Shinano River 2.57

The Shinano River is the longest and widest river in Japan and the third largest by basin area . It is located in northeastern Honshu, rising in the Japanese Alps and flowing generally northeast through Nagano and Niigata Prefectures before emptying into the Sea of Japan. It changes name to as it flows into the Nagano Prefecture.HistoryOriginally the Shinano River would have drained straight into an estuary-like Fukushima lagoon before making its way into the Sea of Japan after flowing down from the Japanese Alps. Over centuries of sediments being brought downstream, a marshy plain formed in the lagoon into what is currently the Echigo Plain. Estimates presented in 1993 place the amount of loose sediment in the river system at 400-. The construction of diversion channels have limited the upkeep required to keep a navigable passage between the Niigata port and the open ocean; however, a consequence of diverting sediment has been that the northern coast of Niigata Prefecture (which includes Niigata and its port) is receding by an average per year (measured from 1947 to 1975) due to sediment being released well-south of the river's original mouth in Niigata.The Shinano River Project, funded by the British Academy, investigates the development of the Shinano—Chikuma River system. It has uncovered some of the earliest examples of Flame-style pottery (kaen doki), dating from the Middle Jōmon period (3500–2500 BCE), have been found at Sanka excavation site in Nagaoka, Niigata, near the confluence of the Sai and Shinano Rivers.