Niyodo River

It originates on the southern slope of Mt. Ishizuchi in Ehime Prefecture, in the center of Shikoku, flows southeast through the center of Kochi Prefecture, and empties into Tosa Bay on the border between Tosa City and Kochi City in Kochi Prefecture. It is a first-class river. It is 124 km long and has a drainage area of ​​1,560 square km. On the Ehime Prefecture side, it is called the Omogo River, and when it enters Kochi Prefecture, it is called the Niyodo River. As it crosses the Shikoku Mountains, the middle reaches in particular form a gorge with significant incisions and meanders, and there is little flat land. Power development and flood control works were carried out early on, and the Odo Dam was constructed. Agriculture, mainly greenhouse horticulture, is thriving in the lower reaches. A road connecting the cities of Kochi and Matsuyama was built along the middle and upper reaches of the river valley from the mid-Meiji period onwards, and this road is succeeded by the current National Route 33. The mountainous areas in the middle reaches of the river were once a producer of papermaking materials such as mulberry, and by utilizing water transport, centers of the Tosa washi paper industry were established in Ino downstream and Takaoka in Tosa City.

[Yasuhiko Owaki]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

四国の中央部、愛媛県石鎚(いしづち)山南斜面に源をもち、高知県中央部を南東流し、高知県土佐市と高知市の境界で土佐湾に注ぐ。一級河川。延長124キロメートル、流域面積1560平方キロメートル。愛媛県側では面河川(おもごがわ)といい、高知県内に入って仁淀川と呼称される。四国山地を横断するので、とくに中流部では穿入蛇行(せんにゅうだこう)の著しい峡谷をなし、平地に乏しい。早くから電源開発、治水工事が進められ、大渡(おおど)ダムなどが建設された。下流部では施設園芸を中心とする農業が盛んである。中・上流河谷沿いに、明治中期以降、高知、松山両市間を結ぶ道路がつくられ、現国道33号に継承されている。かつて中流の山間地はコウゾなどの製紙原料産地で、舟運利用により下流の伊野、土佐市高岡などに土佐和紙業中心地が形成された。

［大脇保彦］

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