Data in units of cumec are used along the y-axis or vertical axis of a flow hydrograph, which describes the time variation of discharge of a river (the mean velocity multiplied by cross-sectional area). A moderately sized river discharges in the order of 100 cumecs.
On a flow hydrograph, which charts the time course of river discharge, data is represented in units of cumecs, typically on the y-axis. A typical river with moderate flow volume discharges around 100 cumecs.