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Exploring Rivers and Streams: Hydrology and Geomorphology

Delve into the dynamic world of rivers and streams, from the hydrologic cycle to sediment transport, flood occurrences, and stream system components. Discover how water moves through different environments and study the influence of factors like terrain and weather. Learn about meandering rivers, alluvial fans, braided streams, and more. Experience virtual river gaging to analyze stream data. Explore the impact of floods and sedimentation, and witness the formation of oxbow lakes and meanders. Uncover the science behind water flow and erosion, and gain insights into the intricate processes shaping our planet's surface water systems.

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Exploring Rivers and Streams: Hydrology and Geomorphology

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  1. RIVERS & STREAMS • Water Reservoirs • The Hydrologic Cycle • Surface Water Systems • Surface Water flow • Sediment Transport • Stream System Components • Floods and flooding.

  2. Where is the Water ?

  3. The Worlds Largest Rivers

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

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

  6. Laminar vs. Turbulent Flow

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

  8. 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

  9. Stream bank 0.6D D - Velocity measurements V Price Meter Pygmy Meter

  10. RATINGS CURVE Collect stage data continuously, transform it to discharge data To get a bit of experience with stream gaging and analysis of stream data, visit http://vcourseware4.calstatela.edu/VirtualRiver/FloodingDemo/index.html and play with it!!!

  11. Sediment Load

  12. Movement of Bedload by Saltation

  13. Sedimentation

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

  15. 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.

  16. Alluvial FansTransition from Tributary to Transport

  17. Flash Flooding & Sheetwash

  18. Coalescing Alluvial Fans

  19. Braided Streams

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

  21. Meandering Rivers

  22. 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

  23. Formation of Meanders

  24. Point bar deposits

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

  26. Cut bank erosion Point bar deposits } Meander loop

  27. Formation of an Oxbow

  28. Meandering stream flowing from top of screen to bottom

  29. Maximum deposition Maximum erosion

  30. Meander scars Oxbow Lake Oxbow cuttoff

  31. 1993 Mississippi Flood

  32. Flood Recurrence, Skykomish R. Want some stream flow data? Try: http://water.usgs.gov/

  33. Flooding & Sedimentation

  34. Flood Causes examples: Snowmelt + Frozen soil examples - 2) Mohawk River, 1996 - January 18-19, 1996 thaw (temp in the 60’s) Heavy rain (4.5”) on top of snow (45”) melted enough snow to be the equivalent of >7” of rain in a few hours (in my back yard the snow went from hip deep to 0 overnight!!) Cohoes monitoring station peak flow 132,000 cfs (100 year flood? Probably not...) January 20, temperature dropped to 20o, decreasing snowmelt and freezing some water in the upper drainage basins 10 deaths, thousands flee erosion caused landslides (1 fatality) $100 million damages

  35. Mohawk River at Cohoes, January 1996 100000 90000 80000 70000 60000 Average Daily Flow (cfs) 50000 40000 30000 20000 10000 0 12/30/95 1/6/96 1/13/96 1/20/96 1/27/96 2/3/96 date

  36. 1999 Ice Jam, Mohawk River, Rexford Bridge extremely cold weather in January --> thick ice, rapid thaw in February cause the ice to rise and break up

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