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Stream Sediment

Stream Sediment. Sediment - particles transported or deposited in stream channels Sediment levels - good indicator of effectiveness of watershed mangement. Erosion is a natural process. Clearwater River, Idaho. The name says what the watershed management goal is. Clearwater River, Idaho.

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Stream Sediment

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  1. Stream Sediment • Sediment - particles transported or deposited in stream channels • Sediment levels - good indicator of effectiveness of watershed mangement

  2. Erosion is a natural process

  3. Clearwater River, Idaho The name says what the watershed management goal is.

  4. Clearwater River, Idaho

  5. Clean gravel beds for spawning

  6. Erosion Process • Detachment • Transport • Deposition Eroded skid trail

  7. Watershed Gross Erosion • Components of gross erosion • Interrills • Rills • Ephemeral gullies • Channels • Landslides or slumping

  8. Interril Erosion Raindrops striking exposed soil detach the soil particles and splash them into the air and into shallow overland flows. Raindrops striking these shallow flows enhance the flows's turbulence and help to transport more of the detached sediment to a nearby rill or flow concentration

  9. Rill Erosion

  10. Gully Erosion

  11. Channel Erosion

  12. Landslides Grand Ditch, Rocky Mountain National Park

  13. Estimates of rill erosion • Universal soil loss equation • Developed by US Dept. Agriculture • Oldest and most accepted estimator • Over-estimates for forest land • Use as a starting point only

  14. Universal Soil Loss Equation A = R K LS C P A = tons/acre/year R = rainfall energy factor K = soil erodibility factors LS = effect of topography C = ratio of soil loss with specified cover and with continuous tillage P = conservation practice factor

  15. R factor R = [∑ ∑ (E I30)] / 100 n) E = storm kinetic energy, ft-t/acre/inch of rainfall I = maximum 30 minute storm intensity, in./hr. n = total number of years m = number of storms in each year R = 150 to 200 for Indiana n m

  16. K factor Describes soil detachability and transport-ability due to soil texture, structure, organic matter, density, compaction, and biological characteristics K = A / (RLSCP) K is given in NRCS soil survey reports

  17. K factor 100 K = 2.1M1.14(10-4)(12-a) + 3.25(b-2) + 2.5 (c-3) M = (%silt + %very fine sand) (100 - % clay) a = % organic matter b = soil structure code used in soil classification c = profile permeability class

  18. LS factor LS = (λ/22.13)a (0.065 + 0.0454 S + 0.0065 S2 λ = slope length a = 0.5 for slope ≥ 5%, and 0.3 for 1 to 3% slope S = slope steepness in %

  19. C factor C = A (with treatment) / A (with clean tillage) C values reported in 3 studies of forested site conditions

  20. P factor P = A (with conservation practice) / A (up-and-down hill cultivation) P = 1 if no conservation practices P < with conservation practices

  21. Recommended Values for P Factor

  22. Example

  23. Drum chopper for site preparation Windrow of logging slash Burning piles of logging slash

  24. Erosion rates for clear cuttings in SE US

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