Surface Water Management

[Step 1:] In a gradually varied flow, the surface profile describes the relationship between the flow depth and the channel slope. There are various surface profiles such as M3 and S1. [Step 2:] For the M3 profile, the normal depth is greater than the critical depth , and the flow depth is less than , which is represented by the statement . [Step 3:] For the S1 profile (subcritical flow), is less than , and is greater than , which is represented by . [Step 4:] Therefore, both statements P and Q are correct based on the characteristics of the M3 and S1 surface profiles.