losing ground: the analysis of the universal soil loss equation model christopher j. porter north...
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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