Mimigawa

This river originates in Shiibason, Kyushu Mountains, in northern Miyazaki Prefecture, flows east, and empties into the Hyuga Nada Sea at Mimitsu, Hyuga City. It is also called "Mimikawa". It is 102 km long and has a drainage area of ​​883 square km. The upper and middle reaches of the river have eroded the Kyushu Mountains, and the lower reaches have eroded the Osuzuyama quartz porphyry, forming a V-shaped valley up to the river mouth, so there is no alluvial plain. As a result, the river basin is made up of the least populated mountain villages, such as the Irigou area, Shiiba, and Morotsuka. The main tributaries are found in the upper reaches, including the Tone River, Fudono River, Nanatsuyama River, and Tsuboya River. The Mimikawa River system was developed with the development of power sources after the Showa era. There are eight power plants, including Kami-Shiiba Power Plant, and National Route 327 runs along the river valley from Hyuga City.

[Junichi Yokoyama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

宮崎県北部、九州山地主部椎葉村(しいばそん)に発して東流し、日向(ひゅうが)市美々津(みみつ)で日向灘(なだ)に注ぐ川。「みみかわ」とも。延長102キロメートル、流域面積883平方キロメートル。上・中流部は九州山地を、下流部は尾鈴(おすず)山石英斑岩(はんがん)を侵食して、河口付近までV字谷を形成するため、沖積平野はみられない。そのため流域は入郷(いりごう)地帯や椎葉、諸塚(もろつか)など人口のもっとも少ない山村地域である。おもな支流は上流部に多く、十根(とね)川、不土野(ふどの)川、七ツ山(ななつやま)川、坪谷(つぼや)川などがある。耳川水系が開けたのは昭和以降の電源開発による。上椎葉発電所など八つの発電所が設けられ、河谷に沿い日向市より国道327号が走る。

［横山淳一］

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