InRomaniaCernescu1961usedIDMtocharacterizethesoilmoistureregimethroughoutthecountryandmadeanaridityzoningmapofRomaniabasedonthisindexHeemphasizedthecorrelationbetweenthesoilmoistureregimeandsoilt ID: 237316
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Abstract.InRomania,aridregionsoccupyalargeareaespeciallyinthesouth-easternandsouthernregionsRomanianDanubePlainandDobrogea,wheremostofthecropsneedtobeirrigatedduringsummertime.Themethodrecom-mendedbyFAOusesthePenman-Monteithration(PM-ETo)todetermineirrigationwaterrequirements(IWRs)andcropevapotranspiration(ETc).Unfortunately,thereareplacesinthiscountryandmostprobablyintheneighbouringcountrieswithsimilarclimate,wherelong-termrecordsofsolarradiation,windspeedandairhumidityaremissing.Thepurposeofthispaperistodocumenttherangeofanaridityindex,calledDeMartonnesaridityindex(I InRomania,Cernescu(1961)usedIDMtocharacte-rizethesoilmoistureregimethroughoutthecountryandmadeanaridityzoningmapofRomaniabasedonthisindex.Heemphasizedthecorrelationbetweenthesoilmoistureregimeandsoiltype.Botzan(1972),Paltineanuetal.(2000),PaltineanuandMihailescu(2005),amongothers,reporteddataonaridordrought-affectedareas,soilmoisturedyna-mics,crop-waterresponse,aswellasIWRsforvariousregionsofRomania.etal.(1989)reportedafirstzoningoftheIWRsinRomania,buttheareasstudiedwerelocatedmainlyinthesouthernpartofthiscountryandtheinterpolationprocedureofdatawasnotreported.However,thereareregionsinthiscountrywithnomeasurementsofsolarradiationorsunshinehours,2mheightwindspeedorrelativeairhumiditytocalculatePM-ET.Inotherregionsthereareonlyshort-termrecordsonclimateparametersofinterestinirrigationdesignandplanningliketheonesdiscussedabove.Forsuchareas,somesimpleindexesneedtobefoundtocharacterizetheclimate.ThepurposeofthispaperwastocorrelateIwhichonlyneedstemperatureandprecipitationdata,withETcaswellaswiththeIWRsforsomerepresentativecrops,inordertofindsimplebutreliablerelationshipsbetweentheseparameters.Thesedataareneededbyplannersinevaluatingtheuseofwaterresourcesandindesigningirrigationsystemsinregionspossessingonlybasicclimateparameters,inordertohelppreservetheenvironmentalwaterresources.MATERIALSANDMETHODSRomaniaissituatedinthesouth-easternpartofEuropeandhasatemperateclimatewithhighspatialvariabilityduetosomelocalfactorslikethepresenceoftheCarpathianMountainsinitsmiddleandtheBlackSeatosouth-east.Twohundredandfifty-twoweatherstationspossessingonaverageaboutonecenturyofclimaterecords,mainlyfrom1900to2000,werestudiedforthisobjective.Thespa-tialdistributionoftheweatherstationsacrossthecountryisrelativelyuniform.Ingeneral,allregionsandreliefformspossessweatherstationsmeasuringairtemperature,airhu-midity,sunshinehoursand/orsolarradiation,precipitation,aswellaswindspeedat10or2mheight.Soilsreflectthegraphicalconditionsacrossthecountryandareverydivers.Thelongtermdatawereusedincalculatingtheclimaticparametersinordertoberepresentativeintime.However,theresultsobtainedinthispaperwillonlyapplyforcurrentconditions,becausefuturepossibleclimatechangecouldinvalidatetheextrapolationsbasedonanalysisofsuchlongdatasets.-DMwascalculatedforthesestationsasbothannualandmonthlyvaluesaccordingtoDeMartonnesmethod(DeMartonne,1926).I-DMvalueswereinterpolatedbetweenstationsusingthekrigingmethod(Matheron,1963;Webster,1985).ETcwascalculatedforvariouscropsforallweatherstationsfromthePM-ETdata(Monteith,1965)andbyhelpofthemethodofAllenetal.(1998)whichusedmonthlycropcoefficients.Thesecropswere:cereals,sunflowerHelianthusannuusL.),soybean(max(L.)Merr.),sugarbeet(Betavulgaris(L.)saccharifera),alfalfaMedicagosativaL.),potato(SolanumtuberosumL.),appleMalusdomesticaL.),pear(Piruscomunis),cherry(),peach(Prunuspersica),plum(Prunusdomesticaapricot(Armeniacavulgaris),strawberry(Fragariamos-),tablegrapes(Vitisvinifera)andtomato(persicumesculentum).Thefruittreesweretreatedintwosituations,asmowedsodtreatmentsbetweentreerows(designatedingraphsandtablesasapplesodinthecaseofapple)andascleancultivationtreatmentsbetweentreerows(designatedasapplecultivatedinthecaseofapple).Thegroundcovermanagementsystemsofthefruittreeswereconsideredinthetwomostcommonsituationsabove,namelyasmowedsodstripsandcleancultivationstrips,respectively,inordertoagreewiththeprocedurerecommendedbyFAO(Allenetal.,1998).IWRsdataforallthesecropswerecalculatedasdiffe-rencesbetweentheeffectiveprecipitation(P)andETc.TheeffectiveprecipitationwasestimatedonamonthlybasisbyusingtheproceduredescribedbySmithetal.(1992).ThemethodreportedbyAllenetal.(1998)wastestedandvalidatedusingfieldexperimentsunderthespecificconditionsofthiscountry(Paltineanu,2005).AsnotalltheweatherstationsmeasuredtheclimaticparametersneededforthecalculationsofPM-ETforthewholeperiod,regressionequationsbetweenPM-ETandtem-perature-basedparametersliketheThornthwaitemethodwasusedtoestimatePM-ETetal.,2006).Consequently,I-DM,ETcandIWRsvalueswerecalculatedforthewholeXXForallweatherstations,regressionequationsbetween-DMandETc,aswellasbetweenI-DMandIWRswerecomputedforannualvaluesaswellasformonthlyvaluesforJulyandAugust.Allweatherdatapairswereconsideredincomputingtheregressionequations,evenifsomecropswerenotgrowninallregions,andifsomeofthem,locatedinhumidregions,hadnegativeIWRs,whicharenotshowninSpatialdistributionofDeMartonnesaridityindexInRomania,I-DMspatialdistributionshowsahighvariability,withthelowestvalues(mm°C)forthedriestconditionsinthesouth-easternareasofthiscountryandthehighestvaluesintheuplandregions:theCarpathian82CR.PALTINEANUetal Mountainsandplateausareas(Fig.1).However,theagri-culturalregions,whicharerepresentedbythemajorareaoftheRomanianPlaininitssouthernandcentralparts,theeasternpartoftheMoldovaPlateau,thebiggestpartoftheTisaPlain,aswellasthewesternpartoftheTransylvaniaPlateau,arecharacterizedby20-30mm°C-DMvalues.Theseacute-aridityregionsofthiscountryhaveaspecificagriculturalprofilewherecereals,vineyards,andsomethermophilefruittreespecieslikeapricotandpeachtreesprevail.Evenifrain-fedagricultureisstillperformedintheseregions,highyieldscannotbeachievedwithoutirrigationapplication.The40and50mm°C-DMisolinespassthroughthemiddleandhighhillyregions,especiallythroughtheplatformsandPre-Carpathianareas.The40mm°CisolineapproximatelyshowsthewayofequilibriumbetweentheannualPandPM-ETvalues.FromtheselocationstowardsthehighmountainpeaksI-DMvaluesalwaysincreaseandexceed100mm°Cinthealpinere-gionsoftheCarpathianMountains,andreachasmuchas160mm°Candevenmore.RelationshipsbetweenI-DMandETcandbetweenI-DMandIWRsRelationshipsbetweenTheregressionequationsobtainedfromtheseparame-tersshowthatthereareinversecurvelinesdescribingthecorrelationbetweenI-DMandETc(Fig.2AccordingtotheETcmagnitude,thetwocropgroups:fieldcropsandhorticulturalcrops,respectively,basicallyhavevaluesintherangeof450-700mmofwater,exceptforalfalfaduetoitshighwaterdemandduringthewholegrowingseason.Thelatterhasthefirstpositioninthisgraphwithvaluesashighas600-800mmfortheI-DMrangeof15-60mm°C.Incontrast,wintercerealsshowabout200-350mmforthesameI-DMrange.Therearealsotwogroupsofhorticulturalcrops,thefruittreeshavingamowedsodspacebetweentreerows(sodtreatments)withETcvaluesashighasaround700mmduringthegrowingseasonforthemostaridregionswithI-DM15-20(mm°C),andthesamefruittreespecieswithcleancultivation(cultivated)togetherwithtablegrapes,strawberryandtomatowhichshowlowervalues(about450-550mm).DEMARTONNEARIDITYINDEXANDWATERREQUIREMENTSFORSOMECROPS83 Adamclisi Adjud Agnita AlbaIulia Alexandria Arad Avrameni Bacau BaiaMare BaileHerculane Bailesti Banloc BaleaLac Barlad Bistrita Blaj Botosani Bozovici Braila Brasov Bucuresti Buzau Calafat Calarasi Calimani Campeni Campina Campulung-Muscel Caracal Caransebes Carei Cernavoda Cheia Chilia Chisineu-Cris Campulung Cluj-Napoca Constanta Corugea Cotnari Craiova Cumpana Cuntu CurteadeArges Darabani Dej Deva Dorohoi Dr.Tr.Severin Dragasani Dumbraveni Fagaras Falticeni Faurei Filiasi Focsani Fundulea Galati Giurgiu Grivita GuraPortitei Gurahont Hirsova Hoghiz Holod Horia Huedin Husi Iasi Ineu Jimbolia Joseni Maicanesti Mangalia Marculesti MiercureaCiuc MoldovaVeche OcnaSugatag Odobesti Oltenita Oradea Oravita Paltinis Penteleu Petrosani PiatraNeamt Piclisa Pitesti Plenita Ploiesti PoduIloaiei Polovragi Popesti Predeal Radauti Rarau Rauseni Resita RamnicuSarat RamnicuVilcea Roman Rosiori Sacueni Salonta SatuMare Sebes Sf.GheorgheCv. Sf.Gheorghe Sibiu SighetulMarmatiei SinicolauMare Siria Slatina Slobozia Stanca Stei Stolnici Suceava Sulina Tebea Tecuci Tg.Lapus Timisoara Targoviste Tg.Neamt Tg.Jiu Tg.Mures Tg.Ocna Titu Toplita Tulcea Tulnici Turda Tr.Magurele Urziceni Varadia Vaslui VatraDornei Videle Viziru VinjuMare Zalau Zimnicea Hunedoara 212223242526272829 44454648 Fig.1.SpatialdistributionofDeMartonnesaridityindex(I-DM,mm°C,dottedcurves)inRomania(PaltineanuandMihailescu,2005)Latitude(°N)Longitude(°E) 84CR.PALTINEANUetal 1520253035404550556065707580-DM(mm/°C)ETc(mm) ETc-tomato ETc-strawberry ETc-applecultivated ETc-applesod ETc-peachcultivated ETc-peachsod ETc-tablegrapes applesod peachsod tablegrapes strawberry tomato peachcultivated applecultivated -DM(mm°CFig.2.RelationshipsbetweenI-DMandthetotalETcforthestudiedcrops;afieldcrops,bhorticulturalcrops,indifferentregionsinRomaniaduringthegrowingseason. 1520253035404550556065707580-DM(mm/°C)ETc(mm) ETc-corn ETc-barley ETc-wheat ETc-sunflower ETc-soybean ETc-sugarbeet ETc-potato ETc-alfalfa sugarbeet soybean sunflower,corn potato alfalfa barley wheat -DM(mm°C DEMARTONNEARIDITYINDEXANDWATERREQUIREMENTSFORSOMECROPS85 1001201401601802002202402602803003203403603804001520253035404550556065707580-DM(mm/°C)TotalIWRs(mm) IWR-corn IWR-barley IWR-wheat IWR-sunflower IWR-soybean IWR-sugarbeet IWR-potato IWR-alfalfa alfalfasugarbeet soybean potato corn sunflower wheat barley -DM(mm°C 1001201401601802002202402602803003203403603804001520253035404550556065707580-DM(mm/°C)TotalIWRs(mm) IWR-corn IWR-barley IWR-wheat IWR-sunflower IWR-soybean IWR-sugarbeet IWR-potato IWR-alfalfa alfalfasugarbeet soybean potato corn sunflower wheat barley TotalIWRs(mm) -DM(mm°C Fig.3.RelationshipsbetweenIDMandthetotalirrigationwaterrequirements(IWRs,mm)forvariouscrops;afieldcrops,bcrops,inregionsinRomaniaduringthegrowingseason. 86CR.PALTINEANUetalParametersofregressionequationsFieldcropsAlfalfa-0.000200.0729-10.626976.580.9157Corn-0.000100.0530-7.5476616.640.9136Sugarbeet-0.000100.0558-8,0376718,750.9148Soybean-0.000100.0551-8.0109701.320.9156Sunflower-0.000100.0520-7.4942609.330.9156Wheat-0.000060.0271-4.5962433.590.9219Barley-0.000020.0135-2.9932329.990.9189Potato-0.000100.0496-7.2123636.540.9144HorticulturalcropsApple-cultivated-0.000100.0557-8.0398650.400.9157Apple-mowedsod-0.000200.0722-10.249852.160.9138Peach-cultivated-0.000100.0546-7.8941633.190.9154Peach-mowedsod-0.000200.0678-9.6513810.080.9142Strawberry-0.000100.0495-7.3321670.110.9159Tablegrapes-0.000100.0427-6.1101561.000.9135Tomatoes-0.000100.0521-7.5585659.180.9143 Table1.Parametersofdegree-3polynomialregressionequations(y)andthecoefficientofdetermination(orthecorrelationbetweenI-DM(mm°C)astheindependentvariable(x)andthetotalETc(mm)underirrigationconditionsduringthegrowingseason,forvariouscropsinRomania;n=252ofdatapairsParametersofregressionequationsFieldcrops-0.00030.1248-15.680604.170.9640-0.00030.1209-15.112520.370.9641Sugarbeet-0.00030.1221-15.310573.800.9644-0.00030.1221-15.312560.890.9645-0.00030.1208-15.112515.710.9647-0.00020.0755-9.2763301.210.9774-0.00020.0535-5.7431175.400.9569-0.00030.1183-14.771521.040.9645HorticulturalcropsApple-cultivated-0.00030.1196-14.952474.560.9650Apple-mowedsod-0.00030.1277-16.047584.150.9632-0.00030.1169-14.588451.220.9652Peach-mowedsod-0.00030.1250-15.682560.690.9637-0.00030.1091-13.549417.640.9660Tablegrapes-0.00030.1063-13.161417.050.9657-0.00030.1197-14.962529.580.9644 Table2.Parametersofdegree-3polynomialregressionequations(y=ax)andthecoefficientofdetermination(forthecorrelationbetweenI-DM(mm°C)astheindependentvariable(x)andthetotalIWRs(mm)duringthegrowingseason,forvariouscropsinRomania;n=252ofdatapairs Irrigationisusuallyappliedinthiscountryinregionsofupto35mm°C-DMvalues,whereIWRsrangebet-weenabout400and600mm.ExtendingtheFishertestfromlineartocurvilinearregressions,itwasfoundthatalltheequationsobtainedarehighlysignificant,showingvaluesofthecoefficientsofdetermination(R)higherthan0.90Table1)forthecropsinvestigated.RelationshipsbetweenTheannualvaluesofI-DMandthevaluesofIWRsovertheentiregrowingseasonwerecorrelatedandinversecurvilinearregressionequationswerealsofoundforallthecropsstudied(Fig.3Forthetwogroupsofcrops,thelowest(from15to20mm°C-DMvaluescorrespondtoIWRsvaluesofupto240-400mmforthefieldcrops,exceptwintercerealswiththesmallestvalues(80-190mm)duetotheirspecificperiodofvegetation,andtoIWRsvaluesof180-360mmforthehorticulturalcrops.IWRsdecreasetoabout100to200mmforthe35mm°C-DMinthecaseofthefieldcrops,exceptforwintercerealswhichshow20-80mmandshouldnotbeirrigatedintheseregionsduetoeconomicalreasons,andtoabout60-160mmforhorticulturalcrops.Fromthehorticulturalcrops,themowed-sodfruittreespeciesandtomatopresentthehighestvalues,whiletheothertreatmentsandcropsshowthelowestones.Thebestfitfortheregressionequationsisalsothedegree-3polynomialtype.TheirparametersareshowninTable2,whereonecanseethehigher(over0.96)RThecorrelationsbetweenthemonthlyI-DMandIWRsvaluesforthemajormonthsinirrigationapplication,JulyandAugust,aredepictedinFigs4and5,respectively.TheregressionequationsobtainedforJulyhavealsoaninverseaspect,butdegree-2polynomialtypearebestfittedwithRashighas0.98and0.99(Fig.4,Table3).FieldcropshaveIWRsvaluesbetweenabout60and130mmmonthfortheregionswithI-DMrangeof15-36mmºCJuly,andthecropsvaluesareclosetoeachother.AccordingtothemagnitudeofIWRs,therearethesametwogroupsofhorticulturalcropsforJulywithvaluesofabout30to125mmmonthtomatoandthemowedsodtreatmentsofthefruittreesshowinghigherIWRsvalues,andstrawberry,tablegrapesandthecleancultivationtreatmentsofthefruittreesshowinglowerIWRsvalues.IWRsvaluesarelowerinAugust(Fig.5)comparedwithJuly,andthedifferencesbetweenthetwomonthsaresmall(Table4).InAugust,IWRsforcorn,soybean,sugarbeetandpotatoareclose,andalfalfaneedsthelargestamountsofirrigationwater,whilesunflower,thelowest.Testingoftherelationshipsbetween-DMandETcandbetweenDMandIWRsTherelationshipsobtainedwiththemethodabovehavebeentestedwithdatafromtwoclimates,thetemperateclimatefromRomaniain15experimentalfieldsforalong-termperiod(GrumezaandKleps,2005),andaneighbourMediterraneantemperateclimateinthenorthernpartofGreece,thewatershed(Paltineanuetal.,1999).TestingoftherelationshipsinthetemperateclimateofRomaniaInRomania,ETcobtainedinfieldexperimentsforwheat,corn,alfalfa,sunflower,sugarbeet,potatoandsoybeanandreportedbyGrumezaandKleps(2005)havebeencomparedwithETcforthesamecropsobtainedbyusingtherelationshipsfromTable1foreachcrop(Fig.6WintercerealshavethelowestETcandarelocatedonthe1:1lineinthelowestpositioninFig.6.Theregressionequationbetweentheseparametersishighlysignificantandthedifferencebetweentheregressionlineandthe1:1linedecreasestowardsthehighestETcvalues.Ingeneral,theexperimentalETcvaluesarehigherthanthecalculatedETcvalues,butthiscanbeexplainedbywaterseepagebeyondplantrootsinthefieldafterstrongrainfalls.Foreachcroptested,Table5presentsthedifferenceandtheratiobetweentheexperimentalandcalculatedETc,aswellasthestandarderrorofestimates(SEE).ExceptforalfalfawhichshowsanegativeETcdifferenceandlessthan1ETcratio,alltheothercropshave,asalreadymentioned,higherexperimentalETcvaluesthancalculatedETcvalues,andtheexplanationhasbeengivenabove.Usually,theexperimentalETcisbyabout2%(potato)to36%(corn)higherthanthecalculatedETc.ForthetemperateclimatespecifictoRomania,thiswouldvalidateETcrelationshipspresentedinTables1-4,becauseIWRsareacomponentofETc.TestingoftherelationshipsintheMediterranean-temperateclimateForsomecropswithavailabledatacorn,alfalfa,to-mato,sugarbeet,sunflowerandgrape,thecomparisonbet-weenreportedIWRsfrom7differentplacesinthewatershed,northernGreece(Paltineanuetal.,1999)andesti-matedIWRsfromtherelationshipsobtainedusingIRomaniandata,aswellastheirdifference,ratioandstan-darderrorsofestimateareshowninTable6.Thetestedpe-riodsareJuly,Augustandthegrowingseason.EveniftheclimateisdifferentenoughfromtheclimateinRomania(thewatershedinGreeceisabout500kmfurthersouthfromRomania)thedifferencesbetweenIWRs,reportedver-suscalculated,arenottoohighinJuly.AllthesixcropsDEMARTONNEARIDITYINDEXANDWATERREQUIREMENTSFORSOMECROPS87 88CR.PALTINEANUetal 1001201401520253035404550556065707580-DM(mm/°C)IWRs(mm/month) IWR-tomato IWR-strawberry IWR-applecultivated IWR-applesod IWR-peachcultivated IWR-peachsod IWR-tablegrapes tomato strawberry applecultivated applesod peachcultivated peachsod tablegrapes -DM(mm°C TotalIWRs(mmmonth 1001101201301401520253035404550556065707580-DM(mm/°C)IWRs(mm/month) IWR-corn IWR-sunflower IWR-soybean IWR-sugarbeet IWR-potato IWR-alfalfa alfalfa,sugarbeet potato,soybean sunflower,corn Fig.4.RelationshipsbetweenIDMandtheirrigationwaterrequirements(IWRs,mm)forvariouscrops;ahorticulturalcrops,bfieldcrops,indifferentregionsinRomaniaduringJuly. TotalIWRs(mmmonth -DM(mm°C DEMARTONNEARIDITYINDEXANDWATERREQUIREMENTSFORSOMECROPS89 1520253035404550556065707580-DM(mm/°C)IWRs(mm/month) IWR-tomato IWR-strawberry IWR-applecultivated IWR-applesod IWR-peachcultivated IWR-peachsod IWR-tablegrapes tomato strawberry applecultivated applesod peachcultivated peachsod tablegrapes -DM(mm°C TotalIWRs(mmmonth 1001101201301401520253035404550556065707580-DM(mm/°C)IWRs(mm/month) IWR-corn IWR-sunflower IWR-soybean IWR-sugarbeet IWR-potato IWR-alfalfa alfalfa sunflower corn sugarbeet soybean,potato Fig.5.RelationshipsbetweenthemonthlyvaluesofI-DMandtheirrigationwaterrequirements(IWRs,mm)forvariouscrops;ahorticulturalcrops,bfieldcrops,indifferentregionsinRomaniaduringAugust. -DM(mm°C TotalIWRs(mmmonth 90CR.PALTINEANUetalParametersofregressionequationsFieldcrops0.0182-3.7637178.590.99060.0182-3.8078171.620.9902Sugarbeet0.0182-3.7496178.330.99080.0180-3.7197170.820.99100.0182-3.7977171.560.99030.0179-3.709170.680.9910HorticulturalcropsApple-cultivated0.0172-3.6263140.770.9915Apple-mowedsod0.0188-3.9492180.440.98910.0167-3.5265132.630.9922Peach-mowedsod0.0184-3.8494172.300.98990.0156-3.2233119.840.9942Tablegrapes0.0155-3.1379125.280.99470.0184-3.8030178.990.9903 Table3.Parametersofdegree-2polynomialregressionequations(y=ax)andthecoefficientofdetermination(forthecorrelationbetweenI-DM(mm°C)astheindependentvariable(x)andthetotalIWRs(mm)duringJuly,forvariouscropsinRomania;n=252ofdatapairsParametersofregressionequationsFieldcrops0.0263-4.2385168.930.99070.0254-4.1607149.320.9917Sugarbeet0.0251-4.0494151.040.99190.0252-4.0840150.900.99190.0238-3.9091124.570.99340.0250-4.0499148.750.9921HorticulturalcropsApple-cultivated0.0247-4.0968135.020.9924Apple-mowedsod0.0270-4.4531171.180.98990.0241-3.9833127.410.9931Peach-mowedsod0.0264-4.3385163.450.99060.0226-3.6437116.120.9941Tablegrapes0.0227-3.6139120.920.99370.0247-4.0269143.030.9924 Table4.Parametersofdegree-3polynomialregressionequations(y=ax)andthecoefficientofdetermination(RorthecorrelationbetweenthemonthlyvaluesofI-DM(mm°C)astheindependentvariable(x)andthetotalIWRs(mm)duringAugust,forvariouscropsinRomania;n=252ofdatapairs DEMARTONNEARIDITYINDEXANDWATERREQUIREMENTSFORSOMECROPS91 y=0.7441x+192.67=0.4831***n=9210000100200300400500600700800900ETcasafunctionofI-DM(mm)ETcfromfieldexperiments(mm) Datafrom15locationsacrossRomaniaforthecrops:wheat,corn,alfalfa,sunflower,sugarbeet,potatoandsoybean 1:1LineFig.6.CorrelationbetweenETcfromfieldexperimentsinRomania,reportedbyGrumezaandKleps(2005),andestimatedETcfromtherelationshipsobtainedusingRomanianI-DMdataforsomecommoncrops,inthegrowingseasonisthecoefficientofdeterminationand***meanshighlysignificantfor99.9%ofprobability.ETcdifferenceETcSEEETcratioWheat14.323.61.04Corn163.6175.21.36Alfalfa-52.286.50.93Sunflower123.3122.01.27Sugarbeet107.0118.41.20Potato7.954.71.02Soybean69.393.51.13 Table5.Difference,standarderrorofestimate(SEE)andratiobetweentheexperimentalETcdata(mm)obtainedin15differentlocationsacrossRomaniaandcalculatedETcdata(mm)forvariouscropsduringthegrowingseasonunderirrigationconditionsIWRsdifferenceIWRsratioIWRsSEEPeriod*JulyAugustGS*JulyAugustGSJulyAugustGSCorn26.018.6152.91.251.201.6631.726.1165.8Alfalfa18.47.3257.41.171.071.8425.720.5271.9Tomato18.5-56.854.91.170.401.2325.957.675.3Sugarbeet18.422.9203.51.171.231.7225.729.7217.6Sunflower36.6-17.4239.11.330.782.0441.121.0249.1Grape-11.5-26.71.90.890.661.0316.728.741.5 *GSgrowingseasonTable6.ComparisonbetweenreportedIWRsfrom7differentplacesinthewatershed,northernGreece(afterPaltineanuetal1999)andestimatedIWRsfromtherelationshipsobtainedusingI-DMRomaniandataforsomecommoncropsstudied.aswellastheirdifference,ratioandstandarderrorsofestimate studiedshowhigherreportedIWRsthancalculatedIWRsinJulyandthegrowingseason,andonlythreecropsshowedsuchdatainAugust.Theratiorangedbetween117and133%inJuly,from40to123%inAugust,andfrom103to204%inthegrowingseason.TheseIWRsdifferencescanalsobeattributedtothedif-ferentperiodsofthegrowingseasoninthetwocountries,andthelongeroneinGreeceexplainswhythehighervaluesoccurinthiscountry.ThecorrelationbetweenthereportedandcalculatedIWRsvaluesandtheircomparisonforJulyandAugustcanalsobeviewedinFig.7TheregressionlineforJulyhasahigherpositionversusthe1:1line,whiletheoneforAugusthasratheralowerpositionversusthe1:1line.Despitetheimportantclimaticdifferencesbetweenthetwocountries,theregressionlinebetweenreportedETcandcalculatedETcisclosetothe1:1line,andthemedium-lowcoefficientofdetermination(R)isstillhighlysignificantforthegrowingseason(Fig.8Evenifclosesimilaritiesbetweenthetwocountrieswerenotexpected,itwasfoundthattherelationshipsobtainedinthispapercouldbeappliedindifferentclimatesfromthesouth-easternpartofEurope.ThemethodofAllenetal.(1998)toestimateETcandIWRswasconfirmedinmanyplacesthroughouttheworldincludinginthiscountry(Paltineanu2005),butminimumdailyrelativeairhumiditydatatoestimatecropcoefficients(Kc)wereneededalongwithweatherdatatocompute.Unfortunately,thereareplacesinthiscountry,andmostprobablyinneighbouringcountrieswithsimilarclimates,wherelong-termrecordsofsuchdataaremissing.Countriesshowingsimilarclimateconditionswouldbe:theRepublicofMoldova,thesouth-westernregionsofUkraine,thenorthernpartofBulgaria,theeasternpartofHungary,andthenorth-easternregionsofSerbia.Eventoday,whenautomaticweatherstationsthatmeasuremanymeteorolo-gicalparametersarewidelyspreadoverinmanycountries,theydonothaveandcannotreplacelong-termdatarequiredtoprocessreliableclimatedataovertime.Inthisrespect,thispapertriestoovercomethoseshortcomingsandtohelpestimatetheorderofmagnitudeforbothETcfortheentiregrowingseasonaswellasIWRsforthemonthswhenirrigationisneededwithacuityJulyandAugust,aswellasforthewholeseason,byusingI-DMcalculatedforthesameperiodormonth.Thewaterrequiredforirrigationintheseregionsisusuallytakenfromrivers,especiallytheDanubeRiverandotherlargetributarystreams,orfreshwaterlakesduringsummertime.However,insummertimeriverdischargehasminimumvalues,andthereisacompetitionforfreshwaterbetweenvariousconsumers.Thisstudycouldthushelphydrologistsandplannersmakeproperdecisionsconcer-ninghowtousescarcewaterresources.Seenlikethis,thispaperappliestoEuropeingeneral.92CR.PALTINEANUetal Augusty=1.375x-44.346=0.4158***020406080100120140160EstimatedIWRs(mm/month)ReportedIWRs(mm/month) 1:1Line Cropscompared:corn,alfalfa,tomato,sugarbeet,sunflower,grapeFig.7.CorrelationbetweenthemeanmonthlyvaluesofreportedIWRs(afterPaltineanuetal.,1999)fromtheGreece,andestimatedIWRsfromtherelationshipsobtainedusingRomanianI-DMdataforsomecommoncropsstudiedforJuly Julyy=0.862x+34.165=0.4871***020406080100120140160180EstimatedIWRs(mm/month)ReportedIWRs(mm/month) 1:1LineCropscompared:corn,alfalfa,tomato,sugarbeet,sunflower,grape ReportedIWRs(mmmonth EstimatedIWRs(mmmonth EstimatedIWRs(mmmonth ReportedIWRs(mmmonth Growingseasony=0.815x+142.48=0.396***0100200300400500600700800900EstimatedETc(mm)ReportedETc(mm) Cropscompared:corn,alfalfa,tomato,sugarbeet,sunflower,grape 1:1LineFig.8.CorrelationbetweenthereportedETcfromtheregion,Greece(afterPaltineanuetal.,1999)andestimatedETcfromtherelationshipsobtainedusingRomanianI-DMdataforsomecommoncropsstudiedforthegrowingseason.ExplanationsasinFig.6. Growingseason ReportedETc(mm) EstimatedETc(mm) 1.InRomania,I-DMspatialdistributionshowedavariability,withthelowestvalues(20mm°C)forthedriestconditionsinthesouth-easternareasofthiscountry.IrrigationisusuallyappliedintheregionswithIvaluesof15-35mm°C2.Therewerestronginverse,curvedlinesdescribingthecorrelationbetweenI-DMandETcthroughregression3.InversecurvilinearregressionequationsbetweentheannualvaluesofI-DMandofIWRsovertheentiregrowingseasonwerealsofoundforallcropsstudied.ThelowestI-DMvaluescorrespondedtothehighestIWRsvalues.HighlysignificantregressionequationsalsowerefoundbetweenthemonthlyvaluesofJulyandAugustand-DMandIWRs.4.Thetestingoftheserelationshipsinvariouslocationsprovedthattheycouldbeusefulforhydrologists.TheserelationshipshavearegionalcharacterandmighthelpirrigationsystemdesignersandplannersestimatetheorderofmagnitudeofIWRsandETcbyusingI-DM.Theycouldbeusedtoevaluateenvironmentalwaterresourcesintem-perateclimateregionslikeareasofRomaniaandneigh-bouringcountries,whereonlymeasurementsoftemperatureandprecipitationexist.5.Duetothecompetitionforwaterbetweenvariousconsumers,thisstudymighthelphydrologistsandplannersmakeproperdecisionsconcerninghowtousescarcewaterresourcesduringsummertime;bydoingthisoveralargearea,resultsofthepapercanbeappliedtoEuropeingeneral.AllenR.G.,PereiraL.S.,RaesD.,andSmithM.,1998.Evapotranspiration.GuidelinesforComputingCropWaterRequirements.FAOIrrigationandDrainagePaper,56,Rome.BotzanM.,1972.WaterBalanceinIrrigatedSoils(inRomanian).Ed.AcademieiRepubliciiSocialisteRomania,Bucharest,CernescuN.,1961.SelectedPapers(inRomanian).StiintificaPress,Bucharest,Romania.DeMartonneE.,1926.Unenouvellefonctionclimatologique:Lindicedaridité.LaMeteorologie,449-458.GrumezaN.andKlepsCr.,2005.IrrigationDesignsinRomania(inRomanian).Ed.Ceres,Bucharest,Romania.GrumezaN.,MerculievO.,andKlepsCr.,1989.ForecastandApplicationofIrrigationinIrrigationSystemsEd.Ceres,Bucharest.JensenM.E.,BurmanR.D.,andAllenR.G.,(Eds),1990.Evapotranspirationandirrigationwaterrequirements.Am.Soc.CivilEng.Manual,70,NewYork,NY.MatheronG.,1963.Principlesofgeostatistics.Econ.Geology,MonteithJ.L.,1965.Evaporationandtheenvironment.Proc.XIXthSymp.Soc.Exp.Biol.,Swansea,CambridgeUniv.Press,205-234.PaltineanuCr.,2005.ComparisonbetweenexperimentalandestimatedcropevapotranspirationinRomania.Int.Agro-physics,19,159-164.PaltineanuCr.,ChituE.,TanasescuN.,ApostolG.,andPufuM.N.,2000.IrrigationwaterrequirementsforsomefruittreesspecifictotheArges-Vedeariverbasin,Romania.ActaHort.,537,1,113-119.PaltineanuCr.andMihailescuI.F.,2005.Ariditydistributionandirrigationwaterrequirementsforthemainfruittreesin.Proc.21stEur.Reg.Conf.Integratedlandandwaterresourcesmanagement:towardssustainableruraldevelopment.May15-19,Frankfurt-S³ubice,Germany-PaltineanuCr.,PanorasA.G.,MavroudisI.G.,andLouisakisA.,Estimatingreferenceevapotranspirationandirriga-tionwaterrequirementsintheGallikosriverbasin,GreeceInt.Agrophysics,13,49-62.PaltineanuCr.,TanasescuN.,ChituE.,andSumedreaD.,2006.UsingmeanmonthlytemperaturevaluestoestimatePen-manMonteithreferenceevapotranspirationinthetempe-rate-climateregionsofRomania.BibliothecaFragmentaAgronomica,Proc.IXEur.Soc.Agron.Cong.PartI,323-324,September4-7,Warsaw,Poland.ThornthwaiteC.W.,1948.Anapproachtowardarationalclassifi-cationofclimate.TheGeographicalRev.,38(1),55-94.SmithM.,1992.CROPWAT-Acomputerprogramforirrigationplanningandmanagement.FAOIrrigationandDrainagePaper,46,Rome.WebsterR.,1985.QuantitativespatialanalysisofsoilinthefieldIn:AdvancesinSoilScience(Ed.B.A.Stewart).New-York,DEMARTONNEARIDITYINDEXANDWATERREQUIREMENTSFORSOMECROPS93