Okawa (Agano River) - Okawa

...The main river has a length of 210 km and a total drainage area of ​​7,710 km2. According to the River Law, the river is called the Agano River from its source at Mount Araki (1,580 m) in the Taishaku Mountains in southern Fukushima Prefecture to where it flows into the Sea of ​​Japan in Niigata City, but generally the upper reaches in Fukushima Prefecture are called the Okawa River, the river from its confluence with the Nippashi River to the Niigata Prefecture border is called the Agano River, and the river after it enters Niigata Prefecture is called the Agano River. The Okawa River originating from Mount Araki flows north to the Aizu Basin, where it merges with the Nippashi River originating from Lake Inawashiro to become the Agano River, which flows west and enters the Echigo Mountains at Yamashina in Kitakata City.

*Some of the terminology that mentions "Okawa (Agano River)" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…幹川流路延長210km，全流域面積7710km2。河川法では福島県南部にある帝釈山地の荒海山(1580m)に発する源から新潟市で日本海に注ぐまでを阿賀野川というが，一般的には福島県内の上流部を大川，日橋（につぱし）川との合流点から新潟県境までを阿賀川，新潟県に入ってからを阿賀野川という。荒海山に源を発する大川は北流して会津盆地に至り，猪苗代湖に発した日橋川を合わせて阿賀川となり，西流して喜多方市山科で越後山脈に入る。…

※「大川（阿賀野川）」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報