The depth downstream of a sluice gate in a rectangular wooden channel of width \(5 \mathrm{~m}\) is \(0.60 \mathrm{~m}\). If the flowrate is \(18 \mathrm{~m}^{3} / \mathrm{s}\), determine the channel slope needed to maintain this depth. Will the depth increase or decrease in the flow direction if the slope is

(a) 0.02;

(b) 0.01?