1. The problem statement, all variables and given/known data Determine the depth of the flow of channel if the best hydraulic channel is needd for composite channel in figure to convey flow rate of 6.5(m^3/s) , Manning coefficient n on bed slope are 0.015 and 0.0015 respectively . 2. Relevant equations 3. The attempt at a solution I assume the total flow rate of composite channel is 6.5(m^3/s) .. so From the table , i gt z = 1 / sqrt(3) , A = (sqrt(3) + 2 ) (y^2) = 3.73(y^2) P = 4y +2sqrt(2) = 6.83 y So , From manning equation , Q = (1/n)(A)(R^(2/3))(sqrt bed slope) , so , n = 0.015 , bed slope = 0.0015 , i found that y = 2.4 , is my ans and concept correct ?