Kamanashi River

A river that flows south through the western part of Yamanashi Prefecture. It is the common name for the upper reaches of the Fuji River. It is 64 km long. It originates on the northern slopes of Mt. Komagatake (2,967 m) to Mt. Nokogiriyama in the northern Akaishi Mountains, flows north along the border between Nagano and Yamanashi Prefectures, merges with the Tateba River from the Yatsugatake Mountains, changes course to the southeast, flows down along the Itoigawa-Shizuoka Tectonic Line, merges with the Shiokawa River and Midai River at the southeastern edge of Nirasaki City, flows south, flows down the western part of the Kofu Basin, and merges with the Fuefuki River near the border between Fujikawa Town and Ichikawamisato Town to become the Fuji River. Located in the upper reaches of one of Japan's three most rapid rivers, and with a granite area in its upper reaches, it has long been known as a rough river, and along with its tributary, the Midai River, it has been one of the key rivers for flood control in the Kofu Basin. Although it is not used for large-scale hydroelectric power generation, it is important as the water source for the Tokushima Weir, which irrigates the western part of the basin, and its underground water is an important water source for the western half of the Kofu Basin.

[Minoru Yoshimura]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

山梨県西部を南流する川。富士川上流部の通称名。延長64キロメートル。赤石山脈北部の駒ヶ岳(こまがたけ)（2967メートル）から鋸山(のこぎりやま)に至る北斜面に源を発し、長野県と山梨県境を北に流下、八ヶ岳(やつがたけ)からの立場(たてば)川と合流して南東に流れを変え、ほぼ糸魚川‐静岡構造線(いといがわしずおかこうぞうせん)に沿って流下、韮崎(にらさき)市の南東端で塩川、御勅使(みだい)川をあわせ南流し、甲府盆地の西部を流下、富士川(ふじかわ)町と市川三郷(いちかわみさと)町との境界付近で笛吹川(ふえふきがわ)と合流し富士川となる。日本三大急流の上流部にあたり、上流部に花崗岩(かこうがん)地域をもつことから、古来荒れ川として、支流の御勅使川とともに甲府盆地の治水の要の一つとなっていた。大規模な水力発電には利用されていないが、盆地西部を潤す徳島堰(ぜき)の用水源として、また伏流水は、甲府盆地西半の用水源として重要である。

［吉村　稔］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例