Liliana ZAHARIA, University of Bucharest, Faculty of Geography, Romania
Gabriela IOANA-TOROIMAC, University of Bucharest, Faculty of Geography, Romania
Gabriela-Adina MOROSANU, Institute of Geography of the Romanian Academy, Romania
Elena TUCHIU, National Administration “Romanian Waters”, Romania
Gabriela OSACI-COSTACHE, University of Bucharest, Faculty of Geography, Romania
This paper investigates the flow variability of the Lower Danube River (LDR), from the entrance in Romania (at Bazias) to the beginning of its delta (at Ceatal Izmail), over a length of about 1000 km. It highlights the spatio-temporal variation of Danube’s discharges (average, maximum and minimum), and observed changes in their time-series. The analyzes are based on processing data from gauging stations (g.s.) located on the Romanian bank of the Danube River, for several periods, ranging from 44 years (1976–2019) to more than 170 years (1840–2012). To identify the linear trends in flow dynamics and their magnitude, the Mann-Kendall test coupled with the non-parametric Sen’s method was used.
The flow regime of the LDR shows the highest discharges in spring and early summer (April – June, with the peak in April) and the lowest flows in late summer – autumn (August-November, with minimum in September). During the period 1931–2019, the highest maximum discharges occurred during the historical flood in 2006. They reached 15,800 m3/s at Bazias and 15,900 m3/s at Ceatal Izmail, but at some intermediate g.s. the discharges exceeded 16,000 m3/s. During the same period, the minimum discharges decreased up to 1,040 m3/s at Bazias (in 1949) and 1,790 m3/s at Ceatal Izmail (in 1947). The two large dams and reservoirs built on the LDR (i.e. Iron Gates I and II, fully operational in 1972 and 1986 respectively), did not significantly impair the water flow of the Danube River. In general, between 1931–2019, no significant linear trends in the annual discharges (average, maximum and minimum) dynamics were identified at the analyzed g.s.. However, at Ceatal Izmail, an upward trend was found in the variation of maximum annual discharges (at α = 0.05 level of significance) and of minimum annual discharges (at α = 0.1 level of significance). The investigation of the Danube River flow dynamics is of high scientific and practical interest for sustainable water and basin management.
Mots clés : Discharge|Spatio-temporal Variability|Trend|Danube River|Romania
A104016LZ