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Flow of a River - Hydrology
Factors of flow: Seasonal variability (pg 3 of 11)

Click to compare hydrographs
Each stream has a typical pattern of flows throughout the year. Streams with significantly different watershed characteristics (such as a stream with a high groundwater content compared to a stream fed almost entirely by runoff) will exhibit different hydrographs. Streams in different regions, with different climates, will exhibit vastly different patterns of intra-annual variability.


Left: Stream at low flow. Right: The same stream at high flow.

Seasonal variability is natural and necessary for the functioning of the river ecosystem. It is important to remember that river organisms have evolved under a regime of high flows and low flows over millennia. Bank-high flows form and maintain the shape of the river channel; flush sediment from feeding and spawning areas; signal migration for certain species; and allow passage upstream. For example, walleye, northern pike, and sturgeon need a seasonal pulse of high water that submerges rapids to be able to reach spawning areas.


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Introduction
Flow
Description
Water cycle
Watersheds
Stream order
Factors of flow
Consequences
Stories
Shape
Connections
Quality
Life
Summary
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