Transcript Workshop - Biological Systems Engineering

J.Q. Wu, S. Dun, W.J. Elliot, H. Rhee
J.R. Frankenberger, D.C. Flanagan
P.W. Conrad, R.L. McNearny
Introduction
•
A crucial component of planning surface mining
operations as regulated by the National Pollutant
Discharge Elimination System (NPDES) is to
estimate potential environmental impacts during
and after mining operations
•
Reliable watershed hydrology and erosion
models are effective and efficient tools for
evaluating postmining site-specific sediment
control and reclamation plans for the NPDES
Objectives
•
The objectives of this workshop are
 To introduce the newly developed WEPP-Mine, an online
GIS interface for the USDA’s WEPP model, as a
management tool for western alkaline surface mines
 To apply WEPP-Mine, in a case application, to evaluate
pre- and postmining watershed hydrological and erosion
processes and impacts of BMPs at the Big Sky Mine,
eastern Montana, USA
 To obtain feedback from and exchange with stakeholders
(state regulatory personnel, researchers, private
consultants) and other workshop attendees to further
refine WEPP-Mine
WEPP
•
WEPP (Water Erosion Prediction Project) was
initiated in 1985 as a new‐generation water erosion
prediction technology for use by federal action
agencies involved in soil and water conservation
and environmental planning and assessment
• WEPP was developed by the USDA‐ARS with user
requirements collected from the Bureau of Land
Management (BLM), Forest Service (FS), and Soil
Conservation Service (SCS)
• The WEPP model is a result of a large team efforts
involving many scientists and experts
WEPP cont’d
•
WEPP was intended to replace empiricallybased erosion prediction technologies (e.g.,
USLE) for assessing the soil erosion impact of
diverse land uses ranging from cotton fields to
mountain forests
•
It simulates many of the physical processes
important in water erosion, including infiltration,
runoff, ET, percolation, subsurface lateral flow,
raindrop and flow detachment, sediment
transport, deposition, plant growth, residue
decomposition, and changes in soil properties
WEPP cont’d
•
The WEPP model can be used for common
hillslope applications or on watersheds
•
In addition to WEPP core codes, the current
version includes a parameter database and various
interfaces, including a GIS and web‐based
interfaces
•
WEPP technologies have been successfully used
in the evaluation of important natural resources
issues throughout the US and in many other
countries
WEPP Watershed
•
•
WEPP discretizes a
watershed into
hillslopes, channel
segments, and
impoundments
An impoundment can
be on the channel
network or at the foot
of a hillslope
WEPP Inputs
•
Climate
 Observed daily values of precipitation (amount, duration,
relative time to peak, relative peak intensity),
temperatures (max, min), solar radiation, and wind
(direction, speed)
 Generated with CLIGEN, an auxiliary stochastic climate
generator
•
Topography
• Slope orientation, slope length, and slope steepness at
points along the slope profile
WEPP Inputs cont’d
•
Soil
 Surface soil hydraulic properties, erosion parameters, and
texture data for the soil profile
 Soil properties of multiple layers to a maximum depth of
1.8 m can be input
• Land management
 Information and parameters for plant growth, tillage, plant
and residue management, initial conditions, contouring,
subsurface drainage, and crop rotation
WEPP Outputs
• Event-by-event summary of runoff and soil erosion
• Graphical output for soil detachment and
•
•
•
•
•
•
sedimentation along a slope profile
Daily water balance
Plant growth and residue decomposition
Snow accumulation and snowmelt and soil frost and
thaw
Dynamic change of soil properties
Sediment yield
Return-period analysis
WEPP Impoundments
•
WEPP simulates foothill small ponds behind
 Filter fence
 Straw bales
•
WEPP also simulates sediment ponds with
hydraulic structures
 Drop spillway
 Perforated riser
 Culvert
 Emergency spillway
 Rock-fill check dam
Drop Spillway
Perforated Riser
Culvert
Emergency Spillway
Rock-fill Check Dam
Filter Fence
WEPP Application to Mining
Areas
•
To simulate the effect of mining operations on soil
erosion and to evaluate sediment control BMPs,
typical WEPP applications to mining areas may
involve the assessment of
 Premining condition as a baseline against which other
scenarios can be compared
 Postmining with revegetation
 Postmining with revegetation and a sediment pond
 Postmining with revegetation and a silt fence
WEPP-Mine
•
WEPP-Mine was developed based on the USDA’s
online GIS interface for the WEPP model
•
It provides functions specifically for applications to
mining areas
 Using user-specified DEMs
 Using reclamation maps
 Simulating watershed-specific sediment ponds
•
It can be accessed using a web browser at
http://wepponlinegis.bsyse.wsu.edu/osm
WEPP-Mine Inputs
•
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USGS 30-m DEM
•
Soil and landuse can also be customized within the
WEPP-Mine interface
•
Special permission is required for uploading userspecified DEMs and reclamation maps
USGS 2006 National Land Cover
NRCS SSURGO soil data
Spatial data automatically retrieved from the online
servers by default
WEPP-Mine Inputs cont’d
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•
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CLIGEN-generated climate based on long-term
monthly statistics is currently used (the use of
observed climatic data will be implemented)
The CLIGEN database includes more than 2,600
weather stations across the US
Weather statistics of the station closest to the
watershed outlet is used by default
PRISM 800-m gridded monthly averages is applied to
the monthly statistics to account for location and
elevation differences from the CLIGEN station
WEPP-Mine Outputs
• Channel network
• Subcatchments
• Watershed summary
• Average annual values of the simulation results
• Return-period and frequency analysis
• Flowpath soil loss map
• Representative hillslope runoff map
• Representative hillslope soil detachment map
• Representative hillslope soil loss map
WEPP-Mine Output cont’d
General Steps for WEPP-Mine
Applications
•
•
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Select area of interest
Generate channel network
Select watershed outlet and discretize watershed
and subwatersheds
• View watershed summary
• Customize watershed inputs
• Run WEPP
• Analyze WEPP simulation results
Computer Requirement
•
•
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A computer connected to internet
A web browser
Following instructions on the web page (select and
click buttons)
Premining Simulation
•
WEPP simulation for the premining conditions can
be accomplished by following the general steps for
WEPP-Mine application without customizing
watershed inputs
Premining Simulation cont’d
Postmining Simulation
•
User-specified DEM is used for topographical inputs for
postmining conditions
•
A reclamation map can be uploaded for postmining
soils and land managements
• Soils at the disturbed mining areas are composed of
mine spoils and a 0.6-m top soil layer if top soil is
applied during reclamation
•
Postmining top soil is a mixture of the onsite soil
described in the SSURGO database
•
Surface soil hydraulic and erosion parameters were
adjusted according to reclamation stages
Postmining Soil and Landuse
Map unit
Description
Land Managements Surface Soils
0
Undisturbed or No Data Shrub
SM Shrub
1
Disturbed—Facilities
Poor grass
Paved or Bare Rock
2
Not Reclaimed
Bare
Mine Spoil
3
Pre-Reclamation
Bare
Regraded Mine Spoil
4
Natural Revegetation
Poor grass
SM Top Soil
5
Seed Phase I
Good grass
SM Sod Grass
6
Seed Phase II
Good grass
SM Bunch Grass
7
Trail-complete
Low traffic road
SM Skid
User-Specified Maps
• The required format includes
 Raster map in ASCII
 30-m resolution
 UTM projection
 0 for “no data”
•
The corresponding projection file for the map needs
to be loaded
•
The IP address of a user is verified for uploading
files to the WEPP-Mine server
User-Specified DEM
Reclamation Map
Sediment Pond
•
After a watershed is discretized, one can specify
sediment ponds
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Impoundment inputs include dimensions of the pond
and related hydraulic structure parameters
•
Default pond dimensions (stage-area-length
relationship) are determined based on horizontal areas
encircled by two half ellipses separated by the widest
line of the area
•
Inputs for chosen hydraulic structures of a pond are
shown after clicking the “Set Structure Parameters”
button
•
User inputs override the default values
Sediment Pond cont’d
Sediment Pond cont’d
Case Application
Study Site
• WEPP-Mine was
applied to Watershed III
in Area A, Big Sky
Mine, a major surface
coal mine in southeast
Montana
Big Sky Mine Area A
•
•
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Mining completed in 1989
Major reclamation activities (regrading, topsoil
replacement, and revegetation) completed in 1992
Since 1984, many watersheds in the Big Sky Mine
have been monitored for channel flow and water
quality
Field Observations
WEPP Simulations
•
Four WEPP runs were made to examine model
performance in simulating the effect of three sediment
control BMPs
 Premining (natural) condition
 Postmining with revegetation
 Postmining with revegetation and a sediment pond
 Postmining with revegetation and a silt fence
Inputs for Premining
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Oldest DEM available for the study area
NRCS SSURGO soil data
USGS National Land Cover dataset for landuse and
management
Soil and management data acquired using the online
WEPP GIS interface
Postmining with Revegetation
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Topographic map taken from the “Big Sky Mine 2008
Annual Report”
Soil and management data for the disturbed areas
from the reclamation and bond status report
Soil and management data prepared based on field
observations
Watershed Delineation: Premining
and Postmining
•
Topographic, soil, landuse, and management
conditions vary from the mining to postmining
period and differ from the natural, premining
conditions
Sediment Pond
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A sediment pond set near the outlet of the watershed
 Volume 60,000 m3
 One culvert 2.4 m above bottom
 Culvert i.d. 18 cm
25
20
15
10
5
0
-5 0
20
40
60
80
100
120
140
Silt Fence
•
A silt fence set on the toe of a hillslope near the
watershed outlet
 Fence height 1m
Curtsey: USDA Forest Service
Rocky Mountain Research Station
Forestry Sciences Laboratory, Moscow, ID
Return-period Analysis
•
25-yr WEPP simulations were carried out using
observed precipitation and temperature for 1984–2009
from Colstrip climate station (5 mi northwest of the
site) and other required climate data generated using
CLIGEN
•
Return-period analyses were performed on field
observations and WEPP simulations
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Runoff and sediment yields of WEPP-simulated events
with a return period of 2, 5, 10, or 20 yr were
compared with field observations
Return-period Analysis
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Return periods were estimated using Chow’s
frequency factor method and Gumbel’s distribution
with an annual maxima series following Patra (2000)
X T  X m  sx  K
K  (0.45005  0.7797 ln(ln( T /(T  1)))
T: the specified return period
XT: the estimated value for a return period T
Xm and sx: the mean and standard deviation of the annual maxima of
the events
Results
Results cont’d
Runoff, mm
Sediment Yield, kg/ha
2
5
10
20
2
5
10
20
0.7
2.3
3.3
4.3
0.8
2.0
2.7
3.5
Premining
2.7
6.8
9.5
12.1
1200
3000
4100
5200
Postmining & Revegetation
6.8
15.9
21.9
27.7
7600
20300
28700
36700
Postmining & Sediment pond
6.1
15.0
21.0
26.7
3300
10800
15700
20400
Postmining & Silt fence
6.8
15.9
21.9
27.7
6700
17800
25200
32200
Return Period (yr)
Observed
Simulated
Results cont’d
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WEPP overestimated observed runoff and sediment
yield
However, WEPP simulation results showed the
effectiveness of the sediment control practices
A silt fence near the watershed outlet would help to
reduce sediment yield slightly from the postmining
revegetation condition
WEPP simulations indicated a sediment pond to be
more effective, with a reduction of sediment yield of
50%
Summary
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WEPP-Mine was developed as a management tool for
evaluating potential environmental impacts during and
after mining operations
WEPP-Mine was applied to a watershed in Area A, Big
Sky Mine, southeastern Montana, to assess watershed
hydrology and erosion as impacted by surface coal
mining activities and postmining reclamation and
sediment control practices
Three commonly used BMPs: revegetation, sediment
basin, and silt fence were evaluated as postmining
reclamation management plans
Additionally, a baseline scenario, the premining
condition, was simulated
Summary cont’d
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The WEPP simulations demonstrated the effectiveness
of the sediment control practices
Future efforts are needed to
 Further evaluate the WEPP-Mine performance through
systematic and statistical comparison of model results and
long-term field observations for different mines under different
geographic conditions in the western US
 Continually refine and develop functions (filter fence, buffer
zone) specific for mining applications
 Develop a comprehensive database of soil and management
for alkaline mines in the western US for using WEPP-Mine
Acknowledgment
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Funding support from OSM; in-kind support from WSU, US
Forest Service, and USDA NSERL
Technical exchanges with and support from P. Clark and D.
Matt
Funding and technical support and data and information
from MT DEQ, T. Golnar, J. Calabrese, Dr. E. Hinz.
Funding and technical support and assistance in field work
from Rosebud Mine engineers and staff
Resources and References
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http://www.ars.usda.gov/Research/docs.htm?docid=10621 (This USDA NSERL site
•
Key references on the overview of the WEPP model
contains extensive documentation and references on the WEPP model, including the free
model downloads)
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Flanagan, D.C., Livingston, S.J. (Eds.), 1995. USDA-Water Erosion Prediction Project User Summary.
NSERL Rep. No. 11, Natl. Soil Erosion Res. Lab., USDA ARS, West Lafayette, IN, 139 pp.
Flanagan, D.C., Nearing, M.A. (Eds.), 1995. USDA-Water Erosion Prediction Project: Hillslope Profile and
Watershed Model Documentation. NSERL Rep. No. 10, Natl., oil Erosion Res. Lab., USDA ARS, West
Lafayette, IN, 298 pp.
Flanagan, D.C., Ascough II., J.C., Nicks, A.D., Nearing, M.A., Laflen, J.M., 1995. Overview of the WEPP
erosion prediction model. In: Flanagan, D.C., Nearing, M.A. (Eds.), USDA-Water Erosion Prediction
Project Hillslope Profile and Watershed Model Documentation. NSERL Rep. 10, Natl. Soil Erosion Res.
Lab., USDA ARS, West Lafayette, IN (Chapter1).
Laflen, J.M., Lane, L.J., Foster, G.R., 1991. WEPP—a next generation of erosion prediction technology. J.
Soil Water Conserv. 46, 34–38.
Laflen, J.M., Elliot, W.J., Flanagan, D.C., Mayer, C.R., Nearing, M.A., 1997. WEPP-predicting water
erosion using a process-based model. J. Soil Water Conserv. 52, 96–102.
Laflen, J.M., Flanagan, D.C., Engel, B.A., 2004. Soil erosion and sediment yield prediction accuracy using
WEPP. Am. Water Res. Assoc. 40, 289–297.
Selected papers on modifying and applying the WEPP model by Dr. J. Wu’s group
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Pieri, L., M. Bittelli, J.Q. Wu, S. Dun, D.C. Flanagan, P. Rossi Pisa, F. Ventura, and F. Salvatorelli, 2007.
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Using the Water Erosion Prediction Project (WEPP) model to simulate field-observed runoff and erosion in
the Apennines Mountain Range, Italy, J. Hydrol. 336, 84–97.
Zhang, J.X., K-T Chang, and J.Q. Wu, 2008. Effects of DEM resolution and source on soil erosion
modelling: a case study using the WEPP model, Int. J. Geogr. Info. Sci. 22, 925–942.
Dun, S., J.Q. Wu, W.J. Elliot, P.R. Robichaud, D.C. Flanagan, J.R. Frankenberger, R.E. Brown, and A.C.
Xu, 2009. Adapting the Water Erosion Prediction Project (WEPP) model for forest applications, J. Hydrol.
466, 46–54.
Dun, S., J.Q. Wu, D.K. McCool, J.R. Frankenberger, and D.C. Flanagan, 2010. Improving frost simulation
subroutines of the Water Erosion Prediction Project (WEPP) Model, Trans. ASABE. 53, 1399–1411.