Flood Gates

Flood gates are another way of flood protection. They are exactly what their name says. Giant gates that can be closed our opened to let water in or out. Flood gates are used in dams to control how much water is going from one side to the other. But for our purposes, flood gates are a valuable weapon in the fight against floods. When fully closed, they can stop water at enormous weights.
During the tsunami in Japan, flood gates were used to protect the citizens against the oncoming rush of water. Interestingly enough, some of the major ones were not closed, some reports say. And if they were closed, it would have had an effect on how much water was let into Tokyo.

This is one of the many floodgates that were in use during the tsunami in Japan. Unfortunately some of them were not closed, and let water in to Tokyo.

This is a floodgate that works on tide level. If the tide is high, the floodgate is put into place, but if it is low tide, it is lowered so that little bits of water can flow through.