(Translated by Google) I decided to take a road bike to the Tone Great Weir on the Bando Taro Tone River, which spans Chiyoda Town, Oura District, Gunma Prefecture, and Gyoda City, Saitama Prefecture.
Tone Weir
🟢Date: 2021/11/03
🟢Location:
Left bank: Chiyoda Town, Oura District, Gunma Prefecture
Right bank: Gyoda City, Saitama Prefecture
🟢Altitude: Approximately 30m
🟢【Tone Weir】
Embankment crest length: 700.0 m
Completion year: 1963/1968
Dam type: Movable weir
Purpose etc:
Water supply to Tokyo and Saitama Prefecture and irrigation to the middle reaches of the Tone River through water conveyance to the Musashi Canal, Minuma Substitute Water, Saitama Canal, and Kasai Canal, and irrigation to the Oura area of Gunma Prefecture through the Oura Canal.
Management road:
The total length of the road is 687.2 m, the effective width is 7 m, and it is used as a road bridge called Musashi Ohashi, and the main local roads of Tochigi, Gunma, and Saitama Prefectural Route 20 and Prefectural Route 306 pass through it.
The road has steep slopes and sharp curves on both banks, and the width and sidewalks are narrow, resulting in many collisions.
🟢 Thoughts
The Tone Weir is one of the largest weirs in Japan, built 154 km from the mouth of the Tone River, one of Japan's largest rivers.
Due to the coronavirus pandemic, the Tone Weir Nature Observation Room, where you can watch salmon swimming upstream through the fish ladder through the underwater window, was closed. It is said that a salmon migration/egg collection observation event is usually held at the Tone Weir in November, but unfortunately it will be canceled this year.
At the time of its construction, the water drawn mainly by the Musashi Canal was supposed to have been the drinking water for southern Saitama Prefecture and the people of Tokyo, but even now, water from the Tone River upper dam group passes through the Tone Weir, and accounts for 40% of Tokyo's water supply, Saitama Prefecture. It is said to supply 70% of the city's water supply.
(Original)
思い立って群馬県邑楽郡(おうらぐん)千代田町と埼玉県行田市に架かる坂東太郎・利根川の利根大堰にロードバイクで行ってきました。
利根大堰(とねおおぜき)
🟢日付:2021/11/03
🟢場所:
左岸:群馬県邑楽郡千代田町
右岸:埼玉県行田市
🟢標高 約30m
🟢【利根大堰】
堤頂長: 700.0 m
竣工年: 1963年/1968年
ダム型式: 可動堰
目的など:
武蔵水路・見沼代用水・埼玉用水路・葛西用水路への導水を通じ東京都・埼玉県への上水道と利根川中流部への灌漑、また邑楽用水路を通じ群馬県邑楽地域への灌漑
管理用道路:
道路全長687.2 m、有効幅員7 m、武蔵大橋(むさしおおはし)として道路橋として供用、主要地方道の栃木・群馬・埼玉の県道20号や、県道306号線が通過。
道路は両岸とも急坂急カーブ接続な上に幅員および歩道が狭く接触事故多し。
🟢感想
利根大堰は日本有数大河の利根川本川の河口から154km地点に建設された日本屈指の規模を誇る堰。
コロナ禍でサケの遡上などを水中窓越しに魚道が見られる利根大堰自然観察室はクローズでした。利根大堰では例年11月にサケ遡上/採卵観察会を開催するそうですが今年は残念ながら中止とするそうです。
主に武蔵水路により引かれる水は建設当時では埼玉県南と都民の飲み水?だったハズですが、現在でも利根川上流ダム群の水が利根大堰を経て、東京都の上水道の40%、埼玉県の上水道の70%を供給しているそうです。