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Using a 13 year(1967-1979)meteorolagical data at Badjgah Meteorological statiori,situated in the middle of a four—hectare alfalfa field, the amount of monthly potential evapotranspiration (ETo)were calculated by the Thornthwaite,modified Blaney—Criddle,Class A pans, modified Penman and Jensen—Haise methods. The latter four methods were calibrated for Badjgah climatic conditions.
Comparison of the calculated ET0 with the actual evapotranspiratiOn (ETa),measured by a water—balance type lysimeter,showed that the first two methods underestimated and the last method overestimated the amount of locaL ETo,but the modified Penman and calibrated Class A pan ETo were in good agreement with the local one.
Using the calculated ETo and the Thornthwaite’s second classification of climate,the climatic water budget and the climatic type were determined at Badjgah Area.The results show that there is ,on the average, water deficiency from second half of May (first half of Ordibehesht) until second half of October(first half of Aban).According to the first 1-Badjgah(29°46’N,52°36E,alt.1810 m)a sunny high—level site, is the
place of Shiraz University College of Agriculture in Northeast of
Shiraz(l8km)
method ,the climatic type is semiarid,mesothermal,large summer water deficiency with a thermal efficiency normal to the mesothermal climate; based on the other methods,which are more reliable,the climatic type is arid,megathermal ,little or no water surplus during winter.But due to existance of regional advection,arid,mesotherual ,little or no water surplus during winter with a thermal efficiency regime normal to the mesothermal climate is considered for this area.
Using the Thornthwaite and calibrated Blaney—Criddle methods and the local class A pan data during 30 years,a reliable climatic map could be prepared for the whole part of the country.