Berardy - Vulnerability in Food, Energy and Water Nexus in Arizona

8/17/2019 Berardy - Vulnerability in Food, Energy and Water Nexus in Arizona

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Vulnerability in the Food, Energy, and Water Nexus in Arizona:

Concerns for Agricultural Production

Andrew erardy Arizona State University, [email protected]!u"unth Natara#an Arizona State University, [email protected]!i"hail Chester Arizona State University, [email protected]

Abstract$ Interdependent systems supporting water and energy services are necessary foragricultural production. hese systems are e!pected to e!perience more fre"uent and severestrains due to anticipated effects of climate change and increased demands from growingpopulations. Arizona relies on water imported through an energy intensive process from otherwater#stressed regions and has a large percentage of thermal generated electricity, which

re"uires water cooling. Irrigated agriculture is the predominant form of farming in Arizona, and isresponsible for the ma$ority of water withdrawals, most of which is powered by electricity. Arizona%s agriculture could be impacted by failures in the water and energy systems, creating afood#energy#water ne!us of vulnerability. emperature change has a non#linear effect on cropyields where increases up to a certain threshold are beneficial, but after that point there aresevere negative impacts on not only yield, but also "uality and even viability. &rops capable oftolerating increased heat re"uire additional irrigation due to increased evapotranspiration rates,which in turn re"uires more energy use. 'or the ma$ority of A( crops, temperature increasesdue to climate change will result in decreased crop yields as well as increased water and energyuse. )e construct a model including irrigation re"uirements based on crop cardinaltemperatures, Arizona#specific yield responses to temperature change where available, andenergy for water delivery divided into categories of water source and pump energy source.

he model predicts decreased yields in agricultural commodities of between half a percent andten percent per degree 'ahrenheit, depending on the crop analyzed, one to seventeen percentincreased water usage for crops, and corresponding increased irrigation energy usage.

Additional wor* is necessary to account for interactions between elements influenced bytemperature increases, as this model treats them separately and as having a cumulative impact.


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Vulnerability in the Food, Energy, and Water Nexus in Arizona: Concerns for Agricultural Production

Proceedings of the International y!"osiu! on ustainable yste!s and #echnologies +ISS -3-#/01 ispublished annually by the Sustainable &onoscente etwor*. 2un#i &hoi and Annic* Anctil, co#editors -4/0.ISSSetwor*@gmail.com.

&opyright 5 -4/0 by Andrew 6erardy, 7u*unth atara$an, 7i*hail &hester 8icensed under &E 3.4.Cite as::ulnerability in the 'ood, ;nergy, and )ater e!us in Arizona< &oncerns for Agricultural =roduction Proc$ I# , Andrew 6erardy, 7u*unth atara$an, 7i*hail &hester. >oi information v? +-4/01

mailto:[email protected]:[email protected]


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%ntroduction$ :ulnerability of the food system to increasing temperatures is e!acerbated byagricultural re"uirements for water and energy. here is potential for failures in energy andwater systems to cascade to food systems, creating an interdependent networ* of systemsthrough which vulnerabilities may propagate. he food#energy#water +';)1 ne!us will faceadditional strain as climate#related events such as droughts and e!treme heat become moreintense and fre"uent and overall demand increases due to a growing population.

Arizona, and especially the =hoeni! region, has characteristics which increase its vulnerability inthe ';) ne!us when considering potential impacts of climate change scenarios. :ulnerability toclimate change is defined by the I=&& as, the e!tent to which climate change may damage orharm a system it depends not only on a system%s sensitivity but also on its ability to adapt tonew climatic conditions,B +Intergovernmental =anel on &limate &hange, /C1. Arizona is a statethat is severely water constrained and dependent upon fossil fuel for most of its electricitygeneration, creating dependencies that limit its adaptive capacity. Arizona is also pro$ected to bethe second fastest growing state in the country, with a population of over /4 million by -434+United States &ensus 6ureau, -44C1. he =hoeni! region is predicted to e!perience anincrease in the number of e!treme heat events by between 3?4 and /D44 percent +6artos E&hester, -4/?1. he combination of dependency, e!posure, and strain contribute to Arizona%s

vulnerability to climate change, especially in the =hoeni! region.

he nature of farming in Arizona%s climate creates a heavy dependence on water for irrigation,delivered through energy#intensive processes, which also use water. In fact, Arizona%s energy#intensity of water supply delivery is twice as high as the national average, and water#intensity ofthermoelectric power generation is 34F higher than the national average +6artos E &hester,-4/?b1. Gainfall in Arizona is only about inches per year, and the remaining demand ofbetween D.0 and . billion cubic meters +m31 +H4F of which is for Agriculture1 is met with ?DFgroundwater, -F surface water, -4F &entral Arizona =ro$ect +&A=1 water, and 3F reclaimedwater +6artos E &hester, -4/?1. Also, H?F of agricultural water withdrawals are lost toevaporation through irrigation application and plant evapotranspiration +6artos E &hester,-4/?a1. 7ost of Arizona%s electricity is produced by nuclear power plants +33F1, coal fired

power plants +3/F1, and natural gas power plants +-0F1, which use water for cooling +US;nergy Information Administration, -4/C1.

Agriculture is not only a *ey part of Arizona%s history and identity, but a significant economicactivity. &rops produced by Arizona farms are worth over 3.H billion in mar*et value andagriculture is the primary occupation of over /3,444 people, based on -4/- values +US>AASS Arizona 'ield Jffice, -4/C1. Arizona%s agriculture is watered primarily by irrigation, so itdepends on both water and energy to maintain production +:ilsac* E Geilly, -4/?1. Arizona%sagricultural production helps meet the demand for food across the US and beyond throughe!port, especially during the winter growing season when many other productive regions are toocold to be productive.

Food Water Energy Nexus in Arizona 'ood, water, and energy are interconnected componentsin which perturbations can spread across systems, leading to both direct and indirect negativeimpacts +Kellegers, (ilberman, Steduto, E 7c&ornic*, -44D1. )ater supplied for irrigation ispumped from groundwater or transported across a long distance through canals, both of whichre"uire electricity. &A= water re"uires -.D )h of electricity per year for pumping to overcome anearly / *m elevation difference over C?/ *m while ground water pumping re"uires 4./HC L)hof electricity per million cubic meters +6artos E &hester, -4/?1. 6ased on data for -4/3,appro!imately 0?F of A( cropland is irrigated and over F of cropland harvested is irrigated,


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with a total application of water from all sources of about 3.HC million acre#feet over aboutDC4,444 acres, translating to about ?.? acre#feet of water per acre irrigated +:ilsac* E Geilly,-4/?1.

Table 1. Irrigation expenses by fuel type and water source. Total expense is about $42 million.Data from (Vilsac ! "eilly# 214%.

Irrigation Fuel Type Total Expense Expense per Acre – Wells Expense per Acre – Surface Water

Electricity $36,90,000 $!"# $6#90

%atural &as $3,30!,000 $69#" '

(iesel ) *io+iesel $!,!9,000 $3#3! $"#63

able / shows the cost of irrigation based on the energy source and water source. here is nodata in Arizona for natural gas used to pump surface water. Apart from the e!penses frompumping, farms also purchase about ? gallons of gasoline per acre, in addition to diesel, to fuelthe different e"uipment that prepares the land, sows the seeds, fertilizes the crops, andharvests the produce +Arizona 'ield &rop 6udgets, n.d.1+Arizona :egetable &rop 6udgets, n.d.1.

he food system feeds bac* into the hydrological cycle in that the e!tent of green coverincreases rainfall levels and the runoff from fields can be treated and stored as groundwaterreserves +8os S et al., -4401.


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&igure 1' &ood)nergy*ater +exus Influence Diagram. ,ri-ona agriculture is connected to interdependentenergy and water systems.

'igure / is an influence diagram which shows the interdependencies of the agricultural systemin Arizona with the energy and water systems. Interactions between food and the other systems


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occur at the points of water and energy for irrigation, land cover influencing rainfall, and energyused for farm operations. 'urther upstream from the influence diagram, water and energy areembedded in farming inputs such as fertilizer and e"uipment production. ;vidence for the water# energy ne!us already e!ists where water is needed as a coolant or as steam to produceenergy while energy is needed to pump the water +Lleic*, /?1. here is increasing interest instudying the role of food connected to the energy#water ne!us, as demonstrated by the recent

S' I';)S initiative to fund C4,444,444 in research on the food#energy#water ne!us+=rogram Solicitation S' /0#C-?1.

Cascading failures emperature is an important aspect of agriculture. &rop#specific cardinaltemperature thresholds govern the e!pected impacts on yield and viability due to temperaturechanges, which also influence evapotranspiration and therefore irrigation re"uirements. &ardinaltemperatures govern the relationship between individual crop types and conse"uences ofambient air temperatures. 8uo +-4//1 provides an overview of the low and high limits for lethaltemperatures, optimum temperatures, and failure points where available for a number of crops,also ma*ing note of distinct temperatures with impacts at different phenophases. Increasingtemperatures pose a direct threat to the productivity of the food system by increasing the waterre"uired for irrigation and successful crop cultivation +6laney E &riddle, /0- ;rie, 'rench,

6uc*s, E Karris, /D-1. Increasing temperatures are the most direct cause of failures within the';) ne!us as they increase demand for water and energy supplied to the agricultural sector.Increased demand couples with reduced supply, which is constrained due to use in othersectors, which may be given priority in shortage scenarios. In fact, agricultural water can becurtailed to preserve water for metropolitan residents and may be interrupted for this purpose+Lammage 2r, Stigler, &lar*#2ohnson, >augherty, E Kart, -4//1. 'inally, water and energyinfrastructure may be impacted due to increased temperature, causing interruptions to supply.here are many scenarios where failures may cascade across the ';) ne!us, including thefollowing<

/1 )ith increasing temperatures, the rate of evaporation along Arizona%s canals and otherconveyance infrastructure for water will increase. his decreases the water available to

the =hoeni! area. If residences are given priority supply to meet their demand, then thewater available for agriculture would be reduced, thus affecting the production capacityof the agricultural system.

-1 Gising temperatures and population will cause elevated demands for electricity to *eephouseholds cool. As more generation capacity is re"uired, the price of electricity will rise,and the potential to re"uire imported electricity will place additional strain on an agingelectric grid. his stress increases the chances of an infrastructure failure and if demandis closer to generation capacity, the system will have lowered capability to compensate.Such failures may result in interruptions to electricity supply for agriculture, which able /demonstrates is the dominant source for fueling irrigation.

31 &omponents of energy and water infrastructure are more prone to failure due to highertemperatures, increasing the potential for service interruptions. 'armers will respond by

accepting increased ris*, shifting to crops that don%t re"uire irrigation, or discontinuingtheir farming activities.

In -4/3, Arizona e!perienced the impact of a lac* of water supplied to farmers. D-D Arizonafarms e!perienced diminished crop yields resulting from irrigation interruptions, including ?D4with surface water shortages, -/H with ground water shortages, 34? with irrigation e"uipmentfailures, //? with energy price increases or shortages, /3C due to the cost of purchased water,and 3H3 with other reasons for a total of HD,/H4 irrigated acres with diminished crop yields+:ilsac* E Geilly, -4/?1. -,/3 Arizona farms rely on irrigation for /44F of their total sales, so


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any such interruptions could be devastating to the viability of these farms +:ilsac* E Geilly,-4/?1. Some farms already feel the effects, with ?/ farms that discontinued irrigation between-44D and -4/3, including ?H that reported shortage of surface water and /- that converted toagriculture that doesn%t re"uire water +:ilsac* E Geilly, -4/?1.

&y'othesis$ Increased temperatures will result in direct and indirect negative effects for the

';) ne!us in Arizona, including reduced yield and increased irrigation re"uirements for ma$orcrops. Increasing temperatures have a negative correlation with crop yields and positivecorrelation with irrigation re"uirements. 'urther, disruptions to energy and water supply alsocaused by increased temperatures will lead to cascading failures that e!acerbate impacts onagriculture by interrupting irrigation.

%n(estigati(e !ethod$ )e construct a model utilizing crop#specific cardinal temperatures andrelevant literature documenting observed effects of temperature changes on plants, using dataspecific to Arizona where available, to predict the e!pected impacts of increasing temperatureon crop yield and irrigation re"uirements in Arizona. he model also accounts for energy usethrough estimation of fertilizer application, farm e"uipment usage, and irrigation pumping

re"uirements.

Vensi!he :ensim software platform is used to construct a model of the ';) ne!us for Arizonaagriculture based on specified parameters defined for Arizona related to agricultural energy andwater use. :ensim is a dynamic simulation platform developed by Argonne ational lab thatallows for the definition of relationships between sub#processes in larger systems and recursiveanalysis to reveal emergent behaviors of comple! systems. Loverning relationships betweensub#processes are defined through data gathered from Arizona#specific sources and e"uationsestablished in the literature to determine consumptive water use, energy use for pumping, andirrigation re"uirements when considering application efficiency and precipitation. emperaturechange is treated as an input variable that influences the governing relationships between many

of the variables included in the model.

Consu!"ti&e Water 'se Arizona agriculture relies on irrigation to meet the water needs of crops, so it is necessary toestimate the e!tent to which temperature increase will change water re"uirements. he 6laney#&riddle formula is used to estimate the consumptive water use of crops based on e!pectedevapotranspiration +6laney E &riddle, /0-1.

In this formula, u is monthly consumptive use per acre, * is an empirical consumptive use cropcoefficient, t is mean monthly temperature in degrees 'ahrenheit, and p is the monthlypercentage of daytime hours of the year.

Irrigation (e)uire!entsIrrigation re"uirements are calculated based on predicted consumptive use minus averageprecipitation on a monthly basis. Although rainfall totals in the =hoeni! region are low, there aresome months where it is sufficient enough to offset irrigation for certain crops. If monthlyprecipitation e!ceeds evapotranspiration re"uirements, the e!cess is assumed to be lost asrunoff and is not applied towards the water re"uirements in the ne!t month. he model thereforeignores any potential water harvesting and storage as a method to offset irrigation re"uirements.


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External Validation;!ternal validation of the model is performed through comparison of the baseline scenariopredictions to reported farm level water and energy use in Arizona. As the model is based ontheoretical predictions of water use based on evapotranspiration, it is e!pected that actualirrigation and energy use will e!ceed model estimates due to farmers% concern with protectingcrops e!ceeding their desire to minimize irrigation e!penses. 'or crops considered in this

model, blue water footprint +evaporated surface and groundwater1 totals about D-- million m3 ofwater based on estimated crop yields and water footprint per ton of crop +Arizona AgriculturalStatistics, -44H 7e*onnen E Koe*stra, -4/41.

Consu!"ti&e Energy 'se'ertilizers contribute considerable amounts to the energy consumed by agriculture. A literaturesuggests that the average embedded energy in type fertilizers is ??72M*g, that of = typefertilizer is -/.0 72M*g and that of the type fertilizer is /4 72M*g +S*owroNs*a E 'ilipe*, -4/?1.he crop budgets developed by the University of Arizona%s &ooperative ;!tension provides dataon the fertilizer used by type. his helps determine the energy embedded in fertilizer. Similarlythe crop budgets also provide information on the amount of natural gas, gasoline, diesel, andelectricity used +Arizona 'ield &rop 6udgets, n.d., Arizona :egetable &rop 6udgets, n.d.1. G;8

estimates the energy intensity of gasoline and diesel at 4.3D 72M 72 of fuel ++Ksu, -4//11.atural gas and ;lectricity are measure in therms and )h respectively. hese are combinedtogether to determine net energy consumed per acre of crop.

Cro" #y"es&rops selected for inclusion in the model to calculate consumptive water use include alfalfa,barley, corn, cotton, sorghum, and wheat. his decision is based on a combination ofrepresentativeness and data availability. hese si! crops account for -F of the acres plantedin Arizona and have data available for acres harvested, yield per acre, economic value, andconsumptive use coefficients.

)esults$

*ields9ields of agricultural commodities are predicted to fall in response to rising temperatures in A(by up to /4F per degree 'ahrenheit, depending upon the crop e!amined. Irrigationre"uirements are e!pected to increase due to rising temperatures in A( by up to /HF perdegree 'ahrenheit, depending upon the crop e!amined.


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&igure 2' ield c/ange estimates for ma0or , crops in response to 1& temperature increase. "ange isbased on data a3ailability and impacts on different plant p/enop/ases.

As figure - shows, crop yields fall in response to temperature increase above the currentaverage temperature in =hoeni!, e!cept in the case of alfalfa, which has a small increase inyield.-.3CO.-!

Irrigation6aseline irrigation re"uirements for crops considered are calculated to be appro!imately -.3Cmillion acre#feet or -. billion m3 of water. he USLS reports total A( irrigation to be about 3.--million acre#feet per year in -4/4, which is about D/F of the total water withdrawals of 3.Hmillion acre#feet per year +7aupin et al., -4/41. his places the baseline estimate at about H3Fof actual reported water for irrigation. Another source provides a lower estimate, which attributes/.D million acre#feet of water per year to agriculture in the Sun &orridor and asserts that HHF of

Arizona water goes to agriculture +Lammage 2r et al., -4//1. Using this percentage and USLSestimates, this would place total A( irrigation at about 3.4C million acre#feet per year, ma*ing thebaseline estimate about HHF of reported irrigation. he difference between calculated andreported irrigation may be e!plained by the fact that the model estimates irrigation re"uirementsbased on evaporative transpiration, meaning that the water use is the theoretical minimum to

ensure successful crops. Jther factors increasing actual water use include low applicationefficiency due to evaporation and farmer%s li*elihood to favor over#watering to under#watering.

Also, the model calculates irrigation offset by precipitation based on a monthly value, but rainfallin =hoeni! often occurs in large amounts over a period of days. his may result in furthere!cess runoff not captured by the farm but assumed in the model to count against irrigationre"uirements.


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Irrigation re"uirements are e!pected to increase due to rising temperatures in A( by up to /HFper degree 'ahrenheit, depending upon the crop e!amined. otal predicted increase in irrigationre"uirements is calculated to be about ?H,C3C acre#feet or CD million m3 of water, e"uating to anaverage increase of about -F for a /P' temperature increase. Irrigation in Arizona is estimatedat 3.-- million acre#feet per year

&igure ' Irrigation re5uirement percent c/ange estimates for ma0or , crops in response to 1& temperatureincrease. "ange is due to crops6 uni5ue factors and growing seasons# w/ic/ are used to calculate

consumpti3e water use.

A /P' temperature increase will result in elevated irrigation re"uirements, especially for corn,which will re"uire /HF more water based on calculations of consumptive water use. &orn has amuch shorter growing season than other crops considered, and a lower total water usage incomparison. Kowever, it also has the highest average * factor considered, so rising temperaturecauses a greater increase in consumptive water use. he combination of the high * factor andlow overall water use mean that as a percentage of total irrigation re"uirements, corn is muchmore sensitive to a temperature increase.

Energy ;nergy re"uirements are tied to irrigation re"uirements, and are e!pected to rise in proportion to

increased demand for water to meet crops% higher evapotranspiration needs.

Table 2. Irrigation types# percent of , total# and t/eir energy use. Data from 7898 2: and ;artos and


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SurfaceM'lood H4#HCF Q4 0CF /C3D m3 HC?Sprin*lers --#-CF -34 HCF /333 m3 04>ripM7icroirrigation -#?F /H4 CF /4C- m3 0C

able - provides information regarding irrigation types and their energy use in Arizona.SurfaceMflood irrigation is the most common type, and fortunately has negligible energy use+6artos E &hester, -4/?a US Leological Survey, -44C1. Kowever, it also has /4F lowerapplication efficiency than sprin*lers and 34F lower application efficiency than drip Mmicroirrigation +6artos E &hester, -4/?a1. Application efficiency below /44F means that theactual application of /,444 m3 of water re"uires additional water supplied based on the efficiencyof the irrigation type. )ater delivery has associated energy costs of ?4 *)h per /,444 m3 delivered in Arizona +6artos E &hester, -4/?b1. herefore, additional water delivery re"uiresadditional energy consumption, adding to the total energy usage. Although this burden is notcaptured by costs directly to the farmer, the overall system energy re"uirement is increased.he lowest total energy cost is in the form of drip M microirrigation due to its high applicationefficiency despite lower energy use than sprin*lers. Sprin*lers have the worst total energy costdue to their high energy use for delivery coupled with only a modest improvement in application

efficiency compared to surface M flood irrigation.

Arizona irrigation withdrawals are about ?D4D million gallons per day, which is /D.- million cubicmeters of water +US Leological Survey, -44C1. 6ased on ranges of percentages irrigated bytype provided in able -, direct energy use for irrigation can be calculated. his information ispresented in able 3.

Table . Total , irrigation energy use# by type of irrigationIrrigation ype =ercent of otal

Irrigation;nergy Use+*)h1 per /444m3 )ater

otal ;nergy Use+*)h1 for Arizona

;nergy Use forIrrigationIncreased by /F

Above 6aseline

SurfaceM'lood H4#HCF Q4 Q4 Q4Sprin*lers --#-CF -34 -4,-4#

/,4?0,C4434,/-#/,4C0,0C

>ripM7icroirrigation -#?F /H4 0/,DD4#/-3,H04 0-,?D#/-?,H

able 3 demonstrates how energy use is tied to irrigation, and "uantifies the total energy use for irrigation of Arizona agriculture. ;nergy use for a /F increase in irrigation is also increased by/F as there is a direct correlation between pumping activity and energy use. Unfortunately, datais are not available for specific crop types irrigated by specific methods in Arizona, so anestimate of energy use for increased individual crop irrigation re"uirements is not possible.

Apart from the embedded energy in water and energy used for irrigation, energy is also usedduring the cultivation process to power farm machinery. he direct energy consumed for theproduction of crops is estimated to be about trillion 6U for the year -4/?. he estimation isperformed using the fuel and electricity budgets from the crop budgets for Arizona +Arizona 'ield&rop 6udgets, n.d., Arizona :egetable &rop 6udgets, n.d.1. Arizona crops with the highest totalenergy consumption are cotton, corn, and alfalfa. Kowever, energy consumption associated withcrops is correlated with the acreage for each crop rather than the crop type. his is due to thefact that fuel consumption is based on the e!tent of the machinery used, and the processes of


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land preparation, seeding, fertilizing and harvesting are "uite similar across most cropsconsidered. &rop yields per acre vary, so energy per *ilogram of crop are different. In this case,cotton, durum wheat, and dry beans are the top three energy#intensive crops in Arizona. his isdue to lower yields per acre than other crops and consideration on that basis rather than totalacreage. As energy consumption is determined based on acreage of crops, there is no influencefrom temperature increase.

Impacts from temperature change come primarily in the form of increased irrigationre"uirements. As the estimations of consumptive use are based on theoretical calculations, it isreasonable to e!pect irrigation re"uirements to rise in proportion to temperature increases up tothe point where crops are no longer viable or fail due to e!ceeding lethal temperaturethresholds.

*iscussion$

&limate change represents a significant but poorly understood threat to agriculture and the ';)ne!us, which re"uires additional research to understand the comple! and interacting dynamics

between temperature and carbon dio!ide concentration and irrigation and energy re"uirementsand yield. 6etter data availability and accessibility would improve the "uality of the model.

#he Energy+Water Nexus in Arizona AgricultureRuantifiable connections in the Arizona ';) ne!us in the conte!t of agriculture are primarily inthe form of supplies provided from energy and water systems. )ater delivery is necessary forirrigating crops and electricity as well as fossil fuels are used in pumping and distributing waterfor irrigation. ;mbedded energy and water in fertilizers are an indirect connection thatdemonstrates interdependency upstream. Some systems e!ist to transform agricultural wasteinto energy and many farms grow biofuel crops, but Arizona does not have any significantbiofuel production. )hen considering interactions in the Arizona ';) ne!us, temperature is theprimary driver of changes that influence other systems. emperature increase causes higher

water re"uirements for successful crop production, which means that more irrigation is re"uired,which also uses more energy. >ecisions made by farmers in response to temperature changecan lead to other outcomes such as changing cultivation practices to lower water use, moredrought tolerant crops. Kowever, for Arizona farms to continue operations, they must be able tocope with the direct and indirect impacts of temperature increases on re"uired energy and water supplies for crops.

'ncertainty Uncertainty e!ists in the model due to the fact that it does not account for interactions betweenelements influenced by temperature increases, but treats them separately and as having acumulative impact on crop yields. 'or e!ample, crop yield decreases due to increasedtemperature can be partially offset by increased irrigation, cooling the plants, but this is not

accounted for. In addition, model calculations are based on theoretical re"uirements forevapotranspiration. 'armers may choose to provide more water than necessary as apreventative measure to protect crops from failure.

Alfalfa Alfalfa, as a perennial crop, has uni"ue characteristics that ma*e comparison to annual cropsdifficult. hese include that it can be harvested multiple times after planting, even over thecourse of several years, depending on management. herefore, data regarding area of alfalfaplanted is not reported to avoid confusion, but data for area of alfalfa harvested is +ational


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Agricultural Statistics Service +ASS1, -4/C1. Kowever, for the purposes of this study, it issufficient to *now the acreage of alfalfa harvested as a representation of the area irrigated andcultivated to estimate associated energy and water use. Alfalfa is important to include in thismodel due to the fact that more than half of water used for Arizona agriculture goes to hayproduction li*e alfalfa +Lammage 2r et al., -4//1.

Ada"tation About CF of Arizona farmers use a soil or plant moisture sensing device to determine when toirrigate, and about /CF use a scheduling service or daily evapotranspiration reports, leaving alarge number of farmers that rely on reacting to the condition of the crop or the feel of the soil+:ilsac* E Geilly, -4/?1. Irrigation scheduling based on monitoring soil water and estimating cropwater use rates can save /.C to -.4 inches of irrigation water +7artin, >orn, 7elvin, &orr, Eranz, -4//1. Increased irrigation efficiency is possible through better use of technology andreports rather than relying on traditional methods. Jf 3.HC million acre#feet of water used forirrigation, about /F comes from recycled or reclaimed water +:ilsac* E Geilly, -4/?1. Increasingpercentage of reclaimed water use could reduce overall consumptive water use. Irrigationmethod has an impact not only on energy use associated but also efficiency of application ofwater. ?H/ A( farms use drip, tric*le, or low#flow micro sprin*lers, while /,0?4 farms use

traditional sprin*ler systems and 3,44C use gravity systems +:ilsac* E Geilly, -4/?1. his leavessignificant room for improvement in water efficiency through e!tended use of drip irrigation. 'orinstance, -4/3 corn farming using gravity systems for irrigation resulted in ?.D acre#feet appliedper acre and a yield of /CD bushels per acre while a pressure system only used -. acre#feetper acre and yielded -/0 bushels per acre +:ilsac* E Geilly, -4/?1. Jnly about half of A( farmswith gravity systems for irrigation engaged in any water conservation techni"ue +:ilsac* E Geilly,-4/?1.

%arriers'armers cite many barriers to ma*ing improvements to reduce energy use or conserve water,including that type of investment not being a priority, believing there is a ris* of reduced yield orpoorer crop "uality, physical fieldMcrop conditions that limit improvements, lac* of savings to

cover installation costs, inability to finance improvements, and uncertainty about futureavailability of water +:ilsac* E Geilly, -4/?1.

#rade+offsSome adaptations provide significant benefits in one or more areas, but cause disadvantages inothers and the conse"uences both positive and negative must be weighed to determine the bestcourse of action. 'or e!ample, lowering the operating pressure of an irrigation system willreduce energy use, but increase water application rate, increasing the potential for runoff andwater waste +7artin et al., -4//1. In this case, the ideal would be to minimize pressure up to athreshold past which runoff would occur.

Ac"nowledge+ents$ his wor* is supported by an S' I';)S supplement to S' )S&

Award o. /304C4.

)eferences Arizona Agricultural Statistics. +-44H1. Field cro"s.6artos, 7. >., E &hester, 7. :. +-4/?a1. Supporting Information for< he conservation ne!us<

:aluing interdependent water and energy savings in Arizona. En&iron!ental cience and #echnology , - +?1, -/3-/?. http., E &hester, 7. :. +-4/?b1. he conservation ne!us< :aluing interdependent water


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and energy savings in Arizona. En&iron!ental cience and #echnology , - +?1, -/3-/?.http. 8., >orn, . )., 7elvin, S. G., &orr, A. 2., E ranz, ). 8. +-4//1. ;valuating ;nergyUse for =umping Irrigation )ater. Proceeding of the 12rd Annual Central Plains IrrigationConference, %urlington, /4?//0.

7aupin, 7., enny, 2., Kutson, S., 8ovelace, 2., 6arber, ., E 8insey, . +-4/41. Esti!ated 'seof Water in the 'nited tates in 1343 .

7e*onnen, 7. 7., E Koe*stra, A. 9. +-4/41. #he 5reen, %lue and 5rey Water Foot"rint of Cro"sand .eri&ed Cro" Products: Volu!e 1 : A""endices +:ol. -1. >elft, he etherlands.

ational Agricultural Statistics Service +ASS1. +-4/C1. Acreage.United States &ensus 6ureau. +-44C1. 1336 Interi! tate Po"ulation Pro7ections. Getrieved

from https. +-4//1. 8ife &ycle Assessment of Lasoline and >iesel =roduced via 'ast =yrolysis

and Kydroprocessing. ational Genewable ;nergy 8aboratory. S*owroNs*a, 7., E 'ilipe*, . +-4/?1. 8ife &ycle Assessment of 'ertilizers< a review.

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https://ag.arizona.edu/arec/arizona-vegetable-crop-budgetshttps://ag.arizona.edu/arec/arizona-field-crop-budgetshttps://ag.arizona.edu/arec/arizona-vegetable-crop-budgetshttps://ag.arizona.edu/arec/arizona-field-crop-budgets


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Vulnerability in the Food, Energy, and Water Nexus in Arizona:Concerns for Agricultural Production

Andrew erardy Arizona State University, [email protected]!u"unth Natara#an -First 0ast/ Affiliation, email address!i"hail Chester Arizona State University, [email protected]
mailto:[email protected]:[email protected]

Berardy - Vulnerability in Food, Energy and Water Nexus in Arizona

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