Following and analysing trends in evapotranspiration plays important role in understanding and analysing hydrological cycle and processes dynamics, which define this cycle. Increasing of evapotranspiration leads to lower amount of available water for human activities (such as drinking water, irrigation) and natural processes.
In thesis trends in evapotranspiration data in Slovenia are calculated for 55-year period (1961–2016). Analysis of reference evapotranspiration in Slovenia, calculated by the standard FAO Penman-Monteith equation, is made for 18 meteorological stations using R software. Mann-Kendall test of trends for chosen station was made on the basis of the daily values of evapotranspiration, monthly and annual maximum values and annual sums of evapotranspiration. The results of analysis indicate that the majority of the stations in moderate continental climate have statistically significant or insignificant positive trend. Furthermore, the annual sums of evapotranspiration are also increasing for more than a half of the considered stations, which indicates that trends of evaporation in Slovenia are increasing. Additionally, natural geographic variety of Slovenia has major impact on diverse values of evapotranspiration.
Analysis of the influence of four variables on reference evapotranspiration is conducted using linear correlation. Analysis shows that the most influential variable of individual station is average air temperature, followed by solar radiation, average relative humidity and average wind speed.