ارزیابی و واسنجی سه معادله تبخیر تعرق در منطقه ای نیمه خشک

نوع مقاله: مقاله پژوهشی

نویسندگان

1 هیئت علمی/ دانشگاه آزاد واحد مرودشت

2 استاد / بخش آبیاری دانشگاه شیراز - شیراز

چکیده

در این مقاله سه روش مختلف برای تخمین تبخیر تعرق بالقوه سطوح گیاهی (ET0) در منطقه باجگاه ( استان فارس, ایران) ارزیابی می شود. با استفاده از میانگین داده های هواشناسی در سال‏های 2002- 1986 در (17 سال) , مقادیر ماهانه ET0 با معادله‏های پن من - فائو  , پن من - مانتیث و هارگریوز تخمین زده شد. معادله‏های پن من - مانتیث و هارگریوز بر اساس روش پن‏من- فائو که در مطالعات قبلی مناسب ترین معادله برای تخمین ET0 شناخته شده واسنجی گردید.
بررسی‏ها نشان داد که نتایج معادله های پن من – مانتیث و هارگریوز تا اندازه‏ای به هم شبیه‏اند. ولی میزان ET0 را برای همه سال‏ها کمتر از روش پن من – فائو تخمین می زنند. برای واسنجی معادله‏های پن من – مانتیث و هارگریوز رابطه رگرسیون خطی به کار برده شد. همچنین در واسنجی معادله هارگریوز، تغییرات شیب خط برای مقادیر مختلف ET0 در دو روش محاسبه کویر ضرایب واسنجی شده معادله هارگریوز (CH) برای ماه‏های مختلف بدست آمد. همچنین ET0 سالانه بدست آمد.

کلیدواژه‌ها


عنوان مقاله [English]

Evaluation and Calibration of Three Evapotranspiration Equations in a Semi-Arid Region

نویسندگان [English]

  • H. R Fooladmand 1
  • A. R Sepaskhah 2
1 Marvdasht Islamic Azad University, Marvdasht, Email:hrfoolad@yahoo.com
2 Professor, Department of Irrigation, Shiraz University, Shiraz
چکیده [English]

This paper evaluates three different methods for estimation of reference crop evapotranspiration (ETo) in Bajgah area, Fars province, in Iran. Monthly values of ETo were estimated with Penman-FAO, Penman-Monteith and Hargreaves equations using the mean monthly weather data from 1986-2002 (17 years). The Penman-Monteith and Hargreaves equations were calibrated based on Penman-FAO method which was recognized as the most appropriate equation for ETo estimation, according to the previous studies. This study showed that the results of Penman-Monteith and Hargreaves equations are similar to but somehow they underestimate ETo compared with Penman-FAO method. To calibrate the Penman-Monteith and Hargreaves equations, a linear regression was used. The results of calibration for Penman-Monteith equation showed the variation of the slope of the line and ET0 the calibration coefficient (CH) of the Hargreaves equation for each month. annual ETo estimated. 

کلیدواژه‌ها [English]

  • Reference crop
  • Potential Evapotranspiration
  • Penman-FAO
  • Penman-Monteith
  • Hargreaves
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