Groundwater
Geology 101 with Gibson at Texas A&M University
About this deck
By: Sarah Van Sciver
Textbook:
Essentials of Geology with Geotours Workbook (Third Edition)
Created: 2012-05-02
Size: 52 flashcards
Views: 23
Textbook:
Essentials of Geology with Geotours Workbook (Third Edition)Created: 2012-05-02
Size: 52 flashcards
Views: 23
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groundwater
water that is stored in cracks and pores beneath earth's surface
Aquifer
A body of saturated rock or sediment through which water can move easily
water table
the upper level of the saturated zone of groundwater
saturated zone
a subsurface zone in which all rock openings are filled with water
an aquifer overlain by an aquitard or aquiclude
- higher temp
- higher ph
- higher hardness
- less dissolved oxygen
Lowering of the water table around a pumping well.
flowing artesian well
an artesian well in which water flows freely at Earth's surface because the pressure surface is above ground level
Hydraulic Gradient
The slope of the water table.
Darcy's Law
V=K[(h1-h2)/L]
Relationship of groundwater flow rate between two points to the difference in hydraulic head between them.
Water flows "downhill"
Velocity of GW is related to Hydraulic gradient (slope) and conductivity (permeability of rock/sediment & density/viscosity of fluid)
Aquitards
- Impermeable layers that hinder or prevent water movement
Unsaturated zone –
the area above the water table where openings in soil, sediment, and rock are not saturated but filled mainly with air
Primary Porosity
original porosity in the rocks (i.e., initial empty space between/within the particles that make up the rock)
secondary porosity
develops from fractures, dissolution, and cavities (igneous rocks, volcanic rocks)
Lithification
The process in which sediments compact under pressure, expel fluids, and gradually become a solid rock.
reduces porosity
streams and lakes
Occur where the water table is above the surface
aquifers
highly permeable rock or regolith - economically useful as a source of water
Perched water table –
a localized zone of saturation above the main water table, created by an impermeable layer (aquiclude)
Recharge zones
areas where water infiltrates into an aquifer (often very slowly). Aquifers are most likely to become contaminated in recharge zones.
Discharge Zones
An area where groundwater emerges from the subsurface to become or join a surface waterbody
Phreatic zone
-The region of rock or soil in which pore spaces are completely filled with liquid
-AKA saturated zone
GW flow
Slow in the Phreatic Zone
Fast in Karst Topography
High Plains Aquifer
Provides 30% GW used for irrigation in the U.S.
Recharged with rainwater
Potentiometric surface
- The height that the water pressure would raise the water if the water was unconfined.
Water Towers
idea of potentiometric surface is used to get water to all the houses
this is why it is placed at a high elevation
Well
A hole dug below the water table which is used to pump out water for use
wells will refill naturally unless pumping rate exceeds the natural flow rate => Cone of depression
Rule of Capture
A property owner may withdraw as much water as he likes from beneath the surface of his property without liability, even if it withdraws water from underneath his neighbor’s property. “First in time, first in right.”
Consequences of Rule of Capture:
a. Resources will be used up.
b. Leads to overinvestment in capture technology.
c. Example - Ozarka
Groundwater Districts
used to limit the "rule of capture"
Ogallala Aquifer
-World's largest
averages 60m thick
450,000 km2
-Underneath Great Plains
-Makes agriculture productive(Breadbasket of US)
- big concern: Is being depleted (irrigation for crops)
1930's Dust Bowl
resulted in part from the greater usage of pumps in during the mechanization of farm lands in the 1920s.
Leachate
noxious liquid material capable of carrying bacteria, produced when surface water or groundwater comes into contact with solid waste
Ideal Storage of Hazardous Wastes
would not be affected
- chemically by groundwater
- physically by earthquakes
- accidentally by people
Geology of Safe Sites
Few Fractures, Low permeability
No present or future economic mineral
Local groundwater flow should be away from plans and animal life
Low rainfall
Low probability of earthquake or volcanic activity
Saltwater intrusion
Occurs when the freshwater is depleted along a coastline and it is replaced with salt water seeping in from the ocean
Good minerals in water
Ca
Mg
Trace Metals
infiltration
the seepage of water into soil or rock.
Relative Humidity
the amount of water vapor in the air, expressed as a percentage of the total amount of water the air could hold at the same temperature if it were saturated
Porosity
Percentage of total volume of rock or sediment that consists of pore spaces
Permeability
the ability of a material to transmit a fluid
the best groundwater reservoirs have
high permeability and high porosity
(also true of source rock)
AQUICLUDE
the rock mass or layer that impedes or prevents the movement of ground water
Carbonic Acid
the most abundant, natural acid is:
Most groundwater withdrawn in the United States is used for...
Irrigation
hard water
water with a high concentration of calcium and magnesium
good for the heart
Precipitation includes...
evaporation and runoff
Groundwater comprises how much of the world's drinking water supply?
50%
Groundwater comprises how much of the world's supply of fresh water?
99%
Granite has the _______ porosity
lowest
Which area in Texas has the cleanest drinking water
Houston
Which area in Texas has the nastiest water? Why?
College Station, because of Biocarbonates
potable water
water that is safe to drink
What can contaminate an aquifer?
landfills
agricultural regions
gas stations
About this deck
By: Sarah Van Sciver
Textbook: Essentials of Geology with Geotours Workbook (Third Edition)
Created: 2012-05-02
Size: 52 flashcards
Views: 23
Textbook:
Essentials of Geology with Geotours Workbook (Third Edition)Created: 2012-05-02
Size: 52 flashcards
Views: 23
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj