River Systems Flashcards
What are Hydrological Concepts?
Hydrology is the science of water, its global circulation, distribution, and properties, especially water at and below Earth’s surface. Surface water hydrology and groundwater hydrology
What does Fluvial mean?
-Fluvial means “river.”
When are Processes / landscapes / systems are termed fluvial?
when related to rivers (main channel in a network) and streams (more general term; water flowing in a channel)
What are the two driving forces of Fluvial Systems?
Insolation
Gravity
What is the importance of rivers?
Transport and distribute the products of weathering, mass movement, and erosion. Distribute mineral nutrients.
Shape the landscape
Source of fresh water and habitat for wildlife
Why are rivers important to humans?
Source of energy (hydroelectric).
Source of potable water.
Dilute and transport waste.
Cooling for industry.
Transportation
Etc.
Are are the main regions of rivers (3)?
Net Erosion
Net Transportation
Net Deposition
Where do river beds and banks occur?
River bed and banks occur where friction reduces velocity
What do river beds and banks cause?
Deposition
Where do we find estuaries and mouths?
River estuary and mouth where the tide influences the flow
What do estuaries and mouths cause?
Deposition
What is Zone 1 related to?
Headwaters, Net Erosion
What happens in Zone 1 (headwaters, net erosion)?
Headwater streams swiftly flow down steep mountain slopes and cut deep, V-shaped valleys. Waterfalls and rapids occur in this zone.
What is Zone 2 related to?
Transfer Zone
What happens in Zone 2 (transfer zone)?
Lower-elevation streams merge to flow down gentle slopes. Valleys broaden as coalescing rivers start to meander.
What is Zone 3 related to?
Depositional Zone, Net deposition
What happens in Zone 3 (Depositional Zone, net deposition)?
At the lowest elevations, a river meanders across a broad, nearly flat valley and floodplain. At a river’s mouth, it may divide into separate channels as it flows across a delta extending out to sea. The coastal plain and delta are made of river sediments.
Roughly, how much water is flowing through earths rivers?
500,000,000 Olympic swimming pools worth
Define a Sediment Yeild:
The quantity of sediment that overland flow removes from an area in each period
What are the components of the Revised Universal Soil Loss Equation (RUSLE)?
A = soil loss in tons per hectare per year;
R = rainfall-runoff erosivity factor
K = soil erodibility factor
LS = slope length factor
C = cover management factor
P = support practice factor
What is humid climate associated to?
a humid climate is associated with a high drainage density
What are dry climates associated with?
a typical desert has a very low drainage density.
What is a drainage pattern?
the arrangement of channels in an area
What are drainage patterns influenced by?
influenced by climatic and geologic conditions.
How do you calculate a drainage density?
total length of all stream channels in the basin/area of the basin
What are the seven common drainage patterns?
Dendritic drainage,
Trellis drainage,
Radial drainage,
Parallel drainage,
rectangular drainage,
Annular drainage,
Deranged drainage.
_______________ drainage: Energy expanded by this drainage system is efficient because the overall length of the branches is minimized.
Dendritic Drainage
_______________ drainage: characteristic of dipping or folded topography. Such drainage exists in the nearly parallel mountain folds of the Ridge and Valley Province in the eastern United States (e.g., Tennessee).
Trellis Drainage
_________ drainage: A radial drainage pattern results when streams flow off a central peak of dome.
Radial Drainage
____________ drainage: associated with steep slopes.
Parallel drainage
________________ drainage: formed by a faulted and jointed landscape, which directs stream courses in patterns of right-angle turns.
Rectangular drainage
_____________ drainage: A pattern of stream flow in which the stream tends to form a circular path around the hill. It happens when there is a layer of less resistant rock in the hill.
Annular drainage
_____________ drainage: in the areas with disrupted surface patterns, such as the glaciated shield regions of Canada. It is associated with no clear geometry and no true stream valley pattern.
Deranged drainage
Define a stream:
Streams, a mixture of water and solids.
How do streams create fluvial landscapes?
through erosion
transport
and deposition of materials in a downstream direction.
What factors contribute to the energy of a stream?
gradient
base level
volume of flow (discharge)
Define a gradient:
The gradient of a stream is defined as the drop in elevation per unit distance.
True or False: a river has a steeper slope nearer the headwaters and a more gradual slope downstream.
true
What level of a stream does not erode its valley?
Base level
What is the ultimate base level?
Sea level
What does geomorphic work depend on?
gradient, base level, and volume of flow (discharge)
What are some characteristics of streams at base level?
No gradient, lowest energy and clay sized.
What are some characteristics of a stream at Headwaters?
High gradient, high energy, and coarse gravel.
how do we find the angle of a gradient?
to find angle of gradient we use rise over run
What type of stream has potential energy?
A stream situated well above base level has potential energy.
When does a stream have kinetic energy?
As the water flows downslope under the influence of gravity, this energy becomes kinetic energy, able to do geomorphic work (erosion).
What is geomorphic work related to?
erosion
What are we referring to when we talk about energy?
mass and velocity
What is the flow of a stream affected by?
The flow of water in a stream is affected by channel geometry.
Why is velocity nearly zero along each bank and increases to a maximum near the stream’s center?
Due to the friction between the water and the banks.
Where does velocity of a stream increase?
near the stream’s center, also increases from the bottom of the channel to the water surface.
Where do we find maximum stream flow?
along the centre line of the channel
What are some characteristics of stream flow?
flow velocity is greatest in the middle and near the top of a stream.
Explain what Discharge is:
the amount of water flowing past a point over time
Why might a streamflows discharge increase downstream?
the area being drained increases
Thus, the discharge may decrease with distance, because of high potential ____________________.
evapotranspiration (or removals)
What are Exotics streams?
Streams may originate in a humid region and subsequently flow through an arid region. Thus, the discharge may decrease with distance, because of high potential evapotranspiration (or removals)
What is an example of an exotic stream?
The Nile River
What are some differences between Typical vs. Exotic Streams?
-Typical: increasing stream velocity and discharge.
-Exotic: Declining discharge with distance downstream.
How are changes of discharge driven?
by precipitation and temperature
What are the three forms of Discharge?
Perennial
Ephemeral
Intermittent
__________________: Flows all year, fed by snowmelt, rainwater, groundwater, or combination (inputs).
Perennial
___________________: Flows only after precipitation events (fed by precipitation).
Ephemeral
____________________: Flows for weeks or months each year, fed by some groundwater inputs.
Intermittent
What is a Hydrograph?
A graph of stream discharge over time for a place.
True or False: Urbanization can increase peak flow and shorten lag time between storm peak and stream discharge peak.
True
How does Urbanization impact flow?
Urbanization can increase peak flow and shorten lag time between storm peak and stream discharge peak.
Explain Fluvial Processes and Landforms:
The ongoing interaction between erosion, transportation, and deposition in a river system produces fluvial landscapes.
Explain Erosion in terms of fluvial systems:
Erosion in fluvial systems is the process by which water dislodges, dissolves, or removes weathered surface material.
True or False: The material eroded in fluvial systems is never transported to new locations.
False, in erosion, it takes away material and transports it.
What is Deposition in terms of fluvial systems?
Deposition is the location which eroded materials end up.
What are Erosion, transport, and deposition affected by?
Discharge
Channel Gradient
Channel Shape
What is Hydraulic Action?
Hydraulic action is a type of erosive work performed by flowing water alone.
When is Hydraulic Action at its maximum?
Hydraulic action is at a maximum in upstream tributaries of a drainage basin, where sediment load is small, and flow is turbulent.
Why is Hydraulic Action highest in upstream tributaries of a drainage basin?
where sediment load is small, and flow is turbulent.
What type of velocity and flow does Hydraulic Action have?
High velocity
Low Volume
Explain Abrasion:
This sediment laden water can mechanically erode the streambed
What size of sediment does abrasion work with?
Large
What is abrasion also called?
Liquid Sandpaper
What does erosion by hydraulic action and abrasion do to the stream?
Causes it to deepen (channel incision)
Widen (lateral erosion)
and/or lengthen (headward erosion)
What are the three types of fluvial transport loads?
Dissolved Load (solution)
Suspended load
Bed load
What is a dissolved load?
A chemical solution
What is a suspended load?
fine-grained particles, impacts water clairty
What is a bed load made of?
Coarser Materials
What are the two Channel Patterns?
Multiple Thread Channels
Single Thread Channels
What are Multiple Thread Channels?
Either braided or anabranching, tend to occur in areas with abundant sediment or in the lowest reaches of large river systems.
What are Single-thread Channels?
They are either straight or meandering. Straight channels tend to occur in headwater areas where gradient is high. In lower gradient areas with finer sediments, meandering is more common.
Where do we find single-thread channels?
tend to occur in headwater areas where gradient is high. In lower gradient areas with finer sediments, meandering is more common.
Which thread pattern forms into a braided pattern?
Multiple-thread channels
What thread channel uses anabranching channel?
Multiple-thread channels
What is an anabranching channel?
multiple large channels are present across a vast floodplain.
many streams in steep mountain regions or in bedrock-controlled channels have a relatively __________ channel pattern.
straight
What is a stream called where channel slope is gradual, streams develop a more sinuous (snakelike) form, weaving back and forth across the landscape?
Meandering Stream Pattern
Where do we find Nickpoints?
Often produced by resistant rock strata, Niagara Falls.
What is a flood?
A flood is defined as high water flow that overflows natural banks
How is flood risk expressed?
Flood forecasting based on magnitude and probability of occurrence
What is Principle of uniformitarianism?
The past is the key to the future.
What is a Proxy?
Proxies allow us to understand how conditions were and have changed since long before we started measuring these things.
What is paleoclimatology?
understanding how conditions were and have changed since long before we started measuring these things.
How can we use of Dendrochronology in flood reconstruction and forecasting?
Trees respond to their environment, either positively or negatively, and this is often reflected in their rings. We can use this to date past floods and cycles.
True or False: Climate change may be changing the baseline for flood forecasting
True.
Why is it important to understand the risk of flooding?
In 1950, the red river saw the largest flood since 1861
Why do floods most often occur?
Caused by the melting of a particularly large snowpack + heavy spring precipitation
True or False: Urbanization can affect flood danger.
True
How does urbanization affect flood danger?
Due to impacts on runoff + an increase in infrastructure at risk of being damaged.
How can we manage foods?
Retention ponds
Restricting development in low-lying areas
Artificial levees Bypass channels
What are human impacts on flooding?
: Damming, diversion, and land use change
How does human impacts influence flooding?
Impact where and how water moves across the landscape, erosivity, erodibility, sediment load, and where sediment is transported and deposited.
Why does changing landscape matter, in terms of flooding?
Changing where water flows and pools can lead to significant disruption or destruction of habitats, which rely on river-fed nutrients, sediment, and water.
True or False: Approximately 40% of all water discharged by rivers worldwide is intercepted by dams, which retain 25% of the sediment flow from the riverbanks to the oceans
True
What are some impacts of flooding?
Nutrient dynamics
-Oxygen levels
-Fish and invertebrate populations
-Evaporation
What are some secondary consequences of damming?
Induced Seismicity
Increased pressure under reservoirs applies stress to underlying rocks, and forces water into cracks and fissures which can lubricate fault lines.
Geopolitical conflict
Define Hydrology:
Hydrology is the science of water and its global circulation, distribution, and properties—specifically, water at and below Earth’s surface.
What are the basic fluvial systems?
The basic fluvial system is a drainage basin, or watershed.
True or False: Drainage divides define the catchment area of a drainage basin.
True
How is discharge calculated?
calculated by multiplying the velocity of the stream by its width and depth for a specific cross section of the channel
what happens when there is excess sediment in a stream?
a stream may become a maze of interconnected channels that form a braided stream pattern
What happens when there is a gradual slope to a stream?
stream channels develop a sinuous form called a meandering stream.
What do Fluvial Depositional Landforms include?
floodplains,
alluvial fans,
alluvial terraces, and
river deltas.
