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Interactions class

Interactions class. Getting and understanding watershed flux data Influence of L arge W oody D ebris (LWD) on rivers Influence of Hillslope materials and processes on rivers Influence of the Atmosphere on rivers, 1927 flood example. 1. Sediment Transport Through Rivers.

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Interactions class

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  1. Interactions class • Getting and understanding watershed flux data • Influence of Large Woody Debris (LWD) on rivers • Influence of Hillslope materials and processes on rivers • Influence of the Atmosphere on rivers, 1927 flood example

  2. 1 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

  3. 1 Sampling for suspended load…….

  4. 1 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)

  5. 1 Dissolvedload varies over time and discharge

  6. 1 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

  7. 1 Data Manipulation Data supplied in mg/l (1/1000 g per 1000 g) or ppm Need to sum all constituents (Ca, Na, Mg, Cl, C03) Need to know daily flow (in liters). How many liters/m3? Multiply concentration by flow m3 = 100 cm* 100 cm* 100 cm = 106 cm3 =103 liters 100 l/s* 60s/min*60min/hr*24hr/day*15mg/l*0.000001kg/mg= 129.6 kg/day dissolved load

  8. 1 TO GET YEARLY LOADIntegration over all flows is a non trivial problem!Need Rating Curves (suspended, dissolved, bedload) Suspended Load Note Scatter Hysteresis loop

  9. 1 Other Approaches…Reservoir trapping (may miss dissolved) Nahal Yael, Negev Desert

  10. 1 SEDIMENT YIELD = what comes out = or ≠ Timescale Steady state Human impact Episodic disturbance SEDIMENT GENERATION = Material generated by erosion

  11. 1 Trimblegram

  12. 2 Importance of Vegetation Bank Stabilization, effective soil cohesion Source, Large Woody Debris

  13. Queets River, Olympic Penninusla, Washington 2 LargeWoodyDebris

  14. 2

  15. 2 Queets -- Meander Jam

  16. 2 Most rivers have been de-snagged Montgomery et al., 2003 Putget Lowland

  17. 2

  18. 2 Reach Scale Effects

  19. 2 In-Channel Effects

  20. 2 Valley Bottom Effects - Wood adds Complexity Nisqually River w/wood Floodplain Elevation (m)

  21. 2 Effects Felt Downstream

  22. 2 • Briaded Rivers • Weak banks • High sediment load • Flashy

  23. 2

  24. 3 Influence of Hillslope Materials and Processes on Channels Slides are frequent in mountain environments Example: Chris Brummer, Squire Creek, North Cascades, Slide into Channel

  25. 3 Toe of Slide - QT VR

  26. 3 Sediment and Woody Debris Supply - pulsed delivery

  27. Stepping of Channel Profile Damming of ephemeral lakes by slides 3 Outlet, overtopping dam

  28. 3 Help set channel roughnessboulders may be delivered by older slides….or underlying bedrock or till

  29. 3 Here, stratigraphic evidence this is not the first slide… Recent Slide Debris Older Slide Debris

  30. 4 1927 Flood • Antecedence --Rainfall during the month of October averaged about 150 percent of normal across the state. In northern and central sections, some stations received 200-300 percent of normal.

  31. 4 Major Channel Change and Realignment - Proctor

  32. 4 Major damage at constrictions, e.g., bridges • Isohyet map

  33. 4 Winooski-Burlington response

  34. 4 Cause of the 1927 Flood Mositure-laden air was forced to rise as it encountered the Green Mountains, resulting in torrential downpours. Rainfall in Northfield totaled 1.65 inches from 4:00 am to 11:00 am on the 3rd, with 4.24 inches falling from 11:00 am to 8:00 pm. The total from late evening of the 2nd to late morning on the 4th was 8.71 inches.

  35. Wednesday Lab • Meet in classroom • Move to the field, Bolton • Cooler weather, be prepared. • Wear sturdy shoes please

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