I was 13 or so when I first read this book. That is perhaps a little over the intended audience age . . . but when I discovered it, I HAD to read it. As I have said in a previous post, I was once a meteorology major. I liked anything weather and/or disaster-related even then.
I also have to note that I appreciate the fact that this takes place in the Netherlands and relates what could be the story of some of my ancestors. At age 13, I did not have much interest in family history . . . that interest was sparked around age 19 (a little maturity never hurts.) My great-great-grandmother's family left the Netherlands - one of the island-like areas that were made, in fact, by the dikes - in the late 1880s after their land was flooded a number of times. They were farmers and shepherds, and the flooded land did not help them make a good living. They send my great-great grandmother Blazina with two of her siblings to relatives in Wisconsin, and then they came later with their youngest (living) child. (Blazina's parents had at least ten babies, but several of them did not survive infancy. A couple of them were recorded as being born still.)
So this book has given me interesting insight into the lives of my ancestors . . . except for the scenes involving helicopter, of course! It takes place during the flooding of 1953. The main character is 13-year-old Lisa Van Rossem. The book opens with all of the family gathered around sharing their greatest wishes. They go to bed, and then awaken in the night to half of their house already under water. They must get up to the attic if they are to survive. At some point they must get up on the roof. Suddenly Tante Anna, who is pregnant, is swept off the roof into the water. They now must all go out in boats and search for her. Some of them do that while some of the men go to the dike and try to fill in the hole so the ocean will stop flooding their land!
In light of the flooding of 1953 (the failure of, in some cases, very old dikes), the Netherlands has rebuilt their levee system to be the best in the world according to this article: http://science.howstuffworks.com/engineering/structural/levee2.htm