That is an engineering nightmare and if life is lost because of it...truly tragic. I know hindsight is perfect vision, and my expertise is not in dams or water management but where are the fail safes in these designs?
mnfish, I hear ya! In most cases, it comes down to cost and how much "chance" there is of the torrential and high amounts of rainfall an area sees. These current rains in TX have never been seen before, even in hurricanes, in many areas. That makes it hard to protect against, and predict, what has never happened before.
