hydrograph A graph showing the plot of water flow in a water course, or the elevation of groundwater in a borehole above a particular datum point, against time. The ‘unit hydrograph’ is the name given to a method of calculation which allows rainfall to be converted to stream flow and so facilitates the prediction of how particular river basins will respond to changing precipitation patterns. The discharge hydrograph shows the flow rate of water against time for a discharging water body. The stage hydrograph shows water level against time.

hydrograph A graph on which the water flow in a water course, or the elevation of groundwater in a borehole above a particular datum point, is plotted against time. The ‘unit hydrograph’ is the name given to a method of calculation which allows rainfall to be converted to stream flow and so facilitates the prediction of how particular river basins will respond to changing precipitation patterns. The discharge hydrograph shows the flow rate of water against time for a discharging water body. The stage hydrograph shows water level against time.