Losing Ground: The Analysis of the Universal Soil Loss Equation Model

CHRISTOPHER J. PORTER

NORTH CAROLINA AGRICULTURAL AND TECHNICAL STATE UNIVERSITY

FACULTY ADVISOR: DR. JOHN ALBERTSON, PROFESSOR AND CHAIR,

DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING

TAN ZI, GRADUATE STUDENT

WISENET IGERT REU FELLOW

Presentation Overview

Hypothesis

Project Background

Methodology

Data/Results

Conclusion

Acknowledgements

HYPOTHESIS

What precipitation factors matter in soil erosion, intensity,

amount or a combination of both?

What would be the roles of different slopes and land

uses in the erosion simulation?

PROJECT BACKGROUND

Soil erosion - Natural process that can occur either

slowly or rapidly and causes severe loss of topsoil and

agricultural production

In order to analyze the erosion, scientist have developed

the USLE – Universal Soil Loss Equation

USLE is capable of suiting the analytical need of various

watersheds, depending on the region and conditions

USLE – UNIVERSAL SOIL LOSS EQUATION

A = R*K*LS*C*P

Normally calculated in tons on an annual basis but other units can

be utilized given the circumstances

Values expressed are determined from tables, maps, charts and

decades of experimentation

Units: metric tons/acre/yr (common) or metric tons/ha/yr (project)

Project Methodology

Review reference articles to find and understand

meaning behind USLE Factors

Generate MATLAB code for LS Factor using elevation,

slope grade and slope length

Determine Soil Erosion Rate and plot maps and

histograms

Study IPCC Report and determine projected

precipitation and climate changes in relation to USLE

Project Variables

Variable Value Units Condition(s)

R 225Interpolated from

Rainfall Map

K 0.3 Silty Loam Soil

LS 0.0038 DimensionlessInterpolated from

LS Matrix

C 15 DimensionlessContinuous Fallow, Rows on Contour

P 0.6 or 0.5 Dimensionless

If %slope is 0.2, P = 0.6

If %slope is 0.3, P = 0.5

Regional Location: Located at 39.23°N by 92.12°W

Figure 1: Rainfall & Runoff Factor (R) Map

Topographic Factor: Slope-Length and Slope-Steepness

Figure 2a: LS Factor Map Figure 2b: LS Factor Distribution

Elevation vs. Stream

Figure 3a: Watershed Elevation Figure 3b: Watershed Stream Path

USLE Graphical Results

Figure 4a: USLE Erosion Map Figure 4b: Erosion Rate Distribution

Figure 5: Near-Term Projection Map (Annual)

Near-Term Projection Results

Long-Term Projection Results

Figure 6a: Long-Term Projection (October-March)

Figure 6b: Long-Term Projection (April-September)

CONCLUSION & DISCUSSION

The information from the USLE is regional and useful

for long-term planning and analysis

Constantly changing slope and varying land use

does have an impact on the rate of soil erosion

There will be impacts to soil erosion rates from the

changes in precipitation that will occur in the near-

term and long-term future

REFERENCES

Change, Intergovernmental Panel on Climate. Climate

Change 2013: The Physical Science Basis: Working

Group I Contribution to the IPCC Fifth Assessment

Report. Cambridge: Cambridge UP, 2014. Print.

Wischmeier, Walter H., and Dwight David Smith. Predicting

Rainfall Erosion Losses: A Guide to Conservation

Planning. Washington: Dept. of Agriculture, Science and

Education Administration, 1978. Print.

ACKNOWLEDGEMENTS

This material is based upon work supported by the

National Science Foundation under NSF Grant #DGE-

1068871 as part of the Integrative Graduate Education

and Research Training (IGERT) program in Wireless

intelligent sensor networks (WISeNET) at Duke

University’s Pratt School of Engineering

Dr. John Albertson

Tan Zi