runoff

Short definition from Wiktionary

Noun

1. 1
   That portion of precipitation or irrigation on an area which does not infiltrate or evaporate, but instead is discharged from the area.
2. 2
   Dissolved chemicals, etc, included in such water.
3. 3
   A second or further round of a competition, after other competitors (often all but the last two) have been eliminated.
4. 4
   A second or further round of an indecisive election, after other candidates (often all but the last two) have been eliminated.