An Evaluation of the Dynamics of Some Meteorological and Hydrological Processes along the Lower Danube

Abstract

The objective of the present work was to perform a 30-year analysis of some significant meteorological and hydrological processes along the Lower Danube. This was motivated by the fact that, due to the effects of climate change, the global configuration of the environmental matrix has suffered visible transformations in many places. Another important factor considered is related to the constant development noticed in the last few decades of European inland navigation, in general, and in the Lower Danube sector, in particular. From this perspective, the processes analysed were the wind speed at a 10 m height, the air temperature at a 2 m height, precipitation, and river discharge. The 30-year period of 1991–2020 was considered for analysis. The ERA5 reanalysis data were processed and analysed in the case of the first three processes, while for the river discharge, the data provided by the European Flood Awareness System were used. The emphasis was placed on the evolution of the extreme values and on the identification of the geographical locations with a higher probability of occurrence. The average values and the seasonal variations of the four processes were also considered. The results indicated that the maximum wind speed and air temperature values along the Lower Danube did not suffer significant changes in the last few decades. However, the values of the minimum air temperatures increased with an average value of about 0.8 °C per decade, and the same tendency was noticed also for the average temperatures. Regarding the precipitation, the trend indicated a tendency to decrease by about 0.5 mm per decade, while for the river discharge, a clear increase of more than 1200 m3/s corresponded to each ten-year period. Finally, it can be concluded that the present analysis provided a global and more comprehensive perspective of the recent environmental dynamics along the Lower Danube, delivering useful information for inland navigation, as well as for other human activities.

Increased Riparian Vegetation Density and Its Effect on Flow Conditions

“…For example, in the S_meadow scenario, the flow velocity in the channel decreases as the flood progresses. After reaching the peak in the third period (23)(24)(25)(26)(27)(28) April; H: 1060-1036 cm), the falling limb slowly starts. At this time, both the in-channel and overbank flow velocities are reduced, and the curve inverts.…”

“…Ecologists have drawn attention to the changing riparian vegetation [23,24], which is rapidly altering as a consequence of extreme hydrological situations, such as recent droughts or long and high floods [25], plant invasions, and altered land use [26]. Over time, the confined floodplains have become ignored by society, traditional land uses (e.g., pasturing) have become neglected, and floodplains are no longer a priority of the nearby communities [27,28], especially in developed countries.…”

The Expected Dynamics for the Extreme Wind and Wave Conditions at the Mouths of the Danube River in Connection with the Navigation Hazards

“…The objective of the present work is to provide a more comprehensive picture concerning the expected dynamics of the extreme wind and wave conditions at the mouths of the Danube River in the Black Sea in connection with the navigation hazards. The focus is on the entrance to the Sulina channel, which represents the main navigation exit from the Danube to the Black Sea [7], being at the same time the southern gate of the seventh Pan-European transportation corridor linking the Black Sea to the North Sea via the Rhine-Main-Danube navigation system (inaugurated in 1992) [8]. The location of the target area in the Black Sea is illustrated in Figure 1.…”

The Potential of Lakes for Extracting Renewable Energy—A Case Study of Brates Lake in the South-East of Europe

“…Galati County is located in the eastern part of Romania, being a major port at the Danube River [15]. Although several renewable projects (for example, wind and solar) are operational in this area, there is little information about the local energy potential that is disseminated from an academic perspective.…”