G-Cans is impressive but there's a lot more than this protecting Tokyo from floods. A 100yrs ago they build the Arakawa river for flood control https://www.you

G-Cans is impressive but there's a lot more than this protecting Tokyo from floods. A 100yrs ago they build the Arakawa river for flood control https://www.youtube.com/watch?v=y3tdYolqiU8 https://www.youtube.com/watch?v=y3tdYolqiU8 Also, the rivers around Tokyo all have giant flood areas (parks, golf courses, farms) they can open to hold water in an emergency.