I'm living in Laos, and I've often heard dams being blamed for flash floods, causing higher water levels than the natural pre-dam floods. Is that possible? It doesn't really make sense to me, as the outflow of a dam should at most equal the inflow when the dam fills up in the rainy season. Unless, of course, the water level is deliberately lowered, but would there be any reason to do that?

Actually dams are supposed to produce a more or less constant outflow, reducing flood problems in the rainy season. But I can imagine that this would cause people to move closer to the river, and then - during exceptionally rainy years - the dam overflows and the river downstream reach pre dam levels. At this point people are taken by surprise as they have forgotten what pre-dam levels were. Am I correct? Can anyone give me further information on this?