That's really interesting. It had not occurred to me that hemming a river in by building levees would lead to a net loss of land, I would have naively guessed i

That's really interesting. It had not occurred to me that hemming a river in by building levees would lead to a net loss of land, I would have naively guessed it was the other way round. But I can see how the loss of silt to the ocean would cause that.