discharge,streamflow and runoff

discharge--the volume of water that passes a given location within a given period of time. Usually expressed in cubic feet per second.

streamflow--the water discharge that occurs in a natural channel. A more general term than runoff, streamflow may be applied to discharge whether or not it is affected by diversion or regulation.

runoff-- That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains or sewers. Runoff may be classified according to speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as surface runoff, storm interflow, or groundwater runoff. 

discharge,streamflow and runoff，定义由广泛向具体？

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