Composite Hydrograph
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The hydrograph above displays flow monitoring data from a residential area recorded over a four week period during normal dry weather conditions. Note that a repeatable daily or diurnal pattern is observed. A more detailed view is obtained by plotting each day on top of the other in a composite 24-hour hydrograph as shown below. The distinctive patterns of weekday and weekend residential flow are apparent.
The light green curve and the light blue curve on the composite hydrograph are the average daily flow patterns observed on weekdays and weekends, respectively. The dark green curves and the dark blue curves are the individual weekeday and weekend traces used to determine the average. These curves provide an indication of the normal variation in flow that can be expected during normal dry weather conditions. Composite hydrographs are used throughout this website and serve as an important reference in the study of sewer sociology.
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