Definition - What does Runoff mean?
Runoff, or surface runoff, refers to any type of water or liquid that drains away from or off of a surface. The surface can either be an area of land or a man-made surface, such as a building or house.
Runoff starts off as heavy dumps of rainfall or snow (stormwater) that fall from earth's atmosphere. Once this precipitation returns back to earth, it is considered runoff if it cannot be reabsorbed by the ground. This happens in cities where areas are covered in concrete, or in fields where soil cannot handle any more precipitation because it is either too dry or too wet.
Another source of runoff is meltwater, which is water that comes from melting ice caps and melting mounds of snow after a blizzard.
MaximumYield explains Runoff
In geography, runoff is extremely important because it is essentially what keeps rivers and lakes full of water; it is also responsible for changing the landscape through the process of erosion.
Some gardeners prefer to collect runoff using things like rain barrels so that they can use it to water their plants.
Another form of runoff that is specific to the gardening industry is the excess irrigation water that is not absorbed by a plant. It is essentially water that has "run off" of the plant's root zone.
In larger gardens and outdoor farms, runoff is referred to as agricultural runoff. If agricultural runoff contains high amounts of chemical pesticides and synthetic fertlizers, it can pollute nearby streams and riverbeds.