Flow Changes in the Po River Catchment during last 150 years

The anthropic effects on the catchment hydrology are very important and not negligible in Land Use Planning. In the river Po basin closed at Pontelagoscuro, the last section of the river before the delta region, with a surface of about 70000 km2 (figure 1) monthly precipitation amounts are compared with the Po River discharge during a period of more than 150 years. The meteorological data, calculated on a 30 km square mesh, are the gridded version of the Italian data-set of secular pluviometric records. In order to avoid biases due to the different lengths of the station records the grid values are calculated starting from the relative deviations from the means. The relative deviations are then converted into absolute values by means of the monthly normals at the grid points. The discharge data are measured in the last hydrometric station before the delta region. The aim of the analysis is to study the evolution of the Po River discharge in the light of the variability and changes in precipitation (amount and yearly cycle) over the Po River catchment to forecast the change in hydrologic processes also due to the basin urbanization and agriculturalisation, especially in the last fifty years, in order to prevent river floods. The annual run-off coefficient of the Po River, defined as the ratio between yearly run-off and rainfall, has been studied to evaluate a possible trend during the last 150 years. The layout of the basin at a latitude of 45° N, along with the fact that the river runs almost exactly from West to East, and finally its surface, not too small, are all important features that make this drainage basin one of particular interest in the study of the hydrologic changes in the Northern Hemisphere.