Official

Let's go up the Sumida River flowing through Chuo-ku upstream. At Shimo, Kita-ku, you will arrive at the point where Arakawa and Sumida River are separated. From here, Arakawa heads to the sea with a thick river width, do you know that this Arakawa is an "artificial river"?
Before the Meiji era, Arakawa flowed along the current Sumida River channel. A record flood occurred in Meiji 43 (1910), causing enormous damage to Tokyo. This triggered the excavation of the Arakawa Floodway and was completed in 1930 (1930).
The Iwabuchi sluice gate is set up on the Sumida River, which is separated from Arakawa. Even in Typhoon No. 19 in October 2019, the Iwabuchi sluice gate was closed with the rise of the water level of Arakawa, protecting the Sumida River from the flood of Arakawa.
Many types of bridges are built on the Sumida River. Why don't you take a walk to the beginning of the Sumida River while looking at the bridge from Chuo-ku?
In addition, the Shingashi River flowing from Saitama Prefecture flows into the Sumida River.
By the way, this spring, I spent two days walking along Arakawa from Iwabuchi sluice gate to near the mouth of the river. It's tanned!