Grower Meeting Aug. 24, 20ll program was modified . lntroduction to - PDF document

8/23/2OLL Fox Canyon Groundwater Today Management Agency . Discuss some background on why the lE Grower Meeting Aug. 24, 20ll program was modified . lntroduction to the new lrrigation Allowance Program lrrigation Training and Research Center . Some issues that are being investigated Cal¡fornia Polytechnic State Univeßity, San Luis Obispo (Cal poly) . Future modifications likely with Grower lnput Dr. Stuart Styles, P.E. Director, ITRC Dr. Dan Howes, P.E. Senior Engineer, ITRC zOtO- ITRC lnvestigated the lE Old FCGMA lE Program Program for FCGMA . Strengths . Task 2.1 - Analysis and annual plant - Attempts to account fur regional and year to year required watervalues for crops in the diffurences in allowable water computations FCGMA - Simple methodology . Task 2.2 - Evaluation of strengths and . Weaknesses weaknesses of the existing FCGMA lE - Too simple. Based on 3 crop categories while there are dozens of difürent crop types grown in program and specific suggestions for FCGMA improvement - Historically weather data utilized has had quality issues xtwî- tnKr?r Old Allowed Water Table lrrigation Efficiency ro¡ ( ¡!p¡ G¡ødnrr.r rr¡tr¡g.qrt.A!qJ 1@ Ero, f,trf,lhrtul¡t ll & rlbH lt ¡r.' a.r V.úor( I EI. The technical definition of lEl is: IB= xlq0o/o This equatim l¡m¡ts lE to less than or equal to 100% - lrigatim wals b€neficially used cânnot be gr€ats than ¡dgat¡m wats eppli€d Irluc H,Á J c¡*, rs srd x Í sø . Notthe correct definit¡on for lrrigation Efficiency Ro bù. LÄ *4. r^ r*rdoE Effiû(1ætl'@h l:fra h6: EÈftr.d l@' ffi d t@ d W E@r4.rræ tÍw'=' ttN'Æ

8/23/207L Genera I Recommendations lrrigation Allowance lndex Formula . Abandon FCGMA lE . Simple Ratio - lmproper computation of lE and other issues . Replace with new lrrigation Allowance lrrigation Allowance lna.r = *ffi*ffik. Program - More Accurate Assessment of ET - lncreased number of crop categories (24+) - Multiple cropping (double and triple cropping) Volues less thon or equol to 1 ore ¡deøl - Perennial crop age (canopy coverage) considered - Utilize 3 ETo Zones lrrigation Allowance I ncludes Recommended FCGMA ETo Zones . Evapotranspiration of lrrigation Water . zone 1 (21)- . lncludes Santa Ana Winds oxnard clMls and . lrrigation waterfor salinity management FCGMA Etting Road Stat¡on . Waterto overcome a reasonable irrigation . Zone2 lZ2l- Camar¡llo CIMIS and system distribution non-uniformity (DU = 0.8 FccMA camarillo Airport Stat¡on is reasonable in FCGMA) . lrrigation waterfor frost protection . Zone 3 (23) - Sånta Paula clMls and Crowing Per¡od 8T'. FCGMA Moorpark InígotlonAlløuzce= Stat¡on ((DU + Læol¡zed Deep Perc on Drip)x ( I - LR)) Use CIMISâ5 pr¡mâry and FCGMA stôt¡on as badup llmt_.sr- Salinity Management Salinity Management . Assumed average basin wide EÇ = 1.8 ds/m . Value is high but common in some areas . 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 Itrj:

8123/20Lr DRAFT I rrigation Allowance New Allowance ProHram . 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 precip¡tat¡on from 2000- 2009. General trends existed allowing grouping ¡ntothe 3 categories. Pr€dpltâtlon fêâr lroe tt-L7 Tvolcel Drv <11 Wel >L7 Year Type Selection Continue to Utilize Weather Stations . 3 ETo Zones each with 2 weather stat¡ons. 74 TFbl I Wet 2_,, . CIMIS station is primary lro "l ä" . FCGMA weather stat¡ons are backup fll . Collect ETo as a check È !6 tl t ¡' . Collect precipitation data for year type Ë4 =. !' selection È . County precipitation gauges can be used as a 0 50 100 1so 20 0 250 annEl P¡..þffin llßb.) check as well. Compar¡son of Allowed Water and lrr¡gation Allowance lmproving Weather Station Site Conditions . All weather stations should look similar to: Cama¡illo Santa Paula clMls itt*': ctMts

8/23laOLL lmportant lmprovements w¡th Proposed Allowance Values Compared to Several Strawberry Grower Applied Water Values lrrigation Allowance Program . For some crops the New lrrigation ETo bn. I Shwb.ryW.bAFlblbn 6nFtun Allowance does not differ much from the original FCGMA values . Key differences - 1 Ëro lE¡ -Canopy coverage (orchard age and ['o thinning considerations) 1". -Differentiating single, double and triple cropping 5,0 &ds¡r Gñ.! Glqr¡ cñr! Canopy Coverage Difficulties -20% Cover . Vegetated vs, Total Farm Acreage . Canopy coverage/orchard age - Requires grower estimates - To confirm est¡mates it is recommended that growers submit an aerial photo of årm from Google/Yahoo/Bing maps - Aerial should be no more than 2-3 years old l[nc-a= *50o/o Cover 4

8/23/2OLL Difficulties (cont.) . Nursery and Sod Farms - lrrigation Allowance r,alues are br 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 ofthe average vegetat¡ve area on an annual basis. - May need further refìnement with addit¡onal studies. 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 operat¡on. - Should be refined w¡th more detailed e!êluation ofgreenhouses in FcGMA (outside ofthe scope of this evaluat¡on) lt?cr.;

8/23/z}tr Cu rrent DRAFT lrrigation Allowance Example - 3 Strawberry Growers . Crop - Strawberries . Zone- 1 . Rainhll year = typical Exomple Colculotion - lrr¡gøt¡on Allwonce lndq =413 itt/29 6 in = 7 39 lllrcs: Summary . The proposed lrrigation Allowance Program provides significant enhancements w¡th minimal increase in complexity Tha n k You . Differentthan the original FCGMA Allowed Water which had no fundamental basis other than ETo . The l¡ritation Allowance values include ET of ¡rrigation water, water for salinity management, and distribution un¡form¡ty Qu estio n s? ? . The values are not "F|NAL", we will be examiningthem forthe first year of the program and updating where necessary. jlfKãi