• A rectangular channel of 5.4 m wide and 1.2 m deep has a slope of 1 in 1000 and is lined with good rubble masonry, for which Mannings n = 0.017. It is desired to increase the discharge to a maximum by changing the channel slope or the form of section. The dimensions of the section may be changed but the channel must contain the same amount of lining. Compute: a) the new dimensions and b) Probable increase in discharge.