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EAS 205 #2
Midterm #2
189
Environmental Studies
Undergraduate 2
11/04/2013

Additional Environmental Studies Flashcards

 


 

Cards

Term
Coastlines
Definition
Rapidly changing or relatively stable
 Usually areas of high population density
 Shoreline geometry is determined by plate tectonics
Term
Active Margins
Definition
Cliffs above water line
 Narrow continental shelf
 Fairly deep drop to oceanic depths offshore
Term
Passive Margins
Definition
 Broad continental shelf
 Extensive development of broad beaches, sandy offshore islands
Term
Waves
Definition
 Induced by the flow of wind across the water surface
 Small undulations in the surface
Term
Refracted waves
Definition
 Cause erosion and deposition along shorelines
 Most approach shore at an oblique angle and are refracted
◦ Results in longshore current and longshore drift
Term
Shoreline Erosion
Definition
 Pounding by water
 Milling and abrasion by entrained particles
 Generally concentrated at the water line
Term
Wave base
Definition
depth at which water motion is negligible
Term
Breaker
Definition
When wave crest velocity > velocity at base. falling over.
Term
Surf zone
Definition
region from break zone to swash zone
Longshore current & longshore drift. From where breaker peaks to where breaker crashes
Term
Swash zone
Definition
Water moving onto coastline after crashing. Beach drift
Term
Beaches
Definition
 Definition:
◦ Gently sloping surfaces
◦ Washed over by waves
◦ Covered with sediment
 Tend to be short-term and unstable features
Term
Beach weaknesses
Definition
 Seasonal cycles with differing wave characteristics
◦ Changes locations of submerged bars, beach configurations, etc.
 Storm surges
 Tides
Term
Hawaii storm surges
Definition
 Storm surge
◦ Low airpressure causes bulging in the water surface, and high winds
◦ May be affected by tidal augmentation
Sloped gradients are bad now.
Term
Storm effects
Definition
Dunes migrate away. Water undercuts the bottoms, then deposits material.
Term
Tides
Definition
 Periodic, regional rise and fall in water levels due to gravitational pull of the
sun and moon.
 Occur twice dail
Term
Spring tide
Definition
maximum difference between high and low tide. Meters! Sun & moon pull along same line. Increase the height! DO NOT want surges during HIGH spring tide. Low is okay.
Term
Neap tides
Definition
minimum difference between the high and low tide.
Term
Sea level changes
Definition
 Changes can be local or global (eustatic) in effect
◦ Tectonic uplift or subsidence
◦ Isostaticrebound
◦ Global warming
◦ Breakup of glacial ice
◦ Shifting of the oceanic currents
◦ Liquid extraction
 Effect on the coastline depends largely on slope
Term
Future Trends of Rise
Definition
 Sea level is currently rising at an average of 30 cm / 100 years.
 Some coastal cities are AT or slightly above sea leve
Term
Drift
Definition
 Longshore currents move or shift sediment laterally along the shoreline. Migration of sediment
Term
Cliff erosion
Definition
 Undercutting at the base
 Slumping and landslides from the top
Term
Mitigation and prevention of cliff erosion
Definition
 Usually works well for the areabeing protected
 Solutions always seem to shift the problem to someone else’s backyard
Term
Pilkey's truths of sunshine
Definition
• There is no problem until someone builds something on it to measure it
by.
• Construction on the beach reduces flexibility and in itself causes
erosion.
• The interests of beach property owners should not be confused with the
natural interest.
• Once you start stabilization, you can’t stop.
• The cost of saving beach property is, in the long run, greater than the
value of the property to be saved.
• In order to save the beach, you destroy it.
Term
Options: Littoral (longshore, beach) drift
Definition
 Put in groins (single) or jetties (paired)
 Revetments
 Breakwaters
 Seawalls?
 Rebuild the beach
 Move further inland
Term
Groin/Jetties
Definition
do the same thing
Term
Groin
Definition
wall built from land into water to trap sediment from moving, allows water. Bad because beach behind loses sediment, THEN need to add ANOTHER.
Term
Jettie
Definition
Stop sediment from moving; closing off a passageway. Built further out.
Term
Revetment
Definition
blanketed retaining walls, trying to Prevent erosion of slope. Protecting something behind it. Break energy of waves, cannot move as much sediment.
Term
Gabeons
Definition
wire crates full of rocks; riffraff, revetments...
Term
Seawalls
Definition
not good for drift issues. Stops everything!
Term
Rebuild
Definition
adding more sediment
Term
Breakwaters
Definition
Pyramid shaped obstructions to provide calmer water along the shore. Doesn't stop erosion.
Term
Plan stabilization
Definition
Good or bad for flooding, also along coastlines.
There to keep sediment in place. Don't want soil bit to be exposed.
Se grass is goof for drift, but awful to swim in.
Mangroves are natural breakwaters, attract certain animals you won't want.
Beach Vitex, introduced in 80s, vines that stabilize. Grows really well and took over. Seen as a pest now. Not native plant.
Term
Miami beach replenishment project
Definition
Only 12% of rebuilt beaches last more than 5 years. Disappears every 5 years.
Term
Stopping cliff erosion
Definition
CANNOT be done. Can slow it, but not stop. Can put something in front that will be eroded instead.
Similar fixes as for drift issues.
Term
Wind Ciculation
Definition
Anticlockwise in NH, around low pressure areas. Reverses in southern hemisphere. Centre pressure is often ~900 mb. Lower pressure in centre, higher the storm surge and further inland.
Term
Storm damage
Definition
Storm surge and tidal augmentations are often the most destructive
Term
Upside to storms
Definition
Easy to track
Term
Storm classification
Definition
Start as tropical depression, once hitting tropical storms (gets a name), once winds are 118 kmh, now a hurricane.
Categorized by maximum sustained winds, what pressure in eye is, and surge height. NO category 6, 5 is the largest value.
1 in 4 hurricanes on land will generate a tornado.
Follows ocean currents, satellites can observe.
Term
Project stormfury
Definition
1962 -1982, dump ice into water, makes hurricane rain out. killed by politics
Term
Hydrosphere
Definition
◦ All water at or near the Earth’s surface.
◦ Remains constant.
 Distribution:
◦ 97.5% in oceans
◦ 0.63% in groundwater
◦ 0.016% in freshwater bodies
◦ ~2% in ice
Term
Hydrologic cycle
Definition
 Movement of water at and near the Earth’s surface
 Major factor in shaping the Earth’s surface
 Dominated by evaporation and precipitation
 Surface runoff
Term
Overland flow
Definition
No guidance, goes wherever
Term
Channeled flow
Definition
has direction, change this even a bit, BUG changes will result.
Term
Stream
Definition
body of flowing water in a channel. Can refer to any flow.
Term
Drainage basin
Definition
◦ Region from which a stream draws its water.
◦ Determines the size of the stream
◦ Separated by divides
Term
Divides
Definition
separate drainage basins: water falls on it, water falls one way or the other. Can be a slight elevation. Determines how much surface water you are dealing with. It is a boundary.
Term
Discharge
Definition
 Volume of water flowing past a given point per unit time
 Given by: Q = A x V
Term
Stream size and shape
Definition
◦ Climate (temperature and precipitation) = how much water
◦ Vegetation type and amount = how fast water can enter; stability of channel
◦ Underlying geology
◦ Regional slope/gradient = flas srufaces don't drain well.
◦ Amount of water to be accommodated
Term
 Stream behaviour
Definition
determined by:
◦ Particle size
◦ Stream velocity
Term
Hjulström's diagram
Definition
What conditions will allow for material to move.
Term
Big pieces
Definition
need lots of energy to GET moving, once going, it doesn't need much.
Term
Particle shape:
Definition
irregular shapes are easier to dislodge. Sand is easiest to pick up and move.
Term
Sediment transport
Definition
◦ Suspension
◦ Saltation
◦ Creep, traction
Term
Suspension
Definition
floats. Silts and clays. Can stay suspended for years even when still.
Term
Saltation
Definition
= bounces on bottom; doesn't get high up off bottom. Sporadic. Normally sand.
Term
Creep/traction
Definition
= material sliding/rolling at bottom. Depends on shape of particle. Heavier objects, typically.
Term
Sediment load
Definition
bed, suspended, dissolved
Term
bed load
Definition
Sediment moved along the bottom of the stream
Term
Suspended load:
Definition
Sediment suspended in water
Term
Dissolved load:
Definition
Usually chemical
Term
Equilibrium Profiles
Definition
 Given stable conditions each stream establishes a characteristic profile
 Steepest gradient at the head (source)
 Flattens along the length to base level
◦ Lowest elevation to which the stream can erode

Tough to get TRUE equlibrium, often tampered with
Term
Stream Types
Definition
Classification is based on:
◦ Channel shape
◦ Number of streams in channel
◦ Relationship of stream to the valley shape
 Most common types:
◦ Meandering
◦ Braided
Term
Braided
Definition
wide, shallow, straighter, coarser material (sand)-mobile as a result. Steeper, sediment influx. Change frequently. Might not see braids unless lower flow.
Term
Meandering
Definition
Where most people live by. Flatter. Variable bends. Flatter area, more extreme bends. Variation of material, tends to be finer. Provides flat areas for building. Banks are more stable.
Term
Helical flow
Definition
 Circular flow in a linear direction.
◦ Velocity is higher on one side than on the other
◦ Erosion on the cutbank
◦ Deposition downstream on the inside of bends (point bars)
Explains meandering; easy to start! Submerged boulder would do it.
Term
Result of helical flow
Definition
lateral channel migration
Term
Mississippi
Definition
migrates all over the place. Eventually cuts off its old bends. Makes a oxbow lake (water left) or a meanderscar (sediment filled).
Term
Alluvial fans
Definition
Made by water flowing seasonally/intermittently; starts channelized, pick up a lot, dumps everything when it reaches its base level.
Term
Delta
Definition
Channels dump sediment when it reaches its base level.
Term
Terraces
Definition
Step like features. not often exposed. ABANDONED flood plain. Won't flood again, in theory. River has deepened.
Term
Channel volume
Definition
is sufficient for maximum discharge each year. Tries to hold its water. Flooding is going from confined to unconfined; leaving the channel.
Term
levees
Definition
channel banks
Term
Flood plain
Definition
where floods go
Term
Flood
Definition
when water overrides channel banks
Term
Precipitation
Definition
◦ Rate, duration and spatial extent
◦ Rate and amount of snow melted
◦ Timing of ice thaw
Term
Infiltration
Definition
What is water on top of? Will it absorb rapidly?
Man made vs natural.
Term
Level of saturation
Definition
= soaked sand won't absorb any more.
Term
Benefits of vegetation for flooding
Definition
acts as a speed bump. Slows water down.
Term
Negatives of Vegetation for flooding
Definition
do not always want to have infiltration in a flood.
Term
Measure stream height at specific stages
Definition
◦ Continuous recording gauges
◦ Physically measuring the level with yardsticks, etc.
◦ Produce hydrographs
Term
Flood stage:
Definition
◦ Stream stage exceeds the bank height
Term
Flood crest
Definition
maximum stage of water
Term
Flood rates
Definition
Comes in fast (1,2,3 hours), localized, can be high. Dissipates quickly. Steeper. Water flows on surface, not enough time to infiltrate.
Term
Upstream flood:
Definition
◦ Smaller, local
◦ Brief but intense water input
◦ Duration is brief
◦ Discharge peaks much sooner and are higher
Surface runoff AND infiltration. Flatter. Slower to move, can evacuate. Will affect a HUGE population though. Nowhere for water to go, has to drain to ocean. FAR worse; will cause the most damage. Secondary affects; long term.
Term
Downstream flood:
Definition
◦ Larger drainage basin affected by prolonged, widespread precipitation
or heavy regional snow melt.
◦ Effects are prolonged and widespread
◦ Discharge peaks much later and to a lower level.
Term
Prediction
Definition
Collect discharge records to construct flood frequency curves
 Determine:
◦ Recurrence interval
 Number of years between events of a specific magnitude, on
average
 RI = (N+1)/M
◦ Probability of flooding (1/RI)
Term
Magnitude for floods
Definition
smaller number is bigger.
N = # of years in data base.
Smaller M was, bigger the flood was.
Probability = odd of happening. Higher number = more likely.
Term
Quality of flood estimates
Definition
◦ Duration of the data record
◦ Number of data sets used
◦ Impact of human activity?

Need a LOT of data to make accurate predictions. human activity undermines previous data
Term
Flooding primary effects
Definition
caused by moving water and debris

◦ Destruction by currents, debris and sediment
◦ Erosion and deposition of sediment and debris
◦ Injury and loss of life
Term
Flooding secondary effects
Definition
Triggered by flooding or erosion by moving water
◦ Mass movements
◦ Hunger and disease
◦ Pollution
◦ Displacement or dislocation
Term
Why would anyone build on a floodplain in the first place?
Definition
◦ Ignorance
◦ Impractical to develop elsewhere
◦ Fertility of the floodplain sediments
◦ Close to transportation
◦ Close supply of fresh water
◦ Scenery
Term
Flooding effects of urbanization
Definition
 Surface runoff:
◦ Rate, duration and areal extent affects severity
◦ Storm sewers reduce the rate of infiltration in the soil
 Peak discharge is higher, peak lag time is lower. Makes for more upstream floods, river peaks higher, covers a larger (and now flatter) area.
Term
Peak discharge
Definition
highest peak in curve,
Term
Lag time
Definition
time from rain beginning until peaking.
Term
Building & flooding
Definition
most material used to build is impermeable. All drains into the river. FASTER route to river!!
Sediment goes into river and raises the bed, less room for water. Flooding!
Building in floodplain takes up room for water. NEED that much less water to flood.
Term
Reduction of flood hazards
Definition
 Zoning and flood-proofing
 Retention ponds
 Diversion channels
 Channelization
 Levées
 Dikes, flood gates, reservoirs, dams
Term
Flood hazard mapping
Definition
Should be mapping BEFORE you move in.
RISK MAP (mapping, assessing, planning) enables fema to improve flood hazard management.
Useful later on, as it indicates what services should be installed.
Term
Flood proofing
Definition
 Build on stilts
 Above the high water mark
Term
Retention ponds
Definition
 Hold back excess run-off and promote infiltration
 Keeps water from entering river system, poor draining areas.
Depressions designed to trap water & sediment
Sediment ponds. Promote drainage elsewhere.
Term
Diversion Channels
Definition
 Artificial channel built to accommodate excess water and convey it
elsewhere
 Requires flood gates and monitoring of stream stages
◦ Red River Floodway, Winnipeg

Push extra water river cannot carry away from an area you don't want to flood. Put it somewhere else. Straight lines.
Term
Diversion channel problems
Definition
Divert water to someone who shouldn't be getting it… River in the new area is not meant for the extra water.
Term
Old river control system
Definition
Stop mississippi tributary diversion

 Very costly to maintain
 Suffers flood damage
 Increases flooding downstream
 Disrupts shipping by lowering water levels
 Disrupts fresh water supply seawater from the Gulf moved upstream
Term
Channelization
Definition
 Artificial modification of the stream’s channel size or configuration
 Common practice in urban regions to accommodate new development
Term
Problems of channelization
Definition
 Upsets the stream’s equilibrium
 Frequent upstream erosion
 Requires consistent and costly maintenance
 Shifts the risk of flooding downstream
 Wildlife?
Term
Levées
Definition
 Natural or artificial bank extensions (dikes)
◦ Increase the stage level necessary for flooding.
Term
Levées problems
Definition
 Flooding downstream
 Upstream flooding
 A false sense of security
 Draining excess water on the floodplain
Term
Flood Control Dams -Reservoirs
Definition
Dams hold excess water for subsequent controlled release
 Benefits:
◦ Hydroelectric generation
◦ Irrigation
◦ Recreation
◦ ‘Guaranteed’ water source
Term
Flood Control Dams -Reservoirs Problems
Definition
 Can cause drought or flooding elsewhere
 Increased erosion downstream
 Increased deposition upstream
An ominous one…
 Require constant maintenance
◦ Often have a short life expectancy
 Reservoir induced earthquakes
 Sudden failure?
Term
Dam failure stats
Definition
 Overtopping 34%
 Foundation defects 30%
 Piping and seepage 20%
 Conduits and valves 10%
 Other 6%
Term
Dam failure
Definition
Adding a lot of water to an area that didn't have water makes stress, water is a lube. Sheer weight adds stress. Induce earthquake strain… BUT, reall bad for dam. Lake mead started having earthquakes once filled with water.
Term
Road material
Definition
Porous materials. For roads, allows water to soak in, drains underneath into the earth. Larger pieces for better infiltration.
Prevents erosion. No runoff problem.
Issues: expensive, can clog with particulate and become impermeable. Also usually only used in parking lots, low traffic areas. Don't want to compress it...
Term
Province with huge risk for landlides
Definition
Quebec
Term
A stable material will
Definition
Stable material will not fail. Ever. If it fails, it wasn’t stable. Stability can change over time.
Term
Material failure will occur when
Definition
▫ Shearing stress acting on the substrate
exceeds
▫ Shear or tensile strength of the material to resist it.
Term
Main form of stress is
Definition
gravity
Term
Rate of movement
Definition
How fast is it. Falling? mm/year or meter/second. May or may not notice it.
Term
Style of movement
Definition
How it falls down the hill
Term
Type of material
Definition
What’s falling
Term
Mass movement classification
Definition
rate, style, type
Term
Falls
Definition
• Material experiences “free fall”during movement
▫ Also moves by sliding, rolling or saltation
• Usually a result of mechanical weathering
• Movement rate in m/s
Term
Topples subgroup
Definition
• Rotation about a fixed point below the centre of mass
• Vertical to sub-vertical planes of weakness
• Triggered by the removal of down slope support
• Movement rate is m/s
Term
Slides
Definition
• Relatively cohesive unit
▫ Moves along a clearly defined plane or zone of failure
• Little or no internal deformation
• Movement rates are variable
▫ m/yr to m/s
• Types:
▫ Translational
▫ Rotational
Term
Translational Slide
Definition
• Moves along a planar surface
▫ Controlled by a discontinuity or break
• Weak planes:
▫ Bedding plane
▫ Cleavage plane
▫ Fractures
▫ Rock and unconsolidated material contact
Term
Rock slide
Definition
Translational. Frank slide. Lots of forces helping to shear. 100 seconds. Fractures were opening at the top.
Term
Debris slides.
Definition
not common. Often becomes a flow. Identified by a Head scarp - all slides have a head scarp.
Term
Rotational Slide
Definition
Very common along river valleys and highways.
Plane of failure is curved. Top often tilts towards slope.
Happens in rivers because undercutting happens. Occurs with clay.
Easiest to spot in advance. Breaks at top. Parallel curved fractures. Covered by vegetation, so hard to see.
Term
Flows
Definition
Most mass wasting events are or become a flows.
Can have anything in them, key is that there is not internal structure. All the material is jumbled. Normally start as a slide or flow.
Toe is spread out, more if wet.
Can go uphill because momentum.
Rates: any speed it wants.
Term
Creep
Definition
• Slow downward movement of material (rock or soil)
▫ Usually a few cm/yr or less
• Result of gravity, water content and temperature (freeze-thaw)
• Usually involves only the upper part of the substrate
Term
Rippling
Definition
folding over itself, like chicken skin.
Term
Avalanche
Definition
usually triggered. waiting to fail. Weight is an issue; skiing/walking over it. Wind is the #1 trigger of natural avalanches.
Earthquakes trigger DEBRIS avalanches.
Snow avalanches start off as slides.
Debris avalanches start off as falls.
Term
Spreads, Sensitive, quick clay
Definition
Like to liquify, not always at the top. Salt keeps it stable. BUT, if you wash out the salt (via rain), it becomes less stable.

Lava flows underneath will also loosen sediments
Term
Slope stability factors
Definition
• Geology
• Geometry
• Moisture content
• Vegetation
• Human activity
Term
Failure of material
Definition
Occurs on contacts. More places where it touches/moves, more likely to fail.
Term
Failure of consolidated
Definition
harder to fail; harder to move.
▫ Tend to be more stable
 Assuming the material is not significantly anisotropic
▫ Failure occurs along planes of weakness
Term
Failure of unconsolidated
Definition
contain more water, promotes weakness. Goes lots of different places. ANY size possible. MANY zones of failure
Term
Effect of Slope
Definition
Steeper slopes promote mass wasting. Flat, gravity holds it together.
SO, what is keeping it in places? Friction, internal strength, etc.
Driving forces = shearing stress, gravity, roots ripping apart.
Term
SF = Σ(resisting forces)/Σ(driving forces)
Definition
How slope is analyzed. SF = sum of resisting forces / sum of driving forces. If over 1, it is stable. Resisting is stronger. If it = 1, have a problem, unstable - on the fence. If less than 1, going down the hill now, might be held by plants.
Term
Angle of Repose
Definition
Angle of repose, is NOT the slope angle. Maximum angle you can pile it up while still being stable of DRY unconsolidated material. Bigger & more irregular the pieces, can pile it higher. Silts and clays are 90 degrees, very steep.
Term
Slope angle
Definition
the real life angle, with water added, you get a steeper slope. Frank slide was this kind of failure.
Term
Water Effect
Definition
Ice wedging, frost heaving
• Freeze and thawing of material causes:
▫ Mechanical weathering
 Reduce tensile and shear strength of the material
Term
Initiated creep,
Definition
make a little moisture near the surface.
Term
Solifluction
Definition
ground moving, wrinkles. SF below 1.
Term
Gelifucation
Definition
freeze thaw motion. Pushes up, and drops down after
Term
Oversaturation
Definition
More water in the material, above the plane of weakness.
Bigger issue on unconsolidated material. Slightly moist is great. A little TOO much water is bad, makes mud. Consistent environment is okay for steeper stuff.
Term
Clays
Definition
• Unstable when combined with fluids
• Tend to absorb water: Increase size and add weight(20X)

Some are worse than others; quick, leda, thixotropic, sensitive clays.
Mess with salt content, becomes unstable.
Term
Vegetation
Definition
A preventive cure and a possible cause
• Prevents or retards erosion
• Encourages infiltration
• Provides cohesion, BUT adds weight
• Causes weathering (breakdown) of material
Term
Human Activity
Definition
Modification of the landscape and slope
• Development
▫ Add weight, water and/or movemen
Term
Precursor signs for mass wasting
Definition
OBSERVATION:
• Many are too slow or subtle to notice -unless you connect the dots
• Reflector and inclinometer studies
Term
prevention of mass wasting
Definition
• Dewatering the rocks or soil
• Modify or reduce slope geometry (gradient)
• Remove excess weight or load
• Erect stabilization features
• Plant vegetation
• Rock bolts
• “Blanketing”the slope
• Build perpendicular to the planes of weakness
• Slide sheds
Term
Dewatering Structures
Definition
• Removes fluid using a drainage system
▫ Toe drains, Interceptor drains, Drainage ditches, Pumped wells

Just removing SOME of the water. Super common in tropical areas.
Term
Plant Vegetation
Definition
• Adds cohesion through root systems
• Unfortunately, it also:
▫ Increases weight, Increases weathering, Reduces shearstrength of the substrate
Term
Reduce Slope
Definition
• Reduce and modify through:
▫ Reduction
▫ Benching
• Regulations on mining tips:
▫ In Alberta, about 25°
Term
Aberfan, Wales 1966
Definition
inspired regulation of slope angles
Term
Reduce Weight
Definition
• Literally removing material from the substrate
• Removing existing structures
▫ May include dewatering structures
Term
Stabilization Features
Definition
• Stabilize the toe
• And/or intersect possible planes of weakness
Term
prevent a slide from sliding
Definition
Stabilize the toe. Prevent the toe from moving.
Term
Gabions
Definition
Are used at toes, looks naturalish, permeable.
Term
Retaining walls
Definition
- ANY kind of barrier, often used for unconsolidated material. From gardens to cliffs. Heavier material, further back you need to anchor it.
Term
Larger buildings
Definition
need cylinder piles, intersecting the ground.
Term
Rockbolts
Definition
• Increase the effective normal stress by bolting the masses down
• Bolts intersect planes of weakness
• Most effective in areas with:
▫ Low slopes
▫ Thin masses
Term
Blanketing the Slope
Definition
Keeps falling material off of the road. Just keep material along the slope.
Concrete slabbing also works, BUT, you must ensure proper draining.

Flanking is still a danger, material moves from all over the place.
Term
Perpendicular Building
Definition
• Work with the dip of anisotropism
▫ Not against it
• Build structures or cuts perpendicular to the dip of the planes of weakness

Look at slabs when determining danger. Small slabs will fail. Small occasional falls are not as bad as a slab falling. Period.
Ideally build perpendicular to plane of failure.
Term
Slide Sheds
Definition
• Allows the failure to occur
• Diverts the “damage”by using by-passes or over-passes

Does NOT try to prevent failures. Just trying to keep something safe. Let it fail, allow it to go through the failure.
Just hope you planned it right. Hope it fails where you put the shed.
Debris sheds are more predictable. A snow shed is harder to predict.
Term
In the oceans?
Definition
Land slides are small compared to what happens underwater.
Get flows often. HUGE. Don’t often notice it, only when it displaces water and causes a tsunami.
Megatsunamis are comically large. Causes are likely from submarine landslides.
Term
Base level
Definition
= lowest elevation stream can erode down to. Usually at surface of what it flows into.
Term
Longitudinal profile
Definition
= sketch from source to mouth, cave upward shape.
Term
Faster a stream goes
Definition
larger and more dense the material it carries. As it slows, it leaves behind the largest and heaviest particles. Super slow streams have only VERY fine material carried.
Term
Deltas
Definition
Where material meets the lake. These are large fan shaped piles of sediment
Term
Alluvial fan
Definition
= formed when tributary streams flow into a slower stream OR when a stream flows from mountains into a plain
Term
Meander
Definition
= Bends in stream
Term
Cut bank
Definition
= where faster water erodes inside of meander
Term
Point bars
Definition
= where sediment deposited on inside of meander accumulates
Term
Braided stream
Definition
= complex patter of braiding that divides stream many times
Term
floodplain
Definition
= area into which streams overflow in floods. Normal product over time
Term
oxbow
Definition
cutoff meanders when flooding redirects stream more effectively downstream. Can either empty or make a lake
Term
percolation
Definition
moving infiltrated water through ground, heads towards gravity.
Term
Stream Hydrograph
Definition
Fluctuations in stream stage over time, establish the norms
Term
Beach
Definition
= gently sloping surface washed with waves and sediment. Produced locally or deposited sand.
Term
Beach face
Definition
= portion regularly washed by waves as tides rise and fall.
Term
Berm
Definition
= flat part of beach landward
Term
Milling
Definition
= grinding effect of pebbles and debris in waves against a surface. Concentrated at waterline.
Term
Long shore current
Definition
= movement of water laterally across the shoreline, sand is also carried. Results in littoral drift.
Term
Littoral drift
Definition
= gradual sand movement down beach, same as water flow. Usually only has a sustainable beach if there is a consistent supply of sand.
Term
Barrier islands
Definition
= long, low, narrow islands paralleling a coastline. Maybe form from longshore currents and delta sands
Term
Estuary
Definition
= body of water along a coastline, open to sea, tide rises and falls making salt & fresh water meet. Problems in that humans mess with the surrounding areas, and the resulting salinity is affected.
Term
Shearing stress
Definition
= downwards pull causing mass movements. Related to mass of material and downward angle.
Term
Talus
Definition
= coarse rubble that accumulates at the foot of a slope
Term
Slid
Definition
= cohesive unit of rock/soil slips downward along a clearly defined surface/plane
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