Alternative solution for determining the irrigation water quantity: ETGauge

Measuring the reference evapotranspiration (ET0) is difficult and costly. Some regions can have variable microclimates and these can often be quite far from climate stations. Therefore, it is optimal to use local measurements rather than a regionally calculated ET0. In this respect, one piece of equipment that provides cheap and reliable measurement results is ETGauge equipment. In this study, ET0 values measured with ETGauge equipment were compared with daily and monthly ET0 values calculated by five different commonly used empirical methods (ThornthwaiteAdj, Blaney-Criddle, Penman-Monteith = PM, Jensen-Haise and ASCE standardised Penman-Monteith = ASCE SZ PM). During the measurement period, daily ET0 values measured with ETGauge varied between 0-10 mm/day and the average was determined as 4.5 +/- 2.7 mm/day in the study area. In the calculations made with the empirical models, the change in ThornthwaiteAdj is 1.3-6.6 mm/day with an average of 3.8 +/- 1.6 mm/day, the change in Blaney-Criddle is 1.8-7.2 mm per day with an average of 5.1 +/- 1.4, the change in PM is 1.2-10.5 mm/day with an average of 5.8 +/- 2.7 mm/day, the change in Jensen-Haise was 5.8 +/- 2.7 mm/day with an average of 5.5 +/- 2.7 mm/day, and the change in ASCE SZ PM was calculated as 1.0-10.1 mm/day with an average of 5.4 +/- 2.5 mm/day. Considering the obtained results, the ETGauge equipment can be used safely in creating irrigation programmes.