Rivers Test #2

Point Source Pollution

"Any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestack" (Hill, 1997)

Transverse Bars

(dominated by sand-size bedload) Tabular in shape; composed entirely of sand; migrate by accumulation of sediment on the lee face and on the sides

The water in acid mine drainage has a pH of....

0.5

What effect does changing sea level have on rivers?

1 ) When sea level rises, it floods deltas and lowland areas, forming an estuary and causing the mouth of the river to retreat 2) If sea level falls, the shoreline retreat seaward

What 3 general processes create the distributary channel network?

1) Channel bifurcations (division into braches) can take place where channels clog due to accumulation of material 2) Bifurcations can take place where channels flood, breaching their own natural levees and est a new channel 3) Flow w/in the delta is not entirely downhill → Cause water to back up the channels closest to the bay → anastomosing channels that split and join around organic rich islands.

How do meanders form (3 Steps)

1) Circulation pushes water to the outside of the bed as a result of angular momentum. Water piled up around the outside of the curve. 2) Superelevation: Higher water surface on the outside sets up circular current across the channel 3) Bottom current of the bend carries the deposits sediment on the point bar. System starts again.

What are pipeline breached often associated with? (3)

1) Corrosion 2) Equipment Failure 3) Human error

What causes increased chances of aggregation?

1) Decrease in sediment supply 2) Change to wetter/stormier climate 3) Increased slope

What are the problems with dredging? (2)

1) Decreasing the amt of sediment in the river → Must buy clean sediment to replace it 2) The "scooper" is not perfect; when you go in and scoop you have the resuspension of the contaminated sediment; this can allow contaminated sediment to travel downstream as suspended flow

Examples of Low Stream Orders: (2)`

1) Ephemeral drainage 2) Creeks

Impacts of grazing (2)

1) Erosion and increased runoff 2) Deterioration of the riparian corridor and aquatic habitats where grazing activities are closely adjacent to stream courses.

What 5 processes does discharge impact?

1) Flood frequency and magnitude 2) Groundwater contributions 3) Flow characteristics (turbulence, competence/capacity, etc.) 4) Precipitation patterns 5) Effects of climate change

The pattern of bedrock rivers is strongly influenced by... (3)

1) Geology 2) Rate of uplift 3) Associated rate of incision

2 Solutions to Subsidence:

1) Groundwater recharge 2) Dams and reservoirs

What factors make a mine a polluter (3)?

1) High rainfall 2) Steep slopes 3) Rainwater infiltrating and bringing water, oxygen, and protons

How do rivers vary downstream? (4)

1) Increase in discharge 2) Less exposed bedrock 3) Finer Sediment 4) Decrease in channel slope

What causes a greater chance of deposition? (3)

1) Increased in sediment supply 2) Change to a drier climate 3) Dam construction

Characteristics of Organochlorine Pesticides:

1) Insoluble in water but turn out to be highly soluble in fats and hydrocarbons; accumulate in biological tissue 2) Tend to stick of absorb into soil particles and organic material, which allows them to be transported in rivers and later stored in sediment.

How does mine clean up occur?

1) Long, drawn out, and expensive 2) There has to be clear ownership and financial resources 3) Have to stop flow of drainage out of the mine when initiating clean up; may have to reroute rivers 4) Tailings must be regrated 5) Can construct a barrier wall (surface to bedrock) to prevent groundwater contamination from reaching rivers and creeks. 6) Groundwater must be treated before it can reenter the water system 7) Increasing vegetation in the region is also effective

Why has U.S. water use remained approximately constant since 1975, even as population has grown by >50 million? (2)

1) More efficient thermoelectric power plants 2) More efficient agricultural practices

What are the nutrients most frequently cited as the cause of degradation of waterways?

1) Nitrogen 2) Phosphorus

How does eutrophication happen? (5)

1) Nutrients enter a water body 2) Algae bloom 3) Plants die and sink to the bottom 4) Bacteria consume the plants and dissolved oxygen through respiration 5) Water body become hypoxic or anoxic and fish die.

How can tiled runoff be improved?

1) Outlet is raised after the harvest to reduce the nitrate delivery 2) Outlet is lowered a few weeks before planting and harvest to allow the field to drain more fully 3) Outlet is raised after planting to potentially store water for crops

What are the 3 general groups of pollutants?

1) Pesticides 2) Nutrients 3) Toxic Metals

How does Cholera spread?

1) Ppl ingest water or food contaminated with cholera bacteria 2) In epidemic, the feces of a diseased persons is a source of contamination

Steps for Remediation/Removal of Wast

1) Preliminary assessment/site inspection 2) Early Action 3) Long-Term Action

Where are imposed form rivers?

1) Recently deglaciated landscapes 2) Volcanic Activity 3) Landslide

2 classes of local impacts of farms on rivers:

1) River alterations associated with drainage, reconfigurations, and increases in runoff and sediment yields. 2) Water quality impacts associated with pesticide applications and irrigation practices.

What are the treatment options for Cholera?

1) Salt solution 2) Intraveneous fluids 3) Antibiotics

What are the 2 processes by which the bedrock is eroded?

1) Sandblasting 2) Plucking

What 4 processes does sediment load impact?

1) Sediment formation and characteristics within watershed 2) Hillslope flow pathways [Horton overland flow, subsurface storm flow, etc.] - How sediment gets to you river 3) Sediment characteristics affecting transport 4) Type of sediment and entrainment values

Criteria for ability of Bankfull discharge to shape channel cross sections: (2)

1) Sufficient stream power to erode banks and deposit lrg volumes of sediment 2) Frequency must be sufficient that the effects are not muted by the weaker, but higher-frequency, smaller-discharge events.

The concave up shape of the river profile indicates river adjustments to: (3)

1) The climate of the watershed (amt of runoff) 2) The tectonic setting of the watershed (Overall relief as well as changes in base level) 3) The geology of the watershed (sediment supply and bedrock's resistance to erosion)

What are the impacts of removing riparian vegetation?

1) The impacts of runoff and sediment yields from surrounding grazed lands are enhanced 2) Reduces the cohesion of bank materials and its resistance to scour leading to accelerated erosion of riverbanks and, ultimately, the complete transformation of a meandering system into a braided system 3) Leads to increased water temperature, reduction of input of large organic material, and decreases in habitat variability

What can generate a knickpoint? (3)

1) Where a river crosses a fault or sharp change in rock type, differences in erosional resistance will typically generate a knickpoint 2) Extensive and recent glacial scouring and localized deposition of glacial till 3) adjustments to long-term shifts in climate, tectonics, and base level.

Rivers that are dominated by bedload transport tend...

1) to be broad and shallow as well as highly unstable. 2)to have less-resistant banks composed of sand and, to a lesser, extent, gravels

What are the environmental impacts of Tar Sand Mining? (5)

1. It uses lots of water (groundwater pumping/contamination) 2. It requires strip or open pit mining (increased erosion, turbidity, reduced recharge) 3. Strips the land and eliminates ecology 4. More runoff that is washed into the watershed 5. Injecting steam and solvents into the ground caused increased contamination of groundwater and aquifers

2 types of bars in a braided river:

1. Longitudinal 2. Transverse

Meander wavelength and amplitude depend on: (3)

1. River Discharge 2. Sediment Load 3. Gradient

How many of CA's abandoned mines are actively discharging waste?

150

Globally, ___ - ____% of irrigation withdrawals are estimated to be unsustainable.

15; 35

Superfund

1980: Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) commonly known as "Superfund" allows the EPA to clean up hazardous waste sites, force responsible parties to clean up the site, or reimburse the government for cleanups led by the EPA

The order of a stream is only increased where..

2 streams of equal order join together

What is the most effective recurrence interval for measuring change in a river?

2 years

A Superfund site covers a ______ -mile stretch of the river.

200

What is the acute toxicity levels of benzene people can be exposed to?

200,000 ppb is ok for up to 8 hrs w/o increased risk for long-term health effects.

It is ___ safer to transfer oil/dilbit by pipeline than by train.

4x

Salmon require at least _____ mg/L of dissolved oxygen.

5

Bankfull discharge has a ___ - _____% chance of happening in a given year.

50-67

There are approximately ______ abandoned mine sites in the US.

500,000

Equation for Photosynthesis

6H2O + 6CO2 → C6H12O6 + 6O2 [ Water + Carbon Dioxide → Glucose + Oxygen]

What is the main mechanism that generates turbulence at the bed?

A decrease in velocity near the bed creates shear, which generates turbulence.

Sediment can be deposited at the foot of mountains due to...

A drop in competence.

Sediment Entrainment

A fancy term for initiating motion of sedimentary particles

What size of river network is more effective in draining overland flow?

A larger network

Meander Belt Axis

A line draw down the center of a meander belt

How is a levee formed?

A lot of sediment is allowed to settle outside of the river when a flood causes it to extend into the floodplain; loses capacity and competence as it spreads out; rivers create this naturally by building up sediment over time

How does a meandering differ from a braided river?

A meandering has low bankfull discharge and slope while a braided river has high bankfall discharge and slope.

The highest contamination of Mine Drainage occurs during...

A period of low flow.

Sinuosity

A reflection of the channel length required to cover a given point-to-point or straight-line distance; Channel length to cover a straight line distance.

Cholera

A waterborne disease of the large intestine. Occurs when bacteria multiply rapidly and the toxins from them penetrates cells of the intestinal wall. This Toxin prevents intestine from absorbing water from digested food; diarrhea. Dehydration results.

Hydraulic mining led to increased ______ in a river.

Aggredation

Rural runoff containing nitrogen and phospherous comes mostly from....

Agriculture

What is the single largest contributor of nonpoint source pollutants nationwide?

Agriculture

Hydraulic Mining

Aimed hose at a mountain, collected the runoff, took the gold, and left everything else. This added 1.5 billion ft3 of sediment to rivers

What do nitrogen and phosphorus stimulate the growth of?

Algae and other photosynthetic plants

Eutrophication

Algal "blooms" associated with the introduction of nutrients can lead to very high biological oxygen demands and a reduction in total dissolved oxygen; can produce anaerobic conditions; can severely alter or eliminate a habitat

What is the typical shape of a river delta?

Alluvial Fan

What is the difference between alluvial fans and deltas?

Alluvial fans occur where rivers spill into valleys whereas deltas occur where rivers spill into standing bodies of water.

Dissolved oxygen < 0.5 is...

Anoxic

Superelevation

As water runs into a tight meander bend it appears to pile up against the cut bank; creates a hydraulic head that sets up a strong secondary flow cell w/in the meander bend; Higher water surface on the outside sets up circular current across the channel

Symmetric or Asymmetric: Meander Bends

Asymmetric

What is the main mechanism controlling channel formation?

Bankfull Discharge

Most sediment in a river is transported around...

Bankfull Discharge or intermediate discharge

Channel length and depth are determined by what process?

Bankfull discharge

What happens to base flow when precipitation increases?

Base flow increases causing more incision

What causes scour?

Bedload transport

Plucking

Bedrock erosion process along zones of weakness (i.e. fractures)

Sandblasting

Bedrock erosion process. Typically, sediment particles protect the bedrock from erosion. When they are removed from the bedrock erosion results from saltation abrasion

What is typically downstream of a braided river?

Bedrock gorge

Map View

Bends (meanders)

What chemical is used to dilute bitumen?

Benzene

Why must bitumen be diluted?

Bitumen is too thick to flow through pipes

What type of river is this?: High sediment and high velocity High slope, high bankfull discharge Crazy; rapidly abandons channels; hard for things to grow

Braided River

River Dispositional Sequence

Build up of a river's floodplain with floods

How is acidity reduced?

By adding lime

Tailing Piles

Byproducts left over from mining and extracting resources. Include finely ground rock particles.

Respiration Equation

C6H12O6 + 6O2 --> 6CO2 + 6H2O

How can a river have a high discharge, but a slow velocity?

Can have a lot of water, but if it is over a large cross-sectional area which will induce a slower velocity

Effects of PCBs

Can result in cancer, learning disabilities, memory problems, etc.

Which country has large tar sand deposits?

Canada

Velocity Gradient

Change in velocity w/distance from the bed

As these levees increase in height what happens to channel capacity?

Channel capacity increases, allowing the channel to contain larger and larger discharges.

Most environmental pollution has to do with _______ effects.

Chronic

Hungry Water

Clear water that is released from dams with no sediment to transport causing it to have excessive stream power.

Sediment typically in the Deep Channel:

Coarse-grained sediments Large-scale cross-bedding

Nonpoint Source

Comes from many diffuse locations: Construction site erosion, residential runoff, agricultural runoff Depends on the scale Many point sources put together; cumulative problem of a whole residential/agricultural area

Gold accumulates at less _______ parts of the river.

Competent (Like pools)

Longitudinal Profile

Concave upward with a relatively short, steep-gradient channel near the head of the watershed, and intermediate length and slope reach in the middle, and a long, shallow, gradient channel in the lower reach.

Delta

Contiguous mass of sediment deposited at the mouth of a river; Fan-shaped landforms developed where rivers spill into standing bodies of water, lose competence & capacity,and deposit sediment

"Instead of remaining on top of the water, as most conventional ___ ____ does, the _______ gradually sank to the river's bottom, where normal cleanup techniques and equipment were of little use. Meanwhile, the ________ and other chemicals that had been added to liquefy the _______ evaporated into the air."

Crude Oil Bitumen Benzene Bitumen

Water Stress Equation

DIA / Q D - Domestic Use I - Industrial Use A - Irrigated agricultural use DIA = D + I + A Q - Mean annual river discharge

Medium/High Water Stress

DIA/Q = 0.2-0.4 (20-40% total water use)

Contemporary population relative to demand per discharge stress threshold

DIA/Q = 0.4

Severe Water Stress

DIA/Q > 0.4 (40% use)

Pools

Deep water areas b/t the riffles; usually scoured during high-flow events, leaving a coarse gravel lag or channel armor and depositing material on the riffles.

Channel Asymmetry of a Meandering River

Deeper on one side with higher water surface on the other

Thalweg

Deepest portion of the channel

What form of drainage network: Occurs where rock types are relatively homogenous and do not differentially influence erosion rates.

Dendritic

What form of drainage network: Treelike branching

Dendritic

What is the most common drainage network pattern in smaller basins?

Dendritic

What can cause changes in a river (straight to sinuous, etc.)?

Depends on bedload/sediment type and geology of the region

What happens when there is a decrease n stream power (decrease slope/discharge) or an increase in resistance to transport (increase sediment size or supply volume)

Deposition

Most miners did/didn't strike it rich

Didn't

What do pools and riffles reflect?

Difference in channel cross sections.

The shape and size of all river channels depend on ________ and ________; however...

Discharge Sediment Load the relative importance of these mechanisms varies

The river channel size and shape is the result of interactions between the river ________ and __________

Discharge Sediment

What form of drainage network: Found on the lower portion of many alluvial fans and involved the division of the channel network into numerous individual channels.

Distributary

The Hundredth Meridian

Dividing line of whether or not agriculture is naturally sustainable. To the east of it you have more than 20 in/yr (sustainable) of rainfall, whereas to the west of it you have less than 20 in/yr (unsustainable)

Total Water Use =

Domestic + Industry + Agriculture

Avulsion

During very large floods, a river will occasionally abandon its meander belt entirely and establish a new channel in the surrounding lower-lying areas of the valley.

Relationship between discharge and water surface.

Elevation of the water surface increases with increasing discharge

Kinetic Energy

Energy formed from conversion of potential energy as water flows downhill. Does the eroding and transporting sediment and generating heat through friction with the bed.

Potential Energy

Energy gained by water when it is raised above some datum

River always moves towards ________, but if the climate or watershed changes, its current and final state will be "______"

Equalibrium Reset

Channel Axis

Equidistant from channel walls

What happens when there is an increase in stream power (increase in slope or discharge) or a decrease in resistance to transport (reduce sediment size or supply volume)?

Erosion

Headward Erosion

Erosion at the channel head; highly variable; involves both HOF and erosion due to rapid discharge of subsurface flow; channels erode at their tips sensitive to changes in discharge/precipitation

Acute Toxicity

Exposure Pathway; exposed to a high level for a short period of time

Chronic Toxicity

Exposure Pathway; happens at a low level over a long period of time (drinking water, eating many fish caught in a polluted river)

Meandering is a response to...

External forcing mechanisms (discharge and sediment supply) Internal mechanism (flow separation and the development of vortices)

True or false: Today, we do not have regulations in place that attempt to hold companies responsible for environmental impact.

False (we do)

Sediment typically in the Shallow channel:

Fine grained sand Small-scale cross-bedding

Suspended Load

Fines that are transported above the zone of bedload transport

Terrace

Floodplains, abandoned due to changes in flood frequency & magnitude, sediment flux, erosion rate

Single Channel River

Flow restricted to a discrete, sinuous channel; surrounded by floodplains

What impact do boulders have on river flow?

Flow separation around boulders generates regions of slow flow and turbulence (Diff b/t slow and fast flow = turbulence as a result of shear created)

Antecedent River

Formed when a river is able to maintain its established course even though it is clearly being affected by tectonic uplift and changes in geology that could disrupt it.

What elements is hard rock mining after?

Gold Silver Copper Zinc Lead Tungsten

Dissolved oxygen > 5 is...

Good (healthy environment)

Clean Water Act (1972)

Governs fishable and swimmable rivers

What color water signals eutrophication?

Green

Dilbit

Heavy crude oil; diluted bitumen

High/Medium/Low Sinuosity: Meandering River

High

Gold has a _____ density than typical sediment.

Higher

The settling velocity of gold is ______ than the typical sediment grain.

Higher

Avulsion causes the river to move from a _____ _____ to ____ _____.

Higher elevation Lower elevation

River Networks

How all the rivers in a watershed work together

Improved Sanitation

Human-waste disposal facilities that can effectively prevent human, animal, and insect contact with that waste. Examples: Public sewer, Septic system, Pit latrine (not open pit, bucket, or public)

PCBs are _______: they don't like water they will stick to any chemical structure that isn't like water.

Hydrophobic

Dissolved oxygen 0.5-5 is...

Hypoxic

Imposed form or self-formed: Bedload transport set by availability of transport sediment

Imposed

Imposed form or self-formed: Channels are armored

Imposed

Imposed form or self-formed: Imposed bed and banks

Imposed

Imposed form or self-formed: Large, rare events set morphology

Imposed

Imposed form or self-formed: Mountain Streams

Imposed

Imposed form or self-formed: Rive has to adhere to the geology for its form

Imposed

Dredging

In dealing with contamination, the riverbed is the biggest issue As a result, in dredging, the sediment will be scooped up and put on a barge to be carried away from the site

Tar Sand Extraction

In order to extract bitumen, the sands are strip- or open-pit mined. You can alternatively inject steam and collect/condense the bitumen fumes.

Immediately after hydraulic mining occurred, where was the excess sediment stored?

In small streams and tributaries, immovable until a high discharge event occurred.

The industrial use of water increase with country ______.

Income

Increasing population and climate change will _______ water stress on most continents

Increase

Riffle/pool spacing _______ with channel width.

Increases

Amount of oxygen water molecules can hold decreases with __________ temperature

Increasing

Less developed countries use far less water for _____ use and much more for _______.

Industrial Agriculture

The point bar is on the _______ of the meander while the cut bank is on the ______.

Inside Outside

What is an important characteristic of braided rivers?

Instability of their Channels Result of varying discharge, overall coarse sediment load, and unstable bank materials.

Bankfull Discharge

Intermediate discharge that appears to exert the greatest influence on the shape and size of channel cross sections and thus on the overall geomorphology of the river. Occurs every 1.5-2 yrs.

Example of Consumptive Use

Irrigation

How do irrigation practices mobilize selenium

Irrigation practices create the ideal conditions for mobilizing selenium and producing one of the more intractable pollution problems. Insoluble at moderate to low pH, but becomes soluble at high pH

What effect does a lower sea level have on stream power?

It causes an increase in stream power

What effect does a sea level rise have on the river profile?

It causes the river profile to move upward.

How does tiling impact runoff?

It increases the infiltration capacity in the region. Putting tile drains down can decrease the inputs of nitrogen and phosphorus; get less runoff and less of the nutrient inputs

What can be said about the available sediment for an imposed form river?

It is "supply-limited"

Describe the sediment discharged from farms.

It is silt to clay in size It increases turbidity and smothering of potential spawning areas It can severely degrade habitats but will also produce significant channel aggradation

Why did the Enbridge breech/spill not make the news?

It occurred 10 days after Deepwater Horizon was capped

What do dams create?

Lakes/reservoirs (captures sediment)

Transgression

Landward migration of the shoreline

Channels migrate _______ w/in alluvial valleys

Laterally

Wavelength

Length it takes for the river to create one meander (start to start)

Decanting

Levee can be breached and water can flow into floodplain.

What can be built in order to avoid avulsion?

Levees

Improved Water Source

Likely to provide safe drinking water. Examples: Household connections, Protected wells, Protected springs, Rainwater collection

Knickpoints

Local perturbations in a river's profile

High/Medium/Low Sinuosity: Straight River

Low

Which had more sediment yield, lower or higher order streams?

Lower

What impact does basin size have on sediment yield and discharge?

Lrgr the basin = ^ amt of sediment and discharge that comes out of it (not arithmetic relationship)

The effects of PCBs decline/magnify as you move up the food chain.

Magnify

What impact does dam construction have on competence?

Max competence can decline

Restrictions on meander growth: (2)

Meanders can only expand to the width of their valleys and its growth is often disrupted by channel abandonment

How are oxbow lakes formed?

Meanders will eventually cause meander channels to intersect, temporarily restoring a shorter and straighter channel and cutting off the channel that originally made up the large meander bed. → Where both ends of these abandoned meander channels are cut off they form horseshoe-shaped lakes

Water Stress

Measure of water useage over supply (unitless)

Water Budget

Measurement of where water comes from and where it is going

High/Medium/Low Sinuosity: Sinuous River

Medium

Bioaccumulation

Metals and other chemicals can be consumed and build up in the body over time.

Longitudinal Bars

Migrate by erosion on the upstream side and accretion on the tope and downstream sides in a manner analogous to the growth of ripples.

Diluted Bitumen

Mined from tar sands, it is a mix of clay, sand, water, and bitumen. It is a very viscous, thick oil it can't be extracted using an oil well.

Meandering Rivers

Most common, typically sand bedded, requires active bank erosion, bed load transport, perturbations in thalweg path tend to grow.

Sediment typically in the floodplain:

Mud and silt

Anoxic

No oxygen

Multiple Channel River

Numerous, unstable channels that bifurcate and join across a relatively broad wash.

When does Bankfull Discharge occur?

Occurs when discharge fills the entire channel cross section w/o significant inundation of the adjacent floodplain.

When to gravel "lag deposits" move?

Only during rare high flow events

What class of pesticides have proven to be most troublesome?

Organochlorine Pesticides

The presence of what species is a sign of water high in nutrients?

Phytoplankton

What is an oil pipeline?

Pipes that transport crude oil, dilbit, gasoline, natural gas, carbon dioxide; safe way of transporting these things

Is the Kalamazoo River pipeline breach an example of point or nonpoint source pollution?

Point Source

Cross-Stream Asymmetries

Point bars and cutbanks

PCBs

Polychlorinated biphenyl compounds Used in transformer and capacitor oil because they withstand high temperatures You generally have 2 fennel rings combined with several chlorine elements

Downstream Asymmetries

Pools and Riffles

Acid Mine Drainage represents a positive/negative feedback loop?

Positive The water becomes more and more acidic with time.

Example of Non-Consumptive Use

Power-plant cooling

Hard Rock Mining

Prospectors guessed where valuable minerals might be located, then dug out pits or tunnels to access the resource; high-risk, high-reward; every mine destined for extinction

Record of Decision

Publicly available document detailing the cleanup method for a superfund site

Discharge Equation

Q = UA Q - Discharge U - Velocity A - Channel Depth * Channel Width

What form of drainage network: Associated with the symmetrical erosion of edifices such as volcanoes or domes

Radial/annular

Today we use hard rock mining to reach what metals?

Rare Earth Metals

Stream Power

Rate of doing work; loss of potential energy per unit length of the channel

What form of drainage network: Form where heterogeneous, well-stratified rock sequences or parallel fractures and faults dominate the evolution of the landscape.

Rectangular/trellis

The differences of single/multiple channel rivers reflect what about the watershed?

Reflect contrasting watershed conditions

Stream Order

Reflects the relative importance of a stream segment to the overall river system.

Waste is ______ (emergency action; immediate risk to public safety) or __________ (GE; long term; complex; not an urgent threat.)

Removed Remediated

What process flips the photosynthesis equation around?

Respiration

What is the gradual build up to rivers associated with dendritic/branching networks?

Rills --> Gullies --> Channels --> Rivers

Imposed Form River

River bedrock does not erode easily; channel size and shape is 'set' by the bedrock patterns

Self-Formed River

River discharge and sediment load controls or strongly influences the river channel size and shape

Entrenched Meander

River stuck in a canyon and cannot escape; further digs down on the bedrock erosion of the canyon.

Given that PCBs are hydrophobic and bond to carbon-containing compounds in sediment particles, where do you expect to find PCBs in a contaminated river? Where would you focus your efforts when designing a cleanup?

Riverbed, Suspended Sediment, Floodplains, River Banks

A river cannot erode below...

Sea level

Regression

Seaward retreat of shoreline

What is the cause of turbidity?

Sediment Load

Downstream Fining

Sediment breaks into smaller pieces (selective transport/sorting) → channel slope does not need to be as steep to carry the imposed sediment load

Placer Gold

Sediment segregates according to settling velocity, so gold would accumulate at less competent parts of the river (pools, etc.) Placer gold mining created a lot of excitement, but didn't have much environmental impact; not a huge effect on watershed

Resistance to transport decreases with decreases in...

Sediment size and supply volume

Resistance to transport increases with increases in...

Sediment size and supply volume

First Order Streams

Segments that lack measurable tributaries

What metal has proven to be a big problem?

Selenium

Imposed form or self-formed: "Alluvial Flows"

Self-Formed

Imposed form or self-formed: Bedload transport rate set by capacity and competence

Self-formed

Imposed form or self-formed: Lowland rivers

Self-formed

Imposed form or self-formed: Mobile bed and banks

Self-formed

Imposed form or self-formed: Morphology set by common high-flow events

Self-formed

Sediment segregates according to...

Settling velocity

The ________ of a channel controls the structure of the flow that travels through it

Shape

Stream power decreases with decreases in...

Slope and discharge

Stream power increases with increases in...

Slope and discharge

Discharge is more frequently _____ than _____.

Small Large

A mine becomes a polluter through the same processes as...

Soil Generation

Gold King Spill

Spill triggered by EPA contractors Wave of yellow water; dissipated after a day or so Contains lead, heavy metals Water became clear after rain, but yellow sediment remains at the river bottom; water clear but contaminants on bottom

All rivers show this general longitudinal profile: ______ near the head and almost _____ at the mouth.

Steep Flat

3 General Classes of Single Channel Rivers:

Straight (SI < 1.05) Sinuous (SI 1.05 - 1.5) Meandering (SI > 1.5)

Scour

Stream Erosion

Graded Stream

Stream with smooth, concave longitudinal profile.

Symmetric or Asymmetric: Straight Rivers

Symmetric

Cross-sectional profile of river varies from ____ to _______.

Symmetric Asymmetric

In the river, bitumen accumulated in..

Tar balls along the river's bottom

Describe the bedload transport of bitumen:

Tar balls were swept along the river's bottom, with the clay, sand, and other organic material. Accumulated in pools.

Sinuosity Index (SI)

Thalweg length / valley length OR length of channel axis / length of meander belt axis

Why is the "50-year" flood named that? Will the flood occur every 50 years?

The 50-year flood occurs, on average, every 50 years over a very long timescale (say 20 times in 1000 years). On a human timescale, the 50-year flood is unlikely to occur in exact 50 year intervals

What is the chronic toxicity levels of benzene people can be exposed to?

The average person can be exposed to 6 ppb for up to a year without adverse health effects. 9ppb is ok for up to 2 wks.

What is the driving force behind the lateral migration of channels?

The balance b/t erosion on one side of a channel and deposition on the opposite side.

You are playing on the beach. You dig a hole in the sand until you reach water, and remove all the water from the hole. Slowly, water seeps in through the sides, refilling the hole. What happened?

The cone of depression was eliminated.

Superimposed River

The course of the river/its channel network is clearly inherited from some previous structure and appears discordant w/the existing rock type and structure of the watershed

How do the effects of overgrazing compare to the impacts of logging in watersheds?

The excessive removal of vegetation by grazing reduces interception and evapotranspiration Combination of limited vegetation cover and low infiltration capacity produces high rates of erosion associated with overland flow and raindrop impact.

Drainage Density

The length of all channels within a basin divided by the total basin area. Variable among watersheds.

Capacity

The maximum amount of sediment that the flow can transport.

Competence

The maximum grain size that can be transported

Erosion Base Level

The mouth of the river where the gradient equals zero; essentially the lowest level to which a river can erode.

You drill a well in your land and water shoots out above the land surface (an artesian well). Which of the following must be true?

The piezometric surface of your aquifer is above ground level.

Deposition

The processes where material being transported by a river is deposited; occurs when a river loses energy. This can be when a river enters a shallow area or towards its mouth where it meets another body of water.

Keystone XL Pipeline

The proposed pipeline would have brought Canadian crude oil to downstream pipes and refineries in the US. The plan was ultimately blocked by presidential veto.

Sediment Load

The rate of sediment that is transported by a river; commonly expressed in tons per day.

Settling Velocity

The time it takes for a particle to sink a certain distance in still water (cm/s); the sum of all downward forces on a particle

What is the danger of transporting oil by train?

The train can derail and explode

Channel Head

The upstream limit of well-defined channelized flow that is usually associated with incision into bedrock or soils

River Discharge

The volume of water flowing through a river channel.

The impact of most pesticides and herbicides on aquatic organisms is usually noted first at or near the ______ of the food chain; they _________ in these substances and can produce die-offs.

Top Bioaccumulate

Riffles

Topographical high points on a bed profile; spaced 5-7 channel widths apart; composed of coarsest bedload that is being transported by a river

Percent Water Use =

Total Water Used / Total Water Supply x 100

Total Transport =

Transport Rate X Time

Total Transport =

Transport Rate x Time

Irrigation Canals

Transport water from its river source to the farm fields Everyone along the canal must take his/her fair share

True or False: Because there is no bedload transport, discharge does not matter for imposed form rivers.

True

True or False: Today, most abandoned mines have no owner and no money to clean them up.

True

Braided Rivers

Typically broad and shallow w/numerous sand and gravel that further increased bed roughness; Multiple channels, high bedload transport, low bank stability (sparse vegetation), rapid variations in Q (discharge)

Stream Capture

Upslope expansion of one tributary eventually leads to capture of runoff from another tributary

Turbulence scales on ______.

Velocity

______ waters have less oxygen. _____ waters have more oxygen.

Warm Cold

Salination

Water is lower that the surface and has nowhere to go → evaporates and leaves minerals, Over time you get the build up of minerals and salts on you land. When it gets to be too much plants can no longer grow.

Unimproved Water Source

Water is not protected from environment and is not safe for drinking.

Consumptive Water Use

Water lost to the atmosphere through evapotranspiration. As you use it you are taking it out of the system.

Non-Consumptive Water Use

Water returned to surface or groundwater systems (that is, where we can conceivably retrieve it)

Subsidence

When ground elevation lowers due to water withdrawal and subsequent sediment compaction

Second Order Streams

Where 2 first order streams come togethe

What happens when a river meets a stream?

Where rivers meet the sea (or any lake) and lose almost all of their competence and capacity, they rapidly dump their sediment, forming a localized accumulation of material right at the ocean/river join.

When can capacity be decoupled from competence?

While a stream may have the competence to move a material, if there is an excess of the material the river will deposit it rather than transport. Hydraulic mining can cause this

What type of impact is a change in sea level?

Whole-profile impact

Amplitude

Width of the meander

Suppose your house floods due to a "500-year" storm. Are you more or less likely to be required to pay flood insurance next year?

You are more likely to have to pay flood insurance, because the 100-year floodplain will expand.

Your house flooded last year. What can you say about the likelihood of your being flooded this year?

Your chance of being flooded is exactly the same as last year.

Relationship between bankfull discharge and wavelength/amplitude:

^ bankfull discharge = ^ wavelength and amplitude

It is not the velocity that entrains sediment but...

bed shear stress.

A river balances and minimizes its energy expenditures through adjustment of its...

channel cross section.

Water use in the US is actually _________ despite rise in population

declining

River pattern is dependent primarily on differences in... (3)

discharge, channel slope, and sediment load.

Alluvial Fans

fan-shaped landforms developed where rivers spill into valleys, lose competence & capacity, and deposit sediment on valley floors

The turbidity (cloudiness) of a river is an indication that _______ are dispersed throughout the water column.

fines

Secondary Circulation

flow that moves downstream in a cylindrical, spiral motion

More sediment moves at a higher/lower discharge.

higher

Exposure Pathways of PCBs

leakage, improper disposal

How much rainfall must you have for agriculture to be sustainable?

more than 20 in/yr

Riffles and pools are a product of ______ _________w/in channels.

secondary circulation

A drop in competence is associated with a drop in....

stream power

Most of the water we use is _______ water for drinking and everything else (89%)

surface

Scarcity of "straight" channels is believed to indicate...

that meandering is the more preferred state of single channel rivers.

One of the most important factors controlling cross-sectional geometry in alluvial rivers is...

the presence and type of bank-stabilizing vegetation.

Point Bar

the prominent sedimentary feature of all meandering rivers formed by deposition; Sandy portion of curve that had sediment from the asymmetry opposite the cut bank

Bed shear stress (the necessary ingredient for entrainment) is proportional to...

the velocity gradient

Due to headward erosion, what happens to a waterfall?

waterfall location migrates upstream