creep
the imperceptibly slow downslope movement of rock and soil particles by gravity
debris avalanche
a sudden, rapid movement of a water-soil-rock mixture down a steep slope
debris flow
a moving mass of a water, soil, and rock intimately mixed. More than half of the soil and rock particles are courser than sand, and the mass has the consistency of wet concrete
driving force
Fd. acts to pull the mass or slope down
fall
material tumbles as it moves
factor of safety
the balance between resisting and driving forces in a landslide. Failure occurs when the factor safety is less than one - when resisting forces are no longer greater than driving forces
friction
A force that opposes motion between two surfaces that are in contact
landslide
the downslope movement of rock/soil as a semicoherent mass on a discrete slide surface or plane
mass movement
the downhill movement of rock and soil because of gravity
mass wasting
a general term for all downslope movements of soil and rock material under the direct influence of gravity
normal force
the force applied perpendicular to the failure plane of a landslide
pore pressure
the stress exerted by the fluids that fill the voids between particles of rock or soil
resisting force
(landslide) friction along the slide plane and normal forces across the plane
rock fall
the rapid mass movement of rock down a steep slope or cliff
rock slide (translational landslide) (block glide)
a landslide in which movement occurs along a well-defined plane surface or surfaces, such as bedding planes, foliation planes or faults
sinkhole
circular depression formed by the collapse of a shallow cavern in limestone
slide plane
a curved or planar surface along which a landslide moves
slump (rotational landslide)
a slope failure in which sliding occurs on a well-defined, concave-upward, curved surface, producing a backward rotation of the slide mass
subsidence
sinking or downward settling of the Earth's surface due to solution, compaction, withdrawal of underground fluids, cooling of the hot lithosphere, or loading with sediment or ice
talus
coarse, angular rock fragments lying at the base of the cliff or steep slope from which they were derived
What is the primary force that makes slopes unstable?
Gravity
What would you look for as evidence of creep? as evidence of a historic debris flow?
tilted fences, telephone poles, tombstones, curved trees... destruction of buildings
How does a rotational landslide (slump) differ from a translational landslide (block glide)?
rotational landslides occur on a curved surface while translational landslides occur on plane surfaces
Which type of mass movement is the slowest?
Creep - slumps - translational slides - debris/earth/mud flows - avalanches - falls
How does water influence mass movement?
water can trigger movements
What are some common engineering solutions to mass movement?
reduce slope, water drainage, redistribute, retaining walls, diversion techniques
What are other ways to mitigate losses due to mass movement?
avoidance
How do mines contribute to collapse?
mine ceiling left unsupported
What are natural causes of collapse?
cave ceilings collapse, anywhere there is limestone
barrier island
a narrow sand ridge rising slightly above high tide level that is oriented generally parallel with the coast and separated from the coast by a lagoon or a tidal marsh
breakwater
an offshore rock or concrete structure, attached at one end or parallel to the shoreline, intended to create quiet water for boat anchorage purposes
dredging
the excavation of earth material from the bottom of a body of water by a floating barge or raft equipped to scoop up, discharge by conveyors and process or transport materials
eustatic sea level change
world-wide sea level change
fetch
the unobstructed stretch of sea over which the wind blows to create wind waves
groin
a structure of rock, wood, or concrete built roughly perpendicular to a beach to trap sand
jetty
structure built perpendicular to the shoreline to improve harbor inlets or river outlets
longshore current
the current adjacent and parallel to a shoreline that is generated by waves striking the shoreline at an angle
longshore drift
the movement of sand along a beach caused by longshore currents
seawall
a rock or concrete structure built landward of a beach to protect the land from wave action
tide
Movement of large bodies of water up and down based on the moons gravitational pull.
wave base
the depth at which water waves die out, equal to approximately half the wavelength
wave length
the distance between two equivalent points on two consecutive waves; ex: crest to crest or trough to trough
wave refraction
the bending of wave crests as they move into shallow water
What creates ocean waves?
...
Why don't submarines experience severe storms at sea?(hint: think about "wave base")
The storm can't reach those depths
How do longshore currents develop, and how do they impact beaches and swimmers?
...
What shoreline structures are built to impede longshore drift? What is the pattern of sand deposition and erosion around them?
Dams,
What effect do sea walls have on the sandy beach next to them?
...
aquifer
a water bearing body of rock or sediment that will yield water to a well or spring un usable quantities
aquitard
do not readily transmit water.. low permeability
artesian wells
wells in which water flows naturally to the surface
bioremediation
use of bacteria to degrade petroleum-based pollutants. Used primarily for remediating soil contamination
cone of ascension
pressure is removed from overlying freshwater, saltwater forms
cone of depression
the cone shape formed by the water table around a pumping well
confined aquifer
water-bearing formation bounded above and below by impermeable beds or beds of distinctly lower permeability
DNAPL
Dense Non-Aqueous Phase Liquid. Includes chlorinated solvents and long-chain hydrocarbons (heavy oils/asphalts), DNAPLs do not adhere to soil particles. TCE from dry cleaners
gaining stream
a stream that receives water from the zone of saturation
ground water
the part of subsurface water that is in the zone of saturation (below the water table)
hydrologic cycle (water cycle)
the constant circulation of water from the sea to the atmosphere, to the land, and eventually back to the sea. Driven by solar energy
LNAPL
Light Non-Aqueous Phase Liquid, Short chain hydrocarbons including gasoline. NAPLs adhere to soil particles
losing stream
a stream or reach of a stream (typically in arid regions) that contributes water to the zone of saturation
perched water table
the upper surface of a body of groundwater held up by a discontinuous impermeable layer above the static water table
permeability
the degree of ease with which fluids flow through a porous medium
plume
In groundwater a plume is an underground pattern of contaminant concentrations created by the movement of groundwater beneath a contaminant source. Contaminants spread mostly laterally in the direction of groundwater movement. The source site has the high
porosity
a materials ability to contain fluid. ratio of the volume of pore space in a rock or sediment to its total volume. expressed as a %
residence time
the average length of time a substance remains in a given reservoir
salt water intrusion
near coastlines. caused by over pumping wells and too little recharge. King and Queens counties on LI import water
saturated zone
The portion of subsurface soil and rock where every available space is filled with water. Aquifers are located in this zone.
spring
A flow of water from the ground at a place where the surface of the land dips below the water table.
sustained yield (hydrology)
the amount of water an aquifer can yield on a daily basis over a long period of time
unconfined aquifer
underground body of water that has a free (static) water table. that is, water that is not confined under pressure beneath an aquacide
unsaturated zone
A layer of rocks & soil ABOVE THE WATER TABLE in which the pores contain air as well as water
water table
the contact between the zone of aeration and the zone of saturation
potentiometric surface
is the elevation the pressurized ground water will rise to if allowed
What happens when too much ground water is pumped from the ground near the ocean coast? Where has this happened in the U.S.?
Salt water intrusions, LI
What are ways to prevent salt water intrusion?
...
What is "Sustained Yield"?
hydrology: the amount of water an aquifer can yield on a daily basis over a long period of time
What is recharge? What human actions reduce recharge?
Rate at which water enters the saturated zone. Urbanization
What are some of the ground water pollution sources in urban areas?
leaking sewer pipes, leaking storage tanks, chemical waste pits, salt off of roads, lawn fertilizers
What does LNAPL stand for? Name an example
Light, non-aqueous phase, liquids. gasoline
What does DNAPL stand for? Name an example
Dense, non-aqueous phase, liquids. TCE from dry cleaners
Which pollutant is best cleaned up by bioremediation?
gasoline. Floats on water table, slowly dissolves into the water, bacteria break it down
Why is MTBE used as a gas additive and why is it bad?
methyl tertiary-butyl ether, Gasoline additive for better air. Contaminates ground water and bacteria won't eat it
chemical weathering
breaks rock into smaller pieces by chemical reactions. Solution, oxidation, hydrolysis
contour farming
Plowing and planting across the changing slope of land, rather than in straight lines, to help retain water and reduce soil erosion.
erosion
the weathering and transportation of the materials of the Earth's surface
frost wedging
the opening of joints and cracks by the freezing and thawing of water
hydrolysis
the chemical reaction between hydrogen ions in water with a mineral, commonly a silicate, usually forming clay minerals
no till farming
Method for reducing soil erosion; plant stalks are left in the field after harvesting and the next year's crop is planted within the stalks without plowing.
oxidation
A chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust
physical weathering
mechanically breaks rock into smaller pieces. Frost wedging, plant activity
residual soil
soil formed in place by decomposition of the rocks upon which it lies
rill erosion
the carving of small channels, up to 25 cm (10 in) deep, in soil by running water
salinization
Accumulation of salts in soil that can eventually make the soil unable to support plant growth.
sheet erosion
the removal of thin layers of surface rock or soil from an area of gently sloping land by broad, continuous sheets of running water, rather than by channelized streams
soil
loose material on the surface of Earth which supports plant life
soil horizon
a layer of soil that is distinguishable from adjacent layers by properties such as color, texture, structure, and chemical composition
solution (chemical weathering form)
the dissolving of rocks and minerals by natural acids or water
strip farming
Planting different kinds of crops in alternating strips along land contours; when one crop is harvested, the other crop remains to protect the soil and prevent water from running straight down a hill
weathering
the physical and chemical breakdown of materials of the Earth's crust by interaction with the atmosphere and biosphere
terracing
Carving small, flat plots of land from hillsides to use for farming
transported soil
soils developed on regolith and transported and deposited by a geologic agent
urbanization
covering soil with buildings and roads
What are the soil horizons and how does each one form?
humus, topsoil (zone of leaching), transition, subsoil (zone of accumulation)
How is erosion different than weathering?
erosion is the removal and transportation of material while weathering is the breaking down of material to make sediments and soil
What are some of the processes of physical weathering?
frost wedging and plant activity
What are the processes of chemical weathering?
Solution, oxidation, hydrolysis
How long does it take soils to develop?
hundreds of years
What is the effect of a humid climate (with lots of rain fall) on the rate of chemical weathering?
Increases the rate
What actions do farmers take to reduce soil erosion?
terracing, strip farming, no till farming, contour farming
Besides erosion, what are two more ways we loose soil?
urbanization, salinization