Geology Reference
In-Depth Information
Some water flows across land in a continuous thin layer, called a
sheet flow.
Some water
makes its way to depressions in the landscape, which are called
channels
and become
streams headed downhill. Throughout a watershed, small streams called
tributaries
flow
into larger streams, such as a river or
trunk stream
that carries the water to its outlet in
the nearest ocean, sea, or lake.
Figure 12-2:
A wa-
tershed.
Two types of flow
Flowing water across any surface can move in one of two ways:
Laminar flow:
The streamlines of the flowing water are parallel to each other, mov-
ing in straight lines, and the water is not mixed. The surface of laminar flowing wa-
ter is relatively flat and undisturbed.
Turbulent flow:
The streamlines and the water are all mixed together. The surface
of a turbulent flow of water is choppy and disrupted.
Figure 12-3 illustrates how the streamlines and surface in a laminar flow and turbulent
flow are different.
Figure 12-3:
(a)
Laminar flow; (b)
Turbulent flow.
