June-August, 1961-2020, Czech Republic
Water balance shows the difference between rainfall amount and the potential evapotranspiration intensity. Positive balance means predominant rainfall and water surplus. Negative balance, in contrast, means predominant evaporation and water insufficiency. Two smaller maps show the total water balance for two 30-year periods. It can be seen that the period 1991-2020 has a lower value of water balance, i. e., less water available in landscape. The difference between the two maps in the top right corner is represented by the large map, where areas with lower water balance represented by hues of red color dominate. In the long term, the most negative water balance is observed in south Moravia and, to a certain extent, in central Bohemia and parts of the Ústecký region. The largest negative difference is observed in the NE and E part of the country. In contrast, an increase can only be observed in a very small area, usually near the borders in Bohemia. The total average water balance for the individual summers is shown on the bar chart in the top left corner, and the average water balance for the individual decades is shown on the bar chart below. One can see a clear decreasing trend, and the last decade (2011-2020) is one with the most negative total, primarily due to the very dry years 2015, 2018, and 2019. Only 10 out of the total 60 summers showed a positive water balance.