Many pathways of water can enter through a dam structure to produce a well-defined nappe. However, engineers classify dams as either overflow dams, where water consistently flows over or is blocked through a gate on top of crest, or non-overflow dams, which channel water through or around the dam with emergency flood gates. They both range in size.
Dams are classified by engineers into two main categories: those that allow consistent overflow and those that channel water through or around the structure using emergency gates. This classification is based on the design of the dam's crest, which can be equipped with a gate to control the flow of water.