What is the primary characteristic of 'sheet flow' in hydrology?

The primary characteristic of sheet flow in hydrology is that it involves the movement of water over large areas in thin layers. This type of flow occurs when rainfall or surface runoff spreads out over the ground, creating a shallow, uniform flow that can cover extensive surfaces, such as fields or parking lots.

Sheet flow is particularly significant in situations where the slope is gentle, allowing water to disperse rather than concentrate into a defined channel. This phenomenon is essential in understanding how water interacts with the landscape, influencing erosion, sediment transport, and the overall hydrology of an area.

The flow in ducts or underground channels, concentrated streams, or any other defined pathways will not represent sheet flow, as they involve movement that is more directed and confined, contrary to the diffuse nature of sheet flow across surfaces.