A rectangular brick-lined channel (n = 0.016) of 4.0-m width i laid on a bottom lope of 0.0009. It carrie a dicharge of 15 m3 / and the fl ow i non-uniform. If the depth at a Section A i 2.6 m, calculate the depth at ection B, 500 m downtream of A, by uing (a) only one tep, and (b) two tep.