazing pressure. Moreover, {\it Planktothrix} strains could be toxic, so the possibility to predict its development and its blooming may represent a great issue in the frame of lake management policies. In order to study the mechanism regulating the ecological behaviour of {\it Planktothrix} a two year long scientific monitoring plan (2002 and 2003) and an intensive field experiment (July 2003) has been performed. The aims of this research are to study the plankton succession during the year and the spatial distribution during stratification. The data collected are elaborated by coupling the ecological model CAEDYM with the hydrodynamic models DYRESM and ELCOM. The scientific approach and the preliminary results of the research will be presented in this work.

This document aims at guiding experts and stakeholders in the implementation of the Directive 2000/60/EC establishing a framework for Community action in the field of water policy (the Water Framework Directive - "the Directive"). It focuses on the implementation of the Annexes II and V with special emphasis on inland surface waters and methods and principles for the establishment of reference conditions and class boundaries between high, good and moderate ecological status. If this is your task, we believe the guidance will help you in doing the job, whether you are: o Establishing reference conditions and ecological status class boundaries for inland surface waters yourself or participating in the process as a stakeholder; o Leading and managing experts undertaking the ecological status analysis; o Using the results of the ecological status analysis for taking part to the policy making process; or o Reporting on the ecological status analysis to the European Union as required by the Directive