Correct Answer - Option 2 : increases, decreases
Explanation:
Tuberculation:
It is the formation of mounds of reddish-brown iron-oxide on a pipe's interior. This phenomenon is classified as a type of bacteria-driven corrosion and is typically associated with older iron pipes. Tuberculation is caused by the action of microorganisms in the pipe medium.
Hazen-William formula to calculate the flow velocity in pipe is
V = 0.85 CH R0.63 S0.54
Where, V = Velocity in m/s
CH = Coefficient of hydraulic capacity of the pipe material (Hazen-William's coefficient)
The smoother the pipe, the greater is the value of CH.
R = Hydraulic mean depth
S = Slope of the energy line
The carrying capacities of pipes decrease with time because with the passage of time their surfaces go on becoming rougher.