Tonegawa River is one of the longest rivers (322km) in Japan passing through
Kanto region from the north-west to the south-east part of it. The river
starts from Mt.Ominakami and many small rivers join to it, finally, it
flows out to the Pacific Ocean at Choshi city in Chiba Prefecture
. Tone River has the largest catchment area in Japan (16,840 square kilo-meters).
Over 12 million of people live in the areas flowing the river.
Originally, Tonegawa River flowed to Tokyo Bay. In early Edo Period
in 1594, Ieyasu Tokugawa
, the founder of Edo Bakufu
, started the Tonegawa Tosen Project
(the project to move Tone River to the east). Finally, the stream of it
directly went to the Pacific Ocean at Choshi City in 1654.
Now there are some advances of the origin the name of Tonegawa River and
sometimes it is called Bando Taro since Tone River is the largest river
in Kanto then it is the first son (Taro) in Bando (Kanto). Some say that
the name 'Tone' comes from 'Tonnai' in Ainu means 'a large valley' or 'a
large river like a lake' in Ainu. And some says there are many sharp peaks
near the springs 利き峰 in classic regional Japanese word and the words are
abbreviated in 'Tone'. It comes from person’s name 'Tone no Atai' or 'Tonetsuhiko'.
And it also comes from the name of some regional name 'Tone Dake' and 'Otone
Dake'. But it has been not decided which one could be correct.
Moreover, Tonegawa River was called in 'Tone' in the Myriad Leaves
Initially, the stream of Tonegawa River
went to Tokyo Bay. And Arakawa River and Watarasegawa River also went
to Tokyo Bay, too. Before Tonegawa Tosen (the project of Moving the streams
of Tone River to east), the boarder areas between Shimousa
and Musashi province
had got several floods every year. And the courses of these rivers had
not been fixed. Therefore, people could not cultivate the land well.
To protect the land from the floods to reclaim it under cultivation, the
first Shogun of Edo Bakufu Ieyas Tokugawa planned the project called Tonegawa
Tosen. He had other aims that the new course to east could be a new route
of transporting goods from northeast Japan and a great boundary like a
moat to protect Edo
. The construction to change the course of the streams of Tonegawa River
from south into Tokyo Bay to east into the Pacific Ocean at Choshi City
started in 1594 and it finished in 1654, so it spent 60 years.