/run"awf', -of'/, n.1. something that drains or flows off, as rain that flows off from the land in streams.2. a final contest held to determine a victor after earlier contests have eliminated the weaker contestants.3. a deciding final contest held after one in which there has been no decisive victor, as between two contestants who have tied for first place.4. Also called rundown. a continual or prolonged reduction, esp. in quantity or supply: a runoff in bank deposits; a sharp runoff in business inventories.5. Stock Exchange. the final prices appearing on the ticker after the closing bell is rung for the trading day.
* * *in hydrology, quantity of water discharged in surface streams. Runoff includes not only the waters that travel over the land surface and through channels to reach a stream but also interflow, the water that infiltrates the soil surface and travels by means of gravity toward a stream channel (always above the main groundwater level) and eventually empties into the channel. Runoff also includes groundwater that is discharged into a stream; streamflow that is composed entirely of groundwater is termed base flow, or fair-weather runoff, and it occurs where a stream channel intersects the water table.The total runoff is equal to the total precipitation less the losses caused by evapotranspiration (loss to the atmosphere from soil surfaces and plant leaves), storage (as in temporary ponds), and other such abstractions.
* * *