Medium-sized Rivers Research Articles

Variations in the Suspended Sediment Concentration in Mountain-Type Rivers Flowing Into the Sea in the Past 60 years—Taking Nanliu River in Beibu Gulf as an Example

Suspended sediment in the water body of rivers flowing into the sea is of great significance to the accumulation process in river basins and change pattern of landforms. In particular, small and medium rivers entering the sea in mountainous areas exhibit the characteristics of both mountains and streams, and the suspended sediment concentration (SSC) greatly contributes to the formation and evolution of deltas. However, scholars rarely give attention to the factors influencing changes in the SSC in small- and medium-sized mountainous rivers, and few studies have examined SSC changes in small- and medium-sized mountainous rivers. Here, based on daily SSC and flow data obtained at the Bobai Station and Changle Station, the percentile method and regression analysis method are employed to analyse the changes in SSC from the Nanliu River to the Beibu Gulf and possible influencing factors. The main research results indicate that 1) the SSC in river water bodies from 1965 to 2020 generally reveals a downwards trend, with significant annual variations. Specifically, the overall trend can be divided into three stages: 1) the SSC is the highest from 1965 to 1971, and the mean yearly SSC reaches 0.25 kg/m3; 2) the SSC is relatively high from 1972 to 2006, and the mean yearly SSC reaches 0.16 kg/m3; and 3) the SSC is the lowest from 2007 to 2020, and the mean yearly SSC reaches 0.11 kg/m3 2) High values of the SSC are mainly concentrated in the flood season, and low SSC values mostly occur in the dry season. The monthly average SSC in the flood season from April to September and the dry season from October to March exhibits the characteristics of a decrease in the flood season and an increase in the dry season. Moreover, the peak SSC value in the watershed obviously occurs out of sync with the peak flow value. Generally, the former precedes the latter. 3) The curve of the flow rate-sediment ratio is an irregular clockwise rhombus. Moreover, the impact of tropical cyclones, land cover changes, regional GDP per capita, and engineering construction are crucial reasons for the observed variations in the SSC in the Nanliu River Basin. In this paper, the obtained research results provide an important guiding significance for the planning and management of water and sediment resources in the Nanliu River and offer a reference for hydrological planning of other river basins discharging into the sea.

Ecological niche differentiation on the example of bottom communities of the Middle and Lower Volga regions

The authors discuss the use of the Greenell concept of ecological niches to analyze the taxonomic structure of communities and their relationship with environmental factors. The modeling of ecological niches was carried out using the results of 30-year studies of macrozoobenthos’ communities on 90 small and 12 medium-sized plain rivers in the region of the Kuibyshev, Saratov and Volgograd reservoirs. Geoclimatic indicators, relief characteristics and hydrochemical assessments of water quality at sampling points were considered as abiotic factors, where 11 variables with the least collinearity were taken. The multidimensional space of the initial abiotic factors was projected onto the orthogonal axes of the first two principal components; there were constructed ordination diagrams with plotted points of presence of species. The model of the potential ecological niche of each species was represented as an area in the space of latent variables, in which the habitat suitability index Z, estimated by the probability density of occurrence, corresponds to the given constraints. The authors used the Schoener and Hellinger indices to quantify the proportion of overlapping niches belonging to two different benthos taxa. The matrix of distances between overlapping niches was formed for all possible paired combinations of 40 most ecologically significant macrozoobenthos species. The cluster analysis of the obtained distance matrix was carried out by the methods of hierarchical agglomeration and fuzzy k-means. In the general multidimensional space of abiotic variables of the studied region, 4 areas of collective niches for groups of species with maximum distances between their centroids were identified. The analysis of intergroup variation of environmental factors is given and the characteristic features of each group are discussed: ecological strategy, biological characteristics and tolerance level.

The analysis of spatial distribution of artificial reservoirs as anthropogenic fragmentation elements of rivers in the Dnipropetrovsk Region, Ukraine

The purpose of the research is to summarise quantitative characteristics and to analyse the spatial distribution of artificial water bodies as anthropogenic fragmentation elements of medium and small rivers within the Dnipropetrovsk Region, Ukraine. The paper uses current data pertaining to existing reservoirs and mineralisation of water in rivers. Comparison included quantitative characteristics, water surface area, and the volume water in ponds and reservoirs. It has been established that although the total ratio was 97% for ponds to 3% for reservoirs, whereas their water surface area 48%, and the volume of water stored only 23% of the total resources. The paper shows the inexpediency and low efficiency of using ponds as water reservoirs feeding small rivers. Increasing the number of ponds in the river basin has a negative impact on the quality of water resources, in particular, by increasing water mineralisation – total dissolved solids ( TDS). Depending on the river, the following indicator of river basin fragmentation has been determined: 6–20 reservoirs per 100 km2 of the river catchment area, and on average 18–36 ponds and reservoirs are built for every 100 km of the river in relation to the length of the hydrographic network. It has shown the regularity of growing water mineralisation due to the fragmentation of rivers by a large number of artificial reservoirs. A strong correlation between regulation and fragmentation of river basins has been established (coefficient of determination R 2 ranges from 0.72 to 0.91). It proves the possibility to estimate the degree of change (increase) of water mineralisation based on the water flow coefficient K w and the river fragmentation coefficient K s fr in the Dnipropetrovsk Region. The paper offers ways of further research for planning and implementation of a water management strategy concerning ecologically safe levels of water use in small and medium-sized river basins.

Optimizing Berth-quay Crane Allocation considering Economic Factors Using Chaotic Quantum SSA

ABSTRACT With the regular development of the global epidemic, the global port shipping supply is tight. The problem of port congestion, soaring freight rates, and hard-to-find container space has emerged. This paper proposes a new joint berth-quay crane allocation model, namely E-B&QC, by taking the minimum of the time in the port of the ship, the cost of extra transportation distance for collector trucks in the land area of the port, and the cost of extra waiting time for ships. Then, the deficiencies of the sparrow search algorithm (SSA) are considered in solving the E-B&QC model, and the SSA is improved based on the three-dimensional Cat chaos mapping and quantum computing theory. Chaotic Quantum Sparrow Search Algorithm (CQSSA) is proposed, population individual coding rules are formulated, also E-B&QC model solving algorithm is established. Finally, a new berth-crane allocation optimization method, namely, E-B&QC-CQSSA, is proposed. Subsequently, the feasibility and superiority of the proposed allocation model and solution algorithm are tested according to the actual data of a small river port in the south and a medium-sized river port in the north. Simulation examples show that the E-B&QC model can develop different high-quality solutions for container ports under different working conditions, and the more complex the actual situation of the port, the more significant the optimization effect. The proposed CQSSA for E-B&QC model can obtain a better solution.

Inundation analysis of Xiuzhen River based on one-dimensional hydrodynamic model

In order to deal with the mountain flood disaster for small and medium-sized rivers and reduce the loss of life and property caused by mountain flood to the people, it is necessary to calculate the flood inundation risk of the region along the river. In this paper, taking Xiuzhen River in Lanshan District of Rizhao City as an example, an one-dimensional hydrodynamic model was established and D8 algorithm was coupled to simulate flood inundation in the target area, and the submerged depth, flood amount and submerged area under different frequency of flood were analyzed. The results show that the method can calculate flood inundation risk and scope quickly and accurately. It provides flood and drought disaster risk information and scientific decision-making basis for the sustainable development of social economy.

Water Level Prediction of Small and Medium-Sized Rivers Using Artificial Neural Networks

Typhoons and rainy seasons are typically a frequent occurrence in Korea’s summer climate (June to August); however, the frequency of local heavy rains has increased in recent years owing to climate change. These heavy rains are characterized by substantial rainfall within a short period of time, causing flash flooding. This in turn causes the water level of small and medium-sized rivers with a narrow river channel to increase rapidly, resulting in considerable damage. The rainfall-runoff model is a physical model that is used to predict the river level of most large rivers according to rainfall events, and damage is consequently minimized through flood forecasting and warning. However, data construction on small and medium-sized rivers is insufficient compared to that on large rivers, thereby leading to difficulties in accurate flood forecasting and warning through physical models. This study, therefore, attempts to predict the river level of small and medium-sized rivers using minimal information provided by the Ministry of Environment and artificial neural networks.

Urban Land-Use Type Influences Summertime Water Quality in Small- and Medium-Sized Urban Rivers: A Case Study in Shanghai, China

(1) Background: Small- and medium-sized rivers in urban areas are unique environments that serve as blue-green corridors for urban residents. The relationship between land-use types and water quality in these rivers provides important information for effectively addressing urban river restoration and pollution management. However, not much attention has been paid on these small- and medium-sized rivers, especially in large urban agglomerations with dense river networks. (2) Methods: This study undertook a field investigation on 130 sampling small- and medium-sized rivers during the late summer and applied data-driven water quality index and landscape analysis techniques to evaluate the direct impacts of riparian land-use types on the summertime water quality in Shanghai’s small- and medium-sized rivers. Riparian land-use types were derived from OpenStreetMap (OSM) datasets, including industrial, commercial, residential, and green spaces. (3) Results: Residential and green space are located closer to these sampled rivers than industrial and commercial land types, suggesting a tentative link between anthropogenic activities and water quality. Further analysis concluded that urban resident settlements, characterized by specific land-use types, DMSP-OLS nighttime lights, OSM road density, and OSM river density, strongly affected the water quality at the sub-catchment scale. We further determined the critical radii for impacts of land use types on urban rivers. Industrial types may influence water quality within a maximum radius of 5 km, followed by green space (4 km), residential areas (3 km), and commercial developments (2 km). These mathematically and statistically computed radii provide updated visions for river health assessment. For a specific land-use type, the assessed water quality index will be biased by using an assessment area with a radius higher or lower than the above-estimated radii. The study also quantified the spatial extent and transmission efficiency of non-point source pollution in a super built-up area of central Shanghai. We observed that contaminants transported by river pathways can reach a larger area than those transported by roads. (4) Conclusions: The high-quality environments in small- and medium-sized rivers are tightly linked to riparian landscape patterns. It is therefore urgent to control domestic pollutions as part of the restoration of megacity’s urban rivers and grapple with the complex challenges of risks to water supply. This study elaborates the importance of integrating land-use planning and water-quality management to maintain the functions and services of small- and medium-sized urban rivers.

Ecological Analysis and Biodiversity of the Helminth Community of the Pool Frog Pelophylax lessonae (Amphibia: Anura) from Floodplain and Forest Water Bodies

This work presents an ecological analysis of the community and biodiversity of helminths of Pelophylax lessonae (Camerano, 1882) from floodplain and forest reservoirs of the European part of Russia. The material for the work was personal collections of helminths made from 2018–2021 in the National Park “Smolny” (Republic of Mordovia). Two hundred and thirty-five amphibian specimens were examined from nine reservoirs and three types of hydrobiocoenoses: (1) floodplains of a medium-sized river (in terms of catchment area); (2) floodplains of a small river; (3) a number of isolated forest reservoirs. Twenty-four species of helminths have been registered: Trematoda (20) and Chromadorea (4). Similar features (common species of trematodes and nematodes) were determined as well as differences in the composition and structure of the helminth fauna, the level of infestation by individual species and groups of helminths, diversity, and community structure. Amphibians of the river floodplain have a richer helminth fauna, they are more infected with a large number of helminths, and their community is more complex. Amphibians of isolated forest ponds, on the contrary, have fewer helminths, they are generally less infected, and their community is simplified (reduced). Having intermediate indicators of composition, structure, and degree of infestation, frogs from the forest floodplain of the small river—differ in the most diverse and maximally evenness community of helminths. The results of the study demonstrate the influence of biotopic factors on the formation of an amphibian helminth community.

Using multisource remote sensing data to predict the maximum flood extent in poorly gauged basins

For small- or medium-sized river basins that suffer from floods, the lack of river gauging data is an important reason why flood warning at the appropriate time is difficult for local stakeholders. As a valuable dataset observed from spaceborne or airborne platforms, remote sensing images can capture slices of time-series information to cover the whole river basin. We consider the Nilwara Ganga tributaries in southern Sri Lanka for our research. The maximum flood extents and the corresponding elevations of flooded areas were determined in the post-flood Sentinel-1 images. Relying only on commonly available remote sensing datasets, the rainfall-triggered flood inundation models were proposed to simulate the maximum inundation extent of a potential flood. The results show that the models proposed here can be well applied in the determination of peak stage, especially for the non-tributary river reach (root mean square error = 0.59, R-square = 0.76). The average of Intersection over Union (IoU) accuracy of the maximum flood extent predictions was 0.75. Validations of two flood events had the IoU accuracy of 0.79 and 0.69, respectively. For gauging data-scarce areas, this approach has great potential to provide a different perspective for flood early warning and will benefit the subsequent risk assessment and disaster mitigation.

Differential Response of Nutrients to Seasonal Hydrological Changes and a Rain Event in a Subtropical Watershed, Southeast China

A large amount of terrestrial nutrients are discharged into the ocean through rivers. However, the impact of seasonal hydrological variations on riverine nutrient concentrations and fluxes remains unclear, especially in the medium-sized subtropical rivers that are highly influenced by human activities. In this study, we investigated the monthly changes in nutrient concentrations (soluble reactive phosphorus, SRP; dissolved silicate, DSi; and dissolved inorganic nitrogen, DIN) in the North Stream (NS) and West Stream (WS) of the Jiulong River (JLR). The results show that the concentrations of SRP and DSi in the NS and the WS displayed a similar seasonal variability, which was different from the pattern of DIN. Hydrological conditions, chemical fertilizer loss and biogeochemical processes are responsible for the seasonal changes in the nutrients in the two streams, especially during extreme rain events. Nutrient concentrations in the NS exhibited a clockwise trajectory along with river discharge during rain events, while a reverse pattern in the WS was observed since it experienced a moderately long rain event. Different rainfall features between the two main tributaries resulted in the majority of nutrients being exported at the start of the rain event in the NS and the end of rain event in the WS. Indeed, the annual high flow (Q/Qm > 3) accounts for ~17.3% of the annual nutrient flux in the JLR even though this period spans only ~4.0% of a year, which suggests the importance of rain events on nutrient export in these subtropical rivers. Although the annual fluxes of DIN and SRP in the JLR were smaller than many rivers worldwide, higher areal yields of DIN and SRP were observed, indicating that the JLR is highly influenced by human activities. Our study systematically evaluated the response of nutrient concentrations to hydrological changes in two tributaries of the JLR, which is useful in better understanding the nutrient dynamics in medium-sized subtropical rivers.

Application of the TOPKAPI Model in Flood Forecasting of the Upstream of the Zhenjiang River in China

The lumped hydrological model and empirical model have the problems of low accuracy and short forecasting period in real-time flood forecasting of small- and medium-sized rivers in a mountainous watershed. The sharing of underlying surface data such as high-resolution DEM, land use data, soil data, and the popularization and application of the Internet of Things, big data, cloud computing, and intelligent calculation methods makes distributed hydrological model an effective method for real-time runoff simulation and prediction. The topographic, kinematic, approximation, and integration (TOPKAPI) model is a distributed hydrological model whose physical mechanism developed gradually in the late 20th century. It has great advantages in real-time flood forecasting in small- and medium-sized watersheds. Based on the data required by the TOPKAPI model, in this study, 26 selected flood events were simulated from 2000 to 2013 at the outlet section of the upper reach of the Zhenjiang River in Guangdong Province, and the effect of application of the model in flood forecasting of small- and medium-sized rivers was evaluated. The results show that the pass rate (considering the peak discharge as the evaluation item) of 18 flood events in the calibration period was 66.67%, and that of 8 flood events in the validation period was 75%, while the mean Nash efficiency coefficient of the selected 26 flood events was 0.789. According to the simulation results, real-time flood forecasting should be closely combined with the dispatching of the small- and medium-sized reservoirs in the basin. The application of the TOPKAPI model can make a scientific and rapid analysis of the flood control situation in the whole basin and provide accurate information and maximum convenience for flood forecasting consultation and decision making. Additionally, it can improve the efficiency of disaster prevention and mitigation work in small- and medium-sized river basins, and has a major significance in enhancing the modernization level of flood forecasting.

Assessment of GRACE/GRACE Follow-On Terrestrial Water Storage Estimates Using an Improved Forward Modeling Method: A Case Study in Africa

Leakage errors derived from spatial filters are the major limitation for estimating terrestrial water storage via the Gravity Recovery and Climate Experiment (GRACE) mission and the recently launched GRACE Follow-On mission. Here we develop an improved forward modeling method and assess its performance of reducing leakage errors over Africa. In noise-free condition, the forward modeling method shows its outperformance in restoring signals, and the improved forward modeling method can further reduce the leakage errors along the coastline of Africa. In noise-contaminated condition, the simulated environment is set as real as possible to GRACE mission and GRACE Follow-On mission. The results based on the simulated GRACE and GRACE Follow-On solutions demonstrate the capacity of improved forward modeling method in reducing leakage errors. In the case of simulated GRACE data, the average improvements of 24 basins over Africa are respectively 37% for annual amplitudes and 36% for trends. When compared with these simulated GRACE data, the improvements via simulated GRACE Follow-On solutions are minor over large and medium size river basins, but they are significant over small size river basins. In the case of simulated GRACE Follow-On solutions, the average improvements over Africa are 39% for annual amplitudes and 41% for trends. Eventually, the improved forward modeling method is used to process GRACE spherical harmonic datasets from the Center for Space Research (CSR). The results present better agreement with those derived from the newly released mascon solutions from Jet Propulsion Laboratory (JPL) and CSR, when compared with those derived from CSR Tellus grids with scale factors. The better consistency between these model-independent approaches indicates the good performance of our improved forward modeling method and the further necessity of careful evaluation of model-dependent approaches when using different prior hydrological models. Overall, experiments based on noise-free observations, noise-contaminated observations, and GRACE datasets indicate that improved forward modeling method is capable of restoring temporal signals.

Использование плоских сплоточных единиц на первоначальном сплаве лесоматериалов

The prohibition of drift floating used in the initial timber rafting led to an increase in the cost of supplying timber to consumers. Nowadays, the technology for rafting operations on small and medium-sized rivers is developing in two directions. The first is the use of bunches (micro-bundles) in initial timber rafting which, after rafting along the rivers with limiting rafting dimensions, are joined together to form, for example, a two-tiered bunch of rafting units. The second is the use of flat rafting units in initial timber rafting. In order to implement modern flat rafting units in initial timber rafting, an in-depth substantiation of the economic advantages of these rafting units compared to micro-bundles is required. The article proposes to carry out the assessment by using an inequality. At one end the inequality expresses the costs for rafting of flat rafting units with their subsequent joining into larger timber transportation units, drift floating of flat rafting units, forming rafts from them, towing these rafts, purchasing machines and equipment to organize rafting, and expenses for hauling the timber, which remain from the wood harvested during the year due to the close of navigation and limitation of rafting volume by insufficient carrying capacity, by overland transport. At the other end the inequality expresses similar parameters for micro-bundle rafting. Analytical dependencies setting up the above-mentioned parameters are found. The costs for timber hauling by overland transport considered in the method indicate that due to inefficient use of the carrying capacity of the rafting stroke the volume of timber rafting on a given section of the rafting route decreases. Consequently, there is a need to deliver the remaining timber to floating depots by land transport. The implementation of flat rafting units in initial timber rafting should provide higher carrying capacity of a rafting route compared to micro-bundles by reducing the draft and hence the volume of timber delivered to the floating depots by expensive overland transport. For citation: Vasiliev V.V., Afonichev D.N. The Use of Flat Rafting Units during the Initial Timber Rafting. Lesnoy Zhurnal [Russian Forestry Journal], 2022, no. 1, pp. 128–142. DOI: 10.37482/0536-1036-2022-1-128-142

Correlation Study and Regression Analysis of Water Quality of Chhoiya River (a tributary of river Ganga) in Bijnor District (UP, India)

Physical and chemical parameters are monitored and used for assessment of water quality for three seasons namely rainy, winter, and summer of a medium-sized river “Chhoiya” in Bijnor District of Uttar Pradesh(India) so that it can be ascertained that the quality of water is fit for public consumption, recreation, irrigation and other purposes. The parameters are pH, electrical conductivity, total dissolved solids, total alkalinity, total hardness, total suspended solids, Nitrate, Sulphate, Dissolved oxygen, BOD, COD, and turbidity. There is a relationship between these parameters that shows that one parameter actually causes change in another parameter. We have used the statistical regression analysis method of three observation stations in all three seasons. A systematic correlation and regression study shows the significant linear relationship among different pairs of water quality parameters. The purpose of the present study is to establish a regression equation between two parameters, which can be used to predict the value of one parameter if the value of the other is known. This helps to find a tool that can be used to assess the value of physicochemical parameters and the extent of pollution theoretically, which is time-saving and cost- effective. This study was done from July 2017 to June 2018 on river Chhoiya to assess the quality of water and its suitability for various purposes.

Новая методика расчета теплового стока рек при отсутствии данных наблюдений

In the paper, a comparative analysis of previously developed methods for calculating the heat flux of rivers in the absence of gauging-station data are given, and a new method for such calculations is proposed. It is based on the Maps of specific annual heat flux of zonal rivers and empirical dependencies of heat flux on the average height of the catchment area. An example of such a map is the “Map of specific annual heat flux (MT, 109× kJ/km2) of rivers in the northeast of the Asian part of Russia” plotted on the data for the period from 1950/1955 to 2018 and on the basis of data from 112 gauging stations. General recommendations for calculating the annual heat flux of medium-sized rivers that do not have posts, the intra-annual distribution of heat flux, the values of heat flux at the mouths of large rivers are set out in the paper. The values of heat flux calculated for the marine mouths of region large rivers and the sections of seacoasts between these mouths are given as an example of the implementation of the new recommendations. The list of new materials that help calculations includes new maps of average monthly water temperatures (May-October), the dependence of water temperature and heat flux on the average height of the catchment area, the division of the territory of the Northeast Asian part of Russia into 10 altitude-thermal zones, the relationship between heat flux and water runoff, the catchment area of the river and other materials. In total, data from 34 weather stations, 231 posts with water temperatures and 145 posts with water discharges were used in the research.

Using fish community and population indicators to assess the biological condition of streams and rivers of the Chesapeake Bay watershed, USA

The development of indicators to assess relative freshwater condition is critical for management and conservation. Predictive modeling can enhance the utility of indicators by providing estimates of condition for unsurveyed locations.Such approaches grant understanding of where “good” and “poor” conditions occur and provide insight into landscape contexts supporting such conditions. However, as assessments are conducted at large extents crossing jurisdictional boundaries, combined datasets are likely not suited for traditional assessment approaches which rely on jurisdictionally-specific reference sites. Here, we used a large dataset compiled from multiple providers to assess the condition of fish habitat for non-tidal streams and rivers in the Chesapeake Bay watershed(CBW), USA. We concurrently used community and species-level analyses to provide a more holistic view of habitat conditions by using random forestmodelsto predictselectedmetricsand species occurrence with landscape data forinland CBW stream reaches.Community analyses included metrics describing composition, tolerances, habitat preferences, and functional traits of fish communities whereas species-level analyses consisted of distribution models for key sensitive and gamefish species. For community analyses, a final index was calculated as the average ofselectedmetric decileswith higher scores inferringless biologically altered (i.e., better) conditions, providing an alternative to using reference sites.For species analyses, species occurrence was predictedforstream reaches, with presence indicating suitable habitat. Uncertainty was calculated for both approaches using model prediction intervals.Results indicated different numbers of suitable metrics for each region,with most in the Northern Appalachian (15) and least in the Southern Appalachian Piedmont (3). Four species(three sensitive)were suitable for modeling.At the CBW scale, predictionsdid not varygreatlyamong decilesfor the community or species analyses for 2001, 2006, 2011, and 2016. Most stream reaches did not vary in mean decile rank or in species occurrence between 2001 and 2016; however, the largest community changes occurred in large rivers in the Coastal Plainsecoregion and the largest species occurrence changes occurred in Torrent Suckers in medium-sized rivers. When compared, results from community analyses agreed for onesensitivespecies (Brook Trout) but notthe other three, potentially due to regionally inappropriate tolerance assignment. Comparisons also demonstrated substantial variation among approaches suggesting a lack of redundancy. While each approach traditionally has its targeted audience and respective strengths and weaknesses, concurrent use of these approaches permits direct comparisons and may assuage shortcomings of each approach when considered separately.

Study of the role of natural and anthropogenic factors in the formation of water quality in small rivers on the example of the Veletma river in the Nizhny Novgorod region

Small rivers of Central Russia often experience a high anthropogenic pressure, and at the same time their study and measures taken to preserve them are incomparably more modest than for large rivers. On the example of the Veletma river in the Nizhny Novgorod region, the factors affecting the formation of the water quality of the small river are considered. The ecological and geographical characteristics of the Veletma river are given. It is shown that the current methodology for assessing the water quality of large rivers by the Specific Combinatorial Water Pollution Index does not allow to determine what is the contribution of anthropogenic pressure to the deterioration of water quality, and what is the contribution of natural factors. Studies of a number of physical and chemical characteristics of the waters of the Veletma river have shown that on a short section of the river, which is less than 400 m, there are significant changes in the physical and chemical composition of water, reaching 45-95%. Such significant changes are associated on the one hand with the influence of the treatment facilities of the city of Navashino, and on the other hand, with the special location of the lake Zelenoe in the path of the river. Satellite images of the Veletma's confluence with the lake Zelenoe show the plume. It is suggested that the lake is characterized by the same processes that take place in the confluence of large and medium-sized rivers into the seas and lakes, called marginal filter, in which not only suspended but also dissolved impurities are retained. This fact is confirmed by laboratory studies.

Spatiotemporal variations of surface water quality in a medium-sized river catchment (Northwestern Germany) with agricultural and urban land use over a five-year period with extremely dry summers

Medium-sized rivers, which are used for intensive agriculture and urban infrastructure, are subject to manifold hydrochemical stressors. Identifying and monitoring these stressors is important for river basin management and a functioning ecosystem. To understand the spatiotemporal variation of surface water quality in a highly modified lowland river, the Münstersche Aa River (Northwestern Germany) with 62% of land used for agriculture and 26% urban/residential area, was exemplarily studied. A total of 519 samples were collected using two automated high-frequency samplers and five catchment-wide sampling campaigns. They covered the five-year period 2015–2020 and included two extremely dry summers. The Münstersche Aa catchment is dominated by low permeable strata resulting in surface water runoff (Baseflow Index: 0.41) which leads to a high amplitude of discharge variation (mean discharge: 0.7 m3/s) with high flow conditions in winter/spring, and low discharge during summer/fall. In wintertime, maximum nitrate concentrations (up to 73 mg NO3/L) and loads (up to 1300 t NO3/a; up to 98% in winter) correlate with high-flow conditions. δ18O and δ15N isotopic analysis indicated manure from farmland as the major source of nitrate whereas the impact of municipal wastewater treatment plants was neglectable. Increased nitrate concentrations are linked to the higher proportion of farmland in the upper catchment (77%) compared with the lower catchment (47%). In summertime, at extremely low flow conditions, surface water consisted of up to 100% of treated wastewater, resulting in the highest measured chloride, sodium and potassium concentrations. The river is impacted by strongly seasonal and different stressors, which can be expected to intensify with ongoing climate change. Results from this study may help to adapt monitoring schemes for the Münstersche Aa but also for other lowland streams with comparable land-use targeting the goals of the Water Framework Directive.

Analysis of Treatment Design of Small and Medium-sized River Engineering

Analysis of Treatment Design of Small and Medium-sized River Engineering

ANALYSIS OF THE DISTRIBUTION AND STRUCTURE OF DIURNAL LEPIDOPTERA (LEPIDOPTERA: HESPERIOIDEA, PAPILIONOIDEA) RANGES IN UDMURTIA

The article analyzes the zonal landscape distribution and the structure of the diurnal lepidoptera ranges on the territory of the Udmurt Republic. The zonal indicators of the dynamics of the species richness of lepidoptera in the region have the following form: the southern taiga - 100 species, the subtaiga as a whole-122 species, including the northern band of the subtaiga-107 species, the southern band of the subtaiga-119 species. The zonal trend is based on the significant participation of the regional fauna of the regional representatives. The general indicators of the numerical participation of structural and arealographic groups in the fauna are as follows: 46 species are located within the generalized part of the area in the region; 22 species are located near the periphery of the area; 42 species are located on the border of the area; 13 species are located on the periphery of the area. The main share of lepidoptera located in the marginal parts of their ranges is made up of southern subboreal (steppe and non-morale) and subboreal-subtropical representatives (72 species). The proportion of such species among the northern geographical groups - the Hypo-Arctic and boreal (16 species) is significantly lower. The most important biochorological units that determine the conditions for the distribution and localization of bulavous are uplands, forest landscapes on the sands, as well as the valleys of large and medium-sized rivers in the southern part of the region.