Average Water Discharge Research Articles

Renewable energy sources in Kyrgyzstan and energy supply to rural consumers

The study assesses the potential of renewable energy sources in Kyrgyzstan and explores their application to provide energy to rural consumers. This study used an approximation of the parabolic function of solar radiation change, statistical processing of data on the average annual water flow of small rivers, as well as calculation of the volume of manure produced and its processing into biogas and bio fertilisers to assess their potential in agriculture and environmental impact. Kyrgyzstan, located between 40 and 68° north latitude, has evenly distributed solar radiation, small rivers and biomass, which have significant renewable resources. The distribution of solar radiation on the territory corresponds to the normal law of the monthly average mathematical expectation of 175.79 kWh/(m²*month) and a standard deviation of 92.44 kWh/(m²*month). On average, each square metre of a solar power plant can produce 0.451 kWh of energy. The intervals of average water discharge between the small rivers of Kyrgyzstan follow a power law distribution with a mathematical expectation of 3.112 m³/s and a standard deviation of 2.46 m³/s. With a natural water flow rate of 0.652 m³/s, a low-pressure micro-hydroelectric power plant (with a water head of 1 to 2 m) can generate up to 8.95 kW of power. The total consumption of biogas by an average farm in Kyrgyzstan and its consumption for heating raw materials in a bioreactor during the cold season ranges from 16.34 to 18.93 kg/hour. This demand for biogas is met by producing domestic feedstock (animal manure) using compact biogas plants with reactors of up to 20 m³. These facts indicate that the use of the above-mentioned renewable energy sources in Kyrgyzstan can provide autonomous power supply to remote rural consumers and contribute to solving existing environmental problems, as well as energy-saving

Dissolved Major and Trace Elements in the Largest Eurasian Arctic Rivers: Ob, Yenisey, Lena, and Kolyma

In contrast to fairly good knowledge of dissolved carbon and major elements in great Arctic rivers, seasonally resolved concentrations of many trace elements remain poorly characterized, hindering assessment of the current status and possible future changes in the hydrochemistry of the Eurasian Arctic. To fill this gap, here we present results for a broad suite of trace elements in the largest rivers of the Russian Arctic (Ob, Yenisey, Lena, and Kolyma). For context, we also present results for major elements that are more routinely measured in these rivers. Water samples for this study were collected during an international campaign called PARTNERS from 2004 through 2006. A comparison of element concentrations obtained for Arctic rivers in this study with average concentrations in the world’s rivers shows that most elements in the Arctic rivers are similar to or significantly lower than the world average. The mineral content of the three greatest rivers (Ob, Yenisey, and Lena) varies within a narrow range (from 107 mg/L for Yenisey to 123 mg/L for Ob). The Kolyma’s mineral content is significantly lower (52.4 mg/L). Fluxes of all major and trace elements were calculated using average concentrations and average water discharge for the 2004–2006 period. Based on these flux estimates, specific export (i.e., t/km2/y) for most of the elements was greatest for the Lena, followed by the Yenisey, Ob, and Kolyma in decreasing order. Element pairwise correlation analysis identified several distinct groups of elements depending on their sources and relative mobility in the river water. There was a negative correlation between Fe and DOC concentration in the Ob River, which could be linked to different sources of these components in this river. The annual yields of major and trace elements calculated for each river were generally consistent with values assessed for other mid-size and small rivers of the Eurasian subarctic.

On the issue of forecasting the runoff of mountain rivers in Uzbekistan

The article discusses the possibility of using dynamic models in the form of first- and second-order differential equations for forecasting water discharges in rivers of Uzbekistan. The models were tested on two small mountain catchments, which differ in the conditions for the formation of river runoff. Verification forecasts of average daily water discharges for five years are made. It was found that water discharges of the Akdarya River are predicted effectively with a daily lead time using both a first-order model and a second-order model. The listed models do not give satisfactory results when forecasting water discharges of the Zeravshan River at the Navoi city. In this case, it is necessary to modernize the models to suit the conditions of river runoff formation with an accurate account of the anthropogenic load, which is significant for the catchments of Uzbekistan.

PERANCANGAN SOLAR IRRIGATION PUMP DENGAN SISTEM SOLAR TRACKER DI SUBAK MALIKODA

Water is a fundamental necessity for agricultural land and can be obtained from various sources depending on its geographical location. The Keliki Village Farmers Group in Subak Malikoda faces the challenge of drought, leading to a shortage of water supply during the dry season. In this research, the Solar Irrigation Pump (SIP) is designed with a solar tracker system to pump groundwater with the aim of enhancing irrigation water supply for Subak Malikoda during the dry season. The design of the solar-powered irrigation pump system consists of an 18.5 kW submersible pump coupled with a 23.1 kWp PV system using 60 monocrystalline solar modules equipped with a solar tracker and utilizing a 30 kW inverter. Based on the conducted analysis, the PVSyst results show that the SIP without a solar tracker can operate for 6,067 hours with an average water discharge of 274.9 m3/day, based on the received global effective irradiation of 1765.1 kWh/m2 in one year. However, with the use of the solar tracker system, the pump can operate for 6,933 hours with a water discharge of 305.2 m3/day and global effective irradiation of 1963.8 kWh/m2 in one year. The results of the analysis conclude that the SIP with a solar tracker system is capable of operating optimally and meeting the water discharge requirements of Subak Malikoda. This positions the solar tracker system as an effective solution in enhancing the water supply for Subak Malikoda during the dry season.

RANCANG BANGUN PROTOTIPE PEMBANGKIT LISTRIK TENAGA SURYA DENGAN SOLAR TRACKER SYSTEM BERBASIS IOT

Water is an essential requirement for agricultural land and can be obtained from various sources depending on its geographical location. The Keliki Village Farmers Group in Subak Malikoda faces the challenge of drought, resulting in a shortage of water supply during the dry season. In this research, a Solar Irrigation Pump (SIP) with a solar tracker system is designed to pump groundwater with the aim of enhancing irrigation water supply for Subak Malikoda during the dry season. The solar-powered irrigation pump system design consists of an 18.5 kW submersible pump coupled with a 23.1 kWp PV system using 60 monocrystalline solar modules equipped with a solar tracker and a 30 kW inverter. Based on the analysis conducted, the PVSyst results for the SIP without a solar tracker show that the pump can operate for 6,067 hours with an average water discharge of 274.9 m3/day. This is based on the received global effective irradiation of 1765.1 kWh/m2 in one year. However, with the use of the solar tracker system, the pump can operate for 6,933 hours with a water discharge of 305.2 m3/day and global effective irradiation of 1963.8 kWh/m2 in one year. The analysis concludes that the SIP with a solar tracker system can operate optimally and fulfill the water discharge requirements of Subak Malikoda. This makes the solar tracker system an effective solution to enhance the water supply for Subak Malikoda during the dry season.

Evaluasi Instalasi Pengolahan Air Limbah (IPAL) Domestik Pada Unit Pengolahan Biologis Terhadap Parameter BOD Di Industri Pakan Ternak Surabaya

Domestic wastewater can be sourced from industrial activities, one of which is the Feedmill Industry. The Surabaya Feedmill Industry has been treating domestic wastewater using a WWTP. The management of domestic wastewater is based on the Technical Approval (PERTEK) of Wastewater Utilization for Application to Land. Based on the results, there are parameters that do not fulfill the quality standards. The parameter is Biological Oxygen Demand (BOD), an evaluation is needed to enhanced WWTP performance. The purpose of this research is calculating the percent removal of BOD, COD and TSS parameters in the biological treatment unit and identifying factors that can affect the removal of BOD parameters in the existing conditions of the biological treatment unit in the Surabaya Feedmill Industry. The method used is a literature study using the Ludwig Sasse equation. In the calculation of the average water discharge of 5.93 m³/day, only 29.6% of the planned discharge. The results of the calculation of HRT in biological unit processing have not met the design criteria, except for the aerobic biofilter. The BOD/COD ratio is 0.33. According to the existing calculation, the final result for the BOD parameter is 5.11 mg/L, COD is 24.38 mg/L and TSS is 37.33 mg/L. The design air requirement is 27.64 m³/day. Other factors that affect BOD removal are Dissolved Oxygen (DO) levels in the Aerobic Biofilter, nutrient requirements, and Food to Microorganism (F/M).

КЛИМАТИЧЕСКИЕ ИЗМЕНЕНИЯ ГИДРОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК НА РЕКАХ РЕСПУБЛИКИ САХА (ЯКУТИЯ)

The paper deals with long-term series of different hydrological characteristics (average annual water discharges, maximum discharges throughout the year, maximum discharges during spring floods and rain floods, spring flood runoff layers, minimum summer and winter water discharges) on the rivers of the Republic of Sakha (Yakutia) and their approximation by models of the non-stationary average (the linear trend and the stepwise change model). It has been found that there are practically no effective non-stationary models for the maximum water discharges, but there are such models for flood layers and for average annual and minimum water discharges, which increased mainly in the late 20th and early 21st centuries due to the possible additional inflow of water from the thawed permafrost. The number of effective non-stationary average models increases from 30% of all cases for flood layers to 50–60% for average annual and minimum summer water discharges, and almost to 100% for minimum winter water discharges. Estimation of the stationarity of the mean values and variances by statistical criteria when dividing the series of stepwise changes by year confirmed the nonstationarity of the mean values for all a priori established nonstationary models and, in some cases, the nonstationarity of the variances. The largest increase in average values up to 100% takes place in the minimum winter water discharges, up to 70–80% – in the minimum summer water discharges, and up to 40–50% – in the average annual water discharges; a change in average values up to 20% cannot be considered statistically significant and reliably determined. Relative to natural variability, the excess is up to 1.5–1.6 standard deviation, but no more. Spatial distributions of the increase in river runoff characteristics in % relative to the previous stationary period and to natural variability are constructed. The greatest increase in the minimum winter water discharge takes place in the northern part of Yakutia. In recent years, water discharges have been observed even on freezing rivers. For the minimum summer and average annual water discharges, the largest increase occurs in the northeast and east.

СЕРЕДНІЙ РІЧНИЙ СТІК ВОДИ РІЧОК УКРАЇНСЬКИХ КАРПАТ У БАГАТОВОДНІ ТА МАЛОВОДНІ ФАЗИ ВОДНОСТІ

he assessment of the average annual runoff of the rivers of the Ukrainian Carpathians in the high-water and low-water phases of water was carried out on the basis of a stochastic analysis and the identification of characteristic patterns of alternation of such periods within the boundaries of the Tisza, Dniester, Prut and Siret river systems. The study was carried out using a methodological base based on statistical means of generalization, data systematization, methods for estimating temporal random sequences, methods for analyzing the long-term variability of time series of water runoff characteristics and identifying their structure. As a result of the study, the variability in the structure of the time series of the average annual water discharge of the rivers of the Ukrainian Carpathians is clearly revealed. Such variability is similar for rivers within the studied river systems and is characterized by common patterns of stochastic relationships and cyclic fluctuations. The high reliability of cycles with periods of 29 ± 2 years indicates a stable recurrence of periods of high and low water content. The graphs of the relationships between the average annual water discharges during the periods of high and low water content and their average long-term values for the rivers of the Tisza, Prut and Siret river systems on the right bank of the Dniester showed that the qualitative characteristics of such relationships are assessed as very high. The estimates of water discharge in the water phase for the rivers of the Tisza, Prut, Siret and the right bank of the Dniester basins were checked using regression equations in comparison with empirical data and their high reliability (the probability of not exceeding probable deviations in dry periods was 77%, in high-water periods – 95%), which made it possible to generalize the probable expected average water discharges in the high-water and low-water phases of the cycle, depending on the average long-term values for the rivers of the studied basins of the Ukrainian Carpathians. Such generalizations can be used for prognostic estimates of possible values of water discharge in high-water and low-water phases for any river of the Ukrainian Carpathians. At the same time, it is necessary to take into account in which system of rivers it is located, to know the average long-term water discharge and the time frame and the chronology of the water phases.

Transformation of the water runoff of the Volga River after the creation of the Zhiguli hydroelectric complex

For the Volga River, studies of interannual changes in water discharges in the period 1958-2021 were carried out. Systematic hydrological observations were carried out at the Zhiguli hydroelectric complex on the border of the Middle and Lower Volga. 97% of the water runoff of the entire Volga is regulated in this section in the seasonal, weekly and daily range. It was found that the average water flow was 7704 m3/s. The amplitude of interannual fluctuations was 5270-10431 m3/s. Temporal changes in the average annual water discharges were characterized by cyclicity, including the change of low-water and high-water phases. From 1958-1975 a low-water phase was observed, from 1976-1996 - high-water and since 1997-2021 - again shallow. A comparison of the historical (1877-1955) and modern (1958-2021) periods showed that over 144 years, the average water flow of the Volga River has not changed much. However, as a result of the regulation of water flow in the period 1958-2021 the value of water discharges in high-water years decreased, while in low-water years it increased.

ОЦІНКА ЗАРЕГУЛЬОВАНОСТІ СТОКУ РІЧКИ СЕРЕТ

The Seret River is a 242 km long left tributary of the Dniester, flowing within the Ternopil region. The basin covers an area of 3900 km2, a river slope of 0,9 and a river network density of 2,44 km2/km. The average long-term water discharge in the river is 12,1 m3/s, the water turbidity is 100-200 g/m3 and the salinity is 350-550 mg/dm3. There are 8 small hydropower plants on the river with a total capacity of 21,57 MW. The aim of the study is to assess the regulated flow of the Seret River and determine the amount of siltation in the reservoirs in its channel. The study found that 8 reservoirs have been created on the Seret River, with a total water surface area of 21 km2 and a total volume of 57,4 million m3. The Seret River is one of the most heavily regulated rivers in the Western Podillia. The Seret River basin contains 30% of all reservoirs in the Ternopil region. The upper reaches of the river are the most regulated, with 5 reservoirs with a total volume of about 33 million m3 and a usable volume of 25 million m3. According to the results of the calculations, it was found that the coefficient of flow regulation of the Seret River is 0,17; the degree of flow regulation is 0,25. The volume weight of sediment in the Seret River is 0,79 t/m3. It was found that the river transports about 57 thousand tonnes of sediment per year. Over the estimated period of operation (40 years), 3 million m3 of sediment will accumulate in the Seret River reservoirs. The siltation of Ternopil reservoir is 3,5 %, Vertelivske – 5 %, Zalozhtsivske – 10 %, Verkhnya Ivachyvka – 58 %, Bilche-Zolotetske – 65 %, Skorodynske – 75 %. Based on the results obtained, it can be concluded that the Seret River is undergoing significant anthropogenic pressure, and there are risks of degradation of the watercourse and a decrease in the energy potential of the reservoirs in the middle and lower reaches of the river. Therefore, there is a need to develop scientifically based measures to optimise nature management and renaturalise the Seret River basin and valley.

ГИДРОЛОГИЧЕСКИЙ ПРОФИЛЬ ВОДОСБОРА БАССЕЙНА ТРАНСГРАНИЧНОЙ РЕКИ ШУ

An analysis of changes in the hydrological indicators of the catchment area of the transboundary Shu River basin in the spatio-temporal aspect, based on information and analytical materials from the hy-drological posts of Kochkarka, Orto-Tokai, Milyanfan, Tashotkol, the Furmanovs hydroelectric com-plex and Ulanbel in a long period of observations covering 1931…2020, shows the presence of their constant fluctuations over the years under the influence of natural and anthropogenic factors. The hy-drological regime of the catchment area of the transboundary Shu River basin on a spatio-temporal scale with a positive or negative trend in the average annual water discharge is determined by the gen-eral nature of natural factors and changes due to increased anthropogenic activity on river systems. The results obtained indicate that the influence of natural and anthropogenic factors are less pronounced in the mountainous and foothill geographic zones than in the foothill-plain and desert zones of the catch-ment area of the transboundary river Shu.

Долгосрочное прогнозирование характеристик весеннего стока рек бассейна Тобола

For the first time, methods have been developed that allow obtaining a long-term forecast of the runoff layer for the second quarter and a forecast of the maximum water level for the spring flood period for seven rivers of the Tobol basin on March 25 every year. Both methods use linear empirical dependences of the predicted value on the maximum snow water equivalent averaged over the catchment area, the logarithm of the average water discharge for November of the previous year, and the average water discharge for the month preceding the forecast release date. To estimate the parameters of these dependencies and verify the forecasts obtained with their help, data of long-term hydrometeorological observations for the period from 1968 to 2021 were used. The analysis of the series of test forecasts showed that both methods give quite satisfactory results for all seven river basins. The methods can be recommended for use in the system for operational hydrological forecasting in order to scientifically substantiate measures on using water resources of the Tobol basin rivers and protecting the population and economic facilities from inundations during the spring flood. Keywords: flood, runoff layer, maximum water level, forecast, snow water equivalent, water discharge, empirical dependence, verification

Probabilistic-forecasting method for determination of low flow discharge of Pivdennyi Buh, Black Sea area, and Lower Dnieper rivers

The aim of the study is to substantiate the probabilistic-forecasting method for forecasting the low flow discharge and its implementation for the Pivdennyi Buh, Black Sea area and Lower Dnieper rivers, taking into account climatic patterns of precipitation distribution and establishing probabilistic characteristics of low flow discharge in multi-year period. The study area is in a zone of significant risk due to the shortage of water resources, the formation of extremely low runoff in the dry flow period, which requires its definition and forecasting. The methodological basis of forecasts is to solve the equation in determining the components of the low flow of rivers by constructing regional dependences for forecasting the average decade summer-autumn low flow from previous water discharge (in runoff modules), establishing their probabilities water discharge for a number of intakes. Results. The paper substantiates the probabilistic-forecasting method for forecasting low flow discharge (in summer, autumn and winter periods) based on the construction of regional dependences of average decadal runoff modules on previous water discharge for groups of basins of studied rivers taking into account climatic dependences of precipitation distribution in the territory and the establishment of probabilistic characteristics of the low flow water discharge in a multi-year period. The methodology of territorial short-term forecasts of average decade water discharge of low flow of summer, autumn and winter river runoff is assessed as satisfactory with a margin of error of 70 % to 97 %, with a number of members of more than 500 points. To determine the cumulative probability of the forecast values of the average decade water discharge of the summer, autumn and winter dry weather flow, the empirical distribution of the average monthly water discharge in the limited seasons, which are generalized in the basins of the studied rivers of Ukraine, is established. Scientific novelty. For the first time for the zone of insufficient natural water content of rivers the method of territorial forecasts of low flow discharge, determination of their probability of occurrence in a multi-year period and cartographic representation of prognostic values have been developed and practically implemented. The practical importance is the use of forecast modules maps of low flow for spatial monitoring and assessment of low water levels on rivers in the whole region, including ungauged rivers, and their probabilistic characteristics – to assess the possible occurrence of low runoff, even when it reaches values close to the environmental runoff, which are critical for the functioning of the river ecosystem.

PEMBANGUNAN POMPA PENDORONG AIR EMBUNG GRIGAK TENAGA SURYA UNTUK PENGAIRAN PERKEBUNAN ECO CAMP MANGUN KARSA

In the Mangun Karsa eco camp area, Gunungkidul, Yogyakarta, a reservoir has been built to be used to collect rainwater and named the Grigak Reservoir. The water from the reservoir will be used to irrigate plantation crops grown in the area. However, due to the location of the reservoir under plantation land, a water pump was needed to lift it. Due to the absence of a PLN electricity source and previously built a solar water pump, so to lift the water from the reservoir, a similar solar water pump was built. The water pump used was a jet pump type with a total head of up to 100m. The average water discharge produced at a height of 40m was 27lpm.

Методики краткосрочного прогнозирования стока рек бассейна Камы

For the rivers of the Kama basin, two methods have been developed for daily short-term forecasting of average daily water discharges with a lead time of 1, 2, and 3 days. The first technique uses the HBV-96 river runoff formation conceptual model and the subsequent correction of forecasts outputs. The second technique is based on the hydrograph extrapolation method and is limited to the data of hydrological observations available by the date of the forecast. For the first technique, the expected values of the COSMO-Ru meteorological model temperature and precipitation forecasts are used for the lead-time period of the hydrological forecast. The influence of meteorological forecast errors on the accuracy of river streamflow forecasts was analyzed. The results of the verification based on an independent sample showed that, in general, both methods give a satisfactory forecast quality. The technique that uses the runoff formation model and meteorological information is slightly more accurate than the hydrograph extrapolation method, and its advantage increases with increasing forecast lead time. Keywords: Kama basin, water discharge, hydrological model, correction, extrapolation, verification, forecast quality

ДИНАМИКА ИЗМЕНЕНИЯ РЕСУРСОВ РЕЧНОГО СТОКА ТОБЫЛ -ТОРГАЙСКОГО ВОДОХОЗЯЙСТВЕННОГО БАССЕЙНА

The study presents results of assessing the resources of the river flow of the Tobyl - Torgai water management basin. The purpose of the work is to update the previously developed methodology for assessing the annual runoff resources of individual rivers and river runoff resources of the considered water management basin of the Republic of Kazakhstan. The calculations used the average monthly and average annual water discharge of the main rivers. Methods have been developed for determining and restoring the observed and natural runoff, long-term statistical characteristics and its values of probability of exceeding. The equations for determining the water resources of local runoff and water resources coming from other regions are obtained. As a result of the work done on the preliminary calculation, the total surface water resources for the Tobyl – Torgai water management basin, formed in Kazakhstan and coming from the territory of the Russian Federation for a long-term period from 1931 to 2019, on average amount to 1,67 km3, of which: resources formed within Kazakhstan - 1,33 km3, inflow – 0,34 km3. The runoff formed in the territory of the basin, for the disturbed period, relative to the conditionally natural period, decreased by 8%, the runoff coming from the Russian Federation decreased by 12%, and the total water resources by 9%

Combining biological and hydrogeological approaches: The grass Molinia arundinacea as a possible bioindicator of temporary perched aquifers in ophiolitic systems

Springs represent relevant habitats which support high levels of biodiversity and productivity, providing refugia to both plants and animals together with essential ecosystem services. However, springs are often overlooked or even destroyed by human activity. Locating, inventorying, and monitoring springs is, therefore, becoming of increasing importance. This study aims at developing a multidisciplinary approach to detect ephemeral springs, which can only be discovered by hydrogeological surveys when discharge occurs. We suggest potential cooperation between hydrogeologists and botanists based on the use of a plant species as an indicator of the occurrence of ephemeral springs fed by ophiolitic perched groundwater aquifers. In this study, the grass Molinia arundinacea was used as a bioindicator, observed in periods when there was no discharge and whose occurrence on ophiolite bodies was revealed by previous studies in the northern Apennines (Italy). A total of twenty ophiolitic bodies were explored and grassland stands including Molinia populations were discovered in 86 springs (15 reported for the first time). Detailed geomorphological and hydrogeological sampling was also performed in ten springs, recording the occupancy area, cover and functional traits of Molinia at two permanent and eight ephemeral springs and along their streambeds. Molinia not only colonised the spring outlets, but also occurred along the streambeds fed by ephemeral springs, with a higher occupancy area where the rocky outcrops were covered by detrital deposits and at the base of the morphological incision. Additionally, the cover of Molina populations was correlated with the average water discharge, with the highest functional trait values found in locations with high soil moisture. Results confirmed that while Molinia performs best on permanently moist soils, it is also able to grow on soils with a fluctuating water-table or even in dry conditions, thus representing an excellent indicator of springs fed by temporary perched aquifers.

Hydrological classification by clustering approach of time-integrated samples at the outlet of the Rhône River: Application to Δ14C-POC

Within the framework of the Rhône Sediment Observatory, monthly time-integrated samples have been collected by Particle Traps in the last decade to monitor particulate contaminants in the Rhône River and its main tributaries. In this watershed with a contrasted hydrology, a clustering approach is used to classify the samples according to the main hydrological events. This approach has been applied to riverine particulate organic radiocarbon signatures (Δ14C-POC) that are strongly affected by the origin of the material and the occurrence of nuclear power plant releases. Suspended Particulate Matter (SPM) samples were collected near the outlet of the Rhône River and analysed for 14C along with particulate organic carbon (POC), chlorophyll a and tritium contents to confirm Δ14C-POC origins. Cluster Analysis, coupled to Principal Component Analysis, was performed based on monthly average water discharges of the Upper Rhône River and the five main tributaries. The classification obtained by fuzzy C-mean logic of the Rhône River hydrology into 5 clusters is similar to that already observed in the literature with Mediterranean/Cevenol flood, oceanic pluvial flood, nival flood, low-water level and baseflow clusters. The contributions of each cluster among the Δ14C-POC values demonstrate the complexity of hydrological classification of time-integrated samples. First, the samples with a unique and significantly dominant cluster are easily explained with negative Δ14C-POC values observed in the flood clusters due to input of 14C-depleted material from soil or rock weathering, and positive values observed in the low-water level and baseflow clusters due to anthropogenic input by nuclear industry. Second, samples that present a homogeneous mixture between several clusters demonstrate the occurrence of different hydrological events during the sampling periods. This tool appears as a solution to estimate the contribution of each hydrological event in time-integrated samples.

АНАЛІЗ ПОВТОРЮВАНОСТІ ДОЩОВИХ ПАВОДКІВ НА РІЧКАХ В БАСЕЙНІ ТИСИ (В МЕЖАХ УКРАЇНИ)

Rain floods on the rivers in the Tisza basin within Ukraine are formed several times during the entire warm period. The purpose of the presented study is a detailed analysis of the frequency of such floods on the rivers of the region under study in terms of the series of annual maximum average daily water discharges and the series of maximum average daily discharges of partial probability. The first series, called the “multi-annual series”, includes only one of the highest discharges each year, in our case, one for the warm period – May-October. The second row includes all values hat exceed some limit value, which corresponds to the smallest value from the series of annual maximum annual water discharges. To carry out the work, we used observational data on the average daily water flow from the following hydrological posts on the rivers: the Uzh River – Uzhgorod, the Latoritsa River – Mukachevo, the Rika River – Mezhgorye, the Teresva River – Ust-Chernaya, the Tisza River – Rakhiv for the observation period 1946 (47 ) to 2019. To obtain the long-term series and partial probability necessary for the study, first, chronological samples of rain flood maxima were formed for both series separately, then they were ranked and the estimated return period was determined for each member of the series. The series of maximums of partial probability according to the data from the studied hydrological stations in their number on average 4-6 times exceed the number of values of the series of annual maxima. The calculated return periods are determined by the inverse formula to the Weibull formula. Graphs of the frequency of rain floods by annual maxima and maxima of partial probability for the stations under study were constructed, which made it possible to notice the following features: 1) the discharges maxima of rain floods with a frequency of less than 5-10 years differ for a number of annual maximum water discharges and a series of partial probability; 2) partial probability series better describe minor floods, especially those with a short return period. The analysis of the frequency of rain floods on the rivers in the Tisza basin within Ukraine made it possible to estimate the possible magnitudes of rain floods that can form during a warm period of time and to estimate their frequency of a certain magnitude. This is of practical interest as knowledge of potential floods can be used to assess the nature of potential floods in the future.

Formation of variability of flow quality in the top of the Luga river in inter-annual and short-term time. Part 1. Interannual variability

The study of the interannual variability of the flow quality of the Luga River was carried out in the section of the village of Tolmachevo 3 km downstream of the confluence of the Oredezh River according to the data of the North-West UGMS 2000–2017. Water pollution in the runoff was assessed in accordance with RD 52.24.643-2002. For 11 years out of 18, the water in the effluent was “very polluted”, 2 years – “dirty”, 3 – “polluted”, and only in 2016 and 2017 – “slightly polluted”. The use of factor analysis showed that the variation of Vzag% of the runoff of the most polluted water of classes 3 and 4 is influenced by factor 1 (33% of the total variance), which is associated with the value of the highest water discharge. Factor 2 (22%) has a positive relationship with the variation in average and lowest water discharges. Four components Mn2+, Fetot, COD and Cu2+ are distinguished, polluting most of the volume of water flow annually. Factor 1 (21%) affects Vzag% of water contaminated with single components. It has a negative relationship with Vzag% of water, the oxygen saturation of which is below normal. This, possibly, can serve as a marker of the contribution of the Oredezh River to the formation of runoff in the section of the village of Tolmachevo. Factor 2 (18%) showed an inverse relationship between the variation of Vzag% of the runoff of water contaminated with Cu2+ and the average annual water discharges