The Calibration of Nutrient Flux Model (MONERIS) for the Po Basin

Calibration of models is a fundamental step both in the overall model development and in the application phase that allows the reduction of errors and uncertainties. Particularly the application of environmental models request a massive availability of data and parameters that comes from measurement activities, statistical elaboration as well as from an excellent knowledge of implied processes. The calibration process requires the selection of acceptable values that sometimes cannot be measured or are difficult to be measured. This paper report the calibration of a nutrient flux model (MOdelling NUtrient Emission RIver System, MONERIS) for the Po River catchment. The application is necessary because the model has been developed in Germany for the Elbe, Danube and Rhine basins. In our case the calibration allows to adapt the model for this specific area that has particular geomorphic and hydrologic conditions for the high antrophic pressure. The calibration process has been made with an interactive process by sequentially focusing on different pathways considered by the model itself. Two steps were used: the first concern the hydrological balance calibration while the second concern the parameters used. Comparison of measured and estimated nutrient loads show limited uncertainties and are in tune with those estimated by other methodologies and authors.