Numerous approaches to local scour forming studies have been developed. This paper presents different scientific approaches to the scour phenomenon using Lane’s relation [1] in its modified form during laboratory studies. The original Lane’s relation is applicable in dynamic balance conditions in alluvial rivers context, and it is not an equation, but a qualitative expression which cannot be directly used to estimate the influence of a change in one parameter on the magnitude of others. Lane's relation, despite its qualitative and simplified character, serves well to describe the nature of the process of forming alluvial stream channels, while modified relation allows transforming it into an equation for laboratory studies of local scour forming in prearranged clear-water equilibrium conditions and gives a new opportunity for this principle application.

Numerous approaches in sediment mobility studies highlighted the key meaning of channel roughness, which results not only from bed material granulation but also from various bed forms presence, caused by continuous sediment transport. Those forms are strictly connected with the intensity of particle transport, and they eventuate from bed shear stress. The present paper comprised of local scours geometric dimensions research in three variants of lengthwise development of laboratory flume in various hydraulic properties, both in “clear-water” and “live-bed” conditions of sediment movement. Lots of measurements of the bed conformation were executed using the LiDAR device, marked by a very precise three-dimensional shape description. The influence of the bed shear stress downstream model on scours hole dimensions of water structure was investigated as one of the key factors that impact the sediment transport intensity. A significant database of 39 experimental series, lasting averagely 8 h, was a foundation for delineating functional correlations between bed shear stress-and-critical shear stress ratio and geometry properties of local scours in various flume development cases. In the scope of mutual influence of bed shear stress and water depth, high correlation coefficients were attained, indicating very good and good functional correlations. Also, the influence of bed shear stress and the total length of the scour demonstrated a high correlation coefficient.

The efficiency and mechanism of orthophosphate—soluble reactive phosphorus (SRP)—inactivation in eutrophic lakes using controlled resuspension and calcite application into the sediment were investigated in this study. Two calcite materials, industrially produced precipitated calcium carbonate (PCC) and natural ground limestone (GCC), were tested in short-term batch experiments and long-term sediment incubations under oxic and anoxic conditions. Maximum SRP adsorption capacity calculated using Langmuir model for PCC (3.11 mg PO₄³⁻ g⁻¹) was 6 times higher than of GCC (0.43 mg PO₄³⁻ g⁻¹), reflecting substantial difference in the surface area of calcite materials (12.36 and 1.72 m² g⁻¹, respectively). PCC applied into the sediment during controlled resuspension reduced SRP release by 95% (oxic) and 78% (anoxic incubation) at medium dose (0.75 kg m⁻²) and suppressed it completely at high dose (1.5 kg m⁻²) for at least 3 months, irrespectively of incubation conditions. The maximum achieved reduction of SRP release using GCC was also meaningful: 78% under oxic and 56% under anoxic conditions, but this required very high doses of this material (6 kg m⁻²). Mechanisms of SRP inactivation by calcites were: (1) adsorption of SRP during application into the resuspended sediment and (2) precipitation of calcium-phosphate compounds (Ca-PO₄) during subsequent incubation, which was reflected in a substantial increase in the HCl-P fraction (phosphorus extractable in 0.5 M HCl) in sediments enriched with calcite, irrespectively of oxygen presence. However, anoxia strongly promoted the formation of this fraction: the rise of HCl-P was 2–6 times higher in anoxic than in oxic conditions, depending on the dose and form of calcite applied. The results showed that SRP inactivation using the controlled resuspension method is only successful if highly efficient reactive materials are used, due to large amount of SRP being released from sediment during resuspension. Thus, calcite materials exhibiting high adsorption capacity should be used in this lakes’ restoration technology to ensure fast and sufficient SRP inactivation. The rise in the HCl-P fraction in sediment suggests SRP inactivation through precipitation of relatively stable Ca-PO₄ minerals, which makes calcite a suitable agent for sustainable, long term SRP inactivation. As anoxic conditions promoted formation of these compounds, calcite seems to be a promising SRP inactivation agent in highly reductive sediments.

Analysis of the connections between hydromorphological conditions and biocenotic diversity on the example of the Zwoleńka River. The paper presents the evaluation of ecological status of two hydromorphologically diverse stream reaches of the Zwoleńka River. The studied sections of 500 m length are localized in a natural river-bed (Siekierka) and river-bed transformed due to a regulation (Zwoleń). The hydromorphological assessment of the stream has been performed by means of River Habitat Survey method (RHS). Level of habitat transformation has been determined with a help of numerical indices of the method: HMS and HQA; their naturalness has been also evaluated. Biotic conditions have been evaluated on a base of macrophyte river assessment and benthos macroinvertebrates. Macroinvertebrates have been determined to the level of family and following water quality indices have been also calculated: BMWP-Pl, ASPT, and EPT%. Value of BMWP-Pl has revealed that waters within the natural section of the stream could be qualified to the II grade of quality, while those in transformed section – to III grade. Moreover, it has been found that EPT% indicator has been much higher in non transformed section. Evaluation of examined stream sections on a basis of Macrophyte Index for Rivers (MIR) has revealed that the numerical value of the indicator has been almost unaffected by the river-bed transformation degree. In both cases, examined fragments of the stream have been qualified as the II grade. In addition, physicochemical determinations of water have been carried out. However, no substantial differences of water quality, that could influence on biocenotic diversity of those habitats, between analyzed stream sections, have been recorded. Content of organic particles in sediments as well as granulation characteristics have been determined as well. Therefore, the present research has allowed to learn some relationships between abiotic and biotic elements of a small lowland river, which can be an initial point for further studies.

Using the River Habitat Survey method in forecasting effects of river restoration. Research presents usability of the River Habitat Survey (RHS) evaluation method in forecasting effects of the Zielawa River restoration, performed in selected section between 18 + 960 km and 19 + 460 km. The EU so-called Water Framework Directive signalizes necessity of achieving a good ecological status of European rivers in the immediate future. Accordingly, river restoration is the main tool for already technically regulated rivers’ quality upgrading. Present research contains a collation of four proposed restoration works variants and the ecological evaluation of chosen river reach before and after initiating restoration works in accordance to various variants, using the RHS method. The conclusion is fact, that in dependence of established variant it is possible to receive improvement of ecological class from present Class V to Class IV (variants 1 and 2) or Class III (variants 3 and 4)