VTEI / evaporation

evaporation

Direct monitoring of water vapor from the free water level of the Vavřinecký pond and its influence on the hydrological balance

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With increased average air temperature, there is an increase in water vapour from a water surface. Between 2020 and 2022, evaporation from the water surface was observed with a floating evaporimeter at Vavřinecký pond in the Central Bohemian region. A floating evaporimeter monitors evaporation from the water surface along with basic meteorological quantities directly on the surface of the water reservoir, so its results should be more accurate than calculations based on data from nearby meteorological stations. The results show that in all three years evaporation exceeded precipitation by more than 100 mm between April and September. However, the issue of the influence of small water reservoirs on the hydrological balance is a very complex topic, where the assessment of negative and positive effects is not always black and white and requires detailed investiga-tion.

Impact of Teplice restoration on river basin runoff – preliminary results

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As part of the project for the Ministry of the Environment of the Czech Republic dealing with the monitoring of the impact of nature­‑friendly measures on improving the hydrological regime of small river basins, the Teplice river basin in the White Carpathians has been observed. Monitoring has been taking place since 2018, the measures were implemented in 2020. Data are available for the time period before the measures were implemented and for the year 2021, on which it is possible to observe the impact of the implemented revitalization. The data show the fluctuation of the daily runoff from the river basin and its overall reduction, which is probably caused by increased evaporation from the newly formed water bodies and increased water infiltration into the underground zone. After evaluating the observed data, there was a visible reduction in the surface runoff from the basin, which may nevertheless also be caused by the low rainfall totals in 2021.

Update of empirical relationships for calculation of free water surface evaporation based on observation at Hlasivo station

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Evaporation from free water surface is one of the essential components of water circulation in nature and significantly affects the overall water balance of the catchment. Due to the complicated direct measurement, it is often calculated from formulas that require available meteorological variables as input data.