DISTRIBUTION graph:The distribution graph introduced by Bernard is a variation of the unit hydrograph. It is basically a D-hr unit hydrograph with ordinates showing the percentage of the surface runoff OCCURRING in SUCCESSIVE periods of equal percentile intervals of D-h.The duration of the rainfall EXCESS (D-h) is taken as the unit interval and distribution-graph ordinates are INDICATED at successive such unit intervals.∴ Bernard’s distribution graph is a plot of time on the x-axis and the percentage of total surface run-off during uniform time interval on the y-axis.The ordinates plotted at D-h intervals and the total area under the distribution graph adds up to 100%. They are useful in comparing the runoff characteristics of different catchments.