2. Objectives Describe how groundwater is stored and moves underground. Movement and Storage of Groundwater Explain what an aquifer is. –infiltration –porosity –zone of saturation –water table –permeability –aquifer Vocabulary

3. About 97 percent of the hydrosphere is contained in the oceans. The water contained by landmasses—nearly all of it freshwater—makes up only about 3 percent of the hydrosphere. Freshwater is one of Earth’s most abundant and important renewable resources. The Hydrosphere The water on and in Earth’s crust makes up the hydrosphere. Movement and Storage of Groundwater

5. The Hydrosphere Movement and Storage of Groundwater

6. Precipitation and Groundwater Evaporation of seawater introduces water into the atmosphere in the form of invisible water vapor and visible clouds. Movement and Storage of Groundwater Precipitation brings atmospheric moisture back to Earth’s surface. Infiltration is the process by which precipitation that falls on land surfaces enters the ground and becomes groundwater. Only a small portion of precipitation becomes runoff and is returned directly to the oceans through streams and rivers.

7. Groundwater Storage Puddles of water that are left after a rain quickly disappear, partly by evaporating and partly by percolating into the ground. Movement and Storage of Groundwater Subsurface Earth materials contain countless small openings, or pores, which make up a large portion of some of these materials. Porosity is the percentage of pore space in a material. Well sorted sediments High porosity Poorly sorted sediments Low porosity

8. Groundwater Storage Subsurface materials have porosities ranging from 2 or 3 percent to more than 50 percent. Movement and Storage of Groundwater The cement that binds the grains of sedimentary rocks together reduces the rocks’ porosity. Well sorted sediments High porosity Poorly sorted sediments Low porosity

9. The Zone of Saturation The zone of saturation is the depth below Earth’s surface at which groundwater completely fills all the pores of a material. Movement and Storage of Groundwater The water table is the upper boundary of the zone of saturation. Above the water table in the zone of aeration, the pores contain mostly air.

10. The Zone of Saturation Movement and Storage of Groundwater

11. The Zone of Saturation Water in the zone of saturation can be classified as either gravitational water or capillary water. Movement and Storage of Groundwater –Gravitational water is water that trickles downward as a result of the force of gravity. –Capillary water is water that is drawn upward from the water table and is held in the pore spaces of rocks and sediments as a result of surface tension.

12. The Zone of Saturation The Water Table Movement and Storage of Groundwater –The depth of the water table varies depending on local conditions. –The topography of the water table follows the topography of the land above it. –Because of its dependence on precipitation, the water table fluctuates with seasonal and other weather conditions.

13. Groundwater Movement Groundwater flows downhill in the direction of the slope of the water table, squeezing through numerous tiny pores in the subsurface material. Movement and Storage of Groundwater Permeability is the ability of a material to let water pass through it. Materials with large, connected pores, such as sand and gravel, have high permeabilities.

14. Groundwater Movement Fine-grained materials typically have low permeabilities because their pores are so tiny. Movement and Storage of Groundwater These materials, such as silt, clay, and shale, are said to be impermeable. Flow velocities through permeable materials are always higher than those through impermeable materials, regardless of the slope of the water table.

15. Groundwater Movement Aquifers are underwater permeable layers where most groundwater flow takes place. Movement and Storage of Groundwater Impermeable layers, called aquicludes, are barriers to groundwater flow.

16. Section Assessment 1.Match the following terms with their definitions. ___ infiltration ___ porosity ___ water table ___ permeability Movement and Storage of Groundwater A.the ability of a material to let water pass through B.the percentage of pore space in a material C.the process through which water enters the ground and becomes groundwater D.the upper boundary of the zone of saturation C B D A

17. Section Assessment 2.Which of the following materials has the highest permeability? Explain why. Movement and Storage of Groundwater Material A has the highest level of permeability because it has the highest porosity. Material AMaterial B

18. ______ Rivers and streams hold less than.01 percent of Earth’s total water supply. ______ The water table is generally located near sea level. ______Because of its high permeability clay is used to line landfills. ______ Only water in the zone of saturation is called groundwater. Section Assessment 3.Identify whether the following statements are true or false. Movement and Storage of Groundwater true false true

19. End of Section 1

20. Objectives Explain how groundwater dissolves and deposits rocks and minerals. Describe how caves form and how karst topography develops on Earth’s surface. –cave –sinkhole –karst topography –stalactite –stalagmite –travertine Vocabulary Groundwater Erosion and Deposition

21. Most groundwater contains some acid, in most cases carbonic acid. Groundwater Erosion and Deposition As a result, groundwater is usually slightly acidic and attacks carbonate rocks, especially limestone. Limestone consists mostly of calcium carbonate (CaCO 3 ), which dissolves readily in any kind of acid.

22. Dissolution by Groundwater The process by which carbonic acid forms and dissolves calcium carbonate can be described by three simple chemical equations. Groundwater Erosion and Deposition –In the first process, carbon dioxide and water combine to form carbonic acid. CO 2 + H 2 O  H 2 CO 3 –In the second process, the carbonic acid (H 2 CO 3 ) molecules in the water split into hydrogen ions (H + ) and bicarbonate ions (HCO 3 – ). H 2 CO 3  H + + HCO 3 –

23. Dissolution by Groundwater –In the third process, the hydrogen ions react with calcium carbonate and dissolve it. CaCO 3(s) + H + (aq) + HCO 3 – (aq)  Ca(HCO 3 ) 2(aq) Groundwater Erosion and Deposition For every carbon dioxide molecule dissolved in groundwater, one hydrogen ion is produced and one calcium carbonate molecule is dissolved. Both the dissolution and formation of calcium carbonate play a major role in the formation of limestone caves.

24. Dissolution by Groundwater Caves Groundwater Erosion and Deposition –A cave is a natural underground opening with a connection to Earth’s surface. –Practically all caves of significant size are formed when groundwater dissolves limestone. –Most caves develop in the zone of saturation just below the water table. –As the limestone formation becomes more permeable the resulting increased downhill flow of groundwater gradually lowers the water table. –The thick limestone formations eventually become honeycombed with caves and caverns.

25. Dissolution by Groundwater Karst Topography Groundwater Erosion and Deposition –Some of the characteristic surface features produced by the dissolution of limestone include: A sinkhole is a depression in the ground caused by the collapse of a cave or by the direct dissolution of bedrock by acidic rain or moist soil. –Karst topography describes limestone regions that have sinkholes, sinks, and sinking streams. A sinking stream forms when a surface stream drains into a cave system, continues underground, and leaves a dry valley above.

26. Karst Topography

28. Dissolution by Groundwater Karst Topography Groundwater Erosion and Deposition

29. Major Karst Aquifers of the United States

30. Virginia’s Ridge and Valley Province The Ridge and Valley Province is a region of Karst Topography

42. Groundwater Deposits Some tap water contains sulfur compounds, and some contains dissolved iron compounds. Groundwater Erosion and Deposition Water that contains iron compounds typically leaves brownish or red stains on kitchen and bathroom fixtures.

43. Groundwater Deposits Hard Water Groundwater Erosion and Deposition –Water that contains high concentrations of calcium, magnesium, or iron is called hard water. –Hard water is common in limestone areas where the groundwater is nearly saturated with calcium carbonate. –Water that contains few dissolved ions is called soft water.

44. Groundwater Deposits Natural Deposits Groundwater Erosion and Deposition –Dripstone formations are built slowly as water drips through caves, depositing a tiny amount of calcium carbonate with each drop. –Stalactites are cone-shaped or cylindrical structures that hang from a cave’s ceiling like icicles. –Stalagmites are mound-shaped dripstone deposits that form as water drops splash to the floor of a cave. –Stalactites and stalagmites may grow together to form dripstone columns. –Travertine is the type of limestone that composes dripstone formations.

51. Section Assessment 1.Match the following terms with their definitions. ___ sinkhole ___stalactites ___ stalagmites ___ travertine Groundwater Erosion and Deposition A.mound-shaped dripstone deposits that form as water drops splash to the floor of a cave B.a depression in the ground caused by the collapse of a cave or by the direct dissolution of bedrock by acidic rain or moist soil C.cone-shaped or cylindrical structures that hang from a cave’s ceiling like icicles D.the type of limestone that composes dripstone formations B C A D

52. Section Assessment Groundwater Erosion and Deposition 2.Why do most caves form in limestone formations? Limestone consists mostly of calcium carbonate, which dissolves readily in any kind of acid. Most groundwater contains some acid, in most cases carbonic acid. The acidic groundwater slowly dissolves any limestone that it comes in contact with.

53. Section Assessment 3.What effect does hard water have on household plumbing? Groundwater Erosion and Deposition Hard water is nearly saturated with calcium carbonate. Eventually deposits of calcium bicarbonate will clog water pipes and fixtures.

54. End of Section 2

55. –recharge –artesian well –spring –hot spring –geyser Objectives Relate the different types of springs to common systems of aquifers. Explain how groundwater is withdrawn from aquifer systems by wells. Describe the major problems that threaten groundwater supplies. Vocabulary Groundwater Systems –well –drawdown

56. Groundwater Systems The average length of time that groundwater remains underground is several hundred years. Groundwater Systems Groundwater eventually returns to Earth’s surface. In most cases, groundwater emerges wherever the water table intersects Earth’s surface.

57. Springs Aquifers are permeable underground layers through which groundwater moves with relative ease. Groundwater Systems Aquicludes, such as layers of clay or shale, block groundwater movement. Springs, or natural discharges of groundwater, tend to occur where an aquifer and an aquiclude come in contact with Earth’s surface.

58. Springs Emergence of Springs Groundwater Systems –In regions of near-horizontal sedimentary rocks, springs often emerge on the sides of valleys at about the same elevation, at the bases of aquifers. –Springs may also emerge at the edges of perched water tables. A perched water table is a zone of saturation that overlies an aquiclude that separates it from the main water table below.

59. Springs Emergence of Springs Groundwater Systems –Springs also tend to emerge along faults, which are huge fractures that offset rock formations and sometimes block aquifers. –In limestone regions, springs discharge water from underground pathways.

60. Springs Temperature of Springs Groundwater Systems –The temperature of groundwater that is discharged through a spring is generally the average annual temperature of the region in which it is located. –Some springs, called warm springs or hot springs depending on their temperature, discharge water that is much warmer than the average annual temperature. –Hot springs are springs that have temperatures higher than that of the human body. –Geysers are explosive hot springs that erupt at regular intervals.

61. Springs Temperature of Springs Groundwater Systems

62. Wells Wells are holes dug or drilled deep into the ground to reach a reservoir of groundwater. Groundwater Systems To produce water, a well must tap into an aquifer. The simplest wells are those that are dug or drilled below the water table, into the zone of saturation, and into what is called a water-table aquifer.

63. Wells Overpumping of the well lowers the water level in it and produces a cone of depression in the water table around the well. Groundwater Systems Drawdown is the difference between the original water-table level and the water level in the pumped well. Recharge is the process in which water from precipitation and runoff is added back to the zone of saturation.

64. Confined Aquifers Water-table aquifers are unconfined and unprotected, and thus, they are easily polluted. Groundwater Systems More reliable and less easily polluted water supplies can be found in deeper aquifers, called confined aquifers, which are generally sandwiched between aquicludes. The aquicludes form barriers that prevent pollutants from reaching such aquifers.

65. Confined Aquifers Artesian Wells –Because the area of recharge is usually at a higher elevation than the rest of an aquifer, a confined aquifer contains water under pressure. –The aquifer is called an artesian aquifer. –An artesian well is a well drilled into a confined aquifer from which water spurts above the land surface in the form of a fountain. –An artesian spring is a spring that discharges pressurized water. –An important artesian aquifer in the United States is the Ogallala Aquifer, which is located in the Great Plains. Groundwater Systems

67. Confined Aquifers Artesian Wells Groundwater Systems

68. Threats to Our Water Supply Freshwater is Earth’s most precious natural resource. Groundwater Systems Human demands for freshwater include household use, agriculture, and industry.

69. Threats to Our Water Supply Overuse –If groundwater is pumped out at a rate greater than the recharge rate, the groundwater supply will inevitably decrease, and the water table will drop. –This is happening to the Ogallala Aquifer as water is withdrawn, mostly for irrigation. Groundwater Systems

70. Threats to Our Water Supply Subsidence –Ground subsidence, or the sinking of land, is a problem caused by the excessive withdrawal of groundwater. –Water pressure helps carry the weight of the material overlying an aquifer. –If that pressure is reduced, the weight of the overlying material is transferred to the aquifer’s mineral grains which then compress. Groundwater Systems

71. Threats to Our Water Supply Pollution in Groundwater –Water-table unconfined aquifers are the most easily polluted groundwater reservoirs. –Confined aquifers, though somewhat protected from local pollution, become contaminated when their recharge areas are polluted. –The most common sources of groundwater pollution are sewage, industrial waste, landfills, and agricultural chemicals. Groundwater Systems

72. Threats to Our Water Supply Pollution in Groundwater Groundwater Systems

73. Threats to Our Water Supply Chemicals –Chemicals dissolved or transported with groundwater are in the form of ions and molecules, and thus, they cannot be filtered out in fine-grained sediments. –Chemicals generally move downslope from a source in the form of a pollution plume, a mass of contaminants that spreads through the environment. –Once chemical contaminants have entered groundwater, they cannot be easily removed. Groundwater Systems

74. Threats to Our Water Supply Salt –In many coastal areas, the contamination of freshwater by salt water is the major problem. –In such areas, the fresh groundwater near Earth’s surface is underlain by denser, salty seawater. –The overpumping of wells can cause the underlying salt water to rise into the wells and contaminate the freshwater aquifer. Groundwater Systems

75. Threats to Our Water Supply Radon –A source of natural pollution is radioactive radon gas, which is one of the leading causes of cancer in the United States. –This form of radon is generated by the radioactive decay of uranium in rocks and sediments, and it usually occurs in very low concentrations in all groundwater. –Radon may seep into houses, and, because it is heavier than air, it can accumulate in poorly ventilated basements. Groundwater Systems

76. Protecting Our Water Supply There are a number of ways in which groundwater resources can be protected and restored. Groundwater Systems –All major pollution sources need to be identified and eliminated.

77. Protecting Our Water Supply –Pollution plumes that are already in the ground can be monitored through observation wells and other techniques. Groundwater Systems –Pollution plumes may be stopped by the building of impermeable underground barriers. –Polluted groundwater can be pumped out for chemical treatment on the surface.

78. Section Assessment 1.Match the following terms with their definitions. ___ spring ___ geyser ___ recharge ___ drawdown Groundwater Systems A.a natural discharge of water from Earth’s surface B.explosive hot springs that erupt at regular intervals C.the difference between the original water-table level and the water level in a pumped well D.the process in which water from precipitation and runoff is added back to the zone of saturation A B D C

79. Section Assessment 2.Identify whether the following statements are true or false. Groundwater Systems ______ Agriculture is the largest use of freshwater in the United States. ______ Water from the Ogallala Aquifer is not being withdrawn faster than it can be recharged. ______Salt pollution is a major threat to groundwater supplies. ______ Groundwater discharged by a spring is usually 10º C warmer than the average annual temperature of the region where it is located. true false true false

80. Section Assessment Groundwater Systems 3.What is a perched water table? A perched water table is a zone of saturation that overlies an aquiclude that separates it from the main water table below.

81. End of Section 3

82. Chapter Resources Menu Study Guide Section 10.1 Section 10.2 Section 10.3 Chapter Assessment Image Bank

83. Section 10.1 Main Ideas Some precipitation infiltrates the ground to become groundwater. Groundwater is stored below the water table in the pore spaces of rocks and moves through permeable layers called aquifers. Impermeable layers are called aquicludes. Section 10.1 Study Guide

84. Section 10.2 Main Ideas Groundwater dissolves limestone and forms underground caverns. Sinkholes form at Earth’s surface when bedrock is dissolved or when caves collapse. Irregular topography caused by groundwater dissolution is called karst topography. The precipitation of dissolved calcium carbonate forms stalactites, stalagmites and travertine deposits, including dripstone columns, in caves. Section 10.2 Study Guide

85. Section 10.3 Main Ideas The natural discharge of groundwater takes place through springs. Springs emerge where the water table intersects Earth’s surface. Wells are drilled into the zone of saturation to provide water for human needs. The pumping of shallow wells produces cones of depression in the water table. Artesian wells tap deep, confined aquifers that contain water under pressure. In many regions, groundwater withdrawal exceeds groundwater recharge and causes considerable lowering of the water table as well as ground subsidence. The most common sources of groundwater pollution are sewage, industrial waste, landfills, and agricultural chemicals. Section 10.3 Study Guide

86. 1.The major factor affecting the flow velocity of groundwater is ____. a.slopec.permeability b.gravityd.temperature Multiple Choice Chapter Assessment Although Slope, and thus gravity, do play a part in determining flow velocity, permeability is the major factor. Flow velocities through permeable materials are always higher than those through impermeable materials, regardless of the slope of the water table.

87. 2.Which of the following is the most common acid found in groundwater? a.carbonic acidc.sulfuric acid b.calcium carbonated.nitric acid Though sulfuric acid and nitric acid are found in groundwater, carbonic acid is more common. Calcium carbonate is the key component in limestone that is readily dissolved in any kind of acid. Multiple Choice Chapter Assessment

88. Multiple Choice 3.What process adds water to the zone of saturation? a.drawdownc.subsidence b.incursiond.recharge Chapter Assessment Subsidence, salt water incursion, and drawdown are all possible results of over pumping water from an aquifer.

89. Multiple Choice 4.What is the type of stone that dripstone formations are composed of? a.karstc.breccia b.travertined.shale Chapter Assessment Travertine is the type of limestone that stalactites, stalagmites, and other dripstone formations are composed of.

90. Multiple Choice 5.What is the cancer causing gas that can naturally pollute groundwater? a.chlorinec.radon b.nitrogend.xeon Chapter Assessment Radon, which is heavier than air, accumulates in poorly ventilated basements of homes in radon prone areas. Radon is one of the leading causes of cancer in the United States.

91. Short Answer 6.Why does the water table generally follow the topography of the land above it? Chapter Assessment Water table topography follows the surface topography because water underground moves slowly and conforms to surface contours.

92. Short Answer 7.Why does salt water incursion occur? Chapter Assessment In many coastal areas, fresh water near Earth’s surface is underlain by denser salt water. The overpumping of wells can cause the underlying salt water to rise into the wells and contaminate the freshwater aquifer.

93. True or False 8.Identify whether the following statements are true or false. ______ Less than three percent of Earth’s water is freshwater. ______ Silt, clay, and shale are considered permeable materials. ______To be an artesian well, the well must have an outlet below the pressure surface. ______ Poorly sorted sediments have a high porosity. ______ In the United States, industry uses more water than agriculture. Chapter Assessment true false true false

94. Image Bank Chapter 10 Images

95. Image Bank Chapter 10 Images

96. Image Bank Chapter 10 Images

97. Image Bank Chapter 10 Images

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