WIND EROSION EQUATION NAMCIRCULAR 2 USDANRCS

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WIND EROSION EQUATIONNAM-CIRCULAR 2USDA-NRCS
Mike Sporcic Wind Erosion Specialist National
Technology Support Center-Central
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• Wind Erosion is a serious problem in the semiarid
  and arid regions of the US.

• Mostly in the West, Upper Midwest, Southwest and
  Florida.

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It causes serious problems on cropland.
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As well as our urban neighbors.
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The Good Old Days
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The Good Old Days cont.
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Then in 1988, Bob Shatton, Ag Engineer, WA.
Wrote a C batch pro- gram to run on our UNIX
machines. It was best thing since apple pie. No
more long hand runs.
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Then the FOCS Module Blunder

• I say blunder because it seemed to be a back step
  to me. I did not know, at the time, that no one
  else had a Bob Shatton.
• Many things were problematic for the module the
  math adding green growth and residue was
  incorrect, there was no templating capability,
  and data management was hard.

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Then came the PC age

• About 1997 a wise NRI specialist in the SO gave
  me the use of a laptop.
• I also attended the West Agronomy Consortium
  meeting in Portland (1997), where Dave Lightle
  told me of Tom Keeps effort to computerize WEQ.
• It was the back half of the model I am presenting
  to you today.

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The Future is WEPS

• By 2002 we will move to WEPS

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National Herd Our Cry

• Many of us have requested changes in WEQ to
  account for irrigation effects, crusting, random
  roughness, I adjustments and climate adjustments.
• Most of these were requests were met in Circular
  2.
• So much for the prelude.

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Introduction WEQ Excel Spreadsheet

• Cover NAM Circular 2 changes
• Changes to Ridge Roughness
• Show data files needed to run
• Discuss limitations of the sheet
• Quick intro to the Excel spreadsheet
• Demo how to edit and make changes
• Answer Questions

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Spreadsheet History

• Started as a North Plains spreadsheet by Tom
  Keep, Ag Engineer (Calc sheet only)
• Then Circular 2, NAM amendment Sept. 12, 1997
  adding the need for additional calculations
• SGe calculations added, 1998
• Input data linked to lookup formulas, 1998
• Krd-Ridge Roughness formulas added, 1998

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Circular 2 Changes

• I adjustment for Irrigated
• -Above 134 no adjustment
• -Less than I134, reduce one I class
• -IF - Irr. factor reduces Erosive Wind Energy
  (EWE) for mgt period
• Random Roughness (Krr) combined with Ridge
  Roughness (Krd)

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Circular 2 Changes Cont.

• Must know Irrigation Type
• Consumptive Use (CU) for the Crop
• Number of irrigation for the mgt period

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ADJUSTMENTS TO I

• Irrigation adjustment (IF)
• -supporting data is limited
• -reduction observed in the field
• -adjustment applies to all soils except fine
  and very fine sands
• -Not for Is gt 134

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EWE IRRIGATION ADJUSTMENT

• Effects of wet soil is accounted for by adjusting
  the EWE for the mgt period
• Bare wet soil remains non-erodible
• 1 day for coarse textured soils
• 2 days for medium textured soils
• 3 days for fine textured soils
• See sheet WEGtab for table

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ADJUSTMENTS TO I - IRRIGATION
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Krr RANDOM ROUGHNESS FACTOR

• Raises threshold wind speed at which erosion
  begins
• Provides some sheltered area among clods where
  moving soil can be trapped
• Spreadsheet reduces RR (clodsize) by one half
  after 15 days.

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Krr RANDOM ROUGHNESS FACTOR

• Non-oriented surface roughness
• Cloddiness
• Usually created by tillage implements
• Values represented as standard deviation of
  roughness heights
• Use RUSLE Handbook 703 Pictures, OR
• Chain roughness method (there is a big diff)
• Must tie predicted roughness to new tillage

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Random Roughness - Krr
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Random Roughness, 0.25
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Random Roughness, 0.40
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Random Roughness, 0.65
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Random Roughness, 0.75
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Random Roughness, 0.85
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Random Roughness, 1.05
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Random Roughness, 1.60
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Random Roughness, 1.70
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Random Roughness, 2.15
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Krr - Adjustments
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Ridge Roughness- Krd

• Revised NAM will have new tables
• Based on I values and Preponderance
• I values 134 and greater have own curve
• As Preponderance goes down (we do not know where
  the wind will come from), Krd goes up (the ridge
  is less effective)
• Krd can be lower than 0.5 now

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Krr Ridge Roughness
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Irrigation Input Requirements

• Need to know when water is applied, this includes
  pre-plant irrigation and post harvest irrigation.
• This is calculated in days so circle irrigation
  is a challenge.
• Drip irrigation also poses a problem. Need to
  estimate the of surface wet.

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Circle Irrigation
This is one irrigation for this circle. It
takes 96 hours for this irrigation.
Suggest that one day would be correct.
Day 3-24 hrs
Day 4-24 hrs
(1 day x 1/4 of field x 4 days to cover field
1)
Day 1-24 hrs
Day 2-24 hrs
Is this one day or four days?
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Unsheltered Distance
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Field Width

• Width for use of the Speadsheet means the short
  side of the field or average short side of a
  polygon.
• A square field would use the side length.

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Field Width vs Unsheltered Distance
Field Width
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Field Width vs Unsheltered Distance

• The Excel Spreadsheet is able to determine the
  correct L using the Width of the field only.

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Computer Requirements

• Need 486/33 min.
• 586 is better
• Windows 95, 98, or NT
• Excel version 7.0
• 16 mg of RAM or better
• File name WEQvs7.02.xls
• Input shaded cells and pull down arrows

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INSTR sheet
Read this sheet first.

• Wind Erosion Model Worksheet Legend
• -Definitions
• Describes input data and column headings
• New-Krd, Krr, IF, No of Irr, and TWF

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Res WKS sheetRequired Inputs

• Operation Dates
• Crop Names
• Operations
• Percent Flat Residue
• Number of irrigation per mgt period
• Other data
• -Name, Tract, Loc, C, I, Field Width, LW
  ratio, Tillage Dir, Field Dir, Irr (y/n), etc.

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Calc sheet

• Detailed calculations by Mgt Period
• Note Krd, Krr, and IF factors added here
• No inputs needed or allowed

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Data Tables

• Crop table
• -Need to maintain changes in crop data
• residue produced and green growth
• Tillage table
• -Residue reduction with allowances for
• speed and type of residue tilled
• -Random roughness tied to tillage

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Data Tables cont.

• Climate data, the wind direction, EWE, and
  Preponderance must be added for your climate
  stations in your state.

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Summary

• If Staff can calculate residue reduction and
  understand irrigation, they can operate this
  program.
• State Agronomist must set up wind data (climate
  file), crop data, and operation (tillage) files
  before it can be used in a new state.
• Local CUs for all irrigated crops are needed.

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Limitations

• We can not change tillage direction in each mgt
  period.
• Files are large.
• No preset templates, they can be made and saved
  for later use.
• It does not allow for crusting (no I factor
  adjustment for a period of crusting.

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Limitations

• Need to know Irrigation and CU of the crops
• Do not have good growth curves
• Do not have SGe curves for all crops both green
  and dry
• There is no residue decomposition routine (like
  RUSLE has)
• There is no Krr degradation routine (like RUSLE
  has)

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Where to get more information

• Call me if you have trouble.
• Mike Sporcic, michael.sporcic_at_nm.usda.gov,
  505-761-4424
• Website for SCI and WEQ www.nm.nrcs.usda.gov/techs
  erv/techr/es1.htm

Were Done
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Questions Short Demo
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