Analyzing the Trend of Crop Evapotranspirationin the Isfahan City, Case Study:Wheatcrop

Climate changeisone of humanity''s today problems andis considered as a threat to the planet so Identify and predictits elements¡ is very important for the management of crisis situations. Inthis study thetime variationprocess ofthe evapotranspiration parameterforwheat crop¡ along withthetemporal changesoftemperaturein Isfahancity¡ was studied. Therefore¡data fromsynopticweatherstationsofthe47-year period(1964-2010) were usedandwith usingparametric¡ RegressionAnalysis and nonparametric¡Mann-Kendall tests¡ significant formonthly and annualtime seriesof95and99percentsignificancelevelswas evaluated. The resultsshowed thatthetemporal variations ofevapotranspirationof wheathave been declining. The most significant monthlyevapotranspirationtrendwas observedinJuly andAugust¡ althoughthere was no significanttrendofincreasing temperature. Based on theannual time series¡ evapotranspirationshowed a significant down ward trendin the level of 99percent¡ with a slopeof about29%¡ however¡the temperature increasewas not significant. Comparing the
results of both evapot ran spiration and temperaturechangesby both testsindicatethatthisphenomenon of evaporation paradox existedin Isfahancity.