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Take a photo of the river! Assessing the feasibility of using Google Street View images as source materials for assessing river hydromorphology
Chara-lakes with higher macrophyte diversity than vascular lakes: evidence from lacustrine ecosystems of the Pisz Forest
Richness of macrophyte functional groups in relation to hydromorphological and hydrochemical factors of organic rivers in the Biebrza National Park
Environmental Restoration and Changes of Sediment and Hydrodynamic Parameters in a Section of a Renaturalised Lowland Watercourse
In Europe, the routes of most watercourses were straightened and shortened, leading to the destruction and degradation of many natural environments. Currently, in places where it is possible, as part of the implementation of the Water Framework Directive, efforts are made to improve environmental sustainability, including improving the ecological condition of rivers. This paper presents the impact of three in-stream deflectors on changes in the section of a small lowland river—the Flinta (Poland)—where (from 2018 to 2023) detailed, systematic geodetic, and hydrometric research and an assessment of the ecological conditions were carried out. The presented results show the influence of deflectors on the initiation of fluvial processes in the transverse and longitudinal layouts of the channel. The river channel was narrowed from 6 to 5 m, and the current line shifted by almost 3 m. Changes were observed in the distribution of velocities and shear stresses, varying along the surveyed section of the river. In the first year after their application, an increase in velocity at the deflectors can be observed (from 0.2 m∙s−1 to 0.6 m∙s−1 in the deflector cross-section). In the following years, on the other hand, a clear decrease in velocity was observed in the sections between the deflectors (to 0.3 m∙s−1). The introduction of deflectors resulted in a significant increase in the values of shear stresses (from an average value of 0.0241 N∙m−2 in 2018 to 0.2761 N∙m−2 in 2023) and local roughness coefficients (from 0.045 s∙m−1/3 before the introduction of the deflectors to 0.070 s∙m−1/3 in 2023). Based on analyses of sediment samples, erosion and accumulation of bottom material were initially observed, followed by a subsequent stabilisation of particle size. Differences in grain size were observed, especially in the cross-section of the deflectors (increase in granularity d50% downstream of the deflector from 0.31 mm to 3.9 mm already 2 years after the introduction of deflectors). This study confirmed the positive impact of using deflectors on hydromorphological processes as deflectors facilitate the achievement of a good ecological status, as required by the WFD. The innovation of this paper lies in demonstrating the possibility of using small, simple structures to initiate and intensify fluvial processes, which may contribute to improving the ecological conditions of watercourses.
Diversification of macrophytes within aquatic nature-based solutions (NBS) developing under urban environmental conditions across European cities
Hydromorphologische Prozesse und ökologische Effekte nach dem Einbau von Weiden-Deflektoren am Beispiel des Tieflandflusses Flinta (Polen)
The Impact of Spontaneous and Induced Restoration on the Hydromorphological Conditions and Macrophytes, Example of Flinta River
Highly modified riverbeds are not able to spontaneously reproduce natural processes. The restoration of natural river systems is an important challenge to modern river engineering. Various procedures and solutions, both technical and non-technical, are applied in this process. This involves looking for simple solutions that are close to nature and that interfere with river ecosystems to a minimal extent. One of these solutions is deflectors, which constitute a type of simplified spur. This study presents the results of the research on the transformations of hydromorphology and macrophytes on selected sections of the Flinta River, which represents the most common type of river in the Central European Lowlands (a small river with a sandy substrate). Two neighbouring sections of the watercourse were selected. The first one has not been subject to any regulatory measures for over 30 years and is undergoing spontaneous restoration, while the second one was significantly altered (straightened, cleared of hydrophytes, and desilted) ten years ago. Three deflectors were introduced in this section in the years 2017–2018. Research conducted on both sections enabled the determination of the possibility of initiating renaturalisation processes by way of implementing simple solutions in the form of low-cost wooden deflectors. It also provided the basis for the assessment of the impact the measures taken had on the hydromorphological status of the watercourse and on macrophytes. Based on the studies conducted, it was possible to determine the size, dynamic, and scope of the changes taking place in the river under various conditions of its transformation, including those resulting from anthropopressure.
Fit for Purpose—Analyses of Macroinvertebrate Communities for Environmental Flow Assessment
ABSTRACTEnvironmental flow assessment is crucial for sustainable water management. In assessing environmental flows using the most common methods, for example, habitat suitability modelling (HSM), it is assumed that the distribution of aquatic organisms is driven by hydraulic features and substrate type of the habitats. However, most of the existing research does not consider analyses of organisms' ecological traits and their community structure. To bridge this gap, we present the results of analyses of macroinvertebrate communities carried out for environmental flow purposes. The study was performed at two reaches of the Flinta River, a European, lowland, temperate and perennial river, with different degrees of hydromorphological alterations. We state that more detailed analyses of organisms' community in environmental flow assessment are needed. Thus, we assess the dissimilarity of the organism community structure sampled during field campaigns by means of statistical tests, and we analyse macroinvertebrate ecological traits and indicators commonly used to evaluate river status. Afterwards, we discuss the applicability of the analyses and provide recommendations for the future environmental flow assessments.
Long-Term Changes in and Conservation Guidelines for Water Caltrop (Trapa natans L.) in Two Reservoirs in Poland
Climate change, worsening freshwater quality, and anthropogenic factors have caused water caltrop to lose approximately 80% of its habitat in Poland since the early 1980s. The presence of this plant species has substantially changed since the end of the 19th century. Our aim in this study was to examine the habitat and conservation status of Trapa natans in the Szumirad reservoir and Nowokuźnicki pond reserve in Poland and to indicate sources of potential hazards for the analyzed population. To achieve this aim, we spatially analyzed the changes in the total reservoir area, dynamics of species population, physico-chemical parameters of water, and climatic data. For the Szumirad reservoir, we observed substantial changes in water caltrop quantity and condition. For the Nowokuźnicki pond reserve, we found a serious threat to the Trapa habitat posed by the developing Nupharo–Nymphaeetum albae association, which is a strong competitor of nymphaeids. The obtained results indicated that surface waters localized in protected areas might play an important role in maintaining the population of water caltrop. On the basis of our analyses of selected populations, we emphasize that present protection procedures should be supplemented with the active protection of the species.