Unit 5 Chapter 16 Groundwater
Section 1 Water beneath the surface
Ground water is ______________________________
_______________________________________
Properties of Aquifers
Aquifer - ______________________________________
- As the distance from water source increases,
the depth of the aquifer increases
Porosity
Porosity – ______________________________________
Water movement needs large spaces, the bigger,
the more water that moves.
Greatest pore space ___________________________________
Least pore space ______________________________________
Permeability
Permeability - ______________________________
- ____________________________________
- Permeable: sand, gravel, sandstone
- Impermeable: clay, igneous rocks, metamorphic
rocks, shale
- Cracks in rocks increase permeability, rocks like
granite becomes permeable
-Pumice can be porous but it is not permeable
_______________ – water that passes over a sedimentary
or rock that forms a film of water on the object. This can
only be removed by transpiration or evaporation. This can
make some material seem impermeable.
Zones of Aquifers
As groundwater seeps into the ground, zones or layers are
created. Some layers will contain water while others may
not.
Zones of Saturation
Zone of Saturation _____________________________________
Water Table:
Water Table - level of saturated sand underground
-water underground is very clean - drinkable
-ground water is held in pore spaces
-sand is approximately 40% pore space
Zones of Aeration
Zone of Aeration _______________________________________
- soil can hold more water
Capillary action – interaction between water & soil
ex. Wet a paper towel see the water travel up the
paper
Movement of Groundwater
Gradient will affect the water table along with permeability
and porosity. If it is steep, water will run off more, if it is
flat, more will sink into the ground.
Topography and the Water Table
Location of the water table:
At the surface:
Humid Climates
_________________________
Deserts:
_____________________________
Woods, Fields, Farmland:
_____________________________
Hill Side Areas:
_____________________________
_____________________________
Factors that determine the depth of the water table:
1. rain fall
2. seasons – time between rains
3. slope of ground (land)
4. soil thickness
5. Climate
6. Human Factor (drilling)
Perched Aquifer – impermeable layer above the water table
Conserving Groundwater
Regulating the use of groundwater is among some of the
ways we can conserve our water. Recycling and purifying
the water are ideas. Using recharge zones (areas where
water can re-seep into the ground. Don’t pollute.
Wells and springs
A well is a hole in the ground below the water level so you
can get water.
Ordinary Wells and springs
An ordinary well is man made by drilling into the ground. It
must be below the lowest level of the water table.
_____________________ formed when water from a well is
pumped and it lowers the water table in the ground by the
well.
Ordinary spring is the water table on the surface of a hillside
or by rugged terrain.
Artesian Wells and springs
An artesian well is water under pressure that flows freely
from an aquifer under an impermeable layer; no pumping
needed nature does it all alone. It can be a source of water
from some artesian springs.
Hot Springs
A __________ is water that is naturally heated. As you go
down in the earth the temperature rises 1o C for every
40 meters of depth. This causes the water to become
superheated.
A ________is a crack in the rocks that allow water to reach
the surface. They may form an oasis in the desert.
________ occur when hot water moves through clay. The
clay liquefies and bubbles and becomes molten.
Geysers
Geysers are gushes of hot water & steam that erupts
through water tube with constrictions. Water gets
trapped, superheats, pressure builds until it opens the
constriction, water explodes out, turns to steam.
Yellowstone - "Old Faithful"
Section 2
Ground water and chemical weathering
As water enters the ground minerals that are in the soil
become dissolved. The more layers the water passes the
more chance it has to have many mineral seep into the
water supply.
Also affecting the mineral content is the distance that the
water travels, the type of rock it travels over and the water
temperature.
Minerals can dissolve in the ground water
Hard Water - ________________________________
Ca - comes from Calcite
Soap Scum - __________________________________
Results of Weathering by Water
Hot ground water from cracks and fissures can leave behind
deposits after the water evaporates, from geysers is silica
but you can also find quartz, calcite, gold & silver.
_______________– formed from minerals left from
evaporated water deposit in buried wood. The minerals
replace the actual wood in every detail. Arizona’s petrified
forest is formed this way from silica left behind.
Caverns
Forming Caverns
Dissolving limestone forms cracks or fissures that run
horizontally between rock beds. After 1000’s of years the
cracks become bigger and bigger forming a network of large
open areas.
Stalactites and Stalagmites
Stalactite - _____________________________________
Stalagmites - ___________________________________
Sinkholes
Sinkhole formed when CO2 & water dissolve the rock away
or rock dissolves underneath, the land caves in, leaving a
hole in the ground.
Guatemala (June 2010)
Natural Bridges
A natural bridge occurs when the roof of a cavern collapses
in several places and a relatively straight line of sink holes
form.
Virginia
Karsts Topography
It is a term given to an area that has unusual topography.
The landscape will be different from the rest of the area. It
will usually be in areas where the bedrock is either calcite or
dolomite (why do you think)
It is characterized by:
1. lost rivers – surface streams disappear underground
2. arches and spirals
3. underground rivers and ponds
You can find this in places like:
New England (especially New Hampshire)
Mammoth Cave Kentucky
Alabama, Florida, Tenn and Indiana