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River Systems

River Systems. Earth Space Science Mr. Coyle. The Hydrologic Cycle. Infiltration = Groundwater System. Runoff = Surface Water System Runoff = Precipitation - Evapotranspiration. Where is the Water ?. RIVERS & STREAMS. Water Reservoirs The Hydrologic Cycle Surface Water Systems

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River Systems

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  1. River Systems Earth Space Science Mr. Coyle

  2. The Hydrologic Cycle • Infiltration = Groundwater System • Runoff = Surface Water System • Runoff = Precipitation - Evapotranspiration

  3. Where is the Water ?

  4. RIVERS & STREAMS • Water Reservoirs • The Hydrologic Cycle • Surface Water Systems • Meandering • Deltas/Alluvial Fans • Floods and flooding

  5. www.aquatic.uoguelph.ca/rivers/chintro.htm Importance of rivers • Rivers: • Provide water and nutrients for agriculture • Provide habitat to diverse flora and fauna • Provide routes for commerce • Provide recreation • Provide electricity

  6. Natural Watercourses • Discharge- volume of water • Velocity- rate of water movement • Gradient- slope of inclined surface

  7. Variation in time and space • The shape, size and content of a river are constantly changing, forming a close and mutual interdependence between the river and the land it traverses.

  8. www.dec.state.ny.us/website/2000/watersheds.gif www.epa.gov/watertrain/ecology/ecology21.html www.aquatic.uoguelph.ca/rivers/chwater.htm What is a Watershed?

  9. The Worlds Largest Rivers

  10. U.S. Precipitation Map Notice the effect of the Rocky Mountains U.S. Runoff Map

  11. Laminar vs. Turbulent Flow

  12. Near-Laminar flow in the center of a river channel Turbulent flow in the headwaters of a rushing mountain stream

  13. So Where Does The Stream Move Fastest? • Headwaters move slowest • Mouth of stream moves fastest • Laminar flow is more efficient than turbulent flow. • Deeper stream move faster than shallow streams

  14. Sediment Load

  15. Movement of Bedload by Saltation

  16. Sedimentation

  17. Longitudinal Stream Profile Can be divided into 3 main parts Drainage (Tributary) System Transport System Distributary System

  18. Drainage System • Stream energy is spent eroding downward into the basement rock and... • Moving sediment • Creates “V” shaped canyon and valleys • When streams emerge from the mountain front, they often deposit some of this sediment forming alluvial fans.

  19. Alluvial FansTransition from Tributary to Transport

  20. Aging Rivers: How Old Is It? • Young- rapid bed erosion, waterfalls, rapids, v-shaped valleys, few tributaries, low volume • Mature- well established tributaries, larger volume of water, erode banks and not the bed (bottom), meanders, oxbow lakes

  21. Flash Flooding & Sheetwash

  22. Braided Pattern = high slope + high stream power + coarse bed materials

  23. Braided Streams & Rivers • High sediment load • Constantly changing course • Floodplain is completely occupied by channels • Many small islands called mid-channel bars • Usually coarse sand and gravel deposits.

  24. Meandering Rivers

  25. Meandering Rivers • Constantly erode material - Cut bank • Constantly deposit material - Point bar • Change their channel course gradually • Create floodplains wider than the channel • Very Fertile soil • Subjected to seasonal flooding

  26. Formation of Meanders

  27. Point bar deposits

  28. Point Bar Deposits Point bar deposits grows laterally through time

  29. Cut bank erosion Point bar deposits } Meander loop

  30. Formation of an Oxbow

  31. Meandering stream flowing from top of screen to bottom

  32. Maximum deposition Maximum erosion

  33. Meander scars Oxbow Lake Oxbow cuttoff

  34. 1993 Mississippi Flood

  35. Flooding & Sedimentation

  36. Deltas - Distribution Systems

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