Hydrometeorological Parameters Research Articles

Soil water and stable isotopes in the unsaturated zone profile – field observations and analysis

In this review, we provide research data emphasizing the role of groundwater table and hydrometeorological parameters variation on soil water fluctuations in the unsaturated soil profile. We focused on soil water content, air temperature, precipitation and groundwater table observations. The ThetaProbe Soil Water Sensors basing on changes in the apparent dielectric constant were used for soil volumetric water content measurements. The sensors were installed at the different depths of the unsaturated zone profile under natural atmospheric conditions. The observations lasted more than five years (14 November 2013 – 31 December 2018). Groundwater table data was obtained using Diver data loggers, which continuously recorded water pressure and temperature. For more detailed investigations of water and mass transport at the Maišiagala radioactive waste repository site water, stable isotopes as environmental tracers were used as well.

Геоінформаційна веб-система представлення результатів інвентаризації викидів атмосфе-рних забруднень у м. Київ

In the current work, there has been developed for the first time a geo-information web-system for presenting the results of the inventory of air pollution emissions in Kyiv from industrial en-terprises on the basis of the processing of data from the State Statistics Service of Ukraine, as well as estimates of geo-distributed emission fields from vehicles. The system contains infor-mation on emissions of 21 pollutants, including those that are regularly monitored in Kyiv by governmental agencies. The system is available via the link http://env.kiev.ua:8080/pollutionsystem/ pollutionsystem.html. Its main features – viewing on the map the locations of industrial emission sources for the selected substance, and the corre-sponding amount of emissions – can be used even by unregistered users. The developed system can be used in combination with the existing public and state systems for monitoring of air pol-lution in Kyiv for preliminary (screening) analysis of possible causes of high levels of air pollu-tion during their observing with the monitoring systems. The paper presents a relevant example of the system application to explain the high levels of hydrogen sulfide concentrations at one of the stations in Kyiv. Another purpose of the system may be to detect shortcomings in the exist-ing inventory of industrial emissions, namely the lack of information on certain sources, as well as verification and adjustment of data on emissions from the registered sources. To fully use the system potential, it is necessary to expand its functionality in the direction of mathematical modeling of the spread of pollution due to emissions from industrial enterprises and vehicles. For this purpose, it is also necessary to integrate hydrometeorological parameters and levels of air pollution in Kyiv into the data monitoring system.

Climate Change in the Hydrometeorological Parameters of the Black and Azov Seas (1980\u20132020)

To study the nature of climate change in the hydrometeorological parameters of the Black and Azov Seas—surface air temperature (SAT), sea surface temperature (SST), ice cover, and sea level—under conditions of ongoing global warming, we used reanalyses and remote sensing data, as well as information from known publications of recent years. It was found that against an increase in SAT over the Black–Azov Sea region (+0.053°C/year in 1980–2020) and SST of the Black Sea (+0.052°C/year in 1982–2020), the values of these parameters in the 2000s differ significantly from those in the 1980s–1990s: the maximum average monthly summer and minimum average monthly winter temperatures have increased, as well as the number of mild winters. The average annual SST of the Black Sea, which practically did not exceed 15°C in the 1980s–early 1990s, has exceeded 16°C in most cases since 2010 (maximum 16.71°C in 2018). In the 2010s, the average monthly winter minima, with the exception of the winters of 2011/2012 and 2016/2017, did not fall below 8°С. A consequence of the increase in winter temperatures was a decrease in the ice concentration in the Sea of Azov (the trend of the mean monthly concentration is –1.2%/10 years). From about 2004–2010 in the Black Sea and since 2004 in the Sea of Azov, the tendency towards increase in their levels (on average) has been replaced by a slight decrease, so that the average positive trends for the period 1993–2020 (+0.32 ± 0.16 cm/year in the Black Sea and +0.21 ± 0.05 cm/year in the Sea of Azov) were approximately 2.5 times less than in 1993–2012. The reason for this decrease in levels (on average) in the last 10–15 years was apparently a decrease in the incoming part of the freshwater balance of both seas, which is indirectly confirmed by the observed increase in salinity of their waters.

The Hydrological Urban Heat Island: Determinants of Acute and Chronic Heat Stress in Urban Streams

AbstractDuring and after rainfall events, the interaction of precipitation with hot urban pavements leads to hot runoff, and its merger with urban streams can result in an abrupt change in water temperature that can harm aquatic ecosystems. To understand this phenomenon and its relation to land cover and hydrometeorological parameters, we analyzed data spanning two years from 100 sites in the eastern United States. To identify surges, we first isolated temperature jumps of at least 0.5°C over 15 min occurring simultaneously with water flow increase. Surge magnitude was defined as the difference between peak stream temperature and baseflow temperature right before the jump. At least 10 surges were observed in 53 of the studied streams, with some surges exceeding 10°C. Our results demonstrate that the watershed developed area and vegetation fraction are the best descriptors of surge frequency (Spearman correlation of 0.76 and 0.77, respectively). On the other hand, for surge magnitude and peak temperature, the primary drivers are stream discharge and stream temperature immediately before the surge. In general, the more urbanized streams were found to be already warmer than their more “vegetated” counterparts during baseflow conditions, and were also the most affected by temperature surges. Together, these findings suggest the existence of a hydrological urban heat island, here defined as the increase in stream temperature (chronic and/or acute), caused by increased urbanization.

Quantifying the actual sediment load flux into Lake Baikal: A case study of the main tributary – The Selenga River (Russia)

The significant reduction of sediment load flux into Lake Baikal from its main tributary – the Selenga River began in the mid-1970s, and can be explained by climate change and socio-economic activities. Integrated analysis was done of changes in hydro-meteorological parameters (water discharge, sediment load, air temperature, and precipitation) and their tendencies over periods of 1946–1975 (baseline) and 1976–2017 (warming). Changes in natural processes and human activity were negligible during the baseline period. In the warming period, against the background of an increase in temperature, the water discharge had a slight decreasing trend (−13%) whereas the sediment load has significantly decreased (−53%) these are consist with the precipitation change (−9.4%). Analysis of hydro-climatic data using statistical methods showed that in the warming period the greatest reduction in river sediment runoff occurred in the interval 1996–2017. In this period the sediment load was 768 × 103 t/yr, which is less than the average value during the warming period – 1048 × 103 t/yr. Considering sedimentation in the Selenga River delta, the actual sediment load flux from the Selenga River into Lake Baikal amounted to 515 × 103 t/yr, which is three times less than the average multiyear value 1535 × 103 t/yr for observation period (1946–2017).

National research & education network of meteorological monitoring in V. I. Vernadsky Crimean Federal University

The article describes the experience in organizing work of the meteorological monitoring network across the Republic of Crimea based on the best available technologies. V.I. Vernadsky Crimean Federal University applied approaches of the meteorological monitoring network for scientific and educational purposes. According to the studies, technical requirements, methodological approaches in organizing meteorological measurements and educational and practical base for students training and retraining were formed. The monitoring system allows collecting detailed meteorological data in the ground layer and studying the local formation features of hydrometeorological parameters across various natural climatic zones and landscapes in Crimea. The article also provides methodological requirements and results on creating system for collecting, storing and processing information on a personal server by organizing a thematic geoportal and visualizing data using web gis. According to the research results, we received appropriate patents, created an educational platform and a competence centre for training and re-training staff in subject-matter and related specialties in the Crimea in order to form knowledge, skills and abilities in the field of regional meteorological monitoring.

Exploring the Factors Affecting Streamflow Conditions in the Han River Basin from a Regional Perspective

Considerable attention has recently been focused on the impacts of climate change and human activities on river streamflow conditions. This study explored these effects using three hydrological modeling techniques such as multi-regression, a two-parameter hydrological model, and hydrological sensitivity analysis, followed by trend analysis and change point detection. The non-parametric Mann-Kendall test was used to analyze the trends in hydro-meteorological parameters. The non-parametric Pettitt test and double cumulative curve techniques were used to identify change points in annual streamflow series during 1978–2014. After determining the change point year to be 1997, the series were split into two parts: a pre-change (natural) period (1978–1997) and a post-change (human-induced) period (1998–2014). The hydrological models were calibrated and estimated for the pre-change (natural) period, which provided the relative change in annual streamflow for the post-change (human-induced) period. The contribution of climate variability ranged from 36.3% to 55.9%, and human activities accounted for 44.5% to 63.7% of streamflow variability. These results suggest that human activities are more impactful than climate variability. The outcomes of this study show that streamflow in the basin was influenced by climate variability, but human actions were also major driving forces in altering the streamflow.

The structure of currents and water exchange in the overgrowing shallows

The morphometric characteristics and bottom topography of typical shallows behind the island are characterized. The long – term and seasonal dynamics of the water level in the Rybinsk reservoir during the period from 1947 to 2020 is considered. The periods of fluctuations of the main hydrometeorological parameters in relation to the investigated section of the reservoir are shown. Based on archival and modern observation data on the structure of currents, the patterns of water transport and water exchange in the shallows are investigated, taking its seasonal overgrowth with macrophytes into account.

Development of an information and analytical system for presenting data on the refractive properties of the environment

The article proposes a variant of constructing an information and analytical system that makes it possible to control the refractive properties of the environment (atmosphere) based on the actual values of its parameters, as well as to determine the numerical values of the refractive index of the atmosphere. Its operation is based on a method that makes it possible to detect errors during measurements by optical systems in a real atmosphere. The main feature of the method under consideration is the comparison of the refractive indices in a real and ideal atmosphere. The difference in the corresponding values of the refractive index of the atmosphere makes it possible to correct the results obtained during measurements by optical systems. This article describes the operation of the software algorithm, which allows not only measuring and evaluating based on information on hydrometeorological parameters and refractive properties of the surface layer of the atmosphere, but also visualizing the results of measurements carried out by optical systems. Experimental studies carried out confirm the high adequacy of the models underlying the described complex.

Forecasting Abrupt Depletion of Dissolved Oxygen in Urban Streams Using Discontinuously Measured Hourly Time‐Series Data

AbstractDepletion of dissolved oxygen (DO) is a major cause of fish kills in urban streams. Although forecasting short‐term DO concentrations in streams prior to hypoxic events is necessary, such efforts have been rarely made. In this study, 24‐h forecasting models were developed for DO concentrations in three urban streams of South Korea. To forecast the DO concentrations at the outlet sites, which coincide with fish kill hot spot areas, water quality parameters at the lower reaches and hydrometeorological parameters were used as input variables. The monitoring data were measured hourly between 2017 and 2018 and divided into training and test sets at a ratio of 8:2. Tenfold cross validation was performed for hyperparameter optimization. Due to the dynamic characteristics of DO concentrations and the discontinuity in time‐series data, a long short‐term memory (LSTM) neural network modeling approach was selected. Overall, a high degree of accuracy was recorded for all study streams. Although hypoxic events were forecast with lower accuracy, the timing and magnitude of abrupt DO depletion were well captured. Water temperature and DO concentrations at the lower reaches and 24‐h cumulative precipitation were important variables for forecasting DO concentrations at all stream outlets. In particular, the importance of cumulative precipitation across all streams indicated that the effects of nonpoint sources were critical in depleting DO in urban streams. Monitoring of both lower reaches and outlets in conjunction with a variable importance analysis enhanced interpretability of the LSTM model outputs. This study improves our understanding of precursors of hypoxic events in urban streams.

Suspended sediment dynamics and associated hydro-meteorological interrelations in east rathong glacier, eastern himalaya, india

The records of suspended sediments and associated hydro-meteorology of the glacierized catchments are very limited in Sikkim Himalaya. Therefore, we carried out the first-ever estimate of suspended sediment transport from the meltwater stream of East Rathong Glacier for June-September during three consecutive melt seasons (2013–2015). These records were used to estimate the suspended sediment concentration (SSC), load (SSL), yield (SSY) and erosion rate (ER). The daily mean SSC was 105.75, 84.20, and 91.51 mg/l during melt seasons of 2013–2015 respectively. The monthly mean SSC of the combined melt season of 2013–2015 was 92.72, 107.14, 105.93 and 60.46 mg/l for June-September, respectively. The observation shows that July-August contributed to maximum SSC, accounting 70.45% of total SSC. Similarly, the monthly mean SSL for June-September was 55.64, 69.61, 65.75 and 25.72 tons, respectively. We observed high variability in SSL (CV = 0.54) than SSC (CV = 0.38) since the estimation of SSL depends on both discharge (Q) and SSC. The relationship between monthly mean SSC and Q was highly significant (R2 = 0.98) than daily SSC and Q (R2 = 0.25) due to reduced variability on a monthly scale. Further, mean SSY in the catchment was high during peak melting season (July-August), which substantially reduced during the end of the melting season. We estimated the mean SSY of 281.93 ton/yr km2 during the combined melt season (2013–2015). The average ER for the East Rathong Glacier basin was 1.04 mm/yr, which is lower than the ER of most of the Himalayan glaciers. We observed significant meteorological control of Tmean, Tmax and Rainfall in the transportation of suspended sediments from meltwater stream at a monthly scale. These in-situ based records on dynamics of suspended sediment and associated hydro-meteorological parameters are relevant for the planning and management of freshwater resources and planning for hydropower projects under a changing climate.

The 2016 flood of Bihar, India: an analysis of its causes

Flood is common in the sub-Himalayan plains of the Indian state of Bihar. During the massive flood of the Ganga between 18 and 31 August 2016, 15 (out of 38) districts and 3459 villages of the state were affected. The flood inundated 6006 km2 of area, harmed 8.82 million people, and caused damages worth US$ 73.99 million. To investigate the factors behind the event, we utilised SRTM elevation data and Landsat-8 OLI images to extract drainage networks and reservoirs of the region. Inundated area was delineated using MNDWI on MODIS data of 25-Aug-2016. Different hydrometeorological parameters employed in the study include percentage departure of monthly rainfall, discharge data of selected dams and barrages, and gauge data from six stations along a 526 km stretch of the Ganga: Buxar, Gandhi Ghat (Patna), Hathidah, Munger, Kahalgaon, and Manikchak Ghat. It was found that the flood was mainly caused by rapid release of water from the Bansagar Dam on the Son from 18 to 20-Aug-2016, as a tropical storm traversed through its upper catchment. Contributions from the Ganga’s Himalayan tributaries and upstream of the flooded area were negligible. The flood peak (50.52 m), recorded at Gandhi Ghat on 21 August 2016, passed downstream, and reached Manikchak Ghat (25.78 m) on 27–28 August 2016. The upstream extension of flooding due to the highest recorded flood level of 26.66 m of the Ganga at Farakka can only reach up to 6 km above Kahalgaon. Therefore, impoundment of the Ganga by the Farakka Barrage cannot have any impact on inundation of the areas above that limit and did not cause the 2016 floods.

Prediction of Combined Terrestrial Evapotranspiration Index (CTEI) over Large River Basin Based on Machine Learning Approaches

Drought is a fundamental physical feature of the climate pattern worldwide. Over the past few decades, a natural disaster has accelerated its occurrence, which has significantly impacted agricultural systems, economies, environments, water resources, and supplies. Therefore, it is essential to develop new techniques that enable comprehensive determination and observations of droughts over large areas with satisfactory spatial and temporal resolution. This study modeled a new drought index called the Combined Terrestrial Evapotranspiration Index (CTEI), developed in the Ganga river basin. For this, five Machine Learning (ML) techniques, derived from artificial intelligence theories, were applied: the Support Vector Machine (SVM) algorithm, decision trees, Matern 5/2 Gaussian process regression, boosted trees, and bagged trees. These techniques were driven by twelve different models generated from input combinations of satellite data and hydrometeorological parameters. The results indicated that the eighth model performed best and was superior among all the models, with the SVM algorithm resulting in an R2 value of 0.82 and the lowest errors in terms of the Root Mean Squared Error (RMSE) (0.33) and Mean Absolute Error (MAE) (0.20), followed by the Matern 5/2 Gaussian model with an R2 value of 0.75 and RMSE and MAE of 0.39 and 0.21 mm/day, respectively. Moreover, among all the five methods, the SVM and Matern 5/2 Gaussian methods were the best-performing ML algorithms in our study of CTEI predictions for the Ganga basin.

Assessing Available Water Content of Sandy Soils to Support Drought Monitoring and Agricultural Water Management

In the future, according to regional climate-model simulations, the Carpathian Basin (in Central Europe) is predicted to be exposed to intensifying weather extremes that will exert a growing pressure on water resources. In recent past decades, water already has become a significant limiting factor for the natural environment and many agro-economic sectors in the southern Carpathian Basin. Therefore, there are increasing attempts to develop monitoring systems to detect water stress. In this study, changes in soil moisture conditions were monitored within two Arenosol profiles of extreme water balance during years characterised by different hydrologic conditions and under the impact of irrigation in the Great Hungarian Plain. Hourly data series of hydrometeorological parameters and soil moisture from six different soil depths during 2014–2018 were provided by on-site monitoring stations; humus, carbonate content, porosity, field capacity and wilting point were measured in the laboratory. On the basis of the newly definied so-called ‘available water percent’ (AW%) and a developed classification method, the rate, time and duration of water-shortage periods were evaluated for the years 2014–2018. The results show that drought monitoring cannot be effective without investigation of soil moisture content. Detailed analysis of available water percentage (AW%) can be used for real-time drought monitoring and as a precise indicator of the evolution of drought. This can help us prevent and manage damage from drought, and it is extremely important for agriculture.

Study on Relationship of Land Cover Changes and Ecohydrological Processes of the Tuul River Basin

The Tuul River Basin is the most important socioeconomic and political base area of Mongolia. Therefore, studying the interrelationships between changes in the ecohydrological processes of this basin and its land cover is of great importance for maintaining sustainability and the environment. This study investigated the annual average air temperature, total annual precipitation, and river discharge variability, and land cover changes at selected stations of the basin by using the hydrometeorological analysis, satellite analysis, and land cover determination statistical analysis. During the study period, the average annual air temperature rose from −1.5 °C to +0.3 °C (1.8 °C 361 °C). The average annual precipitation exhibits relatively low change during this period. River discharge varied during the study period. A significant decreasing trend in river discharge was observed at the Terelj (φ = −2.72) and Ulaanbaatar (φ = −5.63) stations, whereas the other stations, Altanbulag, Lun, and Orkhontuul, showed a significant increasing trend. During the study period, changes in land cover were directly related to main hydrometeorological parameters. Between 2000 and 2020, the amount of grassland decreased by 319.67 km2, while the area of water bodies increased by 28.36 km2. In the study area, mainly water bodies and sensitive areas of the land cover types were changed due to changes in precipitation. Studies in the arid and semiarid regions of Central Asia show that changes of ecohydrological processes have a significant impact on land cover changes.

Multidecadal variability of the hydrometeorological parameters in the Caspian sea

NCEP/NCAR reanalysis data for the period of 1948–2017 were used to study the multidecadal variability of the hydrometeorological parameters (thermal, dynamic and humidity) in the Caspian Sea region. Polynomial approximations of the time series of the annual mean values indicated the non-linear nature and periodicity of the long-term variability of considered parameters. Three temporal intervals of duration 10–25 years with multidirectional trends of parameters changes are detected, which is considered as a manifestation of multidecadal variability. The North-Eastern wind regime prevails over the sea basin, with the major portion of heat advection into the region provided by zonal (Eastern) transport. Phases of air warming/cooling coincide with a weakening/strengthening of the Eastern wind transport. The time lag between the shift of dynamic and thermal (as well as humidity) regimes is about 6–8 years suggesting a leading role of the large-scale atmospheric forcing variations in the regional variability of thermal and humidity parameters. Specific humidity is positively correlated with air temperature and decreases/increases during periods of cooling/warming. In contrast, relative humidity and precipitation rate variations are negatively correlated with air temperature trends. Intensification of Eastern transport and associated cooling over the Caspian Sea coincide with a situation when the North Atlantic Oscillation (NAO) index decreases to negative values, and the East Atlantic-West Russian pattern (EAWR) index is significantly positive. On the contrary, weakening of the Eastern transport and warming occur during a period of sharp strengthening of the NAO, coinciding with strongly negative values of the EAWR index.

Actual inflow of riverine sediment load into Lake Baikal: main tributaries the Selenga, Upper Angara, and Barguzin Rivers (Russia)

Abstract. The sediment load delivery into Lake Baikal from its main tributaries the Selenga, Upper Angara, and Barguzin Rivers has been reduced since the mid-1970s. This is explained by climate change and socioeconomic activities. Integrated analysis of changes in hydro-meteorological parameters (water discharge, sediment load, air temperature, precipitation) and their trends over the period 1946 1975 (baseline) and 1976 2017 (warming) is performed. Changes in natural processes and human activity were negligible during the baseline period. During the warming period, the greatest reduction of the sediment load inflow against the background of temperature rise and precipitation decrease occurred in the interval between 1996 and 2017 in the Selenga River, between 1985 and 2017 in the Upper Angara River, and between 1992 and 2017 in the Barguzin River. The flux of the sediment load into these rivers was 768 103, 88 103, and 29 103 t y 1, respectively. This is 2 3 times less than the average multiyear values for all period of 1946 2017, which are usually used when characterizing sediment load runoff from these rivers. Currently the values in the given intervals correspond to the actual sediment load flux into Lake Baikal from the main tributaries.

МОДЕЛЬ НОРМИРОВАНИЯ ВОДОПОТРЕБЛЕНИЯ И РАСЧЕТА ЭКСПЛУАТАЦИОННОГО РЕЖИМА ОРОШЕНИЯ СЕЛЬСКОХОЗЯЙСТВЕННЫХ КУЛЬТУР

Purpose: development of a current model of water consumption rationing and calculation of the corresponding rates and terms for agricultural crops irrigation under various hydrometeorological parameters. Materials and methods: the basis for the developed model is a series of field experiments conducted in 2012–2014, as well as analytical studies, the scheme of the experiment, soil and hydrometeorological characteristics, water balance dynamics, precipitation and total moisture supply of the irrigated massif, water consumption according to the development stages of summer planting potatoes were determined. Results and discussion: the model under consideration includes taking into account the water-physical properties of soil, the lowest moisture capacity and moisture reserves, setting critical limit for the irrigation regime, temperature and air humidity deficit, the duration of the growing and inter-irrigation periods, on the basis of which the water consumption of the selected crop is calculated according to the growth phase. Further, the irrigation regime is calculated: the irrigation rate and the difference in moisture reserves, which comparison with the critical limit allows to conclude on irrigation necessity or its prediction for the near future (up to five days) after which irrigation will be needed. A complex for differentiating the irrigation regime with the determining deficits and standards for the parameters under consideration is provided. Conclusions: the model of water consumption rationing, performed on the use of two hydrometeorological factors, taken into account the growth and development phases of the crop under consideration, makes it possible to substantiate the actual calculation of the corresponding norms and terms of agricultural crops irrigation. The model is stable and can be used in land reclamation practice as a part of general technological complex for agricultural crops cultivation on irrigated lands.

Trend analysis of hydro meteorological parameters: A case study for Ramganga River Basin (India)

The watersheds in the mountainous basin are highly sensitive to climate change. So, any erratic change in long term climatic pattern may ultimately influence cropping pattern and streamflow. Thus, detection of trends and magnitude of the hydro-climatic variables (temperature, rainfall, relative humidity and streamflow) are of prime importance. In the present study, the trend analysis has been performed by using parametric (linear regression) and non-parametric (Mann-Kendall test and Sen's estimator of the slope) methods on a seasonal and annual basis for the Ramganga basin. Annual and monsoon rainfall is falling significantly (at 95% confidence interval) at Lansdowne station, at the rate of -23.81 mm/year and -19.33 mm/year respectively. Analysis of discharge in the Marchulla sub-watershed indicates that there is a falling trend in annual, monsoon, post-monsoon and winter season discharge data although it is not significant at 95% confidence level.

БАЙЕСОВСКАЯ ОЦЕНКА ТОЧКИ НАРУШЕНИЯ ОДНОРОДНОСТИ В ПОСЛЕДОВАТЕЛЬНОСТЯХ КОРРЕЛИРОВАННЫХ СЛУЧАЙНЫХ ВЕЛИЧИН ГИДРОМЕТЕОРОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК

The paper considers the method for determining the point of change (the disturbance of stationarity) in the time series of hydrometeorological parameters characterized by a sequential change in stationary states of a random process. The method is based on the Bayesian approach to obtaining the distribution of the change point, which is generalized for a case of correlated sequences with non-Gaussian marginal distribution laws.