Running Water


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Running Water

  1. 1. RUNNING WATER Physical Geology The Walker School
  2. 2. Distribution of Earth’s Water  1.36 billion km3 of water on Earth
  3. 3. Hydrologic Cycle Water Characteristics •Flow •Viscosity •Infiltration Capacity •Gradiant Fig. 15-3, p. 460
  4. 4. Water Cycle Statistics  85% of water enters the atmosphere each year from the upper 1 m layer of the ocean through evaporation.  80% of the Earth’s precipitation falls back into the oceans.  36,000 km3 falls on land each year and eventually returns to the oceans.
  5. 5. Laminar Flow Fig. 15-4a, p. 461
  6. 6. Turbulent Flow Streamlines are the paths taken by water molecules. Fig. 15-4b, p. 461
  7. 7. Stream Gradient Water moves more slowly with greater turbulence near a channel’s bed and banks because of friction. Fig. 15-5, p. 462
  8. 8. Running Water, Erosion and Sediment Transport Sediment from talus cones. Sediment loading from a river’s banks. Fig. 15-7b, p. 464
  9. 9. Sediment Transport and Deposition Note: 1. Bed Load 2. Suspended Load 3. Dissolved Load Fig. 15-9a, p. 466
  10. 10. Relation to Particle Size and Density Fig. 15-9b, p. 466
  11. 11. Fig. 15-9, p. 466
  12. 12. Braided Stream Grinelwald, Switzerland Develop when sediments exceed transport capacity. Characterized by broad, shallow channels and bed- load transport. Fig. 15-10b, p. 467
  13. 13. Meandering Streams Deposits are mostly mud deposits on flood plains. Fig. 15-11, p. 468
  14. 14. Flood Plain Deposits Natural levees build up by repeated deposition of sediments during numerous floods. Fig. 15-14, p. 471
  15. 15. Marine Delta – Stream Dominated Mississippi River delta on the U.S. Gulf Coast is stream dominated. Fig. 15-16a, p. 472
  16. 16. Mississippi Delta Formation Erosion over millions of years produced 7 different alluvial fans which add land mass to the continent. p. 495
  17. 17. Marine Delta – Wave Dominated Nile delta is wave dominated.
  18. 18. Marine Delta – Tide Dominated Ganges delta is tide dominated.
  19. 19. Alluvial Fans and their Deposits  Formed during periodic rain storms.  Surface run-off is typically funneled into mountain canyons.  The run off is confined so it can’t spread latterly.  Repeated deposits create alluvial fans.
  20. 20. Types of Floods Flash flood in West, VA. Table 15-1, p. 474
  21. 21. Why do people build in flood zones?  Fertile soils  Level surfaces  Proximity to water for agriculture and industry. Fig. 15-18, p. 474
  23. 23. USGS Water Monitoring
  24. 24. Real Time Water Data
  25. 25. Samples Hydrograph Fig. 15-19, p. 475
  26. 26. Flood Frequency Curve Note: Meteorologists typically watch for 2, 5, 10, 20 and 100 years floods. Fig. 15-20b, p. 475
  27. 27. Flood of 1993  Caused by intersection of the jet stream and air masses over the Midwest.  Responsible for 50 death and displaced 70,000 people. Concept Art, p. 476
  28. 28. World’s Largest Floods
  30. 30. Flood Control Methods  Dams and Reservoirs  Levees  Floodways  Floodwalls Fig. 15-21a, p. 478
  31. 31. World Drainage Basin  An area which a stream or river and its tributaries carry all surface runoff.
  32. 32. Ocean Drainage Basins  The Atlantic Ocean drains approximately 47% of all land in the world.  The Pacific Ocean drains just over 13% of the land in the world.  The Arctic Ocean basin drains most of Western and Northern Canada east of the Continental Divide.  The Indian Ocean drains around 13% of the Earth's land.  The Southern Ocean drains Antarctica.
  33. 33. River Basins  The three largest river basins (by area), in order of largest to smallest, include the Amazon basin, the Congo basin, and the Mississippi basin.  The three rivers that drain the most water, from most to least, are the Amazon, Congo , and Ganges Rivers.
  34. 34. Mississippian Drainage Basin Fig. 15-22b, p. 480
  35. 35. Endorheic Drainage Basins  Inland basins that do not drain into an ocean;  18% of all land drains to endorheic lakes or seas.  The largest of these consists of much of the interior of Asia, and drains into the Caspian Sea and the Aral Sea.  Evaporation is the primary means of water loss  Water is typically more Aral Sea Drainage Basin saline than the oceans.
  36. 36. Types of Drainage Systems 1. Dendritic Drainage 2. Rectangular Drainage 3. Trellis Drainage 4. Radial Drainage 5. Deranged Drainage Fig. 15-23, p. 481
  38. 38. Drainage Patterns and Geology Dentritic Drainage Erosion Deposits Rectangular Drainage Regional Joint Systems Trellis Drainage Folded Sedimentary Rock Radial Drainage Volcanoes Swamps and Lakes Deranged Drainage
  39. 39. Canyons and Gorges  Most canyons were formed by a process of long-time erosion from a plateau level.  The cliffs form because harder rock strata that are resistant to erosion and weathering remain exposed on the valley walls.  Canyons are much more common in arid areas than in wetter areas because weathering has a greater effect in arid zones.  A canyon may also refer to a rift between two mountain peaks such as those in ranges such as the Rocky Mountains, the Alps, the Himalayas or the Andes Grand Canyon, AZ.
  40. 40. Largest Canyons  Grand Canyon in Arizona, USA  Copper Canyon in Chihuahua, Mexico Copper Canyon, Mexico
  41. 41. Deepest Canyons on Earth  The Yarlung Tsangpo Canyon, along the Yarlung Tsangpo River in Tibet, China  Kali Gandaki Gorge in Nepal  Polung Tsangpo Canyon in Tibet  Cotahuasi Canyon (3,535 m deep and the deepest in the Americas)  Hell’s Canyon on the Snake River in Idaho, which is 2400 meters deep  The Tekezé gorge (2000m+ deep and deepest in Africa)  Grand Canyon while the largest canyon in area is only 900 meters deep. Hell’s Canyon, ID
  43. 43. Processes Involved in Valley Formation  Downcutting  Lateral Erosion  Sheet Wash  Headward Erosion  Mass Wasting Downcutting off the San Juan River
  44. 44. Evolution of a Valley – Part I The stream widens its valley by lateral erosion and mass wasting, while simultaneously extending its valley by headward erosion. Fig. 15-28a, p. 486
  45. 45. Evolution of a Valley – Part II As the larger stream continues to erode headward, stream piracy takes place when it captures some of the drainage of the smaller stream. Fig. 15-28b, p. 486
  46. 46. Stream Piracy  Occurs when headward erosion breaches a divide and diverts some or all of the drainage of another stream system. The Hadhramawt Plateau of South Yemen exhibits a complex dendritic drainage pattern and excellent examples of quot;stream piracy”. B A. - Wadi Hadhramawt opens into the sand-filled Ramlat Sabatayn in the southwest corner of the Rub-al-Khali (The A Empty Quarter), B - yet drainage is toward the sea.