Chapter 14 · Chapter 15 1 Fluvial Processes Most significant agent of landscape denudation ......
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11/27/2017 1 Chapter 15 1 Fluvial Processes Most significant agent of landscape denudation Processes that erode, transport, and deposit material as a result of running water are referred to as _____________________ Material deposited as result of fluvial processes called _____________ 2 Drainage Basins Area that contributes runoff and groundwater flow to a stream Also called a _________ or ___________ Separated by ridges or upland areas called _________________ or _________________ 3
Transcript of Chapter 14 · Chapter 15 1 Fluvial Processes Most significant agent of landscape denudation ......
11/27/2017
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Chapter 15
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Fluvial Processes
Most significant agent of
landscape denudation
Processes that erode,
transport, and deposit
material as a result of
running water are referred to
as _____________________
Material deposited as result
of fluvial processes called
_____________2
Drainage Basins
Area that contributes runoff
and groundwater flow to a
stream
Also called a _________ or
___________
Separated by ridges or
upland areas called
_________________ or
_________________3
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Base Level
Level to which a fluvial system erodes6
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Where do streams begin?• A stream or (network of streams)
initially develops as:
• ____________ flow is concentrated
by converging topography
• increased depth results in _________
flow
• causing entrainment of particles and
incision
• micro-channels develop into rills,
then gullies, and finally streams
• streams erode ___________ either
randomly or controlled by rock/sed
structure7
Drainage Density and Patterns
Drainage density is a
measure of how
efficiently a drainage
basin collects and
transports water
Dd = stream length /
basin area
Ranges from 1.5 to 6
km/km2
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Common Drainage
PatternsSpatial organization or arrangement
of stream segments in a basin
• Function of:
• slope direction
• surface and subsurface geology
• folding, faulting, jointing
• anthropogenic influences
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Deranged
Drainage in
Quebec
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Stream Order
A way of quantifying and comparing drainage basins
- increases with basin area and segment length
- decreases with number of segments and gradient 11
Streamflow Characteristics
Discharge how much water (volume)
passes by over a given period of time
Q = A x V OR (W x D) x V (ft3/s or m3/s)
Varies significantly since velocity and area are highly variable
Area changes as the water level rises and falls
Velocity is a function of slope; generally decreases downstream
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Streamflow Characteristics
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Streamflow Characteristics
Q = W x D x V
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Fluvial ErosionThree processes:
1. Corrosion
2. Abrasion
3. Hydraulic action
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Stream Transportation
Streams transport load in FOUR different ways 16
Competence and Capacity
Competence
largest particles that can be
transported
Capacity
total amount of material (load)
transported
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Graded Streams
Equilibrium between erosion, transport, and deposition
Gradient is adjusted to transport the load of the stream 18
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Nickpoints
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Flow CharacteristicsThalweg
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Channel Morphology:
Meandering Streams
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Channel Morphology:
Braided Streams
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Evolution of a
Meandering
Stream
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Floodplains
Figure 14.23 Copyright © 2013 Pearson Canada Inc.
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Shifting Meanders
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Alluvial Fans and Deltas
Both produce fan shaped deposition features due
to a sudden reduction in flow velocity as either:
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Alluvial Fans and Deltas
Both produce fan shaped deposition features due
to a sudden reduction in flow velocity as either:
a stream enters a larger
body of water and forms a
____________
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Alluvial Fans and Deltas
Both produce fan shaped deposition features due
to a sudden reduction in flow velocity as either:
a stream spills out into a
valley where it forms an
_____________
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Alluvial Fans and Deltas
Both may result in formation of distributaries
Courser material deposited first, finer last
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Alluvial Fans and Deltas
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Alluvial Fans and Deltas
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Alluvial Fans,
Pembina Valley
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Stream
Discharge
Measurement
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Discharge from Stage
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Recurrence Interval From Discharge
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Stream HydrographsGraph of stream discharge over
a specified period of time
Illustrates relationship between
precipitation and stream flow
Base flow represents the
groundwater contribution to
stream flow
Area under curve represents
runoff of precipitation
The "flashyness" or
"peakedness" of hydrograph
indicates response of stream to
a precipitation event39
