Dokai Bay - Dokaiwan

A bay in the northern part of Fukuoka Prefecture, surrounded by the four districts of Wakamatsu, Tobata, Yahata Higashi, and Yahata Nishi in Kitakyushu City. It was formed by the submerged graben between the Ishimine and Sarakura mountain ranges, stretching from east to west, and was formerly called Kukinoumi. Today, more than half of the bay has been filled in during the formation of the Kitakyushu Industrial Zone, and it is a canal-like bay about 8 kilometers long and 1 to 2 kilometers wide. In 1758 (8th year of the Horeki era) during the feudal era, the Horikawa Canal was completed, connecting it to the Onga River, and the transportation of Chikuho coal to Wakamatsu Port by river boats (flat-bottomed wooden boats) became popular, strengthening its role as a coal transportation route. Since the opening of the railway between Wakamatsu and Nogata in 1891 (Meiji 24), many large factories have been built on reclaimed coastal land, including Yawata Steel Works (now Nippon Steel & Sumitomo Metal), which was founded in 1901, Asahi Glass, Mitsubishi Chemical (now Mitsubishi Chemical), Kurosaki Ceramics (now Kurosaki Harima), and Yaskawa Electric, which have become the core of the Kitakyushu Industrial Zone and currently play an important role as its artery. As a port, it is part of the Wakamatsu Port District of the Kanmon Port (Kitakyushu Port), which was integrated in 1964 (Showa 39). As industry developed, the sea became a dead sea due to severe pollution caused by wastewater from large coastal factories and urban wastewater, but since 1973, purification efforts have progressed, including the dredging of about 350,000 cubic meters of sludge and the strengthening of wastewater standards, and fish have returned. The Wakato Bridge was completed near the mouth of the bay in 1962, helping to alleviate congestion at the mouth of the bay.

[Masaaki Ishiguro]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

福岡県北部、北九州市の若松(わかまつ)、戸畑(とばた)、八幡東(やはたひがし)、八幡西の4区に囲まれた湾。石峰(いしみね)、皿倉(さらくら)両山塊間の地溝が沈水したもので、東西に細長く延び、古くは洞海(くきのうみ)とよばれた。現在は、北九州工業地帯の形成過程で半分以上が埋め立てられ、長さ約8キロメートル、幅約1～2キロメートルの運河状を呈する。藩政時代の1758年（宝暦8）、堀川運河(ほりかわうんが)の完成によって遠賀川(おんががわ)と結ばれ、若松港まで川艜(かわひらた)（木製の底の平たい舟）による筑豊炭(ちくほうたん)の輸送が盛んとなり、石炭運搬路としての性格を強めた。1891年（明治24）若松―直方(のおがた)間の鉄道開通以降、1901年創業の八幡製鉄所（現、新日鉄住金）をはじめ、旭硝子(あさひガラス)、三菱(みつびし)化成（現、三菱ケミカル）、黒崎窯業(ようぎょう)（現、黒崎播磨(はりま)）、安川電機など多数の大工場が、沿岸埋立地に立地して北九州工業地帯の中核となり、現在はその動脈的役割を果たしている。港としては1964年（昭和39）に統合された関門港(かんもんこう)（北九州港）の若松港区に属する。工業の発展に伴い沿岸の大工場からの排水や、都市排水などで著しく汚染されて死の海となっていたが、1973年以降約35万立方メートルのヘドロの浚渫(しゅんせつ)や排水基準の強化などで浄化活動が進み、魚類も戻ってきた。湾口付近に1962年若戸大橋(わかとおおはし)が完成し、湾口部の混雑の緩和に役だっている。

［石黒正紀］

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