Flooding
Tama River is very prone to flooding, and has wreaked havoc on surrounding areas throughout history. On occasions the river even changed its course after massive floods, sometimes dividing pre-existing settlements in two. As a result, there are several locations where the place names on opposing sides of the river are the same, such as Todoroki. The current course was set as a result of a 1590 flood.
Levees have been in place for hundreds of years, but floodwaters have breached them numerous times in history. Extensive engineering projects in the early 20th Century have dramatically reduced the amount of flood damage, although a 1974 typhoon caused floodwaters to burst a levee in Komae and washed away 19 houses.
The levees have not been breached since 1974. Projects to further upgrade the levees have been underway since 1990.
As with most major rivers in Japan, the levees are built some distance away from the river itself to accommodate the extra floodwater. The open expanse between the levees and the river in the middle is covered in grass and shrubbery, forming a much-needed belt of greenery and wide open space which is used as playing fields in many places.
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