Discharge		the amount of water in ther river system.
Rainfall		a graph showing a river's discharge responding to a particular storm.
Peak discharge		the time between peak rainfall and peak discharge.
Lag time		the speed of the river. Measured in metres per second.
Rising limb		the amount of water that fell during a storm. Measured in millimetres.
Falling limb		an area of land drained by a main river and its tributaries.
Drainage basin		a graph showing discharge of a river at a given point.
Volume		the maximum discharge.
Velocity		increase in discharge before the peak.
Hydrograph		velocity of the river x the volume. Measured in cumecs (cubic metres per second).
Flood hydrograph		decrease in discharge after the peak.