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~ ~ - ~ ~':'.:~rlr ~, ,.,._ - -~ "'"' <U~ q. <T~ ' )~' r"f' ~ ~ x- = {g~ ~rm._ olfriri-ID>and ~ ~ t 9/7/2011 Fox Canyon Groundwater Today Management Agency Discuss some

slide-1
SLIDE 1

Fox Canyon Groundwater Management Agency

Grower Meeting-- September 8, 2011

Irrigation Training and Research Center

California Polytechnic State University, San Luis Obispo (Cal Poly)

  • Dr. Stuart Styles, P.E. Director, ITRC
  • Dr. Dan Howes, P.E. Senior Engineer, ITRC

2010 -ITRC Investigated the IE Program for FCGMA

  • Task 2.1-Analysis and annual plant

required water values for crops in the FCGMA

  • Task 2.2- Evaluation of strengths and

weaknesses of the existing FCGMA IE program and specific suggestions for improvement

Old Allowed Water Table

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  • Not the correct definition for Irrigation Efficiency

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Today

  • Discuss some background on why the IE

program was modified

  • Introduction to the new irrigation Allowance

Program

  • Some issues that are being investigated
  • Future modifications likely with Grower Input

Old FCGMA IE Program

  • Strengths
  • Attempts to account for regional and year to year

differences in allowable water computations

  • Simple methodology
  • Weaknesses
  • Too simple. Based on 3 crop categories while

there are dozens of different crop types grown in FCGMA

  • Historically weather data utilized has had quality

issues

Irrigation Efficiency

The technical definition of IE1 is:

9/7/2011

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in RZ 11a1t, JIDI'QS•) This equation limits IE to less than Of equal to 100%

  • Irrigation water beneficially used cannot be

greater than irrigation water applied

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1

slide-2
SLIDE 2

General Recommendations

  • Abandon FCGMA IE
  • Improper computation of IE and other issues
  • Replace with new Irrigation Allowance

Program- More Accurate Assessment of ET

  • Increased number of crop categories (24+)
  • Multiple cropping {double and triple cropping)
  • Perennial crop age (canopy coverage) considered
  • Utilize 3 ETo Zones

Ill>=

Recommended FCGMA ET

0 Zones

Use CIMIS as primary and FCGMA station as backup

  • Zone 1 (Zl)-

Oxnard CIMIS and FCGMA Etting Road Station

  • Zone 2 {Z2)-

Camarillo CIMIS and FCGMA Camarillo Airport Station

  • Zone 3 (Z3)- Santa

Paula CIMIS and FCGMA Moorpark

Station

Salinity Management

  • Assumed average basin wide ECw =

1.8 dS/m

  • Value is high but common in some areas

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Irrigation Allowance Index Formula

  • Simple Ratio

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_ Irrigation Allowance Index = -: Irrigation Allowance Values less than or equal to 1 are ideal

Irrigation Allowance Includes

  • Evapotranspiration of Irrigation Water
  • Includes Santa Ana Winds
  • Irrigation water for salinity management
  • Water to overcome a reasonable irrigation

system distribution non-uniformity (DU = 0.8

is reasonable in FCGMA)

  • Irrigation water for frost protection

/"/galion Al/ommce• Growing Period ET,. ((DU +Localized Deep Perc.on Drip) x (/- LR))

Salinity Management

  • Research underway on strawberries and

already conducted on tomatoes show drip influences salinity management

  • Utilized the most resent research to estimate

water needed for salinity management

  • May need to be fine tuned as additional

information becomes available

9/7/2011 2

slide-3
SLIDE 3

DRAFT Irrigation Allowance

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9/7/2011 New Allowance Program

  • Single value for each ETo Zone dependent on

rainfall during the year- From CIMIS

  • 3 year types- Wet, Dry, and Typical
  • Determined through examining modeled effective

precipitation vs. total precipitation from 2000-

  • 2009. General trends existed allowing grouping

into the 3 categories. Precipitation Year Type RanceJJnchest Typical

11- 17

Dry

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Year Type Selection

Continue to Utilize Weather Stations

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50 10.0 150 20 0 250

30 0 Annu.l Pr.clptt.tlon (lnct.s)

Improving Weather Station Site Conditions

  • All weather stations should look similar to:

Camarillo

CIMIS Santa Paula CIMIS

  • 3 ETo Zones each with 2 weather stations

.

  • CIMIS station is primary
  • FCGMA weather stations are backup
  • Collect ETo as a check
  • Collect precipitation data for year type

selection

  • County precipitation gauges can be used as a

check as well.

Comparison of Allowed Water and Irrigation Allowance

3

slide-4
SLIDE 4

Allowance Values Compared to Several Strawberry Grower Applied Water Values

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Canopy Coverage

~20%

Cover Important Improvements with Proposed Irrigation Allowance Program

  • For some crops the New Irrigation

Allowance does not differ much from the original FCGMA values

  • Key differences-
  • Canopy coverage (orchard age and

thinning considerations)

  • Differentiating single, double and triple

cropping

9/7/2011

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Difficulties

  • Vegetated vs. Total Farm Acreage
  • Canopy coverage/orchard age
  • Requires grower estimates
  • To confirm estimates it is recommended that

growers submit an aerial photo of farm from Google/Yahoo/Bing maps

  • Aerial should be no more than 2-3 years old

""SO% Cover 4

slide-5
SLIDE 5

"'SO% Cover

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9/7/2011 "'70% Cover or More

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Difficulties (cont.)

  • Nursery and Sod Farms
  • Irrigation Allowance values are for full canopy or

vegetative cover

  • However, at any time only 50-90% (or less) of the

area may be cropped.

  • Need growers to provide estimates of the average

vegetative area on an annual basis.

  • May need further refinement with additional

studies.

Sod

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5

slide-6
SLIDE 6

Greenhouses and Tunnels

  • Used information from grower survey and

published data to estimate growing period ETiw in greenhouses and tunnels

  • Best available information:
  • However, many different methods of greenhouse
  • peration.
  • Should be refined with more detailed evaluation
  • f

greenhouses in FCGMA (outside of the scope of this evaluation)

Current DRAFT Irrigation Allowance

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Thank You Questions??

Example- 3 Strawberry Growers

  • Crop- Strawberries
  • Zone- 1
  • Rainfall year= typical

Growerl Grower 2 Growet 3 lndles Inches lndles

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Applied Water 41.3 33.6 25.3 Allowed Water Estimate 37 37 37

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Allowance: Index 1.U 0.91 0.68 Example Calculation ·Irrigation Allowance Index= 41.3 in/37in = 1-12

Summary

  • The proposed Irrigation Allowance Program provides

significant enhancements with minimal increase in complexity

  • Different than the original FCGMA Allowed Water which

had no fundamental basis other than ET0 The Irrigation Allowance values include ET of irrigation water, water for salinity management, and distribution uniformity The values are not "FINAL''. We will be examining them for the first year of the program and updating where necessary.

9/7/2011

Jill.=

6