SPECIFIC FEATURES OF WATER CHEMISTRY AND QUALITY IN THE LENA RIVER BASIN

Introduction. The Lena River is one of the largest rivers in Russia and the main transport artery of Yakutia. Methods. In the course of the study, we considered the water regime of the Lena River in 1981–2019 in relation to the monthly average water discharge. The hydrochemical runoff was quantitatively assessed based on the widely used landscape-hydrological method. The analysis made it possible to estimate the relationship between the natural water quality and the environmental state of catchments. Results. An increase in the winter temperature reduced the depth of soil freezing and increased the drainage properties of soil as well as the number and duration of winter thaws. The most pronounced annual water discharge was observed in the Aldan River basin in the eastern part of the Lena River basin. The current state of the surface water quality was assessed by the main hydrochemical characteristics: water salinity, principal ions (sulfates (SO4 2–)), nutrients (nitrite nitrogen (NO2–)), organic matter (BOD5 and COD), oil products, phenols, and iron (Fe) and copper (Cu) compounds. The water has quality class 3 and is characterized as “polluted” or “very polluted” in different zones of the river basin, with the situation being most acute in the Olekma River. Conclusions. We present the results of an analysis of the spatial and temporal variations in the content of the most informative hydrochemical components for two periods (2001–2009 and 2010–2019) in the Lena River basin in accordance with the most stringent commercial fishing standards in force. We also plotted and mapped the temporal variations in the main pollutants. Graphs and maps of the time dynamics of the main pollutants are constructed.

HYDROLOGICAL CHARACTERISTICS OF RIVER RUNOFF IN GEOECOLOGICAL STUDIES OF SURFACE WATER IN THE SLAVSKY DISTRICT, KALININGRAD REGION

An important issue in geoecological studies of watercourses can be considered the presence of integral and continuous hydrological series. On their basis, most of the hydrological calculations and structures are made, without which high-quality and rational water use is impossible. Unfortunately, in the Kaliningrad region, there are a number of difficulties with obtaining a complete set of recorded results of hydrological monitoring carried out over watercourses. The aim of the work was to collect hydrological information and calculate the main hydrological characteristics of the river flow of some watercourses in the Slavsky region. All the available data on hydrometric observations of the rivers of the considered territory were collected, on the basis of which hydrological series of average annual discharges were compiled. These rivers are: Zlaya, Osa, Matrosovka and Nemoninka. The missing data in the hydrological series of the average annual water discharge of the rivers under consideration were restored. The curves of the provision of average annual expenditures have been built according to the reconstructed data, and the average long-term expenditures, coefficients of variation and coefficients of asymmetry of the studied water bodies have been calculated. The entire methodology was based on the current set of rules for hydrological calculations. The results obtained can play an important role in further geoecological studies of watercourses in the Slavsk region, planning their use and in various project activities to develop water use.

SOURCES OF UNCERTAINTY AND PROBLEMS OF INCREASING THE ACCURACY OF FLOW ASSESMENT FOR THE TRANSBOUNDARY NARVA RIVER

The water regime of the transboundary Narva River has always been constantly addressed by the hydrometeorological community. For many years, at the interstate level (the Russian Federation and the Republic of Estonia), there has been a discussion about the accuracy of flow assessment and the correctness of the methods applicable for these purposes. In some years, the discrepancies between the estimates of the average annual water discharge obtained by the Estonian and Russian sides reach values of 20-27%. Sustainable, reliable water use requires updating approaches and achieving greater unambiguity in the flow assessment. In the presented article, various sources of uncertainty in the Narva river flow assessment as hydrodynamic, seasonal factors and imperfection of existing methods are considered.

ИЗМЕНЧИВОСТЬ ГОДОВОГО СТОКА РЕКИ АЛАЗАНИ (ГАНЫХ)

The analysis of spatial and temporal regularities of the annual runoff of the transboundary river Alazani (Ganikh), which flows through the territory of Georgia and Azerbaijan, has been carried out. The series on the average annual water discharge of 6 hydrological gauges for the period from 1925 to 2017/2019 was used. It was found that for the researched rivers, the fluctuations of the average annual water discharges are in phase, however, the absence of strict synchronicity in the fluctuations of the annual runoff leads to a decrease in the spatial correlation coefficients. In the studied series of river Alazani (Ganikh) both on the territory of Georgia and Azerbaijan, there is no trend; however, for a number of annual runoff of the Ayrichai River, the main tributary of the r. Alazani (Ganikh), a significant positive trend was revealed. It should be noted that the reason for the nonstationarity is the climate change, the impact of which on runoff has become noticeable in recent decades. It was found that the variance of the second half of the analyzed series increased. The annual runoff of the Alazani (Ganikh) River has changed very little over 1991-2017 / 2019 compared with the period 1961-1990. For the Ayrichai River, the second period is characterized by increased water content. Keywords: River Alazani (Ganikh), Annual runoff, Water discharge, Transboundary river, Runoff change.

ŞİRVAN ÇAYLARININ AXIMININ ÇOXİLLİK TƏRƏDDÜDLƏRİ

The article is devoted to the analysis of long-term fluctuations of the annual flow of the Shirvan rivers. The analysis used data from 4 rivers with an observation period of more than 50 years. linear trends were identified in the observation series, and their significance was assessed. The annual water discharge observations are divided into two series, covering 1961-1990 and 1991-2018. The dynamics of annual precipitation data of meteorological observation stations located in the study area were also analyzed. Annual precipitation increased in Goychay and Ismayilli meteorological stations, and partial decrease in Gabala and Oguz meteorological stations. The seasonal variation of the annual flow is also analyzed. According to data of Alijanchay and Girdimanchay, a decrease in annual flow was observed, and an increase was observed in Goychay and Turyanchay rivers. The seasonal fluctuations of the flow increased in the cold seasons and decreased in the warm seasons. Keywords: annual flow, long-term fluctuations, linear trends, climate changes

QARABAĞ ÇAYLARININ SU EHTİYATLARI

Karabakh is one of the main regions in Azerbaijan where local water resources are formed. The article calculated the water resources of the area using the data of hydrological observation stations operating on the Karabakh rivers before the occupation. For research and analysis of average annual water discharge, multiyear observation data of hydrological stations operating on the Karabakh rivers were collected and integrated into the SpSS Statistics program. For the study multi-year average observation data of 32 hydrological stations in 20 rivers were collected. In order to determine the exact location of the hydrological stations operating in the area, a map was compiled using the Geographic Information System with reference to the fund and archive materials. In addition, hydrological zoning of the flow was carried out depending on the orographic features of Karabakh. During the analysis, two hydrological regions were identified. The first hydrological region is the Tartarchay-Guruchay hydrological region, and the second region is hakari-Oлchuchay hydrological region. As a result of the study, it was determined that the water resources of the Karabakh rivers are 1.64 km3 , which is 5.31% of the total water resources of Azerbaijan. During the implementation of water management measures in the area, in order to ensure the water security of the area, the resource potential of atmospheric precipitation and river flow for the area was analyzed and maps were compiled. Keywords: Karabakh rivers, hydrological station, water catchment area, water resources, water balance, hydrological zoning

Impact of climate change on superficial water resources in the South of France: statistical modelling over historical and future scenario periods

<p>In the Mediterranean, climate change and human pressures are expected to significantly impact surface water resources. We studied these impacts on the water discharge of six coastal drainage basins of the Gulf of Lions in southern France over the sixty-years period 1959-2018. Our approach was based on statistical analyses of hydrological, climate, land use and water management data. Results suggested that the annual water discharge of the six rivers studied can be predicted with high confidence by only two climatic indices, exclusively calculated from monthly temperature and precipitation data. This is a strong argument that climate is clearly the dominant driver of water discharge trends in the study region. These models also easily allow individual testing of the role of temperatures and precipitations on the evolution of annual water discharge. The latter decreased with about 30-45% in the study catchments over the 1959-2018 period and 25% can be attributed solely to the annual temperatures increase. Considering future projections of different climate models under a RCP 8.5 scenario, which depicts the strongest climatic changes, the annual water discharge could still decrease about 49-87% during the 2006-2100 period. For all models, we furthermore examined the relationships between the observed and simulated climatologies, our climatic indices and the large scale teleconnection patterns in order to better understand the spatial and temporal variabilities in the predicted water discharge series.</p>

MULTIVARIATE FACTOR ANALYSIS OF THE HYDROPOWER POTENTIAL MODULES IN THE PRIPYAT BASIN RIVERS (UKRAINE)

The importance of assessing hydropower resources in recent years determines the study of the quantitative characteristics of river hydropower. Interesting and at the same time important for understanding the assessment of hydropower potential and its module is a multivariate analysis of the determining factors that determine their magnitude. This approach makes it possible to establish the impact and assess the possible relationship between natural and anthropogenic indicators on its formation. It is especially important to establish the factors that determine the magnitude of the modulus of the hydropower potential, an indicator by which it is possible to reflect the total hydropower of rivers in a spatial context. Since the magnitude of the hydropower potential and its modulus is influenced by numerous factors that may be weakly interdependent, it was decided to apply multivariate analysis to establish the most significant indicators using factor analysis. Studies have shown that hydropower, runoff indicators, catchment area, indicators of erosional activity of the catchment, and indicators of the river’s slope exert the greatest influence on the magnitude of the modules of the hydropower potential. The indicators of plowing, forest cover, and regulation indirectly affect the magnitude of the modulus of the total hydropower potential. In the course of the study, the dependences of the hydropower potential on the catchment area and the average annual water discharge, the module of the hydropower potential and the indicator of the depth of the erosional incision of the rivers were built. The connections are characterized by good degrees of correlation and can be used to calculate the magnitude of hydropower in rivers for which there are no or insufficient input data. In a conclusion, the use of factor analysis made it possible to establish a relationship between all 15 factors, according to 26 hydrological stations, and to identify the main determining factors influencing the formation and spatial distribution of the total hydropower potential module for the Pripyat basin rivers within Ukraine. According to the results of the calculation by the method of factor analysis, five main groups of factors with the corresponding factor load. The first two groups of factors accounted for more than 80% of the total variance of the distribution.

SPATIAL-TIME VARIABILITY OF THE ILE RIVER RUNOFF UNDER CONDITIONS OF ANTHROPOGENIC ACTIVITY

To solve the problems of sustainable management of water resources in the catchment area of the Ili River basin, it is becoming demanded to study the dynamics of the average annual water discharge, taking into account anthropogenic activities, since their intensity is constantly growing. At the same time, the integral indicator of natural conditions in the catchment is the average annual water discharge of river basins, and the importance of this parameter lies in the fact that they can be considered as a function of the response to any changes in the catchment. In this regard, the analysis of changes in the average annual water discharge of the Ili River basin's catchment area was carried out on a spatio-temporal scale, where linear trends were used to assess and plot graphs, the method of multiple regression analysis and processing of time series were carried out on the basis of Microsoft Excel. Analysis of the dynamics of the average annual water discharge in the Ili River basin's catchment area on a spatio-temporal scale showed that, despite significant variability over the years, all studied hydrological stations are characterized by general patterns of changes in the hydrological regime under the influence of anthropogenic and natural factors.

Unravelling Climate and Anthropogenic Forcings on the Evolution of Surface Water Resources in Southern France

In the Mediterranean, climate change and human pressures are expected to significantly impact the availability of surface water resources. In order to quantify these impacts during the last 60 years (1959–2018), we examined the hydro-climatic and land use change evolution in six coastal river basins of the Gulf of Lion in southern France. By combining observed water discharge, gridded climate, mapped land use and agricultural censuses data, we propose a statistical regression model which successfully reproduces the variability of annual water discharge in all basins. Our results clearly demonstrate that, despite important anthropogenic water withdrawals for irrigation, climate change is the major driver for the detected reduction of water discharge. The model can explain 78–88% of the variability of annual water discharge in the study catchments. It requires only two climatic indices that are solely computed from monthly temperature (T) and precipitation (P) data, thus allowing the estimation of the respective contributions of both parameters in the detected changes. According to our results, the study region experienced on average a warming trend of 1.6 °C during the last 60 years which alone was responsible for a reduction of almost 25% of surface water resources.