Research of individual components of hydrological and hydrochemical regimes of the Danube River within the Ukrainian interval from Reni to Izmail

Introduction. This investigation aims at studying the individual components of the hydrological and hydrochemical regimes of the Danube River (within Ukraine) in connection with the widespread use of the river's water for water supply and irrigation in the southern region, as well as to ensure more effective regulation of water-salt regime of the Danube lakes using the Danube River as a main source for their water renewal. One of important aspects includes the study of the regime of the Danube River's suspended sediments brought to its delta due to their impact on the formation of the delta at the river's mouth of as well as due to the impact on siltation of deltaic and pre-delta lakes and canals connecting the lakes with the Danube River. Purpose. The purpose of the work is to study long-term and current trends related to changes in hydrological (water levels and discharges, suspended sediments runoff) and hydrochemical (mineralization) regimes of the Danube River within the Ukrainian interval from Reni to Izmail, internal annual distribution of water runoff, as well as suspended sediments runoff and mineralization during the years of varying water content. Results. The statistical analysis of long-term series of observations over the Danube River within the interval from Reni to Izmail resulted in discovering that time trends of average, maximum and minimum water levels (1921-2015) and discharges (1840-2015) indicate the presence of a weak increase in their growth over time, with a more pronounced increase in maximum water levels or discharges. The annual distribution shows the general synchronicity of fluctuations in runoff characteristics, and the maximum monthly values of water discharge differ have more pronounced seasonal fluctuations. The study shows the presence of a pronounced trend to reduction of suspended sediments runoff of the Danube River at Reni (for the period of 1840-2015), with their most intensive decrease over the period of 1990-2015. Annual distribution of average monthly suspended sediments runoff of the Danube River for the years with typical water content (for the period of 1978-2015) showed that they have seasonal fluctuations. At the same time, there is a decrease in the suspended sediments runoff along the length of the river from Reni to Izmail. The long-term course of average annual mineralization values of the Danube River at Izmail (1981-2015) is characterized by their decrease against the background of a small increase in average annual discharges. As per the annual distribution of mineralization values associated with all water content groups there are the periods related to the phases of the river's yearly water regime during and the economic use of water. Conclusion. Thus, the increase in the long-term period of the Danube River runoff within the interval from Reni to Izmail will contribute to the development of the region's economy and water supply, irrigated farming, regulation of the Danube Lakes filling with weakly mineralized river water. At the same time, the reduction of the suspended sediments runoff will restrain the siltation of the inlet canals connecting the lakes with the Danube River, which will improve the water renewal of the lakes with the river's fresh waters.

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Long-term Changes in Macrozoobenthos of the Kiliya Delta of the Danube River

Hydrobiological Journal ◽

10.1615/hydrobj.v38.i6.50 ◽

2002 ◽

Vol 38 (6) ◽

pp. 7

Author(s):

Z. G. Meteletskaya

Keyword(s):

Danube River ◽

The Danube River ◽

Long Term Changes

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Is the Water Temperature of the Danube River at Bratislava, Slovakia, Rising?

Journal of Hydrometeorology ◽

10.1175/2008jhm948.1 ◽

2008 ◽

Vol 9 (5) ◽

pp. 1115-1122 ◽

Cited By ~ 18

Author(s):

Pavla Pekarova ◽

Dana Halmova ◽

Pavol Miklanek ◽

Milan Onderka ◽

Jan Pekar ◽

...

Keyword(s):

Time Series ◽

Water Temperature ◽

Heat Load ◽

Empirical Relationship ◽

Danube River ◽

Average Heat ◽

The Danube River ◽

Average Temperature ◽

Monthly Discharge

Abstract This paper aims to reveal the annual regime, time series, and long-term water temperature trends of the Danube River at Bratislava, Slovakia, between the years 1926 and 2005. First, the main factors affecting the river’s water temperature were identified. Using multiple regression techniques, an empirical relationship is derived between monthly water temperatures and monthly atmospheric temperatures at Vienna (Hohe Warte), Austria, monthly discharge of the Danube, and some other factors as well. In the second part of the study, the long-term trends in the annual time series of water temperature were identified. The following series were evaluated: 1) The average annual water temperature (To) (determined as an arithmetic average of daily temperatures in the Danube at Bratislava), 2) the weighted annual average temperature values (Toυ) (determined from the daily temperatures weighted by the daily discharge rates at Bratislava), and 3) the average heat load (Zt) at the Bratislava station. In the long run, the To series is rising; however, the trend of the weighted long-term average temperature values, Toυ, is near zero. This result indicates that the average heat load of the Danube water did not change during the selected period of 80 yr. What did change is the interannual distribution of the average monthly discharge. Over the past 25 yr, an elevated runoff of “cold” water (increase of the December–April runoff) and a lower runoff of “warm” water (decrease of the river runoff during the summer months of June–August) were observed.

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Functional diversity of phytoplankton highlights long-term gradual regime shift in the middle section of the Danube River due to global warming, human impacts and oligotrophication

Freshwater Biology ◽

10.1111/fwb.13084 ◽

2018 ◽

Vol 63 (5) ◽

pp. 456-472 ◽

Cited By ~ 22

Author(s):

András Abonyi ◽

Éva Ács ◽

András Hidas ◽

István Grigorszky ◽

Gábor Várbíró ◽

...

Keyword(s):

Global Warming ◽

Functional Diversity ◽

Regime Shift ◽

Human Impacts ◽

Danube River ◽

Middle Section ◽

The Danube River

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Management challenges related to long‐term ecological impacts, complex stressor interactions, and different assessment approaches in the Danube River Basin

River Research and Applications ◽

10.1002/rra.3243 ◽

2018 ◽

Vol 35 (5) ◽

pp. 500-509 ◽

Cited By ~ 11

Author(s):

T. Hein ◽

A. Funk ◽

F. Pletterbauer ◽

W. Graf ◽

I. Zsuffa ◽

...

Keyword(s):

River Basin ◽

Ecological Impacts ◽

Danube River ◽

The Danube River ◽

Danube River Basin

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WATER AND SALT BALANCES OF KATLABUKH LAKE UNDER DIFFERENT CONDITIONS OF WATER RESERVOIR OPERATION

Hydrology, hydrochemistry and hydroecology ◽

10.17721/2306-5680.2019.4.2 ◽

2019 ◽

pp. 23-40

Author(s):

Y.A. Romanova ◽

Zh.R. Shakirzanova ◽

E. D. Gopchenko ◽

I.S. Medvedieva

Keyword(s):

Water Reservoir ◽

Feasibility Studies ◽

Water Levels ◽

Danube River ◽

The Danube River ◽

Management Measures ◽

Mineralized Water ◽

Design Values ◽

Water Salt ◽

Salt Flow

Katlabukh Lake is a part of the Danube Lakes system and is one of the surface water sources for water supply, for agricultural needs and irrigation of the region. Changing the conditions of operation and regulation of the reservoir led to a decrease of water levels and an increase of salinity, which makes it impossible to use water for different management needs. Calculations of the water and salt regimes of the lake based on the solution of the equation of balance said that in the water balance of Katlabukh Lake the main volume of the revenue part for the period 1980-2018 was precipitation (36.1%) and water inflow from the Danube River (38%), and the expenditure part – evaporation together with transpiration (50.5%). Salt flow into the lake is mainly due to surface inflow (53.4%) and water of the Danube River (25.5%), and loss of irrigation (45.1%) and water discharges to the Danube River (31.9%). Simulation modeling of the water-salt regime of the Katlabukh lake under different conditions of exploitation of the reservoir showed that corrective management measures are needed to improve the qualitative indicators of the water in the reservoir. They consist in the fact that for three summer months it is necessary to carry out forced pumping of poorly mineralized water from the Danube River to compensate for evaporation from the water surface (on average in volumes of the order of 55 million m3) or to carry out fences of water from the lake for irrigation in 60 million m3. This will allow to reach the design values of water mineralization in the lake equal to 1.0-1.5 g/dm3. Thus, addressing a range of problems to conserve and restore the rational use of the natural resources of Katlabukh Lake requires effective managerial water management activities that require additional feasibility studies.

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Statistical Analysis and Trend Detection of the Hydrological Extremes of the Danube River at Bratislava

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/906/1/012101 ◽

2021 ◽

Vol 906 (1) ◽

pp. 012101

Author(s):

Veronika Bacová Mitková

Keyword(s):

Statistical Analysis ◽

Anthropogenic Activities ◽

Water Levels ◽

Danube River ◽

Trend Detection ◽

The Danube River ◽

Natural Processes ◽

The Past ◽

Hydrological Extremes ◽

Measured Water

Abstract The territory of the Danube River Basin is one of the most flood-endangered regions in Europe. The flow regime conditions of the Danube River are continually changing. These changes are the result of natural processes and anthropogenic activities. In the present study, we focused on the statistical analysis and trend detection of the hydrological extremes of the Danube River at Bratislava. This paper firstly analyses the changes in correlation between water levels of the Danube River at Bratislava and Kienstock. Studied period of 1991-2013 included one or three hour measured water levels of the Danube River at Bratislava and Kienstock and shorter periods (1991–1995, 1999–2002, and 2004—2013) were selected for identification of the water level changes at Bratislava. One of the factors that recall the necessity to establish empirical - regression relationships was increasing of water levels of the Danube River at Bratislava (due to sediments accumulation at Bratislava). The results of the analysis indicated an increasing of water levels corresponding to the same flood discharges observed in the past. We also can say that travel time of the Danube floods between Kienstock and Bratislava did not change significantly during the analysed period. In the second part of the paper, we have identified changes in commonly used hydrological characteristics of annual maximum discharges, annual discharges and daily discharges of the Danube River at Bratislava during the period of 1876–2019. We examined whether there is a significant trend in discharges of the Danube River at Bratislava.

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Changes in the Quality of the Danube River Water in the Section Smederevo-Kladovo in the Conditions of Backwater Effects

Water Science & Technology ◽

10.2166/wst.1990.0027 ◽

1990 ◽

Vol 22 (5) ◽

pp. 181-188 ◽

Cited By ~ 1

Author(s):

M. Peršić ◽

M. Miloradov ◽

V. Tutundžić ◽

Z. Čukić

Keyword(s):

River Water ◽

Danube River ◽

Hydropower Plant ◽

Biochemical Processes ◽

The Danube River ◽

Global View ◽

Physico Chemical ◽

Composition And Structure

The paper describes specific changes in the quality of the Danube river water under the conditions of backwater effects in the Hydropower Plant Djerdap I storage. The results of longterm tests in five profiles of the investigated section, at various discharges give a global view of the intensity of changes in the composition of water mass. The analysis included changes in the contents of: organic matter, oxygen regime, reduction of turbidity and changes in the composition and abundance of plankton. The specific changes in the domain of physico-chemical and biochemical processes and changes in the biological status of the watercourse (composition and structure of plankton) at varying retention times complete the picture of short-term changes in the investigated system. Presentation of some settling effects and processes in the sediment of the storage provides an idea of some long-term changes in the conditions of backwater effects of the Danube in the investigated section.

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A Methodology for Measuring Microplastic Transport in Large or Medium Rivers

Water ◽

10.3390/w10040414 ◽

2018 ◽

Vol 10 (4) ◽

pp. 414 ◽

Cited By ~ 26

Author(s):

Marcel Liedermann ◽

Philipp Gmeiner ◽

Sebastian Pessenlehner ◽

Marlene Haimann ◽

Philipp Hohenblum ◽

...

Keyword(s):

Spatial Distribution ◽

Water Column ◽

Turbulent Mixing ◽

Suspended Sediments ◽

High Flow ◽

Danube River ◽

Long Term Effects ◽

Plastic Debris ◽

Different Depths

Plastic waste as a persistent contaminant of our environment is a matter of increasing concern due to the largely unknown long-term effects on biota. Although freshwater systems are known to be the transport paths of plastic debris to the ocean, most research has been focused on marine environments. In recent years, freshwater studies have advanced rapidly, but they rarely address the spatial distribution of plastic debris in the water column. A methodology for measuring microplastic transport at various depths that is applicable to medium and large rivers is needed. We present a new methodology offering the possibility of measuring microplastic transport at different depths of verticals that are distributed within a profile. The net-based device is robust and can be applied at high flow velocities and discharges. Nets with different sizes (41 µm, 250 µm, and 500 µm) are exposed in three different depths of the water column. The methodology was tested in the Austrian Danube River, showing a high heterogeneity of microplastic concentrations within one cross section. Due to turbulent mixing, the different densities of the polymers, aggregation, and the growth of biofilms, plastic transport cannot be limited to the surface layer of a river, and must be examined within the whole water column as for suspended sediments. These results imply that multipoint measurements are required for obtaining the spatial distribution of plastic concentration and are therefore a prerequisite for calculating the passing transport. The analysis of filtration efficiency and side-by-side measurements with different mesh sizes showed that 500 µm nets led to optimal results.

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