GC: n

CT: Runoff is the movement of landwater to the oceans, chiefly in the form of rivers, lakes and streams. Runoff consists of precipitation that neither evaporates, transpires nor penetrates the surface to become groundwater. Even the smallest streams are connected to larger rivers that carry billions of gallons of water into oceans worldwide.
Excess runoff can lead to flooding, which occurs when there is too much precipitation. Two recent events in the United States have caused major flooding.

S: http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/hyd/run.rxml (last access: 1 February 2015)

N: 1. Also run-off, “precipitation water drained by streams and rivers,” 1887, from run (v.) + off (adv.). Meaning “deciding race after a tie” is from 1873; electoral sense is attested by 1910, American English.
2. runoff, 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.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=runoff&searchmode=none (last access: 1 February 2015). 2. EncBrit – http://global.britannica.com/EBchecked/topic/512850/runoff (last access: 1 February 2015).

GV: run-off

S: GDT (last access: 1 February 2015); OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=runoff&searchmode=none (last access: 1 February 2015).

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CR: fore apron, renewable energy.