Nakamura Heiya

The plain is located in the lower Shimanto River in western Kochi Prefecture. It is a general term for the alluvial lowlands that spread out in a long, narrow strip in the lower Shimanto River and its tributaries, the Nakasuji River and Ushiro River basins, and it stretches from the southern part of Shimanto City to the eastern part of Sukumo City. The lowlands of the Nakasuji River, which is the main part of the plain, are in the form of a graben. In the past, the area suffered from flooding due to its low, marshy areas, but in recent years, flood control has progressed, with repairs to meandering sections and construction to re-direct confluences. In addition to the cultivation of rush grass, which replaced the Kiryu (Japanese lantern plant) of the past, agriculture such as tobacco and horticulture can be seen. After the Jomon Sea Level Rise, alluvialization progressed, and Jomon and Yayoi ruins can be seen, including the Nakamura Shell Mound from the late Jomon period. The urban area of ​​Shimanto City (formerly Nakamura City), which forms the center of the Hata region, is located and developed near the confluence of the Shimanto River, Ushiro River, and Nakasuji River.

[Yasuhiko Owaki]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

高知県西部、四万十(しまんと)川下流の平野。四万十川下流、支流の中筋(なかすじ)川、後(うしろ)川流域に狭長に展開する沖積低地の総称で、四万十市南部から宿毛(すくも)市東部にまたがる。平野の主要部である中筋川の低地は地溝状で、かつては低湿地のため水患に苦しんだが、近時、曲流部の改修、合流点の付け替え工事など治水も進んだ。かつてのキリュウ（杞柳）にかわるイグサ栽培のほか、タバコ、施設園芸などの農業がみられる。縄文海進期以降、沖積化が進み、縄文晩期の中村貝塚をはじめ、縄文、弥生(やよい)遺跡もみられる。幡多(はた)地方の中心をなす四万十市（旧、中村市）の市街地は、四万十川と後川、中筋川の合流点付近に立地、発展したものである。

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