Lab 8Stream

Processes

Channel Types

• Braided - steeper, large sediment supply

• Meandering - less steep, lower sediment supply

Terminology

• Flood – river overflows its banks• Alluvium – stream deposits• Drainage system – network of streams

and rivers that drain a given area of land• Many types of drainage patterns (e.g., dendritic,

rectangular, trellis, etc.)

Drainage Patterns

Drainage Basins and Divides

• Drainage basin – area of land drained by one stream

• Divides – linear boundaries that separate one drainage basin from another.– Continental divide:

Rocky Mts.

Stream Processes

• Weathering– Dominant process upstream– Headward erosion – streams erode into V-

shapes uphill.– Erode their own valleys and channels

• Transport• Deposition

– Dominant process downstream– Velocity decreases and sediment dumped

River Valley Forms and Processes

• Gradient – steepness of slope • Gradient = (height)/(distance)

• Base level – lowest level to which stream can theoretically erode– Imaginary line between erosion and

deposition• Discharge – rate of stream flow at a given

time and location• Load – the amount of material that is

transported by a stream (mostly sediment)

River Forms• Cutbanks• Point bars• Oxbow lake• Delta• Alluvial fan