Kuma River

This river flows in a U-shape through the southern part of Kumamoto Prefecture. Parts of the upper reaches of the river cross Miyazaki Prefecture and Kagoshima Prefecture. It originates at Minakamigoe (1,458 meters) on the border between Izumi Town, Yatsushiro City, Kumamoto Prefecture and Mizukami Village, Kuma District, and changes direction to the west as it enters the mountain basin (Hitoyoshi Basin) that mainly constitutes the upper and middle reaches of the river. After branching off into the Kawabe, Mae, Mune, and other rivers that flow into the basin, the river continues to flow westward. On the way, it turns northward near Kumamura-Osaka, where the Paleozoic strata (Chichibu series) in the northern Kyushu Mountains, the Mesozoic strata (Shimanto group), and the Cenozoic strata (Neogene volcanic rocks) in the southern Kyushu Mountains collide. It becomes a pre-existing river (a type of horizontal valley) with a well-developed indented meander, and at its lowest point, where a delta can be seen, it branches into three rivers, the Maekawa, Honkawa, and Minamikawa, before flowing into the Yatsushiro Sea. In poetry, it is also called the Yuba River (Yuba River), and is known as one of Japan's three fastest rivers, along with the Mogami River and the Fuji River. Its length is 115 kilometers. The river basin, with an area of ​​1,880 square kilometers, is the third largest in Kyushu, and is home to four cities (Yatsushiro, Hitoyoshi, Ebino, and Isa), five towns and five villages, and a population of about 140,000. The river basin includes the second-highest rainfall area after Mount Aso (the Shiragadake area), and more than 20 power plants supply the river with an electricity output of nearly 800,000 kilowatts. In addition, boat transportation, which was fully opened up to the mouth of the river in 1664 (Kanbun 4), fell into disuse with the opening of the old Kagoshima Main Line (now the Hisatsu Line) in 1908 (Meiji 41). In its place, "river boating," which was established in 1910, continues to this day due to the beautiful scenery along the river and the thrill of boating down the rapids. The course from the boat departure point on the opposite bank of the Hitoyoshi Castle ruins to the landing point 19 kilometers downstream where there is a limestone cave (Kyusendo Cave) is the center of tourism in the Kuma region.

[Yamaguchi Morito]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

熊本県南部をU字状に流れる川。上流部は一部宮崎県、鹿児島県にかかる。熊本県八代(やつしろ)市泉町と球磨郡水上(みずかみ)村との境界にある水上越(ごえ)（1458メートル）にその源を発し、上・中流域を主として構成する山間盆地（人吉盆地(ひとよしぼんち)）に入って流向を西に変える。同盆地に流入する川辺(かわべ)川、万江(まえ)川、胸(むね)川などの諸河川を支流としたのち、なおも西流、途中、九州山地北部に属する古生代の地層（秩父(ちちぶ)系）、同属の中生代の地層（四万十(しまんと)層群）、さらに同山地南部に属する新生代の地層（新第三紀火山岩）がぶつかり合う球磨村大坂間(おおさかま)付近で北流に転じて、嵌入蛇行(かんにゅうだこう)の発達した先行性河川（横谷の一種）となり、三角州のみられる最下流域で、前川、本川、南川に3分流して、八代海に注ぐ。詩歌には木綿葉川(ゆうばがわ)（夕葉川）とも詠まれ、最上(もがみ)川、富士川とともに日本三急流の一つとしても知られる。流路延長115キロメートル。流域面積1880平方キロメートルは九州第三の広さで、4市（八代市・人吉市・えびの市・伊佐市）5町5村、約14万の人口を擁している。流域には阿蘇山に次ぐ多雨地帯（白髪岳(しらがだけ)一帯）があり、20余もの発電所が約80万キロワット近い電力を供給している。また、1664年（寛文4）に河口まで全面開通した舟運は、1908年（明治41）の旧鹿児島本線（現、肥薩(ひさつ)線）の開通によって廃れ、かわって開設（1910）された「川下り」は、川沿いの優れた景観、急流下りのスリルゆえに今日も続いており、人吉城跡の対岸にある発船場から19キロメートル下流の鍾乳洞(しょうにゅうどう)（球泉洞(きゅうせんどう)）のある着船場のコースは、球磨地域観光の中心となっている。

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