The wave method is based on the physically accurate concept that transient pipe flow occurs as a result of pressure waves generated and propagated from a disturbance in the pipe system (valve closure, pump trip, etc.) This method was developed and first described by Don J. Wood in 1966. A pressure wave, which represents a rapid pressure and associated flow change, travels at sonic velocity for the liquid pipe medium, and the wave is partially transmitted and reflected at all discontinuities in the pipe system (pipe junctions, pumps, open or closed ends, surge tanks, etc.) A pressure wave can also be modified by pipe wall resistance.  This description is one that closely represents the actual mechanism of transient pipe flow.