Book of Abstracts. XLII International School of Hydraulics: FRESHWATER SYSTEM HEALTH: A HYDRAULIC PERSPECTIVE. Radocza, Poland, 20–23 May 2025

Abstract:

The 42nd International School of Hydraulics, titled “Freshwater System Health: A Hydraulic Perspective”, held on May 20–23, 2025, in Radocza near Kraków, continued a series of events focused on broadly understood hydraulics. The conference covered the fundamentals of hydraulics in the context of understanding and managing the health of rivers, lakes, and other aquatic ecosystems. It highlighted new and challenging topics in both applied and basic research. ISH2025 aimed to foster a fruitful exchange of knowledge, ideas, and experiences in various fields of hydro-environment research. It also served as a platform for intellectual growth, collaboration, and innovation, helping to build new connections and strengthen existing ones. ISH2025 sought not only to provide answers and explore new ideas, but also to offer a global forum for scholars, decision-makers, and enterprises sharing a common interest in the field.

Abstract:

The present study takes advantage of Google Earth Engine and the JRC Yearly Water Classification History dataset to depict temporal changes in permanent water conditions (i.e., river channel always covered by water) along the reach of the Vistula River from Dęblin to Włocławek.

Abstract:

This conference paper describes numerical simulations of water flow in the Vistula Lagoon using the HEC-RAS 2D (version 6.6) hydrodynamic model. The model was validated by comparing its results with previous simulations and field measurements conducted by the Polish Institute of Meteorology and Water Management (IMGW-PIB). Preliminary findings on the impact of climate change are also discussed, highlighting how an increase in wind speed over the lagoon may elevate water levels in the Żuławy Elbląskie region and subsequently heighten flood hazard from the Vistula Lagoon waters.

Abstract:

Soil erosion is causing major concerns across the world, as the loss of soil jeopardises not only environmental sustainability, but also land productivity, eventually leading to reduced resources for populations that heavily rely on land. However, how runoff drives soil erosion and the impact of different land coverages on this is not yet well understood, also because of the lack of data acquired in controlled conditions. To fill this gap, experiments were performed in the Yan Gou runoff observation site (China) by controlling runoff volume, sediment transport, soil loss, and soil water content in five square plots, each with an area of 100 m2, covered by different vegetation and having different topography. The results presented here focus only on plots covered by citrus but have different slopes, to decouple the effects of vegetation coverage and soil topography. Assuming a constant hydrological forcing (i.e., fixed precipitation), it was observed that plots with down-slop ridge drive a larger runoff, as expected, which implies that more sediments are mobilized causing higher soil loss. At the same time, this loss of soil influences the content of water differently, which changes more significantly in the horizontal plot than in the inclined one. Comparing all plots, it was noticed that standard terraces are the most effective method to conserve soil, reducing the runoff and keeping the content of water more constant over time.

Abstract:

The increasing frequency of extreme weather events, driven by climate change, poses significant challenges to hydraulic structures such as earth dams. These structures are increasingly exposed to sudden inflows of large water volumes, which can exceed their discharge capacities. When overtopping occurs, the resulting erosion of the earth dam can lead to catastrophic releases of retained water, endangering downstream areas. In Poland, two such disasters have taken place in recent years: in 2010 in Niedów and in 2024 in Stronie Śląskie. These events emphasize the critical need for advanced computational tools to model erosion processes and enhance the safety of areas located downstream. This study presents the application of a one-dimensional numerical model based on the physics of erosion phenomena. The simulation results were validated through experimental studies conducted at Wrocław University of Science and Technology, where physical models of earth embankment erosion were tested. The comparative analysis demonstrates the robustness of numerical approaches in a predicting erosion dynamics. The findings underscore the vital role of integrating numerical simulations and laboratory experiments to improve the predictive capabilities of dam safety assessments in the context of a changing climate.

Abstract:

Spatial distribution of riparian vegetation is a critical factor altering flow hydrodynamics and transport processes in rivers. Distribution of riparian vegetation in the form of distinct patches is typical for riverbanks and floodplains, but scarcely investigated from the viewpoint of its hydraulic impacts. The present study aims to investigate reconfiguration of the riparian vegetation patches in relation to the mean flow conditions.  Experiments were conducted over a range of mean flow velocities (0.1 to 0.6 m/s) and under low relative submergences (h/h_d ≈ 1 and 2). The results showed a substantial increase in the patch reconfiguration and flow resistance with the increase in velocities. The extent of these phenomena depends on the patch density and shape.

Abstract:

Resistance to flow governs flow and sediment transport capacities in rivers and streams and is a critical factor in hydraulic and environmental engineering applications, including projects dealing with flood management, stream restoration and re-naturalization, establishment of environmental flows to sustain aquatic ecosystems, and mitigation of climate change. Flow resistance arises from factors such as bed granular roughness, bed forms, and channel bends.

Abstract:

Thermal powerplants for energy production often pump water from a colder source (e.g. river or lake) into their refrigeration circuit to later release it in a form of a jet or plume into the aquatic environment. Since the released water is at a higher temperature than the surrounding environment, it will contribute to its warming, thus potentially causing environmental damage like the increase of algae and eutrophication.

Abstract:

In this contribution, two 3D numerical models are tested using laboratory records to properly calibrate and validate these models. 1D numerical techniques are also used for this purpose. Mesh sensitivity analyses, different roughness coefficients, and Acoustic Doppler Velocimetry (ADV) records were applied to increase the reliability of the 3D model results. Thanks to these analyses, the output of the models can be used for design purposes to properly assign the geometry of leaky barriers in real world cases to enhance flood resilience above all in urban areas.

Abstract:

Hydropower plants restrict or completely block fish downstream migrations, which play a critical role throughout their life cycles. Recent experimental and field studies indicate that there is a need for efficient finer bar rack screens to protect multiple fish species, including the small-bodied ones, at water intakes with minimum head loss.

Abstract:

In this contribution, the authors developed a hydrological model based on the SCS-CN curve methodology and GIS (Geographic Information Systems) to estimate flood hydrographs in the upper parts of the Biała Lądecka River basin.

Abstract:

Many studies on the hydrodynamics and mixing processes due to vegetation have significantly simplified the physical characteristics of plants by representing the stem distribution, e.g. for reeds, as an array of cylinders. These studies often use single diameter cylinders, placed in regular arrays, producing unrealistic preferential flow paths. New solute tracing studies (Machibya 2024) were performed using realistic plant forms, with leaves, stems and branches. Experiments were conducted in a 12.5 m long, 300 mm wide flume and longitudinal dispersion coefficients (Dx) were determined over a range of discharges. The results confirm the linear relationship between Dx and the mean velocity, u observed in cylinder arrays. The longitudinal dispersion coefficients for the realistic plant forms were found to be an order of magnitude greater than those from studies conducted using cylinders. This illustrates and quantifies the effect of plant structure on solute mixing processes.

Abstract:

In Leonardo Da Vinci’s body of work, its genius is also expressed in his water flows drawings. In Da Vinci drawings, different fluid flow phenomena were illustrated e.g.: the impinging jet and the flow around obstacles. Aiming at obtaining more quantitative infor-mation about the drawings of Da Vinci an experimental setup was built at the Institute of Hydro-Engineering of the Polish Academy of Sciences to reproduce the impinging jet in a basin and measure it with modern measurement techniques such as imaging techniques with high-speed cameras.