Po basin

The Po Valley, Po Plain, Plain of the Po, or Padan Plain (Italian: Pianura Padana [pjaˈnuːra paˈdaːna], Val Padana or Padania) is a major geographical feature of Italy. It extends approximately 650 km (400 mi) in an east-west direction, with an area of 46,000 square kilometres (18,000 sq mi) including its Venetic extension not actually related to the Po river basin; it runs from the Western Alps to the Adriatic Sea. The flatlands of Veneto and Friuli are often considered apart since they do not drain into the Po, but they effectively combine into an unbroken plain.

The plain is the surface of an in-filled system of ancient canyons (the "Apennine Foredeep") extending from the Apennines in the south to the Alps in the north, including the northern Adriatic. In addition to the Po and its affluents the contemporary surface may be considered to include the Savio, Lamone and Reno to the south, and the Adige, Brenta, Piave and Tagliamento of the Venetian Plain to the north, among the many streams that empty into the north Adriatic from the west and north.

Geo-political definitions of the valley depend on the defining authority. The Po Basin Water Board (Italian: Autorità di bacino del fiume Po), authorized in 1989 by Law no. 183/89 to oversee "protection of lands, water rehabilitation, the use and management of hydro resources for the national economic and social development, and protection of related environment" within the Po basin, has authority in several administrative regions of north Italy, including the plain north of the Adriatic and the territory south of the lower Po, as shown in the regional depiction included with this article. The law defines the Po basin as "the territory from which rainwater or snow and glacier melt flows on the surface, gathers in streams of water either directly or via tributaries...". The United Nations Environment Program includes the Alps and Apennines as far as the sources of the tributaries of the Po but excludes Veneto and that portion of Emilia-Romagna south of the lower Po; that is, it includes the region drained by the Po but only the Po and its tributaries.

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