District Po — subbasins

Information layers related to the second and upper basins (commonly called main basins and subbasins respectively), between them and with the layer of the Po basin geometrically and topologically coherent. The main basins (number 35) generally concern the basins of the main tributaries of the river Po (Adda, Oglio, Dora Baltea, Ticino, Tanaro, Parma, Secchia, etc.). In some cases it is the basin union of the basins of two or more secondary tributaries of the Po. In other cases, the overall basin has been divided into several main basins (as for the present Po with three main basins: Piedmontese Po, Asta Po, Delta Po). The main basins bordering other Adbs or foreign states may include territories outside the Po Basin. Sub-basins (number 81 plus two extra-Po sub-basins, belonging to the Rhine and Danube basins) are a division of the main basins: — basins of the tributaries of the main watercourse (example: Serio basin, tributary of the Adda); — subdivision between its components of the main basin (example: the Basin of Trebbia and the Basin of Alto Trebbia) or the part of the basin relating to the main shaft ‘residual’ after considering the subbasins of some tributaries (e.g. the main basin Sesia is divided into Elvo and Cervo, its tributaries, and in Valsesia and Basso Sesia, which make up the ‘residual’ basin of the main shaft); — separation of the separate river basins of the Po formerly considered together as the main basin (example: Curone basin and Scrivia basin, components of the main basin Scrivia). In some cases the main basin has not been further divided and is therefore identical in sub-basins (example: Agogna Basin). The non-national territory in the Po Basin is included in the main basins and sub-basins concerned. The encodings of the main basins and consequently of the sub-basins represent the different characteristics of their composition. The coding system is based on the coding of the watercourses used in AdbPo and so called ‘Sibapo’. The first installation of the information layers was carried out for the PSFF — Stralcio delle Fasce Fluviali (1997), subsequently merged into the PAI — Extract Plan for Hydrogeological Sitting (2001). Subsequent amendments were made to the Po — PdGPo River River Management Plan (redefinition of the boundaries — 2010) and the Flood Management Plan — PDGA (introduction of coding — 2014).