I rarely like The New Yorker writings, but this is actually a good one. Importantly, because it starts with short description of a whole, and then goes into the

I rarely like The New Yorker writings, but this is actually a good one. Importantly, because it starts with short description of a whole, and then goes into the detail. Most The New Yorker writers consider it ok to start (and continue) the article with something like: "On a warm sunny autumn day he was sitting in the park, wearing his grey merino-wool polo shirt and khaki pants". The only thing I'd like to be explained more thoroughly: what actually is this dam? I.e., how does it work? Going to wikipedia I see a whole list of different types of dams, and it is not clear to me, what does this specific construction in the article actually do, and how its failure would cause a tsunami-like wave.