The is a Class B river in

Kanagawa Prefecture is a prefecture of Japan located in the Kantō region of Honshu. Kanagawa Prefecture is the second-most populous prefecture of Japan at 9,221,129 (1 April 2022) and third-densest at . Its geographic area of makes it fifth-smallest. Kana ...

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 ...

, about 50 kilometers southwest of Tokyo. It begins in Kashio,

Totsuka-ku, Yokohama is one of the 18 wards of the city of Yokohama in Kanagawa Prefecture, Japan. As of 2010, the ward had an estimated population of 273,418 and a density of 7,640 persons per km2. The total area was 35.70 km2. Geography Totsuka Ward is loc ...

at the confluence of the Akuwa River (阿久和川) and the Hiradonagaya River (平戸永谷川) and flows for 11 kilometers to the city of Fujisawa, where it merges with the Sakai River at the confluence known as Kawana (川名). The conjoined river, which is sometimes known as the

Katase River The is a Class B river in Tokyo and Kanagawa Prefecture which flows into the Bay of Sagami of the Pacific Ocean. The Sakai River The Sakai River has with the length of 52.1 km and the basin size of 210.7 square km. It starts from Aihara ...

, then flows into

Sagami Bay lies south of Kanagawa Prefecture in Honshu, central Japan, contained within the scope of the Miura Peninsula, in Kanagawa, to the east, the Izu Peninsula, in Shizuoka Prefecture, to the west, and the Shōnan coastline to the north, while the ...

Enoshima is a small offshore island, about in circumference, at the mouth of the Katase River which flows into the Sagami Bay of Kanagawa Prefecture, Japan. Administratively, Enoshima is part of the mainland city of Fujisawa, and is linked to ...

Island. The catchment basin of the Kashio River is approximately 84 sq. kilometers. Because the Kashio River is a short, meandering stream, with a minimal descent, it has long been notorious for flooding. The predecessor of the Kashio River was the shallow Ōfuna Estuary (大船入江), which existed from the end of the last

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

to about 300 BC. Subsequently, earthquakes caused crustal uplift, which cut off the estuary from the bay, making it into a floodplain with the Kashio River at its center. As the river often flooded, it formed a lake that left behind a swamp as it drained. The early lake formed in the floodplain of the Kashio River is probably the lake mentioned in the

Enoshima Engi The ''Enoshima Engi'' (江嶋縁起) is a history of the temples and shrines on Enoshima Island in Sagami Bay. It was written in Chinese language, Chinese, the scholarly language of the time, by the Japanese Buddhist monk Kōkei (monk), Kōkei in 10 ...

, a history of the area.

References

External links

* (mouth) Rivers of Kanagawa Prefecture Rivers of Japan {{Japan-river-stub