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

Clean gravel beds for spawning

Erosion Process Detachment Transport Deposition Eroded skid trail

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

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

Rill Erosion

Gully Erosion

Channel Erosion

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

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

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

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

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

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

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 %

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 0.0001- 0.001 0.002 -0.004 0.003 -0.009 0.03 NA 0.11- 0.17 0.001 – 0.0034 0.0003 – 0.01 0.001 – 0.022 0.004 – 0.028 0.023 – 0.068 0.00014 0.00019 0.00165 0.00325 0.0242 0.097

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

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

Example

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

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