Takahashi River

A river that flows south through the western part of Okayama Prefecture and empties into the Seto Inland Sea. It is one of the three major rivers in the prefecture, and its drainage basin is in the western part of the prefecture and the eastern part of Hiroshima Prefecture. In the past, it was called the Kawashima River, the Kawabe River, and the Matsuyama River, but when Matsuyama in Bitchu was renamed Takahashi in the early Meiji period, it became the Takahashi River. It originates from Hanamiyama (1,188 meters) in the Chugoku Mountains on the border with Tottori Prefecture, and flows into the Mizushima Nada Sea of ​​the Seto Inland Sea after joining the Kojiro River, Nariwa River, and Oda River on the right bank, and the Osakabe River, Ukan River, and Makidani River on the left bank. It is 111 kilometers long. Its drainage basin area is 2,670 square kilometers. The cities of Niimi, Takahashi, Soja, and Kurashiki are located along the main stream from upstream. The valley is shallow and wide near the source. Until the end of the Meiji period, iron sand was collected by digging holes in the river, which sent large amounts of soil downstream. A gorge was formed before the river entered the Niimi Basin, and where it crosses the Niimi Basin and crosses the Kibi Plateau, the valley walls reach over 300 meters. The limestone region is home to karst topography such as Atetsudai and Kawakamidai, and limestone caves such as Ikurado and Makido, and the Nariwa River basin is home to the reverse fault "Oga no Oshikakuse" (nappe structure), a nationally designated natural monument. A valley bottom plain is formed in the southern part of Takahashi City, and wide alluvial plains exist in Soja City and Kurashiki City.

Shipping from the river mouth to Matsuyama was developed at the end of the Muromachi period, and in the early Edo period, Takase boats traveled to Niimi, continuing until the opening of the Hakubi Line of the Japanese National Railways (now JR) in the Taisho period. Tamashima at the river mouth prospered as a junction of river and sea traffic. The Tatai Weir in Soja City and the Takahashi River East-West Irrigation Canal Joint Weir in Sakatsu, Kurashiki City are historic intakes for the Junigago Irrigation Canal and the Yatsugago Irrigation Canal, and the water of the Takahashi River is sent as far away as the reclaimed land of Kojima Bay and Kasaoka City. Dams have been built on the tributaries, such as the Kosakabe River, Shinnariwa River, and Komoto River, and the main stream is the Chiya Dam (Niimi City), which was completed in 1998. Industrial water for the Mizushima coastal industrial area at the river mouth is also supplied from the Takahashi River. The lower reaches were once divided into two, but renovation work was carried out from the end of the Meiji period to the end of the Taisho period, resulting in the East Takahashi River being abandoned and the current downtown area of ​​Mizushima, Kurashiki City being located on the abandoned riverbed.

[Shogo Yuihama]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

岡山県西部を南流して瀬戸内海に注ぐ川。一級河川。県の三大河川の一つで、県西部と広島県東部を流域とする。古くは川島川、川辺川(かわべがわ)、松山川とよばれたが、明治初期に備中(びっちゅう)松山が高梁と改称されたのに伴い、高梁川となった。鳥取県境の中国山地の花見山（1188メートル）に発し、右岸の神代(こうじろ)川、成羽(なりわ)川、小田川、左岸の小阪部(おさかべ)川、有漢(うかん)川、槇谷(まきだに)川などを合流して瀬戸内海の水島灘(なだ)に注ぐ。延長111キロメートル。流域面積2670平方キロメートル。本流沿岸には上流から新見(にいみ)、高梁、総社(そうじゃ)、倉敷の各市がある。源流付近は谷が浅く広い。明治末期まで鉄穴(かんな)流しによる砂鉄採取が行われ、大量の土砂を下流に流出した。新見盆地に入る前に峡谷をつくり、新見盆地を越えて吉備(きび)高原を横断する部分では谷壁は300メートル以上になる。石灰岩地域では阿哲(あてつ)台、川上台などのカルスト地形、井倉洞、満奇(まき)洞などの鍾乳(しょうにゅう)洞が発達し、成羽川流域には国指定天然記念物の逆断層「大賀の押被(おおがのおしかぶせ)」（ナップ構造）がある。高梁市南部からは谷底平野を形成し、総社市、倉敷市では広い沖積平野がある。

　舟運は河口から松山までは室町時代末期に開発され、江戸初期には新見まで高瀬舟が通い、大正期の国鉄（現、JR）伯備(はくび)線の開通まで続いた。河口の玉島は河川・海上交通の接点として繁栄した。総社市の湛井堰(たたいぜき)、倉敷市酒津の高梁川東西用水合同堰は、歴史的な十二ヶ郷用水、八ヶ郷用水などの取水口で、高梁川の水は遠く児島(こじま)湾の干拓地や笠岡(かさおか)市にまで送水されている。支流には小阪部川・新成羽川・河本(こうもと)などのダムが築造され、本流には1998年（平成10）完成の千屋(ちや)ダム（新見市）がある。河口部の水島臨海工業地域の工業用水も高梁川から供給される。下流部はかつて二つに分かれていたが、明治末期から大正末期にかけて改修工事が行われ、東高梁川は廃され、その廃川敷に現在の倉敷市水島の市街地の立地をみた。

［由比浜省吾］

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