What term describes the force applied per unit area on the wetted area of a channel?

The term that describes the force applied per unit area on the wetted area of a channel is shear stress (channel). In the context of fluid flow in open channels, shear stress is a critical concept as it directly relates to the frictional forces acting between the flowing water and the channel bed/walls.

Shear stress is quantified as the force exerted by the fluid parallel to the surface divided by the area over which the force is applied. This force influences both the sediment transport within the channel and the hydraulic behavior of the flow. Understanding shear stress is essential for analyzing erosion, sediment deposition, and overall channel stability.

The other terms presented either do not fit the definition or refer to broader concepts. Hydraulic pressure relates to the pressure exerted by a fluid at a particular depth, which is not specific to the wetted area and does not consider the dynamics of flow along the channel surface. Fluid dynamics encompasses the study of fluids in motion, which includes a wide array of phenomena beyond just the forces acting on channel surfaces. Channel stress is a less commonly used term and lacks the precision of shear stress, making it less suitable in this context.

In summary, shear stress (channel) is the most accurate term for describing the force per unit area acting