Warm – Up 2/6
 Draw a meander and label these locations: erosion,
deposition, faster water, and slower water.
Groundwater
Springs, Wells, and Aquifers
Movement and Storage of
Groundwater
The Hydrosphere: water on and in
Earth’s crust
 97% contained in the oceans
 3% of this water contained by landmasses (nearly all
freshwater)
 More than 90% of freshwater on Earth in the form of
polar ice caps and glaciers
 Remaining freshwater is groundwater
 Rivers, streams, lakes only small portion of Earth’s
freshwater
Precipitation and Groundwater
 Evaporation of ocean waters, forms
clouds/precipitation, weather systems and winds
move this moisture build up all over Earth
 Falls to land and enters ground through infiltration,
becoming groundwater (solid precip. stays for longer
periods of time until melting)
 Groundwater moves through ground, returns to
surface via springs, then flows back to oceans.
Groundwater Storage: Where does
the water go?
 Subsurface materials contain pores; the amount of
pore space in material called porosity
 The greater the porosity, the easier water can flow
through subsurface materials
 Large quantity of groundwater are stored in the pore
spaces of rocks and sediments
The Zones
 Def: depth below Earth’s surface at which
groundwater completely fills all the pores of a
material
 Upper boundary of this zone= water table
 Only the water in the zone of saturation is called
groundwater
 Above the water table, materials are moist, but
because they are not saturated with water, air
occupies much of the pores. This area is called the
zone of aeration.
The Water Table
 Depth varies with local conditions
 In stream valleys groundwater is close to the
surface; water table only few meters deep
 Hilltops/arid regions tens to hundreds meters
deep
 Water table fluctuates with season and
weather conditions because of its
dependence on precipitation
Groundwater Movement
 Flows downhill in direction of slope of the water table
 Moves extremely slow because the water has to travel
through numerous tiny pores
 Ability of material to let water pass= permeability
 Large connected pores= high permeability (sand and
gravel)
 Silt and clay=tiny pores=impermeable
 Steeper slope of water table= higher velocity of
groundwater
Aquifers
 Most groundwater flows through permeable layers
known as aquifers
 In aquifers, the pore spaces are large and connected.
 Aquicludes: barriers to groundwater flow; these
layers are impermeable because the pores of
materials are small.
Springs
 The exact places where groundwater emerges
depend on the arrangement of aquifers and
aquicludes in an area.
 Where aquifers and aquiludes come in contact,
groundwater will discharge at Earth’s surface. This
area is called a spring.
Groundwater Erosion and
Deposition
Dissolution By Groundwater
 Dissolution and formation of calcium carbonate play
role in formation of limestone caves
 Cave: natural underground opening with connection
to Earth’s surface
 Formed when groundwater dissolves limestone
 Most develop in the zone of saturation just below
water table
Karst Topography
 Sinkhole: depression in the ground caused by the
collapse of a cave or by the direct dissolution of bedrock
by acidic rain or moist soil
 Disappearing Streams: feature that occurs when a
surface stream drains into a cave system and continues
flowing underground, leaving a dry valley above.
 Limestone regions that have sinkholes and disappearing
streams are said to have karst topography
Groundwater Deposits
 Hard Water: contains high concentration of calcium,
magnesium, or iron
 Common in limestone areas
 Deposits of calcium bicarbonate can clog water pipes
Groundwater Deposits
 The most remarkable feature produce by
groundwater are the rock formations called
dripstones. They decorate many caves above the
water table.
 The formations are built over time as water drips
through the cave.
 Each drop of water hanging on the ceiling of a cave
loses carbon dioxide and precipitates calcite (calcium
ion)
Types of Dripstone
 Stalactites: hangs from the cave’s ceiling like icicles
and forms gradually as minerals buildup from
precipitated groundwater.
 Stalagmites: found on the cave’s floor as a moundshape; they are made over time by water dripping to
the floor.
Wells: Ordinary and Artesian
 Wells: holes dug or drilled into the ground to reach an
aquifer.
Ordinary Well
 The simplest wells are those that are dug or drilled
below the water table, into what is called a water-table
aquifer.
 How it works: as water is drawn out of a well, it is
replaced by surrounding water in the aquifer.
 Overpumping of the well lowers the water level and
creates a depression around it.
 Drawdown: the difference between the original water
level and the new water level after pumping.
 Recharge: water from precipitation replenishes the
water content of an aquifer.
Artesian Well
 An aquifer’s area of recharge is often at a higher
elevation the rest of the aquifer.
 An aquifer that contains water under pressure is
called an artesian aquifer. This pressure is due to the
aquifer being located between aquicludes.
 When the rate of recharge is high enough, the
pressurized water can spurt above the land surface
creating a fountain known as an artesian well.