RUNNING WATER
THE HYDROLOGIC CYCLE
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The hydrologic cycle is the flow of water circulation from ocean
to atmosphere to land and back to the ocean.
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The river or stream is the component of the hydrologic cycle
that will be focused on in our studies.
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From our perspective on land, the amount of water in streams
and rivers on Earth seems infinite, yet in context of all the water
on Earth, rivers and streams represent less than 0.002%.
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There is 1000 times more water in all of the glaciers on Earth.
DISTRIBUTION OF WATER ON THE EARTH
97.2%
2.15%
0.03%
RUNNING WATER
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The amount of water in all rivers and streams on Earth (termed
running water) is small in relation to all of the water contained
in the oceans, glaciers and under the ground, running water is,
by far the most important agent in sculpting and shaping the
land’s surface
WHERE DOES THE WATER COME FROM?

You may say precipitation is the source for water for stream
runoff, however it is not the number one source.
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The majority of water that feeds streams comes from water that
has seeped into the ground (percolation) and returns slowly to
the surface. The major source is groundwater.
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Once on the surface,
water will move under
the force of gravity.
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Streams are the liaison
between land and
ocean.
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Water flows from high
elevations to low.
STREAMS
Streams flow in channels,
the V-shaped feature on
Earth’s surface.
The base of the channel is often
referred to as the bed.

The high point where water flows from is termed the
headwaters, and where it terminates, the low point is the
mouth.
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The difference in elevation from headwaters to mouth, or the
slope, is referred to as the gradient of the stream.
The gradient varies along a stream but generally decreases
from headwaters to mouth.
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DRAINAGE BASINS
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Streams form an interconnected network comprising the main
stream and its tributaries (or feeder streams).
The land area that feeds or drains into a network of streams is
a drainage basin or watershed.
Canada has
four main
drainage
basins
TYPES OF DRAINAGE BASINS
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Streams and tributaries in a
drainage basin have a definite
geometric relationship.
This relationship can be
demonstrated by assigning a
stream-order to each stream.
When two or more first-order
streams join, a second-order
stream is formed.
This patter continues on and
on.
Network patterns

Streams and their tributaries form distinctive patterns. These
patterns are dependent on topography, underlying geology and
the history of the stream.

All streams tend to follow a branching pattern but the shape of
the branching pattern may vary.

Most stream systems belong to one of four main patterns or
drainage types
DENDRITIC

This pattern resemble the branches on a tree. The
randomness of the stream pattern is due to the uniformity of
the underlying bedrock.

The underlying bedrock does not vary in terms of its resistance
to erosion. It can cut as easily in one place as in another.
Most streams are of this pattern.

RADIAL
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This drainage pattern is characterized by streams radiating
outward in all direction from a high central point. This would be
streams developing around an extinct volcano.
RECTANGULAR
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When the underlying bedrock is crisscrossed by perpendicular
fractures, this pattern occurs. The fractures form zones of
weakness vulnerable to erosion and stream development.
TRELLIS

Following the pattern that resembles the stems of a vine on a
trellis, is where this pattern name comes from. Again the
underlying bedrock is the cause of this pattern. With the
bedrock composed of several different rock types it causes
differences in resistance to erosion.
STREAM VELOCITY
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Streams within a network are characterized by their streamorder and pattern, but as an individual it can be described by
its velocity and discharge.
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Velocity of a stream is measured in terms of the distance the
water travels in a unit of time. Velocity= distance/time

The velocity of a stream varies from stream to stream, along a
stream’s gradient, and also within a stream.

Along straight stretch of a stream, the velocity is greatest in the
centre of the stream
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Where there is a bend , the velocity is greatest near the outside
of the bend.
DISCHARGE
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This is the amount of water passing through a stream channel
in a unit of time. Discharge = volume/time
Usually measured in m3/s
To gain some perspective, a discharge of 1 m3/s would fill
2000 backyard swimming pools in a day.
Mississippi river discharges around 14,000 m3/s
Amazon river is 12 times the Mississippi, 168,000 m3/s or
336,000,000 swimming pools.
Discharge is directly related to a stream’s channel velocity,
depth, and width, as well as the streams drainage basin and
availability of water.