Geoscience Reference
In-Depth Information
Upper reaches
High slope gradient
High water velocity
Narrow V-shaped valley
Shallow depth
Low stream order (few tributaries)
Low discharge
Middle reaches
Slope decreases
Reduced water velocity
Wider valley (meanders)
Greater depth (downcutting)
Alluvial deposition (small terraces)
Middle stream order (more tributaries)
Larger discharge (occasional flooding)
Lower reaches
Low slope
Low water velocity
Wide valley (floodplain)
Greater depth
Thick alluvial deposition (broad terraces)
High stream order (many tributaries)
High discharge (major flooding possible)
Figure 16.29 Relationship of stream order, valley form, and hydraulic variables along a graded stream.
Streams in the upper
reaches of the profile typically have the highest slopes and velocity, but the lowest widths, depths, and discharge. With distance along
the profile, stream order and discharge increase, and gradient and velocity correspondingly decrease.
