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 hours, 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.

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)

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.

The EU Water Framework Directive demands maintaining or attaining good quality of the water bodies within the territory of the member states, which is strictly connected with the planning process of the water resources management. The water management plans have to include the assessment of the water body quality condition and further propose the actions to be implemented to enhance the quality of the European water resources. In order to answer the question of whether there is a risk of failure to achieve the WFD objectives, an assessment of the current status should be carried out, followed by an estimate on how likely achieving a good water status in the future is. One of the most popular valorization methods used for the water quality assessment is the River Habitat Survey (RHS) that enables the determination of two indicators, which summarize many single basic parameters, to assess the hydromorphological properties of rivers in a numerical form. Two indices are used most widely: Habitat Modification Score (HMS), which defines the range of transformations in river morphology and Habitat Quality Assessment (HQA), which is based on the presence and diversity of natural elements of the stream and river valley. The application of the above mentioned numerical indices allows calculating the hydromorphological quality status of the studied section following the expectations of the Water Framework Directive. Five ecological classes are distinguished. RHS is described as objective, suitable for statistical analyses, multidirectional and applicative method. However, the final valorization results are strongly affected by the presence of vegetation, which varies during the whole year. This contribution describes the analysis and comparison of the RHS results over the four seasons, namely: spring, summer, autumn and winter of three small lowland rivers in Poland (Zielawa, Zwoleńka and Zagożdżonka). It was unequivocally found that the value of the HQA parameter varied during the seasons, and the changes in its numerical value mainly depended on the condition, development level of vegetation, and the number of species observed. It was demonstrated that depending on the season, the Habitat Quality Assessment variation could change in about 5% of the maximal value, which could lead to a step from one hydromorphological class to another.

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