Midterm Flashcards
What is fresh water?
Glaciers and ice caps 68.6%+ groundwater 30.1%+surface water and other freshwater 1.3%
What is the total global water?
96.5% of oceans +saline lakes 0.07%+saline ground 0.93% + freshwater 2.5%
What’s surface water and other freshwater?
Ice and snow 73.1%+ lakes 20.1%+ soil moisture+ swamps and marshes 2.53%+ revers 0.46%+ biological water 0.22%+ atmospheric water 0.22%
Percent of useable water, groundwater, lakes, rivers and water useable by humans
99% of unusable 1% of water useable by humans 99% of groundwater 0.86% of lakes 0.02% of rivers
What’s water?
It is :
Bipolar, adhesive( sticks to charged surfaces), Hightower surface tension( attraction to itself), low viscosity, transparent, capillary( controls water in the vadose zone), also universal solvent( salts, acids, sugar, oxygen, carbonate), high heat capacity( high boiling and melting point) and 3 distinct phases( solid, liquid, gas)
What’s hydrogeology ?
The study of the occurrence, movement, distribution of geological interaction of water in the earth’s crust.
What’s hydrology?
The study of the occurrence and movement of water on and over the earth’s surface.
What’s groundwater?
Water in the pore spaces of the surface below the water table.
Whats water table?
A boundary between the zone of saturation and the zone of unsaturated.
What’s the saturated zone?
It’s below the water table all spore space is saturated with water.
Whats the surface water bodies?
Are areas where the water table intersects the earth’s surface.
Groundwater flows…
(Slowly) though pore space and cracks, pulled by gravity and pushed by the force of water above and behind it.
What’s recharge area?
an area where water enters the aquifer moving downward from the surface to the water table.
What’s discharge area?
The area where the water exists the aquifer
Groundwater contributes:
> 50% of the domestic water supply of the USA
Over 30% of the Canadian domestic water supply
Over 80% of our rural water supply
23% of Alberta’s water
40%of Canadian municipalities
Famous examples of aquifer ‘mis’ use:
- Mexico City ( compaction of aquifer has led to differential subsidence)
- holland ( drained for agriculture)
- cenotes( dissolution and collapse features common in the yucatan peninsula)
- disappearance of the Everglades.
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Application for hydrogeology:
- water resources and supply
- groundwater quality and remediation
- mineral and petroleum accumulations
- geologic and geomorphic process
What’s the water cycle?
The continuous circulation of water between ocean, atmosphere and land both on the surface and within the surface.
What is transmissivity?
It’s the rate at which groundwater flows horizontally through an aquifer.
What’s storativity?
It’s the volume of the water released from the storage per unit decline in hydraulic head.
What’s residence times?
It’s the average time required to replace an entire volume with new water. ( variability of water quality and quantity)
What’s the surface environment ?
- comprised of porous media( ie un consolidated media)
- pores may contain water and or air( near surface contain both fluids unsaturated(vadose) or aerated) (also deeper regions contain only water the saturated (phreatic zone)
What’s the capillary fringe? And what’s its height?
It’s a subsurface layer which groundwater flow from the water table to fill pores by a capillary action, pores are filled with water due to the tension saturation. The height of capillary is related to the pore size( small pore= large fringe)
What’s an aquifer? Types of Aquifer?
It’s a permeable material where water flows and storage( limestone,sandstone and gravel).
2 types: unconfined and confined
Unconfined: an aquifer where the water table is upper boundary also called phreatic aquifer.
Confined: it’s an aquifer bound by aquitards( bed rock aquifer)
What’s a perched aquifer?
It’s a special type located above the regional water table due to low permeability layer beneath it
Whats an artesian aquifer?
occurs when there is positive hydraulic head in the aquifer, when an aquifer’s recharge area is higher in elevation than the drainage point. This allows the porous aquifer to have a positive pressure and possibly even flow water to the ground.
whats hydraulic head?
it is the sum between elevation and pressure head
flowing artesian aquifer?
an aquifer with positive hydraulic head that will discharge to the surfaceT
whats the structure of porous media?
the amount of available pore space (storage) and the size and interconnectivity of pores (transmission)
4 types of porosity:
- primary porosity is the space or voids between pores.
- secondary porosity included voids from fractures, joints, faults, solution cavities,
- effective porosity is the interconnected pores that contribute to flow (permeable porosity)
- controlled in unconsolidated sediments by packing, grain size, grain orientation, sorting, grain shape.
Main types of porosity
1) Inter granular(sand and gravel)
2) Crevice(Igneous rocks)
3) Solution(Limestone)
whats permeability?
a measure of the ability of material (such as soils or bedrock) to transmit fluidslterna
What is porosity?
The percentage of a material’s total volume that is pore space.
What causes the variation in porosity values?
- Grain size and shape
- Packing style
- sorting
- Rock type
what is high and low porosity?
high porosity(gravel(well storage),clay) low porosity ( cement sandstone, limestone, gravel, sand, clay, shale)
darcy’s law?
THE VELOCITY OF THE FLOW PROPORTIONAL TO HYDRAULIC GRADIENT [flow rate Q= -KA(h1-h2)/l (l3/t) K: (L/T)
processes transforming rocks
- Melting
- Recrystallization
- Weathering
- mechanical,
- chemical,
- Mass wasting,
- Erosion (wind, ice, water),
- deposition
- Lithification
- Metamorphism
Weathering and types
the physical disintegration and chemical decomposition of rocks and minerals at or near Earth’s surface.
2 types: mechanical and chemical
mechanical weathering?
When a rock undergoes mechanical weathering, it is broken into smaller and smaller pieces, each retaining the chemical characteristics of the original material.
Four important physical processes that lead to the fragmentation of rock:eT
Frost action
Unloading or pressure release
Thermal expansion and contraction
Organic activityface
frost action
Water expands when it freezes, as a result, water that seeps into the cracks and voids in rocks will, upon freezing, expand and wedge the rock apart.
This process is called frost wedging
Thermal expansion and contration
So heating causes the rock to expand, cooling causes it to contract.
Organic Activity
Plant roots grow into fractures in rock, roots wedge the rock apart.
Mass wasting
the downslope movement of rock material under the influence of gravity is called Mass Wasting, i.e Landslides
Factors such as cohesion and friction define a slope’s shear strength and combine with the angle of slope to influence how and when mass wasting occurs
Erosion-Water
The ability of a stream to erode and transport material is directly related to its velocity.
Erosion - Ice
the slow movement of glacial ice profoundly modifies the landscape through erosion, sediment transport, and deposition. Flow in three different processes:Bulldozing, plucking, abrasion
Erosion- Wind
Wind is not confined to channels, so it can spread sediment over wide areas, as well as carry it high into the atmosphere
- Deflationis the lifting and removal of loose surface material
- The resulting surface of coarse pebbles or gravels is called desert pavementor an ablation surface
- wind also erodes by abrasion, natural sandblasting
- can create landforms: dunes or loess (extensive blankets of windblown silt or clay)
Chemical Weathering
Involves the complex processes that alter the internal structures of minerals by removing and/or adding elements
Rates of weathering
- Size of the particles
- Mineral makeup
- Climatic Conditions, esp. Temperature and moisture
- Differential Weatheringresults in spectacular/peculiar landforms like hoodoos and natural bridges, arches, etc.
Sedimentary Rock
Sediments are deposited and lithified to become Sedimentary Rocks (remember the Rock Cycle)
sediments may be:
Detrital
Organic chemical
Inorganic chemical
lithification?
the process by which sediments compact under pressure, gradually become solid rock, usually occurring through compaction and cementation, but includes all the processes which convert unconsolidated sediments into sedimentary rocks.
Methods of transportation and its results
Wind (cly,dust), ice, water(river). Transport results in sorting, rounding, and maturation.
types of sediments:
Detrital: composed of rock fragments and mineral grains which are moved by wind, water or ice and settle out when current energy can no longer transport them
Chemical: precipitated out from a solution either inorganically or organically
whats the size of gravel?
Gravel is made up of fragments >2 mm in diameter and consists of fragments and pebbles of other rocks.
whats the sand size?
Sand sized particles range from 1/16 mm - 2 mm and typically consist of individual mineral grains.ocks.e
whats the silt size?
Silt sized particles range from 1/256 mm -1/16 mm
whats the clay size?
Clay sized particles are <1/256 mm in diameter.
Chemical sediments:
inorganic(accumulation of dissolved minerals over the vast length of geological time has contributed to the saltiness of the ocean) or organic(Sediments that are the result of precipitation aided by biological processes are referred to as organic), classified by composition, texture, appearance, and physical components (e.g. Fossils)
what is soil?
the mixture of minerals, organic matter, gases, liquids, and micro and macro organisms that support plant life. Acts as a medium for plant growth, water storage, supply and purification, habitat, and modifies the atmosphere. Composition reflects the climate, elevation, slope, parent materials, and time
soil profile:
1) oldest soil layer
2) Youngest soil layer
3) Parent rock
4) rotten rock
what are passive and active techniques?
PASSIVE TECHNIQUES: Detect variations in natural earth fields such as gravitational or magnetic
ACTIVE TECHNIQUES: Signals are generated and transmitted into the Earth, and subsequently recorded as they have passed through and been modified by the Earth
Seismic Refraction:
is used for investigating subsurface ground conditions utilizing surface-sourced seismic waves.
seismic refraction: applications
Map faults and fracture zones
Determine depth and dip of bedrock
Determine depth to groundwater
seismic refraction: advantages
- Fast field operation
- requires less time and expense than comparable seismic reflection methods or drilling
- Estimate material properties from acquired seismic velocity data
- Greater vertical resolution than electrical, magnetic, or gravity methods
- Limited intrusive activity and is non-destructive
electromagnetic: applications
- Mapping groundwater contaminants
- Minerals exploration
- Detection of buried metallic structure
- Detection of buried waste materials
Electromagnetic: Advantages
- Fast, accurate and cost effective
- Conduct surveys under most geologic conditions
- Exploration depth to 20 feet
- Allows measurement without electrodes or ground contact
GROUND PENETRATING RADAR
uses high frequency pulsed electromagnetic waves (generally 10 MHz to 1,000 MHz) to acquire subsurface information.
Energy is propagated downward into the ground and is reflected back to the surface from boundaries at which there are electrical property contrasts.
GPR is a method that is commonly used.
GPR applications:
Detection of pipes, drums, barrels, and other metallic and non-metallic object, detection of hydrocarbon contamination
GPR advantages:
Fast and cost effective
Non-Intrusive and Non-Hazardous
Operational in arctic environmentsganic
spontaneous potential
measures the electrical potential field caused by ambient DC electrical currents in the earth.
LIDAR
a remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light
