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Fluxes of water, sediment, and elements class

This article introduces the instrumentation and approach for surveying and flow gauging in order to quantify the fluxes of water, sediment, and elements in a given channel. It covers topics such as Manning's equation, floods and bankful discharge, and obtaining and understanding watershed flux data.

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Fluxes of water, sediment, and elements class

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  1. Fluxes of water, sediment, and elements class • Introduce instrumentation and approach for surveying and flow gauging • Introduce and understand Manning’s equation • Consider the meaning of Floods and Bankful Discharge • Getting and understanding watershed flux data • Logisitcs

  2. 1 FLOW GAUGING • QUANTIFY VOLUME OF WATER MOVING THROUGH CHANNEL • NEED CHANNEL GEOMETRY • NEED VELOCITY

  3. 1 Survey Across Stream Distance Velocity Water Depth

  4. 1 The auto level Your view

  5. 1 Level the instrument :( (:

  6. 1 TOP = DISTANCE BOTTOM = DISTANCE CENTER LINE - ELEVATION D

  7. 1 Good Data Table is key

  8. 1 Flow meter for measuring water speed

  9. 1 Divide and Conquer

  10. 1 Add up the pieces

  11. 1 From counts to speed

  12. 1 Stage and Discharge related through rating curve

  13. 1 Water Resources of North Dakota The top of a U.S. Geological Survey staff gage (a graduated rod against which water levels can be read) is barely visible above the water.The top of the gage represents a water level or river stage of 54.50 feet, 2 feet above the 1997 East Grand Forks city levee.During the 1997 flood, the Red River crested at 54.35 feet; the National Weather Service flood stage at Grand Forks is 28.00 feet.

  14. 1 WEIR is the permanent solution Q = 2.47h2.5

  15. 2 Manning Equation Use fudge factor of 1.49 when units are feet

  16. 2 SLOPE

  17. 2 Wetted Perimeter

  18. 2

  19. 2 http://wwwrcamnl.wr.usgs.gov/sws/fieldmethods/Indirects/nvalues/ Boundary Ck at Porthill, Idaho n = 0.073 Clark Fork at Missoula, Montana n = 0.030

  20. 3 Flow Levels Try to define in field using observations Bank full flow About once a year “Channel-forming flow” This is for alluvial channels

  21. 3 Extreme Floods How does the Huntington Fit?

  22. 3 DEFINE BASIN AREA COUNT BOXES OR USE DIGITIZER

  23. 4 Sediment Transport Through Rivers Bedload -- material moving along the bed, shear forces exerted by water sufficient to move clasts -- rarely measured (at % level) Suspended Load -- material kept in the water column by turbulence and lift forces (easy to measure in grab samples) Dissolved Load -- material in solution (easy to measure in grab samples) Bedload usually <<< than suspended load and ignored Dissolved load varies, usually < than suspended load

  24. 4 Sampling for suspended load…….

  25. 4 Mass Loadings and Erosion Rate Estimation Integrate suspended load over all flows (mass/time) + Integrate bedload load over all flows (mass/time) + Integrate dissolved load over all flows (mass/time)

  26. Load varies over time and discharge

  27. USGS Water Quality Data on lineDissolved and Suspended Load http://nwis.waterdata.usgs.gov/nwis/qwdata?site_no=04282815&agency_cd=USGS&begin_date=&end_date=&format=html_table&inventory_output=0&rdb_inventory_output=file&date_format=YYYY-MM-DD&rdb_compression=file&qw_sample_wide=0&submitted_form=brief_list

  28. 4 Integration over all flows is a non trivial problem!Need Rating Curves (suspended, dissolved, bedload) Suspended Load Hysteresis loop

  29. 4 Other Approaches…Reservoir trapping (may miss dissolved) Nahal Yael, Negev Desert

  30. 4 SEDIMENT YIELD - What comes out = or ≠ Timescale Steady state Human impact Episodic disturbance SEDIMENT GENERATION - Material generated by erosion

  31. River Lab Logistics • On Huntington, in water • Warm clothes, food, $, Daily Bread • Measure discharge - survey and velocity • Trace flow • Compare pools and riffles • Field estimate of bankfull stage • OLD TENNIS SHOES! Teva/toenail story

  32. Downstream Organization Survey one of each type Calculate discharge for one of each type Calculate roughness for one of each type COMPARE

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