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Evaporation from the water surface
Novotný, Eduard ; Šobr, Miroslav (advisor) ; Šuhájková, Petra (referee)
Evaporation and evapotranspiration are significant components of the hydrological cycle. Accurate measurement or calculation of evaporation is essential for studies of water resource development and management, as well as for efficient crop irrigation in agriculture. Throughout history, many models have been developed to calculate potential evapotranspiration based on various meteorological parameters. The accuracy of these models needs to be determined by comparing them with measured evaporation values obtained from an evaporation pan. In this study, 7 models for calculating potential evapotranspiration or evaporation from a free water surface based on air temperature are compared with evaporation measured by the VYPAR-1200 evaporation pan during the evaporation season 2021 at the Vrchlice meteorological station. The most accurate results were obtained with the models presented by Oudin et al. (2010) and Šuhájková et al. (2019), with RMSE values of 1.061 and 1.105 mm/day and MBE of 0.554 and 0.303 mm/day. Even so, the deviations are quite significant and for more accurate calculation of evaporation for the Vrchlice region, parameterization of these models would be necessary. Key words evaporation, water surface, evaporimeter, meteorological station Vrchlice
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Summary of a potential evapotranspiration calculation methods in the selected river basins
Bedáňová, Jana ; Benáčková, Kateřina (referee) ; Marton, Daniel (advisor)
The master's thesis deals with the research of available methods for calculating potential evapotranspiration and the subsequent application of selected methods. The text part describes general knowledge about evapotranspiration, specific types of vapors from different surfaces (water, soil, vegetation, snow cover, urbanized area). The following are methods of direct measurement, where the types of vapor meters are described, for which types of vapors they are used. Indirect measurement methods for determining potential evapotranspiration and their distribution are also described here. The main part of the research is empirical methods for calculating potential evapotranspiration, here is a selected list of these methods. Furthermore, a practical application of the method according to Thornthwaite, Hargreaves-Samani and Hargreaves-Allen is carried out using data from the Olomouc-Holice precipitation station, the data of which are available from the ČHMÚ portal. Then a comparison of the used calculation methods is made.
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