2What You’ll Learn How large amounts of water are stored underground. How groundwater dissolves limestone and forms caves and other natural features.How groundwater is removed from the ground by humans and what problems endanger our groundwater supply.
3Vocabulary Terms Infiltration Porosity Zone of saturation Water table PermeabilityImpermeableAquiferTopographyCaveStalactiteStalagmiteTravertineSpringGeyserDrawdownArtesian Well
4Movement and storage of groundwater 3%freshwaterThe Hydrosphere97%Ocean WaterThe hydrosphere iswater on or inEarth’s crust.“hydros” is the Greek word for water.
5Movement and storage of groundwater 10%50%90%From the 3% offreshwater, how much do you think is trapped in the polar ice caps and glaciers?97%Ocean Water
6What is the greatest source ????Polar capsGlaciersBoth a and bWhat is the greatest sourceof freshwater on Earth?
7Movement and storage of groundwater Precipitation and Groundwater
8Movement and storage of groundwater Precipitation and GroundwaterMuch of the precipitationthat falls on land enters the ground through a process called infiltration and becomes groundwater.Only a small portion of runoff is directly returned to the oceans through streams and rivers.Precipitation
9Movement and storage of groundwater Precipitation and GroundwaterSolid precipitation such as snow takes a long while before it becomes runoff or infiltrates to become groundwater.Eventually, the groundwater returns to the surface through springs and then flows back to the ocean.Precipitation
10Movement and storage of groundwater The amount of space between rock particles in underlying sediment is referred to asporosity.Well sorted Highsediments Porosity
11Movement and storage of groundwater The amount of space between rock particles in underlying sediment is referred to asporosity.Poorly sorted Lowsediments Porosity
12Movement and storage of groundwater b.Q: Which of these two do you think will absorb groundwater faster after rainfall?
13Movement and storage of groundwater The porosity of sand can range from 2% to 50% ! The greater the porosity…the faster water is absorbed.
14Movement and storage of groundwater The Zone ofSaturationThe depth below the Earth’s surface at which groundwater completely fills the pores of material is called the zone of saturation.
15Movement and storage of groundwater The Zone ofSaturationThe upper boundary of the zone of saturation is called the water table.
16Movement and storage of groundwater The Zone ofSaturationOnly the water that exists in theZone of saturation is called groundwater.
17Movement and storage of groundwater The Zone ofSaturationZone of aeration – materials are moistbut contain mostly air.
18Movement and storage of groundwater The WaterTableThe depth of the water table varies with the slope of the land.
19Movement and storage of groundwater The WaterTableThe topography of the water table follows the contours of the land.
20Movement and storage of groundwater The WaterTableThe water table rises and falls depending on the season and the amount of precipitation.
21Where is the water table closest to Earth’s surface? FloodplainA SwampA HilltopWhere is the water table closest to Earth’s surface?
22Movement and storage of groundwater In saturated sediment all materials are coated with a thin film of motionless water.In coarse grained materials like sand, this film occupies a relativelysmall portion of the “pore space”.1 mm
23Movement and storage of groundwater Because of thismoving water can flow freely past the open pore spaces.Groundwater flows downhill due to gravity and in the direction of the landscape slope.1 mm
24Movement and storage of groundwater Because water has to squeeze through the small pores in the subsurface material, it usually travels very slow.1 mm
25Movement and storage of groundwater 1 mmvs.0.1 mmSometimes the pores are so small not even a single water molecule can get through.
26Movement and storage of groundwater 1 mmvs.0.1 mmThe ability of a material to let water pass through it is called permeability.
27Movement and storage of groundwater 1 mmvs.0.1 mmFlow rates for these materials can be as fast as 1 m/h (one meter per hour).Q: Which of the two examples of sediment above have the highest permeability.Highly permeable materials include sandstone, limestone, and fractured bedrock.
28Movement and storage of groundwater 0.1 mm0.1 mmWith such tiny pores, some fine grained material is considered impermeable.Examples of impermeable materials are silt, clay, and shale.Flow velocities in impermeable materials are often measured in m/yr (meters per year).
29What two factors determine the flow velocity of groundwater? Answer:The flow velocity depends on the slope of the water table and the permeability of subsurface materials.What two factors determine the flow velocity of groundwater?
30Movement and storage of groundwater Most groundwater flow takes place through permeable layers called aquifers.
31Movement and storage of groundwater Impermeable layers called aquacludes are barriers to groundwater flow.
32? ? ? ? What is an aquifer? Answer: An aquifer is a permeable layer that allows groundwater to flow through it.
33Springs Groundwater Systems Aquifers are commonly composed of sand, gravel, sandstone and limestone.Remember: Limestone is easily dissolved by groundwater…..that’s how cavities in aquifers appear. (A cavity is an open space…like a cave).
34Groundwater Erosion and Deposition CavesCaves form near or below the water table.
35Groundwater Erosion and Deposition CavesStream valleys are lowered and streams become empty as they infiltrate cave openings.
36Groundwater Erosion and Deposition CavesCollapsing caves (or dissolved bedrock) near the surface of the Earth produce sink holes on the Earth’s surface.
37????Answer:Since there are a lot of open spaces due to dissolved limestone, the ground water can flow FASTER in this area of an aquifer.Since the Limestone area of an aquifer is filled with “cavities”, how would this affect the rate of groundwater flow?
38Groundwater Erosion and Deposition CavesCaves are usually located just beneath the water table.As water drips from the ceiling of a cave, it leaves behind small trace amounts of minerals found within the water itself.After a long period of time, these minerals collect to form cone shaped structures called “stalactites”.
39Groundwater Erosion and Deposition CavesAs the water drips to the floor, minerals left begin to build up mound shaped, dripstone deposits.This type of deposit is called a “stalagmite”.Eventually, stalactites and stalagmites will join together to form dripstone columns within the cave!
40So what happens when an aquifer meets an aquaclude? Answer:The aquaclude stops water flow…so when aquifers and aqucludes meet, water is forced out of the Earth….see photo on page 249.So what happens when an aquifer meets an aquaclude?
41Springs Groundwater Systems When aquifers meet aquacludes at or near the surface of the Earth, water is forced out of the Earth….thus producing a SPRING.
42GroundwaterSystemsSpringsThe volume of water produced by a spring can be a mere trickle or a raging river!In a “Karst Region”, springs yield extremely fast moving waters….. they’re called Super Springs.
43Springs Groundwater Systems In areas where there is horizontal sedimentary rock, Springs emerge in valleys very close to aquifers.
44Springs can occur at the edges of perched water tables. GroundwaterSystemsSpringsSprings can occur at the edges of perched water tables.
45Springs Groundwater Systems Springs can also emerge at fault lines.Sometimes Springs emerge along fault lines!
46Sometimes Springs emerge along fault lines! GroundwaterSystemsSpringsIn Limestone regions, springs discharge water from underground pathways.Sometimes Springs emerge along fault lines!
47Temperature Of Springs Groundwater vs. Air Groundwater Systems Spring water can be hot, warm, or cold….depending upon where the spring is located.Winter SummerTemperatureGroundwater vs. AirAirWaterAirWater