What is the term for the portion of a hydrograph where the flow rate decreases after reaching its peak?

The portion of a hydrograph where the flow rate decreases after reaching its peak is known as the Recession Limb. This term describes the decline in river discharge following the peak flow event, which typically occurs after a rainfall event or snowmelt has concluded. During this phase, the water levels gradually decrease as runoff and contributions from the watershed diminish, and the flow stabilizes.

Understanding the hydrograph is vital for managing stormwater and floodplain planning since it helps in predicting how long water will remain elevated in a river or stream. Recognizing the characteristics of the recession limb aids engineers and planners in making informed decisions about infrastructure design and flood management strategies.