محاسبه تبخیر و تعرق گیاه مرجع با استفاده از لایسیمتر سه تنی مستقر در حوزه معرف و زوجی زیدشت شهرستان طالقان استان البرز، ایران

Water balance is very important in watershed management and consists of several important components. The aim of this research is to measure the actual evapotranspiration of the reference plant in the in Zydasht paired watershed,, using a three-ton weight gravitation Lysimeter. In this research, Poa was used as a reference plant and it was grown on the lysimeter for 19 months. The main data of the lysimeter included the weight of the lysimeter and the amount of Seepage water from the soil monolith of the lysimeter. The data was measured every minute by precision weighing systems and its average was recorded hourly and then sent to the user's system by the lysimeter modem. The general water balance equation was used to measure the actual evapotranspiration of the reference plant. Plant evapotranspiration was calculated by two methods including: a) hourly lysimeter weight difference and b) daily lysimeter weight difference. The results of these two methods were compared using correlation analysis. The results showed that the actual evapotranspiration calculated with these two methods have a high correlation (92%), but because the hourly weight difference method takes into account all the changes in evapotranspiration during the day, it is more accurate. In total, the amount of evapotranspiration of the reference plant during the cultivation period was about 1510 mm. The highest amount of evapotranspiration was related to June, July and August with 255, 228 and 256 mm respectively and the lowest amount was related to January and February with 1 and zero mm.