Many dams have been destroyed or at risk of destruction when spillway gates did not open when they should have. Overspill spillways are the most reliable, but labyrinth spillways should be considered as an alternative to gates for increasing storage. South Africans have developed a gate that relies on the upstream water level for operation. It can be opened remotely but cannot be prevented from opening in the event of dangerously high water levels. Flap gates are also an option but need a power supply to close and may need a control system that relies on an electrical supply. 

This presentation will also propose guidelines for the design of spillways that cover the above and include emergency spillways.