Transcript Fluvial Systems - Paradise Valley

Fluvial Systems
GPH 111
What are Fluvial Processes?
 Collection of surface water into organized sequence
of channelized forms whereby sediment is
transported from the continents to ocean basins.
Fluvial Processes within
Geomorphology
Sierra Estrella Mountains
and the Gila River
Fluvial Deposition - Mountains
weather and erode, rivers then
transport the debris to the sea.
The Amazon
River Delta
Brazil, South
America
The Longitudinal Profile!
Maintains an “Equilibrium
Gradient”
Rivers only want the energy to transport
their water and supplied sediment to
ocean basins, and nothing more!
Key Concepts!
Discharge - Amount of water flowing in a river
Slope– The inclination of the river channel
Sediment Load – Sediment transported
Vegetation – Along and within the channel
Rivers only want the energy to transport
their water and supplied sediment to
ocean basins, and nothing more!
How do rivers adjust over time?
Too Full! – Upset
passengers, not
enough fuel or
flights to transport
customers
Equilibrium - Just enough
fuel to carry planes full of
passengers to their
destinations and nothing
more – Happy Company!
Too Empty! – Upset
passengers, too much
fuel or too many
flights to transport
customers.
Similar to an airline that tries to fill all
seats for their flights, no MORE or LESS.
How do rivers adjust over time?
Channel Aggradation
Massive sediment
input leads to
extreme
aggradation.
“Steepens channel
to increase
available energy”
Channel Incision
 Commonly takes place through knickpoint
retreat!!
“Lowers available
energy”
Let’s go outside!!!
Channel Incision
Channel Widening and
Narrowing
 The role of width
to depth ratios in
fluvial energy
 Higher width to
depth ratios the
more energy loss
to friction
Channel Widening
Increase width to depth ratios…
“Decreases available energy”
Channel
Narrowing
Decrease width
to depth ratios…
“Increases available
energy”
Lengthening and Shortening Channel Meanders
Areas of maximum
velocity causes
erosion generating
meander bends
that move in a
downstream
direction
Lengthening and Shortening Channel Meanders
Lengthening and Shortening Channel Meanders
Famous Oxbow Lake in the Making!
Lengthening and Shortening Channel Meanders
Channel develops more meanders – “Lowers available energy”
Channel develops less meanders – “Increases available energy”
Key Concepts!
Discharge - Amount of water flowing in a river
Slope– The inclination of the river channel
Sediment Load – Sediment transported
Vegetation – Along and within the channel
Rivers only want the energy to transport
their water and supplied sediment to
ocean basins, and nothing more!
How do rivers adjust over time?
Let’s do the
Lab!!!
What do rivers do?
Things to Know:
 Hortanian versus Saturation overland flow
 Stream Order, drainage basins, drainage
divide
 Types of fluvial sediment transport
 What is a river’s equilibrium gradient?
 What alters a river’s equilibrium gradient?
 How can river’s respond to channel
change?
Help: Chapter FS