Using the METRIC Evapotranspiration Model to Compute Water Use by Irrigated Agriculture in Idaho

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Using Evapotranspiration Datain Idaho
Anthony Morse, William J. KramberIdaho
Department of Water ResourcesBoise,
Idaho Richard G. Allen University of
IdahoKimberly, Idaho
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METRIC

• Mapping EvapoTranspiration with high
• Resolution and Internalized Calibration

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OUTLINE

• How METRIC Works
• IDWR METRIC Applications

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METRIC SEBAL

• Trademark Issues with SEBAL
• SEBAL Commercially Available
• METRIC Uses Agrimet
• METRIC Tied to Reference ET

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HOW METRIC WORKS

• Requires Satellites with Red, Near IR, and
  Thermal IR
• Complete Energy Balance for Each Pixel

ET Rn - G - H
Rn
H
ET

G
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HOW METRIC WORKS

• Water vapor from soil and vegetation
• 24-hour ET from instantaneous overpass
• METRIC used for Landsat overpass dates, and
  Penman-Monteith equation between overpasses
• Use of hot and cold pixels for calibration.

Seasonal
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HOW METRIC WORKS

• ET from soil as well as
  vegetation
• Not Vegetation Index driven.

24-hour ET June 6, 2000
Landsat FCC June 6, 2000
.
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METRIC 24 HOUR ET
ETrF ET / ETr
ETrF at 11am
(ETr is ET for alfalfa)

24-Hour ET Computation ET24 (ETrF11am) (24-hour
ETr)
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METRIC 24-HOUR ET
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METRIC CALIBRATION
calibration is internal setting hot and cold
pixels
cold pixel
hot pixel
Maximum
Frequency
ET
0
Relative Temperature Landsat Thermal Band
absolute temperature is not needed
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ET APPLICATIONS AT IDWR

• Aquifer depletion
• Water rights buy-back
• Planning ET by land use class
• Water use by irrigated agriculture
• Water rights compliance monitoring
• Modeling ET for computing water budgets
• Analysis of water-rights curtailment alternatives.

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AQUIFER DEPLETION
METRIC Advantages

• time 2 weeks vs. 6-8 months
• cost 119 per well vs. 25 per well

accuracy pumpage vs. ET
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WATER RIGHTS BUY-BACK
1079mm Alfalfa Nampa Agrimet 984 mm
METRIC 1079 mm K-Factor 1240 mm Power
Consumption Curve 1341 mm Pump Performance
Curve 1034 mm Alfalfa Grand View Agrimet
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ET BY LAND USE CLASS

• How Does Water Use Change as Land Use Changes?

ET By Land Use / Land Cover
Land Use / Land Cover
ET From METRIC
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ET BY LAND USE CLASS

• Seasonal ET
• 3/15/2000 to
• 10/15/2000

 

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AGRICULTURAL WATER USE
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AGRICULTURAL WATER USE
RESULTS

• 2000 9,313,505 1,437,520 790 -
  1021 Alfalfa (.77) IDWR/METRIC
• 2002 -- 1,176,516
  -- Census of
  Agriculture
• 2000 -- 1,367,859
  -- USGS
• 1997 -- 1,241,522
  -- Census of
  Agriculture
• 1995 4,396,707 1,097,225 490
  (807 Alfalfa) (.61) USGS
• 1992 -- 1,169,710
  -- Census of Agriculture
• 1990 6,817,991 1,235,348 670
  (957 Alfalfa) (.70) USGS/IDWR
• 1987 -- 1,146,018
  -- Census of Agriculture

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WATER RIGHTS COMPLIANCE

• Irrigation Without a Water Right

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WATER RIGHTS COMPLIANCE
irrigation in excess of the diversion rate of
flow
Method
1. Select 426 well-field combinations

• 2. Use 2 consecutive Landsat overpasses (17
  Days)
• 3. Compute 17-day cumulative ET (ET17)
• 4. Compute water depth using 17-day maximum
  diversion rate (DR17)
• 5. If ET17 gt DR17, investigate.

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OPERATIONAL APPLICATION Water Rights Compliance
Monitoring
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WATER RIGHTS COMPLIANCE

• 18 Fields Exceeded Rate Limits
• 15 of 18 Due to Water Right File Issues
• 3 Valid Positives.

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WATER BUDGETS

• Recharge Diversion Precipitation - ET
• Benefits
• Increased Accuracy
• Lower Cost

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METRIC BENEFITS TO IDWR

• More accurate ET data
• New Information on water use
• Less expensive, faster monitoring.

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THE FUTURE

• Landsat 5 limping badly
• 18 years past design life
• Landsat 7 scan-line corrector broken
• Landsat follow-on
• LDCM 2011 launch no thermal yet.

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FINAL THOUGHTS

• Thermal data are critically important for water
  resources applications, and need to be included
  on future Landsats.

2. Status of thermal for Landsat 8 (LDCM)
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INFORMATION

• www.idwr.idaho.gov/gisdata
• www.kimberly.uidaho.edu/water/metric/

The Boise River