Evolution of deficit volumes and mean and low flows in the Czech Republic.

The presented work deals with the evolution of river flows in the Czech Republic in the last few decades with a focus on hydrological drought. It starts with a detailed review of literature that concerns drought, its types, causes and impacts. It includes a list of the most frequently used methods of drought quantification and a review of papers on past and future trends of flows in the Czech Republic and Europe. Further, it describes how a new period for the evaluation of hydrological characteristics, which have been issued by the Czech Hydrometeorological Institute, were selected. The period of 1931-1980 has become out of date and the selection of a new period was requested. Following a number of statistical tests, the period of 1961-2005 was selected. The new period was evaluated regarding the trends of mean annual and monthly discharges. Mean annual flows did not show significant shifts. On the contrary, significant trends were found in mean monthly flows. Increasing trends in discharges of winter months and decreasing trends in spring months correspond with results of other studies which dealt with flows in Central Europe. The period of 1961-2005 was later reviewed and the current norm is 1981-2010. After the evaluation of mean flows, the characteristics of hydrological drought were analysed...