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

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

9. 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

10. Rill Erosion

11. Gully Erosion

12. Channel Erosion

13. Grand Ditch, Rocky Mountain National Park
Landslides
Grand Ditch, Rocky Mountain National Park

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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 %

20. C factor C = A (with treatment) / A (with clean tillage)
C values reported in 3 studies of forested site conditions
Undisturbed mature forest
Thinned to 50% density
Clearcut, no site preparation
Clearcut, roller chopped
Clearcut, complete site prep.
Clearcut, site prep., fallowed
0.03 NA
0.001 –
– 0.01
0.001 – 0.022
0.004 – 0.028
0.023 – 0.068
0.0242
0.097

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

22. Recommended Values for P Factor
Land slope %
Contouring
Contour stripcropping
Terrace and stripcropping
1 to 2
0.60
0.45
0.30
3 to 5
0.50
0.38
0.25
6 to 8
9 to 12
13 to 16
0.70
0.52
0.35
17 to 20
0.80
0.40
21 to 25
0.90
0.68

23. Example

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

25. Erosion rates for clear cuttings in SE US
Treatment
Recovery time
Annual erosion
(t/ha)
Natural NA
0.00 – 0.05
Logged and roaded 3
0.10 – 0.50
Burned 2
0.05 – 0.7
Chopped
0.05 – 0.25
Chopped and burned 4
0.15 – 0.40
Windrowed
0.20 – 0.24
Disked
2.50 – 10.0