Unit 1: Are flood defences a public good?

They are often cited as an example. This clip from Aljazeera allos you to judge for yourself

http://www.youtube.com/watch?v=sIaIH5GvkW0

a) Are these flood defences non-excluable?
b) Are these flood defences non-rival?
c) So, are these flood defences a pubic, quasi-public or private good?