Official

The Sumida River is a symbolic river in Chuo-ku. Where is the water from this river flowing from? I studied a little and went to the field, so if you know or don't know, please get along a little bit.
The Sumida River is included in the Arakawa River System, which is a "first-class water system" stipulated in Article 4, Paragraph 1 of the River Law. Before Ieyasu Tokugawa entered Edo Castle, Arakawa was a tributary of the Tone River that poured into Tokyo Bay. The downstream channel is the current Sumida River. In the world of Tokugawa, the projects of "Tonegawa Togen" and "Arakawa Nishigen" are carried out, and the framework of the Kanto river to this day is built. In the wake of the flood that hit eastern Japan in 1910 (Meiji 43), the current spillway downstream of Arakawa was opened, and the Sumida River became a flood control system protected from the flood of Arakawa at the Iwabuchi floodgate. .
The current Arakawa River has a basin area of 2,940 square kilometers and a trunk river channel length of 173.0 km, and originates at Kobu Nobugatake (2,475 m above sea level) in the Chichibu Mountains, Saitama Prefecture, which separates the Fujikawa and Shinano River water systems. . Therefore, if you go back up the Sumida River and go back upstream, you will reach Chichibu in Saitama, and the upstream water source will be adjacent to Nagano and Yamanashi prefectures.

On a hot summer day, I drove near the headwaters of the Arakawa River. While the city center of Tokyo exceeded 30 degrees, Okuchichibu was 26 degrees as of 12:00 noon. I sweated at "roadside rest area Otaki Onsen" and tried to eat "Nise Dam Curry", but it said that "Dam Curry is closed today", so there is no image (.)m sorry!
However, near the headwaters of the Arakawa River, extremely steep valleys are engraved, and you can enjoy the beauty of greenery while feeling the greatness of the former erosion, and enjoy the Futase Dam (Ministry of Land, Infrastructure, Transport and Tourism), Urayama and Takizawa Dam (Water Resources Agency) There are many "high quality" objects for infrastructure tourism, such as learning the role of many built dams.
Kanto infrastructure connected to Chuo-ku. Why don't you look at both macro and micro?