Gokase River

This river originates in the Kyushu Mountains in Gokase Town in northern Miyazaki Prefecture, flows east, and empties into the Hyuga-Nada Sea in Nobeoka City. It is a first-class river. It is 106 km long and has a drainage area of ​​1,820 square km. The upper reaches of the river include Kumamoto Prefecture, and form deep gorges such as the Soyo Gorge and Takachiho Gorge. Both were created by eroding the plateau of large amounts of welded tuff erupted by the Aso volcano. In the upper reaches, it collects tributaries such as the Iwato River, Hinokage River, and Tsunanose River. At its mouth, it joins the Kita River and Houri River to form the complex delta of the Nobeoka Plain. In Nobeoka City, the river branches into the main stream and the Oose River to the south, creating a wide river island. The Asahi Kasei Chemicals Group in Nobeoka City is located on the Gokase River, which has abundant water and hydroelectric power, and Asahi Kasei accounts for 42,000 kilowatts of the system's maximum output of 72,000 kilowatts. Ayu trap fishing is popular in the midstream. The name Gokase is said to be derived from the five rapids in the river, from upstream: Tonose, Mado-nose, Araraginose (Takachiho Town), Tsunose (Hinokage Town), and Oose (Nobeoka City).

[Junichi Yokoyama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

宮崎県北部、五ヶ瀬町の九州山地に源を発し、東流して延岡市(のべおかし)で日向灘(ひゅうがなだ)に注ぐ川。一級河川。延長106キロメートル、流域面積1820平方キロメートル。上流部は熊本県を含み、蘇陽(そよう)峡や高千穂(たかちほ)峡などの深い峡谷をなす。いずれも阿蘇(あそ)火山の噴出した大量の溶結凝灰岩の台地を侵食してつくられた。上流域で、岩戸(いわと)川、日ノ影(ひのかげ)川、綱ノ瀬(つなのせ)川などの支流を集める。河口は北(きた)川、祝子(ほうり)川と合流して延岡平野の複合三角州をつくる。延岡市では、本流と南の大瀬(おおせ)川に分流して広い川中島がある。延岡市の旭化成(あさひかせい)化学工場群は、五ヶ瀬川水系の豊富な水と水力発電を立地条件とし、同水系最大出力7.2万キロワットのうち旭化成が4.2万キロワットを占めている。中流部はアユ簗漁(あゆやなりょう)が盛ん。なお、五ヶ瀬とは、上流から吐(と)ノ瀬・窓ノ瀬・あららぎノ瀬（高千穂町）、綱ノ瀬（日之影町）、大瀬（延岡市）の五つの瀬をとってつけた名という。

［横山淳一］

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