1 / 48

OUTLINE

OUTLINE. Introduction Groundwater and the Hydrologic Cycle How Earth Materials Absorb Water The Water Table How Groundwater Moves Springs, Water Wells, and Artesian Systems How Groundwater Erodes and Deposits Material How Humans Affect the Groundwater System

brit
Download Presentation

OUTLINE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. OUTLINE • Introduction • Groundwater and the Hydrologic Cycle • How Earth Materials Absorb Water • The Water Table • How Groundwater Moves • Springs, Water Wells, and Artesian Systems • How Groundwater Erodes and Deposits Material • How Humans Affect the Groundwater System • Hydrothermal Activity and Groundwater • Geo-Recap

  2. CHAPTER OBJECTIVES 1 Groundwater is one reservoir of the hydrologic cycle and it represents approximately 22% of the world’s supply of freshwater. 2 Porosity and permeability are largely responsible for the amount, availability, and movement of groundwater. 3 The water table separates the zone of aeration from the underlying zone of saturation and is a subdued replica of the overlying land surface. 4 Groundwater moves downward due to the force of gravity. 5 Springs occur where the water table intersects the surface of Earth. In an artesian system, groundwater is confined and builds up high hydrostatic pressure. Wells are human made holes that go down in Earth to the water table. 6 Groundwater is an important agent of both erosion and deposition and is responsible for karst topography and a variety of cave features. 7 Modifications of the groundwater system may result in lowering of the water table, saltwater incursion, subsidence, and contamination.

  3. CHAPTER OBJECTIVES 8 Hot springs and geysers result when groundwater is heated, typically in regions of recent volcanic activity. 9 Geothermal energy is a desirable and relatively nonpolluting alternative form of energy in some locations.

  4. Fig. 13-CO, p. 294

  5. Fig. 13-1, p. 296

  6. Fig. 13-2, p. 297

  7. Table 13-1, p. 297

  8. Fig. 13-3, p. 298

  9. Fig. 13-4, p. 299

  10. Fig. 13-5, p. 299

  11. Fig. 13-6, p. 300

  12. Fig. 13-7, p. 302

  13. Fig. 13-8a, p. 303

  14. Fig. 13-8b, p. 303

  15. Fig. 13-9, p. 304

  16. Fig. 13-10a, p. 305

  17. Fig. 13-10b, p. 305

  18. Fig. 13-11, p. 306

  19. Fig. 13-11a, p. 306

  20. Fig. 13-11b, p. 306

  21. Fig. 13-11c, p. 306

  22. Fig. 13-12, p. 307

  23. Fig. 13-13, p. 307

  24. Fig. 13-14, p. 308

  25. Fig. 13-15, p. 309

  26. Fig. 13-15a, p. 309

  27. Fig. 13-15b, p. 309

  28. Fig. 13-15c, p. 309

  29. Fig. 13-16, p. 309

  30. Fig. 13-17, p. 310

  31. Table 13-2, p. 310

  32. Fig. 13-18, p. 311

  33. Fig. 13-18a, p. 311

  34. Fig. 13-18b, p. 311

  35. Figure 1, p. 312

  36. Figure 2, p. 313

  37. Fig. 13-19a, p. 314

  38. Fig. 13-19b, p. 314

  39. Fig. 13-19c, p. 314

  40. Fig. 13-20, p. 315

  41. Fig. 13-21, p. 315

  42. Fig. 13-21a, p. 315

  43. Fig. 13-21b, p. 315

  44. Fig. 13-22, p. 316

  45. Fig. 13-23, p. 316

  46. CHAPTER SUMMARY • Groundwater consists of all subsurface water trapped in the pores and other open spaces in rocks, sediment, and soil. • About 22% of the world’s supply of freshwater is groundwater, which constitutes one reservoir in the hydrologic cycle. • For groundwater to move through materials, they must be porous and permeable. Any material that transmits groundwater is an aquifer, whereas materials that prevent groundwater movement are aquicludes. • The zone of saturation (in which pores are filled with water) is separated from the zone of aeration (in which pores are filled with air and water) by the water table. The water table is a subdued replica of the land surface in most places. • Groundwater moves slowly through the pore spaces in the zone of aeration and moves through the zone of saturation to outlets such as streams, lakes, and swamps. • Springs are found wherever the water table intersects the surface. Some springs are the result of a perched water table—that is, a localized aquiclude within an aquifer and above the regional water table.

  47. CHAPTER SUMMARY • Water wells are made by digging or drilling into the zone of saturation. When water is pumped out of a well, a cone of depression forms. • In an artesian system, confined groundwater builds up high hydrostatic pressure. Three conditions must generally be met for an artesian system to form: The aquifer must be confined above and below by aquicludes; the aquifer is usually tilted and exposed at the surface so it can be recharged; and precipitation must be sufficient to keep the aquifer filled. • Karst topography results from groundwater weathering and erosion and is characterized by sinkholes, caves, solution valleys, and disappearing streams. • Caves form when groundwater in the zone of saturation weathers and erodes soluble rock such as limestone. Cave deposits, called dripstone, result from the precipitation of calcite. • Modifications of the groundwater system can cause serious problems. Excessive withdrawal of groundwater may result in dry wells, loss of hydrostatic pressure, saltwater incursion, and ground subsidence. • Groundwater contamination is becoming a serious problem and can result from sewage, landfills, and toxic waste.

  48. CHAPTER SUMMARY • Groundwater may be heated by magma or by the geothermal gradient as it circulates deeply. In either case, the water commonly rises to the surface, thus accounting for hydrothermal activity in the form of hot springs, geysers, and several other features. • Geothermal energy comes from the steam and hot water trapped within Earth’s crust. It is a relatively nonpolluting form of energy that is used as a source of heat and to generate electricity.

More Related