Azusa River
{{Short description|River in Chūbu, Japan}}
{{Infobox river
| name = Azusa River
| native_name ={{native name|ja|梓川}}
| name_other =
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| image = Azusa river and Mount Hotakadake as seen from Kamikochi 20110717 0710 photo by Pcs34560.jpg
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| image_caption = Azusa river and Mount Hotakadake as seen from Kamikōchi
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| subdivision_type1 = Country
| subdivision_name1 = Japan
| subdivision_type2 = Prefectures
| subdivision_name2 = Nagano
| subdivision_type3 =
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| subdivision_type4 =
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| subdivision_type5 = Cities
| subdivision_name5 = Matsumoto, Azumino
|length_km=65
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| source1 = Mount Yari
| source1_location = Japanese Alps, Nagano Prefecture
| source1_coordinates= {{coord|36.341944|137.6475}}
| source1_elevation = {{convert|3180|m|abbr=on}}
| mouth = Narai River
| mouth_location = Matsumoto
| mouth_coordinates = {{coord|36.280226|137.946439}}
| mouth_elevation = {{convert|559|m|abbr=on}}
| progression =
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|basin_size_km2=559
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The {{nihongo|Azusa River|梓川|Azusa-gawa}} is a river within the Hida Mountains or Northern Japanese Alps, in the western region of Nagano Prefecture, Japan. The river belongs to the Shinano River watershed, and forms the upper section of the Sai River. The name of the river comes from the {{nihongo|catalpa|梓|azusa, shi}} tree found in the river basin, which are used for Azusa Yumi, a sacred bow in Shinto rituals. The river gives its name to the Azusa limited express train, which is operated by the East Japan Railway Company (JR East), and which runs mainly between Shinjuku Station in Tokyo and Matsumoto Station in Nagano.[http://www.allaboutjapantrains.com/azusa.html Azusa/Super Azusa Limited Express]
Geography
The Azusa River is 65 km long with a watershed of 559 sq km, and has its source on the southeastern slope of Mount Yari in the Chūbu-Sangaku National Park.[https://www.hrr.mlit.go.jp/chikuma/gakushu/mirareru/imgs/bird001.pdf 千曲川・犀川のすがた平成19年3月27日）], Ministry of Land, Infrastructure, Transport and Tourism. Retrieved on 2022-08-27. {{in lang|ja}} The river flows through the {{nihongo|Kamikōchi|上高地|Upper Highlands}} valley - designated as one of Japan's National Cultural Assets, on the list of Special Natural Monuments and Special Places of Scenic Beauty.[http://www.bunka.go.jp/bsys/maindetails.asp Kamikōchi] {{Webarchive|url=https://web.archive.org/web/20080730003006/http://www.bunka.go.jp/bsys/maindetails.asp |date=2008-07-30 }}. {{in lang|ja}} The Agency for Cultural Affairs. Accessed June 28, 2008. Water from the upper reaches of Karasawa Cirque flows through Hontani and joins the Azusa River near Yokō. From here the river continues through Kamikōchi, under {{nihongo|Kappa Bridge|河童橋|Kappa bashi}}, and then flows through {{nihongo|Taisho Pond|大正池|Taishō ike}}, formed in 1915 following the eruption of Mount Yake, an active volcano in the Hida Mountains.[https://www.kamikochi.org/spot/taisho-pond TAISHO POND], Kamikochi Official Site
Chubu Sangaku National Park in Nagano, Japan. Retrieved on 2022-08-27. The river then flows northeast through the cities of Azumino and Matsumoto, where it joins the Narai River near Azumino, Nagano, from where it becomes the Sai River, the most important tributary of the Shinano River, Japan's longest river.
The river and its tributaries flow from or past several of the 100 Famous Japanese Mountains including Mount Yari, Mount Hotakadake, and Mount Yake.
The Kamikōchi Line, a private railway in Matsumoto, follows the general course of the Azusa River between Shimonii Station and Shinshimashima Station.
Water Usage
=Sericulture=
In his 1896 book, Mountaineering and Exploration in the Japanese Alps, the English missionary and mountaineer Walter Weston wrote that the Azusa River was used to power machinery used in sericulture, "The simple machinery for winding off the silk from the cocoons is water powered and gives employment to a score of bright-faced girls, varying from twelve to twenty years of age."[https://archive.org/details/mountaineeringex00westrich/page/22/mode/2up Mountaineering and exploration in the Japanese Alps, p 22]
=Hydroelectricity=
File:Nagawadodam-0A3N80pbxFs6g.JPG runs across Nagawado Dam, with manmade Azusa Lake on the left]]
File:Azumi power station survey.jpg
Several dams are operated by Tokyo Electric Power Company, or TEPCO, along the river, including: the Nagawado Dam, the largest, which holds {{convert|123e6|m3}}; Midono Dam; and the Inekoki Dam.[https://www.tepco.co.jp/rp/business/hydroelectric_power/mechanism/dam/list/nagawado.html TEPCO Nagawado Dam (in Japanese)]{{cite web|title=Nagawado Dam|url=http://damnet.or.jp/cgi-bin/binranA/enAll.cgi?db4=1018|publisher=Japan Dam Handbook|access-date=26 August 2022|language=ja}}{{cite web|title=Midono Dam|url=http://damnet.or.jp/cgi-bin/binranA/enAll.cgi?db4=1022|publisher=Japan Dam Handbook|access-date=26 August 2022|language=ja}}{{cite web|title=Inekoki Dam|url=http://damnet.or.jp/cgi-bin/binranA/enAll.cgi?db4=1019|publisher=Japan Dam Handbook|access-date=26 August 2022|language=ja}} The dams use pumped-storage hydroelectricity, and are collectively referred to as the Azusagawa 3 dams.[https://www.tepco.co.jp/rp/business/hydroelectric_power/mechanism/dam/list/nagawado.html TEPCO Nagawado Dam (in Japanese)]
=Irrigation=
Several weirs, canals, and underground channels draw water from the Azusa River that are used for irrigation, including for wasabi farming in Azumino.AZUSA MON AMOUR. [https://www.kamikochi.org/nature/azusa-mon-amour]|access-date=26 August 2022 The Wada Weir is thought to have been completed in 973.あずさ書店編集部『幻の大寺院 若沢寺を読みとく』あずさ書店、2010年9月、ISBN 9784900354678、43ページ