Estimation of Irrigation Requirement for Important Agricultural Crops at the Different Probability Levels for the Province of Fars

Irrigation requirement equals the difference between the water requirement and the effective rainfall. Crop water requirement and irrigation requirement have been reported by employing the NETWAT program for various crops for the different regions of Iran. However, as the means of climatological paremeters have been used in this program, therefore, the reported values of crop water- and irrigation requirement have been calculated for the 50 percent of probability level. As it is nesessary in some conditions to determine irrigation requirement at the different probability levels, therefore, irrigation requirement of the most important agricultural crops were calculated for some regions of the Province of Fars namely: Abadeh, Eqlid, Darab, Dorodzan, Zarghan, Shiraz, Fasa and Lar, using the climatological data for at least 10 consecutive years. Irrigation requirement of each crop then was determined at the probability levels of 10, 20, 30, 40, 50, 60, 70, 80 and 90 percent. The results indicated that the obtained values for irrigation requirement for most conditions were different from those reported using the NETWAT program. Therefore, it is advisable to determine the irrigation requirement of the most important agricultural crops at the different probability levels using the results obtained in this study for the reported locations in the Province of Fars.