Javad Behmanesh, Vahid Rezaverdinejad, Saeid Mehdizadeh
Department of Water Engineering, Urmia University, Urmia, Iran
Key words: Evapotranspiration, Cropping Pattern, FAO Penman-Monteith, Hargreaves-Samani, Occurrence Probability.
Abstract
Evapotranspiration is a probable parameter. Thus, true estimation of plant evapotranspiration with certain probability level has an important role in agricultural water management. In this research, 24 years of meteorological data of Urmia synoptic station were used to compute reference and crop evapotranspiration. In order to investigate the effect of ET0 calculation method on its value and cropping pattern water requirement (CPWR), FAO Penman-Monteith (FPM) and Hargreaves-Samani (H-S) methods were selected. The daily ET0 values at different probability levels for each method were calculated. Based on dominant cropping pattern in region, wheat, apple and fine vegetables were chosen. Values of cropping pattern evapotranspiration were calculated on two methods: 1) 50% probability level for all the crops and 2) recommended probability levels (50% for wheat, 75% for apple and 90% for vegetables). Considering cropping pattern: wheat: 40%, apple: 30% and vegetables: 30%, and irrigation efficiency: 40%; the results showed that the values of CPWR on recommended probability level at irrigation intervals of 5 and 7 days in FPM method were 1.7 and 2.3 (lit/s/ha) which were 14% and 13% greater than 50% probability level, respectively. For the H-S method, the same values were 0.7 and 0.9 lit/s/ha (8% and 7%), respectively. The results showed that on 50% probability level and 5 and 7 days irrigation intervals the CPWR values for FPM method, were 2.3 and 3.1 (lit/s/ha) which were 21% and 21% greater than the same values from H-S method, respectively. For recommended levels, these values were 3.3 and 4.5 (lit/s/ha).
Get the original articles in Source: Volume 5, Number 2, August 2014 – JBES
Journal Name: Journal of Biodiversity and Environmental Sciences (JBES)
Published By: International Network for Natural Sciences
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