Edogawa

A branch of the Tone River that flows through the Kanto region. It is a first-class river. It branches off from the main Tone River at the northern end of Noda City, Chiba Prefecture, passes through the cities of Nagareyama and Matsudo, and empties into Tokyo Bay at Ichikawa City. It is about 60 kilometers long and has a basin area of ​​about 200 square kilometers. It forms the borders of Ibaraki Prefecture, Saitama Prefecture, Chiba Prefecture, and Tokyo from its upstream. Until the early modern period, it flowed into Tokyo Bay as the Futohi River (Futoi River), which originated from the Watarase River, but in 1654 (Shoo 3), the Edo Shogunate changed the course of the Tone River and the Watarase River to protect Edo from flooding, and made them flow east to Choshi, and then became the Edo River, a branch of the Tone River. In the past, the river that flowed between Urayasu City, Chiba Prefecture and Edogawa Ward, Tokyo and emptied into Tokyo Bay was called Edogawa, but in 1919 (Taisho 8), the Edogawa Floodway was excavated in Ichikawa City, Chiba Prefecture, and under the current River Law, the Edogawa Floodway is the main stream in the lower reaches, and the original Edogawa is called the Old Edogawa. During the Edo period, the river prospered on water transportation along the Tone River, and most seafood and brewed products were transported to Edo via Choshi, Sawara, Noda, and Nagareyama, via the so-called Uchikawa route. In 1890 (Meiji 23), the Tone Canal was opened downstream of Noda to shorten the waterway, and the river continued to thrive until the end of the Meiji period, but after the Taisho period, water transportation rapidly declined. Currently, it serves as the main drainage channel for the Katsushika region, and as a water supply source for the Koto district of Tokyo, the coastal cities on the left bank, Funabashi City, and Chiba City, and is also used for industrial water. The alluvial lowlands formed by the Edogawa River are prone to damage from tidal intrusion, so in the Edo period there were many lotus fields, and the area around Gyotoku was a salt field, but in recent years the area has undergone significant urbanization, particularly since the opening of the Teito Rapid Transit Authority (now Tokyo Metro) Tozai Line in 1969. Downstream are Mizumoto Park and the Edogawa Water Gate, and the large amusement park Tokyo Disneyland is located on reclaimed land in Urayasu City.

[Kikuchi Masao]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

関東地方を流れる利根川(とねがわ)の分流。一級河川。千葉県野田市北端で利根川の本流と分かれ、流山(ながれやま)、松戸の各市を通り、市川市で東京湾に注ぐ川。延長約60キロメートル、流域面積約200平方キロメートル。上流から茨城県、埼玉県、千葉県、東京都との境界をなしている。近世までは渡良瀬川(わたらせがわ)を上流とする太日川(ふとひがわ)（太井川(ふといがわ)）として東京湾に注いでいたが、江戸幕府は江戸を水害から守るため、1654年（承応3）利根川と渡良瀬川の河道を変え、銚子(ちょうし)へ東流させてから、利根川分流の江戸川となった。また、かつては千葉県浦安(うらやす)市と東京都江戸川区の間を流れ東京湾に注ぐ流路を江戸川といったが、1919年（大正8）千葉県市川市に江戸川放水路を開削し、現河川法では、下流部は江戸川放水路が本流、もとの江戸川を旧江戸川とよんでいる。江戸時代は、利根川水運で栄え、いわゆる内川(うちかわ)回りとして、銚子、佐原(さわら)、野田、流山を経、海産物や醸造品の大半が江戸川を利用して江戸に運ばれた。1890年（明治23）利根運河を野田下流に開いて水路短縮が図られ、明治末まで隆盛を保ったが、鉄道の開通によって大正時代以後、水運は急激に衰微した。現在は、葛飾(かつしか)地域の幹線排水路、さらに東京都の江東地区と左岸の沿岸諸都市と船橋市、千葉市の上水道源になっており、産業用水にも利用されている。江戸川が形成した沖積低地は、潮入りの被害があるため、江戸時代はハス田が多く、行徳(ぎょうとく)付近は塩田であったが、近年の都市化の進行、とくに営団地下鉄（現、東京地下鉄）東西線開通（1969）後の沿線変貌(へんぼう)は著しい。下流に東京都立水元(みずもと)公園と江戸川水門があり、浦安市の埋立地には大遊園地東京ディズニーランドがある。

［菊池万雄］

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