Editing Hydrograph (section)

{{Short description|Graph showing the rate of water flow}}
{{distinguish|Hydrography}}
{{refimprove|date=April 2018}}
[[Image:Stream hydrograph.gif|thumb|upright=1.2|A stream hydrograph. Increases in stream flow follow [[rain]]fall or [[snow]]melt. The gradual decay in flow after the peaks reflects diminishing supply from [[groundwater]].]]

A '''hydrograph''' is a graph showing the rate of flow ([[Discharge (hydrology)|discharge]]) versus time past a specific point in a river, channel, or conduit carrying flow. The rate of flow is typically expressed in [[Unit of measurement|units]] of cubic meters per second (m³/s) or cubic feet per second (cfs).
Hydrographs often relate changes of [[precipitation]] to changes in discharge over time.<ref>{{Cite journal |last=Sherman |first=LeRoy K. |date=1932 |title=The relation of hydrographs of runoff to size and character of drainage-basins |url=http://doi.wiley.com/10.1029/TR013i001p00332 |journal=Transactions, American Geophysical Union |language=en |volume=13 |issue=1 |pages=332–339 |doi=10.1029/TR013i001p00332 |bibcode=1932TrAGU..13..332S |issn=0002-8606|url-access=subscription }}</ref> The term can also refer to a graph showing the volume of water reaching a particular [[outfall]], or location in a sewerage network. Graphs are commonly used in the design of [[sewerage]], more specifically, the design of [[surface water]] sewerage systems and [[combined sewer]]s.