Universal Soil Loss Equation for Construction Sites

1
Universal Soil Loss Equation for Construction
Sites

• Dane County Land Conservation Division
• Madison, Wisconsin

2
(No Transcript)
3
(No Transcript)
4
Conceptual Model of Erosion
5
A(R)(R)(K)(LS)(C)

• A Computed Soil Loss Rate (ton/acre)
• R Percent of annual R factor to date.
• R Annual Rainfall and Runoff Factor
• K Soil Erodibility Factor type
• LS Slope length/Steepness Factor
• C Cover and Management Factor

6
Rainfall and Runoff Factor (R)

• Amount of energy in a locations annual rainfall.
  
• The R factor for Dane County is 150.

7
Monthly Distribution of R
Percent of Annual R
8
Soil Erodibility Factor (K)

• Based on the soil type of the site.
• Corresponds to the erosivity of the soil in a
  bare condition.
• Use K factor for subsoil, not topsoil on
  construction sites.

9
Slope Length/Steepness Factor (LS)

• Ratio based on the relationship between the
  percent slope and slope length of the disturbed
  area.

10
Soil Erosion vs. Slope Length
11
130
125
120
100 feet
12
Cover and Management Factor (C)

• The factor representing the sites cover
  protection from rainfall impact.
• The ratio of erosion between a specific ground
  cover and bare ground.

13
Soil Loss Rate (A)
Ordinance Standard 7.5 tons per acre
14
(No Transcript)
15
Soil Particle Size Distribution
16
Why not RUSLE or RUSLE2?

• Needs modifications to reflect urban environment.
• Erosion control practices are not treated
  properly.
• Problems with complex slopes.
• Need to add more erosion control practices and
  techniques.
• Need simple protected version for applicants.

17
Summary

• Able to target areas for more effective
  control.
• USLE Aids in the design of practices.
• Spreadsheet increases efficiency.

18
(No Transcript)