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is a river in
The course of the river was developed in
From the 1960s to the 1990s, the river was the most polluted in Japan, occupying twenty-five times the head of the classification of the most polluted rivers between 1972 and 2007. These pollutions are due to agriculture, to the density of the population living near the basin or the banks, and to industry. This situation led to the first depollution projects in the late 1990s and during the 2000s.
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
.
Geography
The Ayase River, takes its source in the city of Okegawa inSaitama Prefecture
is a landlocked prefecture of Japan located in the Kantō region of Honshu. Saitama Prefecture has a population of 7,338,536 (1 January 2020) and has a geographic area of 3,797 km2 (1,466 sq mi). Saitama Prefecture borders Tochigi Prefecture ...
then joins the Naka River in Katsushika
is a special ward located in Tokyo, Japan. The ward calls itself Katsushika City in English.
As of May 1, 2015, the ward has an estimated population of 444,356, and a population density of 12,770 people per km². The total area is 34.80 ...
, Tokyo
Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.468 ...
. The latter flows into the river Arakawa River
or Ara River may refer to:
* Arakawa River (Kanto)
or Ara River may refer to:
* Arakawa River (Kanto), which flows from Saitama Prefecture and through Tokyo to Tokyo Bay
* Arakawa River (Uetsu), which flows from Yamagata Prefecture and throu ...
, before Tokyo Bay
is a bay located in the southern Kantō region of Japan, and spans the coasts of Tokyo, Kanagawa Prefecture, and Chiba Prefecture. Tokyo Bay is connected to the Pacific Ocean by the Uraga Channel. The Tokyo Bay region is both the most populous a ...
.
Development
The course of the river was developed in Edo period
The or is the period between 1603 and 1867 in the history of Japan, when Japan was under the rule of the Tokugawa shogunate and the country's 300 regional '' daimyo''. Emerging from the chaos of the Sengoku period, the Edo period was characteriz ...
(1603-1868), when Edo (old name of Tokyo) became the shogunal capital of Japan. Historically, the first part of the river is used for irrigation and agriculture, the middle and the end for the supply of water to the population of Tokyo and for river transport (the Ayase river notably allows the connection between the Arakawa and Tone).
The river caused several major floods.
Pollution
From the 1960s to the 1990s, the river was the most polluted in Japan, occupying twenty-five times the head of the classification of the most polluted rivers between 1972 and 2007. These pollutions are due to agriculture, to the density of the population living near the basin or the banks, and to industry. This situation led to the first depollution projects in the late 1990s and during the 2000s.
References
Rivers of Saitama Prefecture Rivers of Tokyo Rivers of Japan {{Japan-river-stub