Which highlighted redlines shows the wetted perimeter of a trapezoidal swale?

Which highlighted redlines shows the wetted perimeter of a trapezoidal swale?

• A. All 4 sides
• B. Just the top
• C. Everything but the top
• D. Just the sides

Answer: (C)

The wetted perimeter of a trapezoidal swale is defined as the total length of the boundary of the flow, which is in contact with water. In the context of a trapezoidal channel, this includes the two side slopes and the bottom of the swale, but it does not include the top edge where the water does not make contact. Choosing all four sides would suggest that the top edge is also included, which it is not, as that area is above the water surface. Only considering just the top excludes the crucial parts of the swale that hold water, while only the sides would mean neglecting the bottom where water could flow. Thus, the correct answer encapsulates the notion that the wetted perimeter comprises the two sloped sides and the base, reflecting the actual contact area where the flow interacts with the channel boundaries.

The wetted perimeter of a trapezoidal swale is defined as the total length of the boundary of the flow, which is in contact with water. In the context of a trapezoidal channel, this includes the two side slopes and the bottom of the swale, but it does not include the top edge where the water does not make contact.

Choosing all four sides would suggest that the top edge is also included, which it is not, as that area is above the water surface. Only considering just the top excludes the crucial parts of the swale that hold water, while only the sides would mean neglecting the bottom where water could flow.

Thus, the correct answer encapsulates the notion that the wetted perimeter comprises the two sloped sides and the base, reflecting the actual contact area where the flow interacts with the channel boundaries.