Arakawa River (Kantō) Arakawa River (Kantō) The is a long river that flows through Saitama Prefecture and Tokyo. It originates on Mount Kobushi in Saitama Prefecture, and empties into Tokyo Bay. It has a total catchment area of . The river is one of Tokyo's major sources of tap water, and together with the Tone River, accounts for around 80% of Tokyo's water supply. Attempts to control flooding of the Arakawa River have been made since the area that is now Tokyo became the de facto capital of Japan during the Edo period. Following a major flood in 1910 that damaged a large
Kantō Plain these plateaus. Among the plateaus, the Musashino Plateau has the largest stretch of land, extending from the western edge of Ōme to the eastern edge of Yamanote which borders the alluvial plains of the Arakawa and Sumida Rivers. Its elevation gradually declines from west to east, measuring 190 m at Ōme and 20 m at Yamanote. Hills in the Kantō Plain stand on Tertiary strata and rise higher than surrounding plateaus, exemplified by the Sayama Hills and Tama Hills, typically, undulating between 100 and 200 m above sea level. Hills located at the western edge of the Kantō Plain, the