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Among the various types of polymeric materials, geosynthetics deserve special attention. A geosynthetic is a product made from synthetic polymers that is embedded in soils for various purposes. There are some basic functions of geosynthetics, namely, erosion control, filtration, drainage, separation, reinforcement, containment, barrier, and protection. Geosynthetics for erosion control are very effective in preventing or limiting soil loss by water erosion on slopes or river/channel banks. Where the current line runs through the undercut area of the slope, the curvature of the arch is increased. If this phenomenon is undesirable, the meander arch should be protected from erosion processes. The combination of geosynthetics provides the best resistance to erosion. In addition to external erosion, internal erosion of soils is also a negative phenomenon. Internal erosion refers to any process by which soil particles are eroded from within or beneath a water-retaining structure. Geosynthetics, particularly geotextiles, are used to prevent internal erosion of soils in contact with the filters. Therefore, the main objective of this review paper is to address the many ways in which geosynthetics are used for erosion control (internal and external). Many examples of hydrotechnical and civil engineering applications of geosynthetics will be presented. [ABSTRACT FROM AUTHOR]

The hydrotechnical construction, damming up the riverbed, creates two zones of hydraulic conditions, which affect the water discharge and sediment transport routes, as well as plant species composition, as a habitat answer to the hydraulic regime. This study examined the diversity of the vascular and rush plant species upstream and downstream of the weir. The Świder River, a small lowland river in Central Poland, was chosen as a study area. An examined river reach was located at 21 + 340 kilometers of the Świder River. Vegetation properties, plant species, and granulometric fraction composition were recognized at chosen cross-sections along the riverbed where specific hydraulic conditions could be met. The spatial distribution of vortices, smooth or rapid flow areas, and velocity pulsations influence the biotic environment, thereby affecting the species composition, quantity, and plant diversity. In the headwater zone, an environment more favorable to grain accumulation could be met, which was mixed with organic components in an agricultural catchment area. This phenomenon leads to creating favorable conditions for increased biodiversity. The present study demonstrated that small weirs could positively affect the composition of vascular and rush plants. [ABSTRACT FROM AUTHOR]

Changes in river channel morphological parameters are influenced by anthropogenic factors, such as climatic changes, river catchment management changes, and hydrotechnical development of rivers. To assess the intensity of individual pressures and the resulting changes in abiotic and biotic factors in the riverbed, water quality monitoring is conducted, including the assessment of the hydromorphological status. The assessment can be based on the River Habitat Survey (RHS) which is a synthetic method that includes the evaluation of habitat character and river quality based on their morphological structure. The input data, which characterise any river include physical features of hydrotechnical structures, bed granulation, occurrence of bedforms, visible morphodynamic phenomena, and a sediment transport pattern. The RHS method allows to determine two quantitative indices used to evaluate the hydromorphological status: Habitat Modification Score (HMS), which determines the extent of transformation in the morphology of a watercourse, and Habitat Quality Assessment (HQA), which is based on the presence and diversity of natural elements in a watercourse and river valley. The proposed method can be divided into three stages. The first assesses the river section hydromorphological indices, describing the degree of technical modification (HMS) and the ecological quality of the reach (HQA), using the RHS method. The second stage describes morphological changes resulting from the technical regulation and estimates indices for the regulated reach. Finally, we compare HQA and HMS indices before and after the regulation. This comparison is described by numerical indicators and related to reference values. [ABSTRACT FROM AUTHOR]

The bridge structure's development causes a riverbed cross-sections contraction. This influences the flow regime, being visible during catastrophic floods. Then the flow velocity increases and water piles up upstream the bridge, where headwater afflux could be observed. These changes depend on the watercourse geometry and the bridge cross-section properties, especially on the degree of flow contraction under the bridge. Hydraulic conditions under the bridge depend on flow velocity, dimensions, and shape of abutments, the granulometric composition of bedload, which can be quantitatively characterized by hydraulic resistance coefficients. The research subject of headwater afflux is equated with the recognition of morphodynamic processes occurring along the passage route. The headwater afflux could be estimated by empirical formulas and by the energy method using Bernoulli's law. Empirical methods are optimized by adopting various statistical criteria. This paper compares the headwater afflux values calculated using two existing empirical formulas, Rehbock and Yarnell, and compares them with the results of laboratory tests. Following the assumption that the free water surface is influenced by flow resistance, an attempt was made to include friction velocity in the empirical formulas. Based on the Authors' database, the coefficients used were optimized using bootstrap resampling in Monte Carlo simulation. The analyses demonstrated that the formula best describing the phenomenon of headwater afflux upstream the bridge is an empirical formula built based on the historical Yarnell formula, which includes friction velocity value. The optimized equation provides an average relative error of 12.9% in relation to laboratory observations. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum: Architectura is the property of Wydawnictwo SGGW and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum. Formatio Circumiectus is the property of Wydawnictwo Uniwersytetu Rolniczego im. Hugona Kollataja w Krakowie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Scientiarum Polonorum. Formatio Circumiectus is the property of Wydawnictwo Uniwersytetu Rolniczego im. Hugona Kollataja w Krakowie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]