Originally Posted by
ShyTorque
I overheard an interesting conversation last night in a restaurant (I admit I cannot verify what was said so it's definitely rumour only).The gist of it was that dams like this were built with side spill outlets controlled by valves. These are meant to be used to control the maximum water level, to prevent over-topping of the wall but unfortunately these valves could no longer be opened at this dam, because the mechanism has rusted solid over many years.
The damaged area is a spillway which is designed to remove excess water when overtopped - for some reason the concrete facing has failed. If you look at the length of the spillway it can release huge amounts of excess water. Something similar happened to the
Oroville Dam in the US not so long ago. The amount of water a spillway takes is massive, any small defect in the spill ways would rapidly become a large one.
Somewhere I have a photo of Laggan Dam (adjacent to the A86 Spean Bridge - Kingussie road) in full spate, the amount of water being released is astonishing. The mist of spray it created could be seen from several miles away. Standing next to it was truly awesome.
What I am curious about is where the bags being lifted are coming from.