Waving or Drowning?

A debate is arising about a plan by the Japanese government to construct 48 foot high tsunami walls along 230 miles of coastline in the prefectures of Fukushima, Miyagi and Iwate, North of Tokyo (http://www.theguardian.com/world/2014/jun/29/tsunami-wall-japan-divides-villagers). The cost would be around £5bn and some experts are not convinced that 'The Great Wall of Japan' is the best way of protecting populations from these destructive phenomena. Construction companies are, naturally, enthusiastic. The walls would certainly change the landscape and the relationship of the people to the sea. I am not convinced that simply putting a wall around land is going to save it but it is difficult for local people to evaluate this suggestion.