Use LiDAR and RUSLE2 Model to Calculate Soil Erosion Rates
in the Rainwater Basin, Nebraska
Zhenghong Tang
University of Nebraska-Lincoln
Rainwater Basin Joint Venture Annual Seminar
02-09-2016
Soil Erosion Process
Destroys soil aggregates and
disperses soil particles
Creating soil crusts
Resulting in increased runoff and soil erosion
Soil Erosion Types
Severe Sheet & Rill Erosion
Ephemeral Gully Erosion
Soil Erosion and Sediment Deposit to Playa Wetlands
Highly-altered watershed
Sediment inputs to wetlands
Sediment with runoff
Corn residue
Sediment from agricultural lands
Sediment blocks the culvert
Impacts of Sediment on Playa Wetlands
• Decrease wetland water holding volume, reduce wetland size, and cause
hydrologic functionality loss
• Degrade water quality of wetlands
• Affect the interplay of hydro-period, seed banks, and vegetation
regeneration
• Disrupt the dynamic bio-geochemical cycling processes and degrade the
natural resiliency
• Degrade the habitat diversity through altering the plant and invertebrate
communities
Rainwater Basin Wetlands
Playa wetlands in the Rainwater Basin provide critical
habitats for 12 million migratory waterfowls to rest and feed.
Revised Universal Soil Loss Equation 2
• RUSLE2 was based on the USLE which was developed by Wischmeier and Smith
in the late 1950’s and early 1960’s at the National Soil Erosion Research Lab
located at Purdue University.
• It was an empirical model based on over 10,000 plot-years of basic runoff and soil
loss data from 49 locations across the United States.
• RUSLE2 is an update of the RUSLE1 model and still uses the basic structure of
the USLE.
• Because of the complexity of the model in terms of the inputs allowed, the types of
information displayed and the variety of situations that can be modeled it can be a
little overwhelming for users.
Revised Universal Soil Equation 2 (RULSE2)
A = R*K*LS*C*P
A = Soil loss per unit area per year;
R = Rainfall intensity factor;
K = Soil erodibility factor;
LS = Slope-length factor;
C = Crop management factor;
P = Conservation practice factor;
The is calculated from
the annual summation
of rainfall energy in
every storm
(correlated with
raindrop size) times
its maximum 30minute intensity.
The higher the value,
the more susceptible
the soil can be eroded.
The Soil Erodibility
Factor (Kf) indicates
the susceptibility of
the soil to sheet and
rill erosion by water.
The higher the value,
the more susceptible
the soil is to sheet and
rill erosion.
LS factor
Slope length (feet)
Slope
(%)
25
50
75
100
150
200
300
400
500
600
800
1000
0.2
0.060 0.069 0.075 0.080 0.086 0.092 0.099 0.105 0.110 0114
0.5
0.073 0.083 0.090 0.096 0.104 0.110 0.119 0.126 0.132 0.137 0.145 0.152
0.8
0.086 0.098 0.107 0.113 0.123 0.130 0.141 0.149 0.156 0.162 0.171 0.179
2
0.133 0.163 0.185 0.201 0.227 0.248 0.280 0.305 0.326 0.344 0.376 0.402
3
0.190 0.233 0.264 0.287 0.325 0.354 0.400 0.437 0.466 0.492 0.536 0.573
4
0.230 0.303 0.357 0.400 0.417 0.528 0.621 0.697 0.762 0.820 0.920 1.01
5
0.268 0.379 0.464 0.536 0.656 0.758 0.928 1.07
1.20
1.31
1.52
1.69
6
0.336 0.476 0.583 0.673 0.824 0.952 1.17
1.35
1.50
1.65
1.90
2.13
8
0.496 0.701 0.859 0.992 1.21
1.41
1.72
1.98
2.22
2.43
2.81
3.14
10
0.685 0.968 1.19
1.37
1.68
1.94
2.37
2.74
3.06
3.36
3.87
4.33
12
0.903 1.28
1.56
1.80
2.21
2.55
3.13
3.61
4.04
4.42
5.11
5.71
14
1.15
1.62
1.99
2.30
2.81
3.25
3.98
4.59
5.13
5.62
6.49
7.26
16
1.42
2.01
2.46
2.84
3.48
4.01
4.92
5.68
6.35
6.95
8.03
8.98
18
1.72
2.43
2.97
3.43
4.21
3.86
5.95
6.87
7.68
8.41
9.71
10.9
20
2.04
2.88
3.53
4.08
5.00
5.77
7.07
8.16
9.12
10.1
11.5
12.9
0.121 0.126
The LS factor is
a function of
slope steepness
and slope
length.
Values for LS
were derived
using
nomographs
and tabulated to
make it easier to
look them up.
The C-factor is the
ratio of soil loss from
a specific crop
management system
to that from a plot
with clean-till,
continuous fallow.
The values represent
the combined effects
of the crop rotation
and tillage and
residue management.
P-factor
• In the RUSLE2 credit was given for applying conservation practices to
reduce runoff and soil erosion.
• The primary practices considered were contouring, strip cropping, and
terraces.
• Values of P are between 0 and 1 and were assigned based on slope
steepness, slope length and row grade.
RUSLE2 Modeling Results
• The mean of soil erosion ratio in the Rainwater Basin is 1.97 tons/acre/year with
the standard deviation of 2.63 tons/acre/year.
Category
WPAs watersheds
WMAs watersheds
Conservation easements
Non-conservation lands
Mean (tons/acre/year)
Standard deviation (tons/acre/year)
1.14
1.40
1.02
1.16
1.12
1.42
2.04
2.71
Implications
• Establishment of vegetation buffers in round-out lands is an effective approach to
lessen sediment accumulation and thus maintain the high level of wetland
functionality.
• Vegetation restoration, management, maintenance are an important component to
upgrade these late successive playas to early successive playas.
• Sediment removal is a primary tool to improve wetland capacity and restore the
full suite of playa functions
• Fully hydrologic restoration or partially hydrologic recovery are the key step to
convert upper lands back to depressional playas.
Acknowledgement
 Andy Bishop, RWBJV
 Ted LgGrange, NGPC
 Randy Stutheit, NGPC
 Jeff Drahota, USFWS
 Neil Dominy, NRCS
 Daniel Shurtliff, NRCS
Thank you!
ztang2@unl.edu