Runoff
Runoff explained in an easy to understand way:
Imagine trying to pour a large cup of water into an already full glass. Just like how the excess water spills over the edge of the glass because there's no more room to contain it, runoff occurs when water flows across the ground because the soil is too saturated to absorb any more. The ground acts like the full glass—once its capacity is reached, any additional water, such as rain, has nowhere to go but over the surface, just as the extra water spills out of the glass.
Practice Version
Runoff: Water that flows on the ground instead of being soaked into it. Runoff. In simple terms, runoff is when rain or melted snow moves over the ground instead of soaking into it.