RUN-OFF

The part of precipitation water that runs off the land into streams or other surface water. Run-off exists during times when there are large water streams flowing across the land surface due to rainfall, melting of snow, and other sources, which occurs as an integral part of the water cycle. Run-off usually falls short of reaching channels, and is called the overland flow process and the landmass that generates runoff to a certain location is referred to as a watershed.