Filters
Diversification of macrophytes within aquatic nature-based solutions (NBS) developing under urban environmental conditions across European cities
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.
Observed and estimated taxonomic diversity of different groups of aquatic organisms in the pristine rivers in the Biebrza National Park
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.