1. Ground Water

2. Ground water is water found beneath the ground surface. –It occupies the pore space between grains in bodies of sediment and sedimentary rock, and – fills cracks and crevices in all types of rock. –Ground water can also be written as groundwater or ground-water

3. Porosity and Permeability A.__________: The percentage of an Earth material's volume that has openings 1.Factors affecting porosity: a)___________: Generally, if the particles are rounded and sorted, particle size does not affect the porosity. As particles become unsorted the porosity decreases due to the smaller particles filling in the pore spaces Porosity Particle Size

4. b) ________________: Loosely packed soils have a higher porosity than more compact soils. As packing increases, the pore spaces become smaller. Particle Packing

5. c)____________: As the angularity of particles increases, porosity decreases. This is because the particles will fit together more effectively. Particle Shape

6. B.______________ 1.Factors Affecting Permeability: a) Particle _____: As particle size increases, permeability __________ The ability of an Earth material to transit a fluid through pores and/or fractures. This is often expressed as a rate (cm/sec.). Permeability Size increases

7. b) Particle _______: As particle shape becomes more angular, permeability ___________. Shape decreases

8. c) Particle ________: As particle packing decreases, permeability _________. Packing increases

9. 2.____________ Materials A material that is impermeable will not allow fluids to move through it. Impermeable Shale Impermeable

10. 3. __________ Permeability: A rock that is otherwise impermeable may permit fluids to move through cracks that have developed due to weathering (ie. limestone, granite). As a result not all permeable rocks have high porosity. Secondary

11. 4. _________Infiltration Depth The depth to which fluids can move through permeable material is 3,000 m (3 km). At this depth confining pressure compresses the rock and closes pores and cracks. Maximum

12. 5. Porous Earth Material Can Be Impermeable Not all porous Earth materials are permeable. For example, clay has high porosity –Because of its very small particles size, its permeability is so low that it is considered to be impermeable. ClayImpermeable clay liner for a landfill

13. Porosity and Permeability

14. Aquifers Any body of saturated rock or sediment through which water can move easily is referred to as an aquifer. ❑ Aquifers are porous and permeable

15. Subsurface Zones 1._____________________: The region in which all pore spaces are filled with water. 2._____________________: The upper limit (“top”) of the zone of saturation. It follows the surface topography. 3._____________________: Zone above the water table in which air occupies the pore spaces.  Water is present, on thesurfaceof the soil or rock particles.  Also called vadose zone 4. ________________: This is the zone above the water table in which water moves upwards from particle to particle due to adhesion and cohesion. Zone of Saturation Water Table Zone of Aeration Capillary Fringe

16. Adhesion and Cohesion Result from the Polar Properties of the Water Molecule

17. Cohesion The attraction of one water molecule for another Due to the polar charges of water molecules

18. Adhesion Water molecules are attracted to other types of molecules such as minerals in rock and soil because they also have charges. –Also attracted glass, metal, or plant leaves Adhesion forces are stronger than cohesion forces.

19. Capillarity and Particle Size a) Capillarity increases as particle size decreases. b) Generally, the capillary fringe is not more than one meter thick.

20. 5. ________ Water Table The top of a body of ground water separated from the main water table beneath it by a zone that is not saturated. It may form as ground water collects above a lens of relatively imermeable shale with a more permeable rock, such as sandstone. Seepage from a spring in CA Perched

21. Movement of Ground Water  Water in the zone of saturation moves downward following the slope of the water table  The water table follows the surface topography

22. B. ___________Aquifers 1.Recharged rapidly by precipitation 2.Partly filled with water 3.Gravity wells yield water by pumping Wet Season Water Table and wells are high Springs and Wells flow readily Dry Season Water table and rivers are low Some springs and wells dry up Unconfined

23. Local Water Table The water level in a gravity well will be the water table A lake’s surface will be the water table.

24. Aquifers and Well Quality Even though the shale has high porosity, it has low permeability The saturated region of the sandstone is the aquifer

25. Aquifers and Well Quality Crystalline rocks (igneous and metamorphic) and some types of limestones are not good aquifers because they are not very porous Wells must intersect fractures to obtain water.

26. The Effect of a Pumping Well on the Water Table

27. C. ___________ Aquifers (Artesian Aquifers) 1.Separated from the surface by an ________________confining bed (often shale or clay) called an ____________ 2.Completely filled with water under pressure 3.Recharged slowly through the confining bed 4.May have no response to seasonal changes in precipitation Confined Aquitard (impermeable) impermeable aquitard

28. 5. ______________ Drilled into confined aquifers and have water that rises under its own pressure Common in South Dakota but also present on Long Island The name is derived from the Arois region of France (artesien in old French) where these wells have been used for centuries. Artesian Wells

29. Artesian Wells in the Dakota Sandstone Will this well be a flowing artesian well? Water level in the well Confined Water Table

30. Flowing Artesian Wells Artesian well in S. Dakota Early 1900’s Dakota Sandstone Montana

31. D. _______ : Water flows natural onto the land surface. Can occur where the water table intersects the land surface. Can also occur – in caverns, along fractures –along faults –or rock contacts that intersect the land surface Springs

32. Natural Springs Spring from a limestone cavern Jasper National Park, Alberta, Canada Spring seeping from the ground at a contact between shale and overlying sandstone in southern Utah

33. Climate and Streamflow Climate influences the relationship between stream flow and the water table.

34. 1.________Streams a)Rainy climates b)The stream’s surface coincides with the water table. c)Water from the zone of saturation flows through the streambed and banks that are below the water table Gaining

35. 2. ________Streams a)Drier climates b)Water is lost to the zone of saturation. c)The stream channel lies above the water table. d)Water lost from the stream can cause a rise in the water table. As a result, in a desert the nearest water source may be below a dry streambed Losing

36. Effects of Ground Water Action Caves, Sinkholes, and Karst Topography

37. Solution of Limestone Forming Caves Great Onyx Cave, KY

38. Howe Caverns, NY

39. Carlsbad Caverns, NM

40. Stalactites

41. Karst Topography Regions characterized by sinks, lost rivers, underground drainage, caves and caverns. Limestone bedrock Named after the Kars region of Yugoslavia Also found in United States (Cumberland Plateau of Kentucky and Tennessee, Shenandoah Valley of Virginia, and Florida).

42. Karst Topography in the U.S. Cumberland Plateau of Kentucky and Tennessee, Shenandoah Valley of Virginia Florida)

43. Sinkholes Winter Park, Florida 1980

44. Karst Topography Timaru, New Zealand West Virginia, USA

45. Mammoth Caves KY

46. Hot Water Underground

47. 1. ___________ Circulation near a magma chamber Circulation near hot, cooling igneous rock Yellowstone Park, WY Japan Hot Springs

48. 2.________ Geysers Hot springs that periodically erupt hot water and steam

49. Geyserite Cone (Sinter) Travertine terraces

50. Yellowstone National Park

52. Geothermal Energy

53. Geothermal Power Plants Geothermal Power Plant The Geysers, CA

54. U.S. Geothermal Resources

55. Other Effects of Groundwater Geodes Found in some limestones Petrified wood Wood replaced by silica Concretions Precipitation of cementing material around an organic nucleus such as a leaf or a tooth Amorphous silica Amethyst crystals

56. Groundwater Pollution Sources Pesticides

57. Groundwater Pollution Sources Household Garbage

58. Groundwater Pollution Sources Animal Waste

59. Groundwater Pollution Sources Industrial Toxic Waste

60. Contaminant Plumes A plume of contaminated water will spread out in the direction of groundwater flow.

61. Density of Pollutants Affects Flow

62. Effects of Bedrock

63. Pumping Wells Causes or Aggravates Groundwater Pollution A pumping well steepens the water table near a landfill Velocity of groundwater flow increases. Contaminants are drawn into the well.

64. Pumping Wells Causes or Aggravates Groundwater Pollution Pumping can reverse the slope of the water table. Direction of groundwater flow changes, contaminating the well.

65. Pumping Wells Can Cause Saltwater Intrusion Along Shorelines Pumping thins the freshwater lens Saltwater is drawn into the well

66. Groundwater Mining Can Cause Land Subsidence Subsidence of 9 m in 52 years near Mendota, San Joaquin Valley, CA Signs on the pole show positions of the land surface in 1925, 1955, and 1977 Subsidence has been reduced to less than a meter since the late 1970’s as a result of –Reduced groundwater pumping –Use of surface water for irrigation