Flood Wave

Flood wave in open channels are also recognized as long progressive waves with the only difference that the movement of water in downstream direction, is also associated with the movement of waves in open channel or reservoir. By associating flood wave with water movement, it gives two type of flood waves:

• The wave which travels downstream is known as primary wave.
• The wave which travels upstream is known as secondary wave.

• In a typical flood hydrograph shape, the measured discharge first increases upto a certain limit until it reaches a maximum value and then starts receding.
•  A reference line is draws in the middle of hydrograph such that the reference discharge is equal to the average of the peak flow and the base flow.
•  Now, we can visualize that the shape of the hydrograph looks like a sinusoidal wave.