The concrete rectangular channel shown is 3.5 m wide and has a bottom slope of 0.001. The channel entrance is rounded and smooth (negligible head loss at the entrance), and the reservoir water surface is 2.5 m above the bed of the channel at the entrance. 

a. Estimate the discharge in the channel if the length is 3000 m.

b. Tell how you would solve for the discharge in the channel if the length is 100 m.