Identification of the historical drought occurrence on the Danube River and its tributaries

Abstract

In the presented paper, the changes in the minimum flows at five stations along the length of the Danube River and at its 5 selected significant tributaries were analyzed. Average daily flows with the longest possible series of observations (since 1901 or since 1921) were used as input data. In the first part, low water content, hydrological drought were statistically analyzed and long-term trends of 1-to 90-day minimum flows were identified. The second part presents changes in T-year minimum daily flows in selected stations. The most extreme drought at Hofkirchen occurred in 1921. Drought at Orsova occurred around 1862/63, 1882/83, 1900, 1920/21, 1946/47, 1961/62, 1971, 1991/92 and 2017 / 19. The analyzes show that there is a more or less regular alternation of water and low-water periods along the entire length of the Danube. Multi-annual dry periods along the length of the Danube occur in the same periods. In contrast, on the Danube tributaries, the dry seasons are time-shifted.