CIV E 530 - OPEN-CHANNEL HYDRAULICS FALL 2011 LAB No. 11:  UNSTEADY GRADUALLY VARIED FLOW Calculate the exponent β of the discharge-area rating for a triangular channel with Chezy friction. Q = α Aβ Q = C A R1/2 S1/2 A flood wave is traveling inbank through a straight river reach of top width T = 320 m wide and length L = 5625 m. For every 1 cm of flood rise, the discharge goes up 10 m3/s. How long will it take for a given discharge to travel the length of the reach?