Due to the topography of the ground surface, a long circular water tunnel is proposed to replace a 20-kmlong escape channel of trapezoidal section, side slopes 1: 1. The tunnel section is best...

Due to the topography of the ground surface, a long circular water tunnel is proposed to replace a 20-kmlong escape channel of trapezoidal section, side slopes 1: 1. The tunnel section is best discharging section (0 = 308°) and the trapezoidal section is best hydraulic section (R = y/2) and both have the same roughness and bed slope. Determine whether the construction of the tunnel instead of the channel will reduce or increase the total cost of the project. The cost of construction of the trapezoidal section is $4 per
, while the construction cost of the tunnel is $20/ .