Running Water

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  • 1. RUNNING WATER Physical Geology The Walker School

2. Distribution of Earths Water 1.36 billion km3 of water on Earth 3. Hydrologic CycleWater CharacteristicsFlowViscosityInfiltration CapacityGradiantFig. 15-3, p. 460 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 Earths precipitation falls back into the oceans. 36,000 km3 falls on land each year and eventually returns to the oceans. 5. Laminar FlowFig. 15-4a, p. 461 6. Turbulent Flow Streamlines are the paths taken by water molecules. Fig. 15-4b, p. 461 7. Stream Gradient Water moves more slowly with greater turbulence near a channels bed and banks because of friction. Fig. 15-5, p. 462 8. Running Water, Erosion and Sediment TransportSediment from talus cones.Sediment loading from a rivers banks. Fig. 15-7b, p. 464 9. Sediment Transport and DepositionNote:1. Bed Load2. Suspended Load3. Dissolved Load Fig. 15-9a, p. 466 10. Relation to Particle Size and DensityFig. 15-9b, p. 466 11. Fig. 15-9, p. 466 12. Braided StreamGrinelwald, SwitzerlandDevelop whensediments exceedtransport capacity. Characterized by broad, shallow channels and bed- load transport. Fig. 15-10b, p. 467 13. Meandering StreamsDeposits aremostly muddeposits onflood plains. Fig. 15-11, p. 468 14. Flood Plain Deposits Natural levees build up by repeated deposition of sediments during numerous floods. Fig. 15-14, p. 471 15. Marine Delta Stream Dominated Mississippi Riverdelta on the U.S. GulfCoast is streamdominated. Fig. 15-16a, p. 472 16. Mississippi Delta Formation Erosion over millions of years produced 7 different alluvial fans which add land mass to the continent.p. 495 17. Marine Delta Wave Dominated Nile delta is wavedominated. 18. Marine Delta Tide DominatedGanges delta is tide dominated. 19. Alluvial Fans and their Deposits Formed during periodic rainstorms. Surface run-off is typicallyfunneled into mountain canyons. The run off is confined so it cantspread latterly. Repeated deposits create alluvialfans. 20. Types of Floods Flash flood in West, VA. Table 15-1, p. 474 21. Why do people build in flood zones? Fertile soils Level surfaces Proximity to water for agriculture and industry. Fig. 15-18, p. 474 22. WHAT TECHNOLOGY IS USED TO MONITOR WATER LEVELS? 23. USGS Water Monitoring 24. Real Time Water Data 25. Samples HydrographFig. 15-19, p. 475 26. Flood Frequency CurveNote: Meteorologists typically watch for 2, 5, 10, 20 and 100 years floods.Fig. 15-20b, p. 475 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. Worlds Largest Floods 29. HOW CAN TECHNOLOGY BE USED TO CONTROL FLOODING? 30. Flood Control Methods Dams and Reservoirs Levees Floodways Floodwalls Fig. 15-21a, p. 478 31. World Drainage Basin An area which a stream or river and its tributaries carry all surface runoff. 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. 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. Mississippian Drainage BasinFig. 15-22b, p. 480 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. Types of Drainage Systems 1. Dendritic Drainage 2. Rectangular Drainage 3. Trellis Drainage 4. Radial Drainage 5. Deranged Drainage Fig. 15-23, p. 481 37. WITH WHAT GEOLOGICAL FEATURES ARE DRAINAGE SYSTEMS ASSOCIATED? 38. Drainage Patterns and GeologyDentritic Drainage Erosion DepositsRectangular Drainage Regional Joint SystemsTrellis Drainage Folded Sedimentary RockRadial DrainageVolcanoesSwamps and Lakes Deranged Drainage 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 AndesGrand Canyon, AZ. 40. Largest Canyons Grand Canyon in Arizona, USA Copper Canyon in Chihuahua, Mexico Copper Canyon, Mexico 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) Hells Canyon on the Snake River in Idaho, which is 2400 meters deep The Tekez gorge (2000m+ deep and deepest in Africa) Grand Canyon while the largest canyon in area is only 900 meters deep. Hells Canyon, ID 42. HOW DO VALLEYS EVOLVE? 43. Processes Involved in Valley Formation Downcutting Lateral Erosion Sheet Wash Headward Erosion Mass WastingDowncutting off the San Juan River 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. Evolution of a Valley Part IIAs the larger streamcontinues to erodeheadward, streampiracy takes placewhen it capturessome of thedrainage of thesmaller stream. Fig. 15-28b, p. 486 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 ofSouth Yemen exhibits acomplex dendritic drainagepattern and excellent examplesof quot;stream piracy.B A. - Wadi Hadhramawt opens into the sand-filled Ramlat Sabatayn in the southwest corner of the Rub-al-Khali (TheA Empty Quarter), B - yet drainage is toward the sea.