What effect does soil roughening have on runoff velocity?

Soil roughening plays a significant role in reducing runoff velocity. When soil surfaces are roughened, such as through the incorporation of vegetation, mulch, or other organic materials, the surface area for water to interact with increases. This interaction creates more friction, which slows down the flow of water across the surface.

The roughness of the soil disrupts the uniform flow of runoff, allowing more time for infiltration and absorption into the soil. Additionally, rough surfaces can create small pockets that temporarily hold water, further decreasing the speed at which water moves. This is particularly important in erosion and sediment control practices, as reducing runoff velocity helps minimize soil erosion and sediment transport, protecting water quality in nearby streams and rivers.

In contrast, smooth surfaces tend to have faster runoff velocities because there is less friction to slow down the water flow. Hence, soil roughening is beneficial in managing stormwater and preventing erosion by effectively reducing the velocity of runoff.