Geology Ch. 12 Running Water

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  1. Where is Earths water?
    • 97.2% of water is in oceans
    • 2.15% is in glaciers and on land
    • 0.65% is in the atmosphere, groundwater, lapes, swamps, and bogs.
  2. Hydrologic cycle:
    • water is continuously recycled from the oceans, through the atmosphere, to the continents, and back to the oceans.
    • Water vapor rises into the atmosphere where the process of cloud formation takes place.
    • 80% of precipitation falls into Earths oceans.
    • 20% falls on land
  3. Runoff:
    The surface flow in streams and rivers
  4. Transpiration:
    water that is used by plants evaporates in this process.
  5. Laminar and Turbulent flows:
    • In laminar flows, lines of flow called streamlines parallel one another with little or no mixing between adjacent layers.
    • In turbulent flows, streamlines intertwine, causing complex mixing within the moving fluid.
  6. What does water during a rainstorm depend on?
    Infiltration capacity
  7. Infiltration Capacity:
    • the maximum rate at which surface materials absorb water.
    • Factors:
    • intensity and duration of rainfall.
  8. Running Water:
    any surface water that moves from higher to lower areas in response to gravity.
  9. Sheet Flow:
    a more or less continuous film of water flowing over the surface. Causes sheet erosion
  10. Channel Flow:
    • surface runoff is confined to trough like depressions that vary in size from tiny rills with a trickling stream of water to the Amazon River in South America.
    • Rill, brook, creek, stream, and river.
  11. Gradient:
    water in any channel flows downhill over a slope nown as its gradient.
  12. Velocity:
    • a measure of the downstram distance water travels in a given time. m/s or f/s
    • The velocity rises as the gradient falls.
  13. Discharge:
    • the volume of water that passes a particular point in a given period of time.
    • In most rivers and streems, discharge increases downstream as more and more water enters a channel.
    • Because of high evaporationa nd infiltration, the flow in some desert waterways decreases downstream until the water disappears.
  14. What kinds of energy can a stream possess?
    Kinetic and Potential Energy
  15. Potential Energy:
    the energy of position, the energy of water at high elevation. During stream flow, potential energy is converted into kinetic.
  16. Kinetic Energy:
    the energy of motion.
  17. Dissolved Load:
    particales too small to see that are carried by a stream or river
  18. Hydraulic Action:
    the direct impact of running water, sets particles in motion.
  19. Abrasion:
    exposed rock is worn and scraped by running water carrying sand and gravel
  20. Potholes:
    circular or oval depressions in stream beds. Formed where swirling currents with sand and gravel eroded the rock.
  21. Suspended Load:
    • consists of the smallest particles of silt and clay, which are suspended above the channe's bed by fluid turbulence.
    • Gives water its murky appearance
  22. Bed Load:
    larger particles, mostly sand and gravel, cannot be kept suspended by fluid turbulence so that it is transported along the bed.
  23. Saltation:
    grains move forward with the water, but also settle and finally come to a rest and then again move by the same process of intermittent bouncing and skipping.
  24. Alluvium:
    collective deposits of rivers and streams
  25. Braided Stream:
    • an intricate network of dividing and rejoining channels separated from one another by sand and gravel bars.
    • Develop when the sediment supply exceeds the transport capacity of running water, resulting in the deposition of sand and gravel bars.
  26. Meandering Stream:
    • have a single sinuous channel with broadly looping curves known as meanders.
    • The deeper side of a channel is known as the cut bank because greater velocity and fluid turbulence erode it.
    • Flow velocity is at its minimum on the opposite bank, a point bar is deposited on this gently sloping inner bank.
    • Meanders commonly become so sinuous that the thin neck of land between adjacent meanders is cut off during a flood, leaving an oxbow lake.
  27. Floodplains:
    made when channels receive more water than they can carry and the overflow their banks and spread across adjacent flat plains.
  28. Natural Levees:
    made when a stream overtops its banks and water pours onto the floodplain, its velocity and depth rapidly decrease.
  29. Deltas:
    An alluvial deposit that causes the shoreline to build outward into a lake or sea, a process called progradation.
  30. 3 main types of marine deltas:
    • 1. Stream-dominated - long fingerlike sand bodies, each deposited in a distributary channel that progrades far seaward.
    • 2. Wave-dominated - also has distributary channels, but the seaward margin of the delta consists of islands reworked by waves.
    • 3. Tide-dominated - continuously modified into tidal sand bodies that parallel the direction of tidal flow.
  31. Alluvial Fans:
    fan-shaped seposits of alluvium on land, form best on lowlands with adjacent highlands in arid and semiarid regions where little vegetation exists to stabalize surface materials.
  32. Drainage Patterns:
    • the arrangement of channels within an area.
    • Dendritic: a network of channels resembling tree branching.
    • Rectangular: characterized by right angle bends
    • Trellis Drainage: a network of nearly parallel main streams with tributaries joining them at right angles.
    • Radial Drainage: streams flow outward in all directions from a central high point, such as a large volcano.
    • Deranged Drainage: characterized by irregularity, with streams flowing into and out of swamps and lakes.
  33. Base Level:
    • the lowest limit to which a stream or river can erode.
    • Ultimate base level: sea level.
  34. Graded Stream:
    a stream with an equillibrium profile in which a delicate balance exists among gradient, discharge, flow velocity, channel shape, and sediment load so that neither significant erosion nor deposition takes place within its channel.
  35. Downcutting:
    takes place when a river or stream has more energy than it needs to transport sediment, so some of is excess energy is used to deepen its valley.
  36. Lateral Erosion:
    valley walls of a river are undercut
  37. Headward Erosion:
    phenomenon involving erosion by entering runoff at the upstream end of a valley.
  38. Stream Piracy:
    the breaching of a drainage divide and diversion of part of the drainage of another stream,
  39. Stream Terraces:
    erosional flood plains that formed when the streams were flowing at a higher level.
  40. Incised Meanders:
    deep, meandering canyons cut into bedrock.
  41. Superposed Streams:
    streams that flow directly through ridges that lie in their path.
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Geology Ch. 12 Running Water
2011-10-31 23:41:33
running water

Running water chapter
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