Small Watercourses Research Articles

Mapping the flood hazard potential of small watercourses in a mountain river basin

AbstractThis study presents a methodological approach for the mapping of the flood hazard potential of small watercourses, based on their hydromorphological attributes, on the example of a mountain river basin in Slovakia. The flood hazard of a watercourse is understood more comprehensively, providing a set of influencing variables and their attributes that affect the flood hazard. The proposed procedure consists of several steps ranging from the selection of stream variables influencing the flood hazard potential to the evaluation of the attributes of the variables in terms of their impacts on the flood hazard and the determination of a flood hazard index. The mapping divides the watercourse into reaches that differ by their level of flood hazard potential. This enables us to identify those river reaches that are critical in terms of flood hazard and that require management interventions. The results are interpreted in the context of cadastral areas through which the watercourses flow, which is particularly important for local authorities.

How do Different Types of River Maintenance Works Affect the Ichthyofauna of Small European Watercourses?

Abstract Watercourses serve the needs of agriculture in certain sections and are subject to strong anthropopressure. When agriculture prevails in the catchment, it often has abundant vegetation, macrophytes in particular, and the bottom is covered by a substantial layer of silt. In order to ensure patency of flow and access to water, small watercourses are very often subject to river maintenance works. The aim of the study was to assess the impact of 3 types of works on the diversity of fish species and density of fish in the 1 and 2 year after the works at 21 sites located on 8 rivers in the European Central Plains Ecoregion. As a result of the works, especially in the 1 year after the works, significant changes were found in hydrochemical and hydrological parameters, especially with the increase in velocity and mean depth in watercourses. Additionally, habitat change contributed to differences in the composition of the ichthyofaunal. After 1 year, the diversity of fish species and fish population density increased or remained unchanged after dredging and removal of plants from the river channel, but they decreased after the removal of macrophytes from river banks. After year 2, a decrease in the diversity of fish species and density was observed, associated with re-infestation and siltation of the watercourses. Particularly in the case of dredging and removal of macrophytes from the river bank, maintenance works should not be done too frequently, because some species of natural value disappear.

ENVIRONMENTAL, SOCIAL AND OTHER NON-PROFIT IMPACTS OF MOUNTAIN STREAMS USAGE AS RENEWABLE ENERGY RESOURCES

<p>The main subject of this manuscript is mountain streams used by construction of small hydro power plants. The motivation for this research stemmed from a number of conflicting opinions about the justification of the construction of small hydropower plants and their facilities. This research encompasses different methods for the analysis of the justification of the construction of a small hydropower plant, starting from tradition in correlation with water mills, through a techno-economic approach to a complex multi-criteria research model. All methods are represented by objective formulas.</p> <p>World experiences are also presented, through the level of potential utilization, compared to the degree of development. The possible positive and negative impacts of the construction of such facilities for the exploitation of the potential of small watercourses were analyzed. After the conducted research, and with respect to the principle of minimum energy, which has become the paradigm of modern civilization, it can be concluded that using the potential of small watercourses by building small hydropower plants belongs to the domain of using renewable energy sources and that it is a function of sustainable development.</p> <p>Decision makers are recommended to exclusively apply a multi-criteria methodology, which can holistically include all technical, economic, environmental, social and other non-profitable but important impacts.</p>

Past and present: changes in the Odonata fauna of small lowland watercourses.

Small lowland watercourses, strongly exposed to anthropogenic activities and climate change, have received negligible odonatological attention. This study provides a revised checklist of three typical lowland small watercourses (Kállai-főfolyás, Konyári-Kálló and Ölyvös) within the Pannonian Lowland and presents the changes in their diversity over the past decades. Results revealed a significant biodiversity loss, with a 31.6% decline in Odonata fauna over the last 53 years. The upper and middle sections degraded the most, where the habitats have dried out or become intermittent. However, a diverse Odonata assemblage (1,277 individuals of 27 species) was observed at the 14 sampling sites of the three watercourses, containing protected and sensitive species (Somatochloraflavomaculata, Orthetrumbrunneum, Aeshnaisoceles, Libellulafulva). However, the low abundance of larval and exuvial forms (59 individuals of 13 species) suggests that the majority of the observed adults were developed in other watercourses. While recolonisation from nearby habitats is still possible, a parallel degradation of adjecent waterbodies could lead to an irreversible biodiversity loss.

A holistic approach to the spatio-temporal variability investigation of the main river water quality – The importance of tributaries

The surface water pollution can cause serious ecological disasters. An example is large-scale fish deaths due to excessive salinity, which is global problem. In order to prevent such situations, it is necessary to carry out regular monitoring of both main rivers and their tributaries. The current monitoring system is neither adapted to the variability associated with the diversified use of catchments nor to changing climatic conditions. The Bzura River is one of the most anthropogenically transformed Polish rivers. So far, no comprehensive assessment of the chemical status of its catchment has been carried out. The presented research is a continuation of the study of the spatio-temporal variability of the Bzura chemistry. It covered 19 tributaries within the boundaries of the Łódź Voivodeship. Samples were collected once a month for one hydrological year. In total, 228 samples were obtained, in which 21 parameters were measured. Spatio-temporal variability of water quality on the basis of coefficients of variation (CVs) and water quality indices (WQIs) was evaluated. Principal component analysis (PCA) and cluster analysis (CA) were also performed. In addition, the datasets were visualized using geochemical maps. Combined monitoring with geospatial analysis brings benefits in terms of efficient control and management of water resources. The tributaries were divided according to the degree of their pollution. It was found that the electrical conductivity and concentrations of dissolved oxygen, nitrates, calcium and magnesium differentiated the tributaries in terms of pollution the most. The strong salinity from agricultural and geogenic sources was found. The WQIs were higher for the tributaries than for the Bzura. It suggests that the Bzura may be polluted by the tributaries under “favorable” climatic and hydrological conditions. Therefore, smaller watercourses should be included in monitoring and become more important in terms of an effective solution to global problem of surface water pollution.

Mapping Small Watercourses from DEMs with Deep Learning—Exploring the Causes of False Predictions

Vector datasets of small watercourses, such as rivulets, streams, and ditches, are important for many visualization and analysis use cases. Mapping small watercourses with traditional methods is laborious and costly. Convolutional neural networks (CNNs) are state-of-the-art computer vision methods that have been shown to be effective for extracting geospatial features, including small watercourses, from LiDAR point clouds, digital elevation models (DEMs), and aerial images. However, the cause of the false predictions by machine-learning models is often not thoroughly explored, and thus the impact of the results on the process of producing accurate datasets is not well understood. We digitized a highly accurate and complete dataset of small watercourses from a study area in Finland. We then developed a process based on a CNN that can be used to extract small watercourses from DEMs. We tested and validated the performance of the network with different input data layers, and their combinations to determine the best-performing layer. We analyzed the false predictions to gain an understanding of their nature. We also trained models where watercourses with high levels of uncertainty were removed from the training sets and compared the results to training models with all watercourses in the training set. The results show that the DEM was the best-performing layer and that combinations of layers provided worse results. Major causes of false predictions were shown to be boundary errors with an offset between the prediction and labeled data, as well as errors of omission by watercourses with high levels of uncertainty. Removing features with the highest level of uncertainty from the labeled dataset increased the overall f1-score but reduced the recall of the remaining features. Additional research is required to determine if the results remain similar to other CNN methods.

General patterns of beavers’ selective foraging: how to evaluate the effects of a re-emerging driver of vegetation change along Central European small watercourses

Along small watercourses, the growth and renewal of native willows and poplars (Salicaceae species) are hindered by the effects of past and recent man-made landscape alteration and climate change, while the selective foraging of the beaver (Castor fiber) is also becoming an increasingly important driver. Knowledge about foraging decisions can refine predictions about vegetational processes and help to develop better nature conservation and forest management strategies. We surveyed the woody plant supply (13,304 units) and its utilization by the beaver at 11 study sites along Central European small watercourses, at two fixed distances from the water. We collected information about the taxon, trunk diameter, and type of utilization (cutting, carving, debarking) of each unit. We built (generalized) linear mixed models aimed at answering questions regarding taxon and diameter preference, their interrelatedness, and their importance in foraging decisions. All of the factors examined had a significant effect on foraging decisions. Utilization was mostly explained by the taxon, with Salicaceae species being generally preferred and utilized in all diameter classes with a high ratio. Several further genera were frequently utilized (mainly Cornus and Ulmus), while others were almost completely avoided (including invasive Amorpha and Robinia). The beavers preferred units with a diameter of 5–9 cm. The type of utilization depended primarily on diameter class. Because native softwoods are the most affected by beaver impact, regardless of trunk diameter, their survival and regrowth should be consciously supported by increasing the water table and improving hydrological conditions.

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

The distribution of organic matter, hydrocarbons, phytopigments, and ecological-trophic groups of microorganisms was studied in the bottom sediments of ten small tributaries of the Amur R. near Khabarovsk. The water showed high concentrations of organic matter, varying from 44.47 to 279.3 mg/L. The concentration of Corg in bottom sediments varied from 1.9 to 23.1% in different types of sediments; the amount of hydrocarbons reached 5081 mg/kg, exceeding the background level by a factor of up to 50. Studies of the molecular composition of hydrocarbons in sediments revealed in some streams the predominance (up to 100% of the total) of light (C8–C13) n-alkanes, typical of oil products and the products of vegetation combustion. High-molecular compounds dominated in HC composition in most watercourses, including n-alkanes, genetically associated with terrestrial vegetation, and heavy fractions of oil products with various levels of microbial degradation. Volatile organic compounds were quantitatively dominated by the products of microbiological transformation (acetaldehyde and methanol). In terms of the concentration of sedimentary pigments (up to 400 µg/g), the sediments of the majority of watercourses belong to the hypereutrophic type. The total abundance of microorganisms in water varied from 2.7 to 488.0 thousand CFU/mL; in sediments, it was distributed symbatically, but ranged from 0.1 to 19.3 million CFU/g. The number of heterotrophic bacteria in bottom sediments correlated with the parameter of overload of the self-purification capacity (r = 0.718), and the number of oil-oxidizing bacteria correlated with hydrocarbon concentration (r = 0.967), thus confirming the indication properties of this bacterial group.

AMI-KMNP dataset: Occurrence records of aquatic macroinvertebrate species from a 10-year-long biodiversity survey in SE Hungary

We outline a 100% georeferenced dataset of aquatic macroinvertebrate occurrence records collected from the operational area of the Körös-Maros National Park Directorate (SE Hungary) between 2012 and 2021. The species-level dataset includes 25,935 records of 644 taxa from 625 localities of wide variety of freshwater habitats from soda pans to lowland marshes and small watercourses to medium-sized and larger rivers. Four non-biting midge species are reported for the first time from the Hungarian fauna. The dataset is available through the Global Biodiversity Information Facility (GBIF).

Processes of Natural Self-Cleaning of Small Watercourses with Increasing Anthropogenic Load in the Dniester River Basin

Processes of Natural Self-Cleaning of Small Watercourses with Increasing Anthropogenic Load in the Dniester River Basin

An Analysis of Hydromorphological Index for Rivers (HIR) Model Components, Based on a Hydromorphological Assessment of Watercourses in the Central European Plain

Assessing the hydromorphological conditions of watercourses is a requirement of the Water Framework Directive (WFD) and national river status monitors (e.g., in Poland,the State Environmental Monitoring, and Water Monitoring coordinated by Chief Inspectorate of Environmental Protection). This paper evaluates the hydromorphological status of 10 watercourses (30 measurement sections) in Poland based on the multimetric Hydromorphological Index for Rivers (HIR). A new approach to the delineation of the river valley (small watercourses) is proposed. An analysis of the influence of river valley management on the value of HIR and its components was carried out using statistical methods (basic statistics, Mann–Whitney U Test and Ward’s cluster analysis). In addition, the relationship between the components of the HDS (Hydromorphological Diversity Score) and HMS (Hydromorphological Modification Score) was analyzed (Spearman’s Rank Correlation Coefficient). HIR values for the watercourse sections ranged from 0.553 to 0.825. HDS values ranged from 27.5 to 75.5 and HMS from 2.0 to 17.5. The results of the basic statistical analyses showed slight differences between the two river valley delineation methods. The Mann–Whitney U Test showed a significant difference in the test significance level of the HDS, HMS and HIR for the river valley delineation methods. Spearman’s rank correlation analysis showed that most of the HDS and HMS parameters components had a low degree of correlation. The juxtaposition of the two methods for delineating a river valley and its influence on the HIR allows for a better understanding of the interdependence between its parameters.

Some Potentially Toxic Elements (Pb, Zn, As, Cd, Cu, Ni, and Cr) in Overbank Sediments of Smaller Water Courses from the Drina River Basin (Republic of Serbia)

Some Potentially Toxic Elements (Pb, Zn, As, Cd, Cu, Ni, and Cr) in Overbank Sediments of Smaller Water Courses from the Drina River Basin (Republic of Serbia)

Метод оценки теоретических характеристик малых осевых гидротурбин

Energy supply to remote areas remains a technical and social challenge. Construction of transmission lines to provide electricity to such areas is expensive and not always possible. One of the promising areas in this area is local energy generation based on local resources, in particular small watercourses, using small hydroelectric power plants. Small hydroelectric power plants are small hydropower facilities that use the energy of small watercourses to generate electricity. They have a number of advantages over traditional energy sources, such as environmental friendliness, low operating costs and high efficiency. However, the widespread introduction of small hydroelectric power plants is hampered by the lack of mass production of small hydraulic turbines and difficulties in designing low-power plants. Designing hydraulic turbines is a complex task that requires solving the inverse problem of hydrodynamics and finding the optimal shape of the flow path. To simplify the design of hydraulic turbines in the modern world, specialized software is used using various methods, including flow analysis, energy loss and blade shape optimization. This article based on an analysis of existing methods for designing and using a mathematical model of a hydraulic turbine with simplified blades, proposes a method for designing and analyzing the theoretical characteristics of the resulting hydraulic turbine. In conclusion, taking into account the use of the methodology for designing a hydraulic turbine for given parameters, its assessment is given, as well as ways to possibly improve the accuracy of the results obtained. Possible areas of application of the outlined design methodology are indicated.

Modern Dynamics of the Northern Dvina Delta: A Study by Multitemporal Space Images

The long-term dynamics of the Northern Dvina delta was studied with the comparison of space images of 1977 and 2020. A map of delta dynamics, compiled by them, shows that the islands at the delta coastline keep increasing and join to the delta, channel islands in the main branches are increasing, and small watercourses in delta islands become narrower and disappear. However, this long-term tendency of the continuing increase in delta area is now accompanied by the processes of shore erosion in islands at delta coastline from the side of the Dvina Bay.

Taming the torrent: changes in flood protection at the Gürbe River (Switzerland) from the nineteenth century until today

This paper analyses the flood protection history of the Gürbe River (Switzerland), a 29-km-long tributary of the Aare River. The upper reach of the river has the character of a mountain torrent and an exceptionally difficult flooding situation. For centuries, riparian communities were only able to take small protective measures. In the mid-nineteenth century, the flood protection strategy changed: between 1855 and 1881, the Gürbe River was channelised and stabilised by a torrent control system. Although the situation improved, flood damage could not be prevented as intended. Therefore, dozens of consecutive projects were implemented—without interruption until today. This paper examines why small watercourses are useful case studies, which protection measures were taken at the Gürbe River, how they corresponded to the prevailing flood protection philosophy, whether they were linked to floods and how flood protection influenced land use. The Gürbe regulation, its consecutive projects and the connected drainages had far-reaching effects: They allowed an intensive agricultural use of the valley floor, the construction of roads, a railway, and new settlements. Consequently, the social and economic pressure on the hazard area increased steadily over the decades. It created a vicious circle: the more that protective structures were built, the more important and profitable flood prevention became, and the more structures were raised. A reevaluation finally took place in the late twentieth century, based on increasing environmental awareness, and fostered by a catastrophic flood. However, the implementation of new projects proved to be difficult due to conflicting interests.

Bottom Sediments as an Indicator of the Geoecological State of Natural Water Currents

The parameters of the natural geochemical background of ecosystems of the Lunnoye deposit area were studied and the geoecological conditions of large and small watercourses of the Yukhukhta — Yukungra interfluve were assessed according to the state of the total pollution index of bottom sediments. 27 elements of the gross content were determined by the method of emission spectral analysis. The elements that determine the geochemical specificity of the territory were revealed: Bi, Li, Sn, Y, Be, Sc, K, Th, Cs and Ra. At the time of research, the state of the surface watercourses of the territory is assessed as moderately polluted. With further monitoring, special attention should be paid to the state of the river basin Yukhukhta and especially the dynamics of changes in the chemical composition of bottom sediments of the brook. Lunny and Mramorny. The elements K, Th, Cs, Ra, Be, Zn, Pb, As, Cr, and Ni are proposed as parameters for monitoring the geoecological state of bottom sediments.

Capacity of River Valleys to Retain Nutrients from Surface Runoff in Urban and Rural Areas (Southern Poland)

Studies on water quality are necessary, as catchments of small watercourses are exposed to anthropogenic influences associated with agricultural activities, settlement, transport and other undertakings, leading to water pollution. There has been insufficient research performed on the valley’s ability to retain nutrients during floods, contributing to water accumulation. The main object of the study was to identify the retention capacity of river valleys under various aspects of human urbanization. To represent soil water retention, the Soil Conservation Service Curve Number (SCS-CN) method was used. Spatiotemporal autoregressive models were exploited to investigate the relationship between pollutants in precipitation and surface water in rivers. In contrast, multivariate analysis was used to identify and reveal patterns of land use for specific chemical compounds in the headwaters. The canonical-correlation analysis (CCA) showed that Mg+2 and Ca+2 cations in rainwater and surface waters play the main roles in the geochemical cycle in urban and rural areas. In the urban catchment area, the strongest relations were found for NO3−, K+ and Na+. The average NO3− concentration in urban headwater was 8.3 mg·dm−3, the highest in the study area. The relationship between NO3− concentration in headwater and rainwater was found for all study catchments using spatial autoregression (SAR). High concentrations of SO42− in surface water have been identified in urban areas. Severe water erosion raises the risk of nutrient leaching in soils prone to surface runoff. As a consequence of low soil permeability and urbanization, retention capacity is significantly reduced in areas with low soil permeability. Land development plans should take spatial retention capacity into consideration. To ensure that large reservoirs can retain water in the face of climate change, riparian buffer zones (protective zones in valleys for small water bodies as well as Nature-based Solution) are important.

HYDROLOGICAL SERIES OF SMALL RIVERS IN THE SLAVSK DISTRICT OF THE KALININGRAD REGION

The article presents the results of hydrological calculations for small watercourses located in the Slavsk district of the Kaliningrad region. This territory is of considerable interest, as it contains the largest array of polder lands in the region. At certain periods, systematic observations of the hydrological characteristics of some water bodies were carried out on the studied territory: Zlaya river - Krasnoznamenskoye village, Osa river - Priozerye village, Nemoninka river - Timiryazevo village; currently there is only one hydrological post. In this work, taking into account the requirements of regulatory documents, the choice of analogous rivers is justified: for Zlaya river - Instruch river, for Osa and Nemoninka rivers - Zlaya River. According to the data of hydrological observations and the restored values, theoretical probability curves of average annual discharge of the studied rivers are constructed and the values of average annual discharge of various probability are determined. The data obtained can be used in the performance of engineering surveys, the development of measures aimed at the sustainable functioning of water management systems, the determination of ecological runoff.

Axial Flux Permanent Magnet Synchronous Generators for Pico Hydropower Application: A Parametrical Study

A pico hydropower plant is an energy harvesting system that allows energy production using the power of the water flowing in small watercourses, and in water distribution network. Axial Flow Flux Permanent Magnet Synchronous Generator (AFPMSG) are particularly suitable for this application, being efficient machines that achieve high power with small dimensions. This paper presents a parametrical study of several configurations and topologies of three-phase and single-phase AFPMSG, for pico hydropower application, to assess the most suitable dimensional characteristics for the most energy production using a safe voltage of 25 V. The AFPMSGs here considered has a simple single stator and rotor configuration, commercial-type permanent magnets, and concentric windings, to facilitate their cost-effective construction and the spread of their use also in developing countries. For each AFPMSG considered, the power output was calculated using 3-D modelling and Finite Element Analysis; besides, the different parameters and features that affect the power output were evaluated at different rotational speeds. The results achieving a power density up to 100 W/cm3, at 1000 rpm with energy produced to 1.7 kWh/day.