[Experimental and numerical investigation of fluid-particle-interactions in water].

For the development of improved sediment transport models, the basic understanding of the interaction between the solid particle and the moving fluid (water) is important. In this article, current developments in the field of fluid-particle interaction are presented based on two research articles by Gold et al. (2023) and Worf et al.

[Movement of a fluvial particle under the influence of coherent structures].

In a fundamental study the influence of coherent structures on the incipient motion of single fluvial grain was experimentally investigated. To fully characterize coherent structures, the three-dimensional velocity field must be known with high temporal resolution. Using a tr-3D PTV system (tr = time-resolved, PTV = particle tracking velocimetry) this could be achieved.

Evaluation of re-depositing hydropower trapped sediments at large rivers to improve flood protection and aquatic habitats - Case study Danube/Austria.

Sedimentation in impoundments of run-of-river hydropower plants is an ongoing and progressing management issue for hydropower operators because of its consequences for e.g., the maintenance of flood protection and waterway parameters.

The coupled socio-ecohydrological evolution of river systems: Towards an integrative perspective of river systems in the 21st century.

River systems have undergone a massive transformation since the Anthropocene. The natural properties of river systems have been drastically altered and reshaped, limiting the use of management frameworks, their scientific knowledge base and their ability to provide adequate solutions for current problems and those of the future, such as climate change, biodiversity crisis and increased demands for water resources. To address these challenges, a socioecologically driven research agenda for river systems that complements current approaches is needed and proposed.

Rheoreaction impacts dispersal of fish larvae in restored rivers.

Connectivity of nurseries and spawning habitats for young of the year life stage is essential for successful recruitment of fish populations and therefore provides a key indicator for river restoration measures. Models for dispersal offer the potential to draw conclusions regarding restoration scenarios and to fill knowledge gaps about possible implications for fish populations. A newly developed rheoreaction-based correlated random walk model (RCRW), in combination with a three-dimensional numerical model and a non-steady-state particle tracing model, was applied for nase carp larvae () before and after a restoration project on the river Danube, Austria.

Modelling sediment fluxes in the Danube River Basin with SWAT.

Sediment management is of prior concern in the Danube Basin for provision of economic and environmental services. This study aimed at assessing current (1995-2009) sediment fluxes of the Danube Basin with SWAT model and identifying sediment budget knowledge gaps. After hydrologic calibration, hillslope gross erosion and sediment yields were broadly calibrated using ancillary data (measurements in plots and small catchments, and national and European erosion maps).

Evaluation of hydropeaking impacts on the food web in alpine streams based on modelling of fish- and macroinvertebrate habitats.

Hydropeaking as a result of peak-load electricity production has been identified as one of the most significant pressures in alpine streams. Scouring of macroinvertebrates leads to downstream transport of aquatic organisms (catastrophic drift). Additionally, invertebrates are affected by periodic drying of wetted area during the dewatering of gravel bars and exposed areas along the banks.

Challenges of river basin management: Current status of, and prospects for, the River Danube from a river engineering perspective.

In the Danube River Basin multiple pressures affect the river system as a consequence of river engineering works, altering both the river hydrodynamics and morphodynamics. The main objective of this paper is to identify the effects of hydropower development, flood protection and engineering works for navigation on the Danube and to examine specific impacts of these developments on sediment transport and river morphology. Whereas impoundments are characterised by deposition and an excess of sediment with remobilisation of fine sediments during severe floods, the remaining five free flowing sections of the Danube are experiencing river bed erosion of the order of several centimetres per year.

Current status and restoration options for floodplains along the Danube River.

Floodplains are key ecosystems of riverine landscapes and provide a multitude of ecosystem services. In most of the large river systems worldwide, a tremendous reduction of floodplain area has occurred in the last 100 years and this loss continues due to pressures such as land use change, river regulation, and dam construction. In the Danube River Basin, the extent of floodplains has been reduced by 68% compared to their pre-regulation area, with the highest losses occurring in the Upper Danube and the lowest in the Danube Delta.

Educating for action: Aligning skills with policies for sustainable development in the Danube river basin.

Sustainable river basin management depends on knowledge, skills and education. The DANCERS project set out to identify feasible options for achieving education for sustainable water management across the Danube river basin, and its integration with broader education and economic development. The study traced the historic, regulatory and educational landscape of water management in the basin, contrasting it with the complex political decision-making, data-heavy decision support, learning-centred collaboration, and information-based participation that are all inherent components of Integrated Water Resource Management (IWRM).

Modelling highly variable environmental factors to assess potential microbial respiration in complex floodplain landscapes.

The hydrological exchange conditions strongly determine the biogeochemical dynamics in river systems. More specifically, the connectivity of surface waters between main channels and floodplains is directly controlling the delivery of organic matter and nutrients into the floodplains, where biogeochemical processes recycle them with high rates of activity. Hence, an in-depth understanding of the connectivity patterns between main channel and floodplains is important for the modelling of potential gas emissions in floodplain landscapes.

Morphodynamic effects on the habitat of juvenile cyprinids (Chondrostoma nasus) in a restored Austrian lowland river.

At the Sulm River, an Austrian lowland river, an ecologically orientated flood protection project was carried out from 1998-2000. Habitat modeling over a subsequent 3-year monitoring program (2001-2003) helped assess the effects of river bed embankment and of initiating a new meander by constructing a side channel and allowing self-developing side erosion. Hydrodynamic and physical habitat models were combined with fish-ecological methods.