Another point is that if the dam is 10m tall, it has to be built to withstand 10m of water. just because it sits at 5m most of the time doesn’t mean a heavy rain couldn’t raise the level, and if the dam collapses that’s going to be catastrophic vs just spilling over the top.
Another point is that if the dam is 10m tall, it has to be built to withstand 10m of water. just because it sits at 5m most of the time doesn’t mean a heavy rain couldn’t raise the level, and if the dam collapses that’s going to be catastrophic vs just spilling over the top.