Aichi Waterworks

A large irrigation canal stretching from the southern part of Gifu Prefecture to the tip of the Chita Peninsula in Aichi Prefecture. It was built to effectively utilize the water of the Kiso River, which flows through the Chubu region, for large-scale agricultural development, as well as for power development and supply of water for the drinking water supply and industry. Water is stored in Makio Dam (Otaki Village, Nagano Prefecture) on the Otaki River (a tributary of the Kiso River) and released into the Kiso River as needed. Water is taken from the Kaneyama intake in Yaotsu Town, Gifu Prefecture, and reaches the southern tip of the Chita Peninsula via the Owari Hills. A 4,600-meter-long undersea water pipe with a diameter of 75 mm was also laid from the tip of the peninsula to supply water to the islands of Shino, Himaka, and Saku through a regional simplified water supply project. The main line is 112 kilometers long, with branches extending 1,012 kilometers. The total construction cost was 42.3 billion yen. The contractor was the Aichi Waterworks Public Corporation, which was established in October 1955. It was completed in September 1961, and industrial water began flowing in December 1961, the drinking water supply in January 1962, and agricultural water in October 1962. Construction funds were provided by a loan from the World Bank (International Bank for Reconstruction and Development), and technical support was provided by an American company (Eric Floors), and the work was carried out using the latest civil engineering machinery. This was also of great help to the later Toyogawa Waterworks. The people who came up with the idea and promoted the project were Shotaro Kuno (Chita City) and Tatsuo Hamajima (a teacher at Anjo Agricultural and Forestry School at the time). The Waterworks Public Corporation was merged with the Water Resources Development Public Corporation in 1968 (transitioning into the Water Resources Agency in 2003), and became its Chubu branch.

Initially, the plan was for water only for agricultural use, but it was expanded to include multiple uses, including urban and industrial use. In 2010, the water use was classified as follows: 54% industrial use, 20% agricultural use, and 26% drinking water, with industrial use accounting for the majority. Meanwhile, the irrigation area for agricultural water was about 10,000 hectares, of which about 1,500 hectares was for farmland, which is only 32% of the original plan. The Owari Hills and Chita Peninsula, which were originally the beneficiary areas, were water-poor regions, and the Chita Peninsula in particular had been barely able to support agriculture thanks to the approximately 13,000 large and small reservoirs. The purpose of the Aichi Canal was to eliminate water scarcity and to open up farmland by digging up the reservoirs, but it cannot be denied that the digging up of many reservoirs led to the subsequent intensification of flood damage. The increase in industrial water use was due to the development of the southern Nagoya coastal industrial zone just before the canal was completed, which increased the demand for water along the canal route, and the resulting increase in population also led to an increase in demand for water for daily life. Meanwhile, output was increased at Otaki Power Station and 15 other power stations downstream. In addition, water shortages were resolved in Morozaki, Minamichita Town, at the tip of the Chita Peninsula cape, which had been suffering from extreme water shortages, as well as on the three remote islands of Shinojima, Himakajima, and Sakushima, making it easier to develop seafood processing and tourism.

Subsequently, from 1981 to 2004, a second phase of the project was carried out to meet increasing water demand, including the construction of the Agigawa Dam and Misogawa Dam and the expansion of various facilities.

[Gohei Ito]

"Aichi Waterworks and Regional Development" edited by Shozaburo Sakai (1967, Toyo Keizai Inc.)" ▽ "Aichi Waterworks History" edited and published by the Aichi Waterworks Public Corporation and Aichi Prefecture (1968), 2 volumes in total" ▽ "NHK Project X Production Team edited "Project X Challengers 15: May the Spirit of Engineers Live Forever" (2002, Japan Broadcasting Publishing Association)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

岐阜県南部から愛知県の知多(ちた)半島の先端に及ぶ大用水路。中部地方を流れる木曽川(きそがわ)の水を有効に活用し、大規模な農業開発を行うとともに、電力開発、上水道用水および工業用水の補給を目的としてつくられた。王滝川(おうたきがわ)（木曽川の支流）の牧尾ダム(まきおだむ)（長野県王滝村）に貯水し、必要に応じて木曽川に放流し、岐阜県八百津町(やおつちょう)にある兼山(かねやま)取水口から取水し、尾張(おわり)丘陵を経て、知多半島南端に達する。また、半島突端部から口径75ミリメートル、4600メートルの海底送水管を敷き、篠(しの)島、日間賀(ひまか)島、佐久(さく)島にも広域簡易水道事業によって給水された。幹線112キロメートル、支線延長1012キロメートル。総工費423億円。施行者は愛知用水公団で、1955年（昭和30）10月に設立された。1961年9月完成、工業用水は1961年12月から、上水道は1962年1月から、農業用水は1962年10月から通水した。建設資金は世界銀行（国際復興開発銀行）からの融資、技術提供をアメリカの会社（エリック・フロア社）から受け、最新の土木機械を使って進められた。これは後の豊川(とよがわ)用水にも大いに役だった。発想と事業推進の功労者は、久野庄太郎(くのしょうたろう)（知多市）と浜島辰雄(はまじまたつお)（当時、安城農林学校の教員）である。用水公団は、1968年水資源開発公団と統合（2003年独立行政法人水資源機構に移行）、その中部支社となった。

　当初は、農業用水のみの計画であったが、都市用水、工業用水など多目的利用となった。用水の利用区分は、2010年（平成22）には工業用水54％、農業用水20％、上水道用水26％で、工業用水が過半を占めている。一方、農業用水の灌漑(かんがい)面積は約1万ヘクタール、うち畑地灌漑面積は約1500ヘクタールで、当初計画からみると32％にとどまっている。元来これら受益地である尾張丘陵、知多半島は乏水性地域で、とくに知多半島は約1万3000余の大小溜池(ためいけ)によって、かろうじて農業を営んできた所である。愛知用水は乏水性を解消し、溜池をつぶして農地化するのが目的であったが、多くの溜池をつぶしたことは、その後の水害激化をもたらしたことは否定できない。工業用水の増加は、用水完成直前に名古屋市南部臨海工業地帯が造成され、用水沿線の水需要量が増加したためで、それに伴う人口増加で生活用水も需要増となった。一方、王滝発電所、下流15の発電所では出力が増強された。また、極度の水不足に苦しんでいた知多半島岬端(こうたん)の南知多町師崎(もろざき)をはじめとして離島の篠島、日間賀島、佐久島など3島では水不足も解消し、水産加工、観光開発が容易になった。

　その後、1981年度から2004年度（平成16）まで、水需要量の増大に対応するため、阿木(あぎ)川ダム、味噌(みそ)川ダム建設や、諸設備の拡充などの第二期事業が行われた。

［伊藤郷平］

『酒井正三郎編著『愛知用水と地域開発』（1967・東洋経済新報社）』▽『愛知用水公団・愛知県編・刊『愛知用水史』全2冊（1968）』▽『NHKプロジェクトX制作班編『プロジェクトX挑戦者たち15　技術者魂よ、永遠なれ』（2002・日本放送出版協会）』

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