WIND EROSION EQUATION Recent Changes (NAM) USDA-NRCS - PowerPoint PPT Presentation

About This Presentation
Title:

WIND EROSION EQUATION Recent Changes (NAM) USDA-NRCS

Description:

Recent Changes (NAM) USDA-NRCS 1 2 3 4 5 7 6 8 9 10 10 10 11 12 13 14 15 17 18 16 16 19 Wind Erosion continues to be a serious problem in the semiarid and arid ... – PowerPoint PPT presentation

Number of Views:577
Avg rating:3.0/5.0
Slides: 34
Provided by: usda173
Category:
Tags: equation | erosion | nam | nrcs | usda | wind | changes | farm | recent | wind

less

Transcript and Presenter's Notes

Title: WIND EROSION EQUATION Recent Changes (NAM) USDA-NRCS


1
WIND EROSION EQUATIONRecent Changes
(NAM)USDA-NRCS
2
  • Wind Erosion continues to be a serious problem in
    the semiarid and arid regions of the US.

3
The Good Old Days
4
The Good Old Days cont.
5
WEQ Changes made!
  • WEQ has been updated to account for irrigation
    effects, random roughness and I Factor
    adjustments.
  • WEQ changes are outlined in the new edition of
    the National Agronomy Manual.

6
Introduction WEQ Excel Spreadsheet
  • Cover NAM changes
  • Changes to Ridge Roughness
  • Addition of Random Roughness
  • Quick intro to the Excel spreadsheet
  • Demo how to edit and make changes
  • Answer Questions

7
Spreadsheet History
  • Began as a spreadsheet by Tom Keep
  • Then Circular 2, NAM amendment Sept. 12, 1997 was
    incorporated
  • SGe calculations added, 1998
  • Krd-Ridge Roughness formulas added in 1998

8
Circular 2 Changes
  • I Adjustment for Irrigation
  • -Above 180 no adjustment
  • -180 or less, reduce one I class
  • IF Irr. Factor reduces Erosive Wind Energy
    (EWE) for mgt period
  • Random Roughness (Krr) combined with Ridge
    Roughness (Krd)

9
ADJUSTMENTS TO I
  • Irrigation adjustment (IF)
  • -adjustment applies to all soils

10
EWE IRRIGATION ADJUSTMENT
  • Effects of wet soil is accounted for by adjusting
    the EWE for the mgt period
  • Bare wet soil remains non-erodible wet
  • 1 day for coarse textured soils
  • 2 days for medium textured soils
  • 3 days for fine textured soils
  • See sheet WEG tab for table

11
ADJUSTMENTS TO I - IRRIGATION
12
Krr RANDOM ROUGHNESS FACTOR
  • Soil cloddiness raises the threshold wind speed
    at which erosion begins
  • Provides sheltered area among clods where moving
    soil can be trapped
  • Spreadsheet reduces RR (clodsize) by one half
    after 15 days.

13
Krr RANDOM ROUGHNESS FACTOR
  • Non-oriented surface roughness
  • Cloddiness
  • Usually created by tillage implements
  • Values represented as standard deviation, in
    inches, of roughness heights
  • Use Random Roughness-Guidance sheet
  • Roughness assigned to each tillage implement
    (ideal conditions)

14
Random Roughness - Krr
15
Ridge Roughness- Krd
  • Revised NAM has new tables
  • Based on I values and Preponderance
  • Low Preponderance values indicate less of the
    erosive wind is from the prevailing wind
    direction.
  • Higher Krd values indicate that ridges are less
    effective
  • Krd can be lower than 0.5 now

16
Irrigation Input Requirements
  • Enter the number of Irrigations, including
    pre-plant and post harvest irrigation
  • Non-erodible wet days will be calculated based
    on soil texture (WEG)
  • Drip irrigation poses a problem. Need to
    estimate the of surface that is non-erodible
    wet

17
Circle Irrigation
The soil texture determines the number of
non-erodible wet days (1,2,or 3) per irrigation
It takes this system 96 hours to make one
complete circle. For WEQ this is one irrigation.
Day 3-24 hrs
Day 4-24 hrs
Day 1-24 hrs
Day 2-24 hrs
18
Field Width
  • With the WEQ Speadsheet, field width is the
    distance across the short side of the field or
    average short side of a polygon.

19
Field Width vs Unsheltered Distance
Field Width
20
Field Width vs Unsheltered Distance
  • The Excel Spreadsheet model will determine L
    using the length/width ratio of the field, the
    angle of deviation, wind preponderance and the
    resulting wind erosion direction factor.

21
Computer Requirements
  • Need 486 minimum.
  • 586 is better
  • Windows 95, 98, or NT
  • Excel version 7.0
  • 16 mg of RAM or better
  • File name WEQvs8.01.xls

22
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

23
Res WKS sheetRequired Inputs
  • Operation Dates
  • Crop Names
  • Operations
  • Percent Flat Residue
  • Number of irrigation per mgt period
  • Yield adjustment
  • Prod., Farm, Tract, Field, C, I, Field Width, LW
    ratio, Tillage Dir, Field Dir, Irr (y/n)

24
Calc sheet
  • Detailed calculations by Mgt Period
  • Note Krd, Krr, and IF factors added here
  • No inputs needed or allowed

25
Data Tables
  • Crop table
  • -Need to maintain crop data
  • residue produced and green growth
  • Tillage table
  • -Residue reduction
  • -Random roughness assigned to tillage

26
Data Tables cont.
  • Climate data, the wind direction, EWE, and
    Preponderance must be added for climate stations
    in your state.

27
Summary
  • If Users have a basic understanding of the EXCEL
    spreadsheet, they can use this model.
  • State Agronomist should become familiar with the
    wind data (climate file), crop data, and
    operation (tillage) files before beginning use in
    a new state.

28
Limitations
  • We can not change tillage direction in each mgt
    period.
  • Need to create templates and save for later use.
  • It does not allow for crusting (no I factor
    adjustment for a period of crusting).

29
Limitations
  • Growth curve data is limited
  • Do not have SGe curves for all crops both green
    and dry

30
Where to get more information
  • Call State Agronomists for assistance
  • State Agronomists can call
  • Mike Sporcic, michael.sporcic_at_nm.usda.gov ,
    505-761-442
  • or,

31
Where to get more information
  • Gary Tibke (785)537-5541
  • tibke_at_weru.ksu.edu
  • Lorenz Sutherland--(719)384-5408
    lorenz.sutherland_at_co.usda.gov
  • Websites for WEQ www.nm.nrcs.usda.gov/techserv
    or www.weru.ksu.edu/nrcs

Were Done
32
Questions Short Demo END
33
The End
Write a Comment
User Comments (0)
About PowerShow.com