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Accurate assessment of bedload transport is a challenging task due to its variable nature in space and time. Bedload transport measurement techniques can be divided into two categories of direct and indirect methods. The focus of this study is on dune tracking as an indirect measurement method that has received much attention in recent years. However, a comprehensive workflow that allows the integration of this method into a routine measurement operation instead of or jointly with the direct sampling method has not been implemented yet. During a three-day measurement campaign conducted in the Rhine River, a detailed workflow for performing bedload transport measurements using the dune tracking method was introduced. Dune tracking validation was thoroughly evaluated, with significant efforts to simultaneously collect data using direct sampling. Direct measurements of bedload transport showed higher and more variable rates compared to dune tracking estimates. It was assumed that finer sediment fractions, moving as patches or small-scale superimposed bedforms were presumably not captured by the dune tracking. However, their significant contribution to bedload transport suggests that dune tracking estimates may have been underestimated. Further research is needed to explore how varying flow and sediment conditions affect bedload transport modes and measurement methods comparability. [ABSTRACT FROM AUTHOR]

High-resolution sedimentological and geochronological investigations of paleochannel systems in the Ried Central d'Alsace (northeastern France) allow for the reconstruction of the late glacial and Holocene fluvial evolution of this section of the Upper Rhine alluvial plain. During the Oldest Dryas, the landscape featured a dominant braided Rhine system and, to a lesser extent, a braided Fecht system. The shift to the Bølling-Allerød saw a narrowing of the Rhine's active channel belt, the development of a complex channel pattern, and the genesis of the Ill River. The river channel patterns remained unchanged during the Younger Dryas. In the Early Holocene, the Rhine's active belt narrowed further, and the Rhine and Ill Rivers developed braided-anastomosing and anastomosing channel patterns, respectively. Throughout the Holocene, both rivers maintained their channel patterns while migrating east and west across the alluvial plain, respectively. In the late glacial, fluvial dynamics in this section of the Upper Rhine plain were primarily influenced by climate-related environmental and hydrogeomorphological changes. Conversely, during the Holocene, the evolution of the fluvial hydrosystems was driven by a complex interaction of climatic and non-climatic factors, including human activity at the catchment scale, alluvial plain architecture, and local neotectonics. [ABSTRACT FROM AUTHOR]

The Rhine River is affected by major human interventions affecting its morphology and sediment regime, which have severely changed its flow and sediment transport. While channelization has increased the sediment transport capacity in the free-flowing sections, the sediment retention behind dams has caused a bedload deficit downstream and has additionally intensified riverbed erosion. The resulting consequences range from the exposure of less erodible sediment layers that pose obstacles for navigation, to the scouring of infrastructure, the lowering of groundwater levels, and multiple negative ecological consequences. To optimize the efficiency of countermeasures, a coherent overview of all sediment-related activities and the state of knowledge on the Rhine catchment is required. That is why the present study aims to give a catchment-wide overview in this regard, identify knowledge gaps and proposing a future research programme. The methodological approach includes a comprehensive literature review and online interviews with experts from six riparian countries working in the fields of sediment research and management. Based on our investigations, we have derived several research topics, each consisting of research questions. Three project ideas were defined that should primarily be realized: (i) the influence of climate change and land use change on the sediment regime; (ii) alteration and improvement of the sediment balance and continuity, sediment transport, and morphology; and (iii) national and bilateral projects on sediment transport processes and management. [ABSTRACT FROM AUTHOR]

Microplastics (MP) can be detected in all environmental systems. Marine and terrestrial aquatic systems, especially the transported suspended solids, have often been the focus of scientific investigations in the past. Sediments of aquatic river systems, on the other hand, were often ignored due to the time‐consuming sample preparation and analysis procedures. Spectroscopic measurement methods counting particle numbers are hardly suitable as detection methods, because there are plenty of natural particles next to a small number of MP particles. Integral methods, such as thermoanalytical methods are determining the particle mass independently of the inorganic components. In this study, a workflow for sample preparation via density separation and subsequent analysis by thermal extraction desorption‐gas chromatography/mass spectrometry is presented, which leads to representative and homogeneous samples and allows fast and robust MP mass content measurements suitable for routine analysis. Polymers were identified and quantified in all samples. Polyethylene and styrene‐butadiene rubber are the dominant polymers, besides polypropylene and polystyrene. Overall, total polymer masses between 1.18 and 337.0 µg/g could be determined. Highest MP concentrations in riverbed sediment are found in sites characterized by low flow velocities in harbors and reservoirs, while MP concentrations in sandy/gravelly bed sediments with higher flow velocities are small. [ABSTRACT FROM AUTHOR]

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This study focuses on exploring the potential of using Long Short-Term Memory networks (LSTMs) for low-flow forecasting for the Rhine River at Lobith on a daily scale with lead times up to 46 days ahead. A novel LSTM-based model architecture is designed to leverage both historical observation and forecasted meteorological data to carry out multi-step discharge time series forecasting. The feature and target selection for this deep learning (DL) model involves evaluating the use of different spatial resolutions for meteorological forcing (basin-averaged or subbasin-averaged), the impact of incorporating past discharge observations, and the use of different target variables (discharge Q or time-differenced discharge dQ). Then, the model is trained using the ERA5 dataset as meteorological forcing, and employed for operational forecast with ECMWF seasonal forecast (SEAS5) data. The forecast results are compared to a benchmark process-based model, wflow_sbm. This study also explores the flexibility of the DL model by fine-tuning the pretrained model with limited SEAS5 dataset. Key findings from feature and target selection include: (1) opting for subbasin-averaged meteorological variables significantly improves model performance compared to a basin-averaged approach. (2) Utilizing dQ as the target variable greatly boosts short-term forecast accuracy compared to using Q, with a mean absolute error (MAE) of 25 m3 s−1 and mean absolute percentage error (MAPE) of 0.02 for the first lead time, ensuring reliability and accuracy at the onset of the forecast horizon. (3) While incorporating historical discharge improves the forecasting of Q, its impact on predicting dQ is less pronounced for short lead times. In the operational forecast with SEAS5, compared to the wflow_sbm model, the DL model exhibits skill in forecasting low flows as evidenced by Continuous Ranked Probability Skill Score (CRPSS) median values of all lead times above zero, and better accuracy in forecasting drought events within short lead times. The wflow_sbm model shows higher accuracy for longer lead times. In the exploration of fine-tuning approach, the fine-tuned model generates marginal short-term enhancements in forecasting low-flow events over a non-fine-tuned model. Overall, this study contributes to advancing the field of low-flow forecasting using deep learning approach.

In response to the problem of urban uniformity and loss of identity, in the past, locality research focused mainly on the physical environment and their symbolic values. This study takes the initiative by applying the zero theory from human geography to the planning and design fields. It has investigated promenades and parks along the Rhine in 20 towns or cities using spatial analysis and on‐site experiences. Four types of waterfront space have been identified from the case studies, and the pattern of their distribution along the Rhine suggests that this is influenced mainly by the varying characteristics of the river and the historical development of the towns. This result permits planning to refer to spatial layout based on a region's character. The research also reveals the dominance of representational thinking in our current design practice and its negative impact. The application of non‐representational approaches reveals the importance of sensory experiences and everyday spaces for better on‐site engagement, thus forming the basis for a set of design guidelines for achieving locality in river‐related open spaces. The paper demonstrates that the non‐representational theory could provide the opportunity to enliven the connection between people and places in locality research. [ABSTRACT FROM AUTHOR]

The genesis of floods in large river basins often is complex. Streamflow originating from precipitation and snowmelt and different tributaries can superimpose and cause high water levels, threatening cities and communities along the riverbanks. For better understanding the mechanisms (origin and composition) of flood events in large and complex basins, we capture and share the story behind major historic and projected streamflow peaks in the Rhine River basin. Our analysis is based on hydrological simulations with the mesoscale Hydrological Model forced with both meteorological observations and an ensemble of climate projections. The spatio‐temporal analysis of the flood events includes the assessment and mapping of antecedent liquid precipitation, snow cover changes, generated and routed runoff, areal extents of events, and the above‐average runoff from major sub‐basins up to 10 days before a streamflow peak. We introduce and assess the analytical setup by presenting the flood genesis of the two well‐known Rhine floods that occurred in January 1995 and May 1999. We share our extensive collection of event‐based Rhine River flood genesis, which can be used in‐ and outside the scientific community to explore the complexity and diversity of historic and projected flood genesis in the Rhine basin. An interactive web‐based viewer provides easy access to all major historic and projected streamflow peaks at four locations along the Rhine. The comparison of peak flow genesis depending on different warming levels elucidates the role of changes in snow cover and precipitation characteristics in the (pre‐)Alps for flood hazards along the entire channel of the Rhine. Furthermore, our results suggest a positive correlation between flood magnitudes and areal extents of an event. Further hydro‐climatological research is required to improve the understanding of the climatic impact on the Rhine and beyond. [ABSTRACT FROM AUTHOR]

A bifurcation in an engineered river system (i.e., fixed planform and width) has fewer degrees of freedom in its response to interventions and natural changes than a natural bifurcation system. Our objective is to provide insight into how a bifurcation in an engineered river responds to peak flows and human interventions. To this end, we analyze the change in hydraulics, bed level, and bed surface grain size in the region of two bifurcations in the upper Rhine delta in the Netherlands over the last century. We show that, over the last two decades, the water discharge in one bifurcate (the Waal branch) has steadily increased at the expense of the other. This gradual increase in the water discharge of the first branch is associated with its erosion rate being larger than the other branch. The quick succession of two or three peak flow events (1993, 1995, and 1998) caused rapid sediment deposition over the upstream part of the bifurcate that has gradually lost discharge, which seems to have triggered the slow change in flow partitioning. Plain Language Summary: A river bifurcation is where a river splits into two branches. Water and sediment from the upstream channel are divided between the bifurcation's downstream branches. This division is important for flood risk, freshwater supply, and navigation. Here we investigate the flow division and related changes in bed level and bed surface grain size in the bifurcation region in the upper Rhine delta in the Netherlands over the last century. We find that, over the last two decades, one branch (the Waal branch) has gradually received a larger share of the water discharge at the expense of the other branch. This gradual increase in the water discharge of the first branch seems to be associated with its erosion rate being larger than the other branch. This slow change in the division appears to be triggered by two or three successive peak flows (1993, 1995, and 1998), which caused sediment to deposit at the upstream end of the branch that subsequently started losing discharge gradually. Our analysis shows that peak flows can play a large role in bifurcation development in engineered river systems. Key Points: Water discharge in one branch at a Dutch Rhine bifurcation has slowly increased at the expense of the other bifurcateThis slow change in flow partitioning is associated with one bifurcate eroding faster than the other bifurcateSudden deposition in one bifurcate (due to rapid succession of peak flows and sediment flux coarsening) likely triggered these changes [ABSTRACT FROM AUTHOR]

Inland container shipping is confronted with significant challenges, both on the demand and supply side. In line with the 2019 Green Deal's ambitious goals and 2020 Sustainable and Smart Mobility Strategy, the European Commission presented an 'Inland Waterway Transport Action plan 2021-2027' with the target of shifting more freight across inland waterways. However, the COVID-19 pandemic together with the low water level raise interest in how these could impact the throughput for container transport on the inland waterways. In this research, the scope is on the container throughput for inland container transport on the traditional Rhine. This study first identifies the market drivers for containerized inland navigation in the medium run and then selects the SARIMAX method to analyse Inland Waterway Transport (IWT) volumes. The model application shows that the throughput for inland container transport on the traditional Rhine is impacted on by periods of low water and the weakening of the economy caused by COVID-19. The results of the study suggest that if the IWT container market is impacted by the identified factors, the throughput for containerized IWT is expected to decline by 8.9% in 2023 relative to the volumes in 2020. The research might act as a decision support tool for analysis, management and planning for policymakers and stakeholders. [ABSTRACT FROM AUTHOR]

Since 2013, romantic Rhine cruises gained immense popularity in Europe. However, these tourism activities also involve the generation of large amounts of waste. As rivers contribute significantly to the plastic waste influx in the marine environment, it is essential that river cruise companies cope with plastics in an environmentally-safe way. In this contribution, we try to overcome knowledge gaps regarding both the plastic practices of river cruise companies and the policies on cruise tourism and environmental pollution. We adopt a multiple-case study approach and use the Social Practice Theory to analyse the companies' practices and challenges. Furthermore, we combine this with the analytical approaches of the Policy Arrangements and Synoptic Governance to explore the policies for environmental protection and tourism. The results show that, overall, river cruise companies have an eco-friendly approach to plastic waste management. However, dealing with plastics in the freshwater environment is not sufficiently rooted in the above policies: river cruise companies face important omissions in policies and facilities, resulting in plastic emissions in the river. Following the results, we formulate recommendations to support sustainable waste management routines onboard and to improve waste reception facilities onshore to protect the aquatic environment. [ABSTRACT FROM AUTHOR]

River regulation alters hydrological and sediment regimes and consequently affects habitat complexity and dynamics, biodiversity and ecosystem services. Although channel bank erosion is a key geomorphological process supplying alluvial channels with coarse sediments and diversifying aquatic and riparian habitats, banks have often been stabilized to limit erosion risk to human activities and facilities. The objective of this paper is to assess the effects, and their sustainability, of bank protection removal on a 300‐m long reach of the Old Rhine (France/Germany) to promote sediment supply, channel diversification and a rehabilitation of fluvial morpho‐sedimentary processes. This action was combined with the construction of two island groynes to locally increase bank erosion processes. Yearly detailed monitoring was implemented over 6 years, including classical bathymetric surveys, airborne topo‐bathymetric and terrestrial LiDAR, and bed grain‐size and bedload tracking. Following a Q15 flood, the restoration induced a weak sediment supply. The restoration diversified habitats due to the implementation of the two island groynes, inducing bank scouring and the creation of new macroforms, as well as local bed grain‐size diversification and fining. The cross‐sectional diversity of the restored water channel was close to the regularization engineering phase. Channel bedform diversification persisted 6 years due to the persistence of the two island groynes. The action induced the rehabilitation of fluvial forms, in a static manner, rather than the rehabilitation of fluvial morpho‐sedimentary processes, which raises questions about the sustainability of the benefits of such management actions in terms of fluvial functionality and naturality. [ABSTRACT FROM AUTHOR]

In snow-dominated river basins, floods often occur during early summer, when snowmelt-induced runoff superimposes with rainfall-induced runoff. An earlier onset of seasonal snowmelt as a consequence of a warming climate is often expected to shift snowmelt contribution to river runoff and potential flooding to an earlier date. Against this background, we assess the impact of rising temperatures on seasonal snowpacks and quantify changes in timing, magnitude and elevation of snowmelt. We analyse in situ snow measurements, conduct snow simulations and examine changes in river runoff at key gauging stations. With regard to snowmelt, we detect a threefold effect of rising temperatures: snowmelt becomes weaker, occurs earlier and forms at higher elevations. Due to the wide range of elevations in the catchment, snowmelt does not occur simultaneously at all elevations. Results indicate that elevation bands melt together in blocks. We hypothesise that in a warmer world with similar sequences of weather conditions, snowmelt is moved upward to higher elevation. The movement upward the elevation range makes snowmelt in individual elevation bands occur earlier, although the timing of the snowmelt-induced runoff stays the same. Meltwater from higher elevations, at least partly, replaces meltwater from elevations below. HIGHLIGHTS Impact of rising temperatures on seasonal snowpacks.; Investigations on the point scale for elevation bands and from a catchment perspective.; Threefold effect: snowmelt becomes weaker, occurs earlier and forms at higher elevations.; Meltwater from higher elevations can, at least partly, replace meltwater from elevations below.;

In bifurcating rivers, an intervention aimed at flood risk reduction may trigger a change in discharge distribution and thus influence water levels throughout the entire river system. This article aims at assessing the impact of interventions on system‐wide water levels, explicitly accounting for a range of discharges and model parameter uncertainty. An idealized 1D model with dimensions of the bifurcating Dutch Rhine River is used. The results show that an unwanted increase in water levels downstream of the intervention occurs due to an increased discharge if a single intervention is implemented in a distributary. This effect can be counteracted by implementing a second intervention that balances the hydraulic effect of the first intervention at the bifurcation. However, unwanted water level increases still occur at other discharges. Furthermore, while interventions may reduce local water‐level‐uncertainty, it appears that uncertainty in discharge distribution is not reduced. This implies that flooding probabilities cannot be reduced throughout the entire river system by the implementation of interventions in upstream reaches. Concluding, for intervention design in a bifurcating river, it is important to consider the entire river system and explicitly account for a range of discharge conditions to avoid unwanted water level increases throughout the river system. [ABSTRACT FROM AUTHOR]

Plastic litter transported in rivers may enter the marine environment. Due to the durability of plastic, the residence times in the aquatic environment are decades to millennia. Plastic litter items come in a wide variety. The density of the item and the flow velocity largely determine the vertical distribution of the plastic litter, although the litter shape and wind can also play a role in a river. Estimates of plastic transport in a river are usually based on observations of visible litter items in the near-surface layer alone. Only a very limited number of studies have observed the vertical distribution in rivers or estuaries. We have carried out 28 sampling surveys in a river bend located in the lower part of the Rhine-Meuse delta that is under the influence of tides. To observe the vertical distribution, we sampled with three nets simultaneously up to 5 m water depth, at both sides of the river bend. In total, almost 90% of the collected debris was organic matter. Plastic litter represented the large majority of the non-organic litter: about 80% by mass, having an average concentration of 0.5 mg/m3, and more than 90% by number. We observed that by mass and by number the plastic mass concentration in the middle net was generally lower than in the lower and upper nets. In total, more plastic litter was present in the two nets lower in the water column than in the surface net. A higher plastic concentration was found at the downwind side of the channel than at the upwind side of the fairway. It was found that the plastic litter mass concentrations were of the same order of magnitude during ebb than during flood tide. The litter size that contributed most to the mass concentration (around 65%) were items in between 25 and 500 mm, which were mostly soft plastics (i.e. foils). In the lower net, relatively more small hard plastic items were found. It was observed that these plastic items were sometimes entangled in organic matter. The plastic flux lower in the water column may follow the transport of organic matter like aquatic plants.

Abstract In bifurcating rivers, an intervention aimed at flood risk reduction may trigger a change in discharge distribution and thus influence water levels throughout the entire river system. This article aims at assessing the impact of interventions on system‐wide water levels, explicitly accounting for a range of discharges and model parameter uncertainty. An idealized 1D model with dimensions of the bifurcating Dutch Rhine River is used. The results show that an unwanted increase in water levels downstream of the intervention occurs due to an increased discharge if a single intervention is implemented in a distributary. This effect can be counteracted by implementing a second intervention that balances the hydraulic effect of the first intervention at the bifurcation. However, unwanted water level increases still occur at other discharges. Furthermore, while interventions may reduce local water‐level‐uncertainty, it appears that uncertainty in discharge distribution is not reduced. This implies that flooding probabilities cannot be reduced throughout the entire river system by the implementation of interventions in upstream reaches. Concluding, for intervention design in a bifurcating river, it is important to consider the entire river system and explicitly account for a range of discharge conditions to avoid unwanted water level increases throughout the river system.

The Rhine region of freshwater influence (ROFI) is strongly stratified, rotational, relatively shallow and has large tides, resulting in a dynamic field of fronts that are formed by multiple processes. We use a 3D numerical model to obtain a conceptual picture of the frontal structure and the processes responsible for generating this multiple front structure in the Rhine ROFI. The horizontal salinity gradient and numerical tracers are used to identify three different types of fronts: outer, inner, tidal plume and relic tidal plume fronts. Tidal plume front (TPF) trajectories together with the tracers demonstrate that TPFs exist for longer than one tidal cycle. A Lagrangian frontogenesis analysis shows that the fronts are strengthened mainly as a result of increased convergence, which is observed to occur at times when tidal straining is large. Additionally the alongshore tidal excursion and the dominance of the tidal currents over the intrinsic frontal propagation speed, trap TPFs within 20 km from the river mouth. Trapping and re‐strengthening maintain several fronts at a time in the mid‐field region, resulting in a multi‐frontal system. The observation of a complex river plume system is expected to be important for cross‐shore exchange, transport and coastal ecology. Plain Language Summary: Rivers transport sediments, nutrients, and contaminants into the coastal ocean. A river plume is formed when the freshwater enters the ocean, where the edges of this river plume are the boundary between river and ocean water. These boundaries are called fronts and relate to large horizontal density gradients. These fronts are important for the transport of freshwater away from the river mouth. Our study shows that multiple fronts are observed in the Rhine region of freshwater influence. These multiple fronts result in a complex system. Our study unravels which processes are responsible for the presence of multiple fronts, which will change the overall dynamics in coastal areas influencing the transport of sediments, nutrients and contaminants. Key Points: Tidal straining re‐strengthens fronts hours after their initial formationTidal advection leads to the trapping of tidal plume fronts, generating a multi‐frontal systemThe persistence of Rhine plume fronts is due to convergence associated with bulk plume circulation [ABSTRACT FROM AUTHOR]

Biological invasions are a global threat to biodiversity especially for aquatic resources. The distribution of alien species is associated with human activities; therefore, exotic species tend to accumulate near big urban areas through different invasion vectors such as ballast water, hull fouling, aquarium and pet releases. The Rhine River region is one of the most economically important in Europe. Around 60 million people live in the river basin that is connected with other large European rivers via the Rhine–Main–Danube shipping canal. The Alpine Rhine flows to Lake Constance, which is the second largest subalpine lake in Europe. Here, eDNA metabarcoding was employed to inventory aquatic species from water samples in six riverine and four lake localities within Lake Constance region. A 313 bp fragment within cytochrome c oxidase subunit I gene was PCR amplified using generalist primers for metazoan and sequenced with MiSeq High-Throughput Sequencing platform. Seven invertebrate invasive species and the invasive fish Oncorhynchus mykiss were detected from eDNA. Species-specific primers were employed to confirm metabarcoded species. Most of the invasive species detected in this study correspond to samples from areas around lake ports, followed by other lake and degraded downstream river areas. Samples taken upstream of Lake Constance were free of invertebrate aliens. To establish common regulation and management actions regarding aquatic invasions in the three countries that share Lake Constance is recommended. [ABSTRACT FROM AUTHOR]

In snow-dominated river basins, floods often occur during early summer, when snowmelt-induced runoff superimposes with rainfall-induced runoff. An earlier onset of seasonal snowmelt as a consequence of a warming climate is often expected to shift snowmelt contribution to river runoff and potential flooding to an earlier date. Against this background, we assess the impact of rising temperatures on seasonal snowpacks and quantify changes in timing, magnitude and elevation of snowmelt. We analyse in situ snow measurements, conduct snow simulations and examine changes in river runoff at key gauging stations. With regard to snowmelt, we detect a threefold effect of rising temperatures: snowmelt becomes weaker, occurs earlier and forms at higher elevations. Due to the wide range of elevations in the catchment, snowmelt does not occur simultaneously at all elevations. Results indicate that elevation bands melt together in blocks. We hypothesise that in a warmer world with similar sequences of weather conditions, snowmelt is moved upward to higher elevation. The movement upward the elevation range makes snowmelt in individual elevation bands occur earlier, although the timing of the snowmelt-induced runoff stays the same. Meltwater from higher elevations, at least partly, replaces meltwater from elevations below. [ABSTRACT FROM AUTHOR]

A review of the history of river managements of large rivers in Europe and America can help to take a long term view, make scientific decisions and identify major current issues in the Yellow River management. The history of managements of Rhine, Mississippi and Colorado rivers show that developed countries have gone through three stages of the development of damming and channelizetion, pollution control and ecological protection. As first developed countries, the key to the success of pollution control is high-quality development of river basins that has been promoted by scientific and technological innovations, but over-developed has left many problems for sustainable development. For the Yellow River management, in order to meet the goal of leapfrogging, integrated management of basin society, economy, water resources and water ecology must be implemented, with the Yellow River Protection Commission as the highest decision-making body. Researches on basin development strategy, multi-objective decision-making models, comprehensive river dynamic monitoring and joint efforts of “industry-university-research-application” to tackle key problems were necessary to carry out efficient crosssector evidence based decision-making, improve adaptive management skills and expedite innovations in sustainable engineering. [ABSTRACT FROM AUTHOR]

• A comprehensive comparative empirical analysis on the container shipping network. • Supported by extensive datasets, incorporates the latest development on river basin. • Combine descriptive and explanatory analysis from interdisciplinary approaches. • A large diversity exists in how inland port systems development. The formation of barge networks on rivers and associated inland port systems is subject to a complex set of influencing factors and mechanisms. This paper aims to present a comprehensive comparative empirical analysis focusing on the container shipping (barge) network in the Yangtze and the Rhine. This analysis is supported by extensive datasets on both river basins, incorporates the latest development on both rivers and is grounded on concepts and methods coming from transport geography and economic geography. We find that a large diversity might exist in how inland port systems and related gateway seaports are dealing with cargo flows and supply chains. In view of explaining this diversity, we make a distinction between geographical/nautical aspects, macro-economic factors and institutional/governance factors. In particular, we discuss the role of institutional and governance factors in barge network development by using the concepts of selection, retention and variation. [ABSTRACT FROM AUTHOR]

An experimental study on internal erosion of coarse-grained soils collected from the Rhine River is presented. The tests performed on laboratory column aim to assess the potential of such soils to suffusion and to characterize their stability and the variation of the soil physical parameters during the suffusion process. An experimental device (large vertical column with 60 cm of height and 26 cm of diameter) has been developed, which allows the application of upward flow to non-cohesive soils under controlled hydraulic loading. The investigation of the parameters affecting the suitability of the soils to suffusion leads to the identification of the hydraulic gradient that initiates the migration of particles to the outlet. The results show an increase in permeability, which is related to the migration and the washing out of fine particles in the upper layer. The particle size distribution of the downward soil layer after test is performed, and the analysis corroborates the localization of particles suffusion. The grain size analysis of the outlet shows that eroded particles are smaller than 500 µm and their size rather increases with increasing hydraulic load. Usual methods based on geometrical criteria proved to overestimate the susceptibility to suffusion of soils from the Rhine, and, therefore, one consider that, for such soils, it is preferable to carry out laboratory tests to evaluate the suffusion process. [ABSTRACT FROM AUTHOR]

Highlights • New mesohabitats were characterized by low flow velocity and fine substrates. • The gain observed on the whole study site favoured burrowing taxa. • Inter-annual analysis showed a decrease in invasive populations, across all sections. • The sustainability of ecological effects is highly dependent of groynes maintenance. Abstract The rise of restoration projects on large rivers is a response to the increasing human-induced pressures on these ecosystems. Despite this, there is a relative lack of data documenting restoration success using macroinvertebrate communities in such environments, with those existing frequently producing contrasting results. Here, we examined post-restoration responses of macroinvertebrates following a unique experimental restoration approach based on controlled bank erosion and artificial groyne implementation, initiated in 2013 on the Old Rhine River (France-Germany). We investigated how macroinvertebrate communities have responded to restoration-induced variations in three main abiotic parameters, i.e. water depth, flow velocity and substrate type, by comparing the restored section with unrestored ones. The Eco-hydro-morphological index (EHMID), a modified version of a hydro-morphological diversity index, showed a gain in mesohabitat heterogeneity along the whole site. Newly created mesohabitats with low flow velocity and finer substrate were dissimilar to those along the rest of the Old Rhine channel, favouring burrowing taxa such as Odonata. The presence of such insect larvae was related to the post-restoration emergence of typical alluvial terrestrial-aquatic border connectivity, and the rise in macrophytes over time. On the whole site, changes in composition or in functional profile diversity were highly related to the high degree of mesohabitat heterogeneity from the restored section, which would persist as long as groynes remain. The main inter-annual effect concerned the decrease in invasive taxa abundance that also varied according to any changes in fluvial forms. Our findings confirmed that macroinvertebrate responses are highly influenced by hydrological events and are dependent on the study-scale monitoring, clearly putting forward fine-scale hydromorphological gradients. Biological results from this restoration project should approach those obtained in smaller rivers restored using deflectors, suggesting a potential application of the hydraulic law of similarities. However, the accuracy of biological prediction using said application is limited by the distance from source populations, biological invasions and internal river dynamics. [ABSTRACT FROM AUTHOR]

The Haringvlietdam tidal barrier was erected in 1971 between the North Sea and the estuary of Rivers Rhine and Meuse (i.e. Lake Haringvliet). The mega structure safeguards the Dutch lowlands against flooding but also hampers fish migrations. Moreover, the sluices wash out on average 1000-2000 kg of freshwater fish per day. Previous studies showed that these fish die, but we suggested that under certain conditions salt tolerant fish like pikeperch can survive and re-enter the estuary. Fifty pikeperch (Sander lucioperca L. 1758) of over 42 cm LT were surgically implanted with VEMCO acoustic transmitters and 17 with transponders for the NEDAP Trail system®. The pikeperch were released in four batches at the seaside of the Haringvlietdam between January 18 and March 17, 2017. The pikeperch displayed searching behaviour at the sluices but were unable to swim against the strong currents. Nevertheless, two pikeperch re-entered Lake Haringvliet via the nearby ship-lock and nine used the fish-culverts that are integrated in pillars of the Haringvlietdam. It was concluded that at river discharges less than 2000 m3/s (which occurs 50% of the time) the chances of re-entrance are slim but increase with higher discharges causing lowered salinities behind the Haringvlietdam. Based upon the results we conclude that many fish could have been saved the past 45 years by optimizing the management of the ship-lock and fish-culverts and by decreasing the flow velocities in the discharge-sluices. We recommend implementing these options in the planned new management of the Haringvlietdam. [ABSTRACT FROM AUTHOR]

Anthropogenic lanthanum predominantly derived from a point source has become an emerging contaminant in the Rhine River, but little is known about its ecotoxicological consequences on bivalve mollusks. A fundamental requirement of aquatic invertebrate adaptation and survival in stressful habitats is the maintenance of energy homeostasis. As such, the present study tested the impact of four dissolved La concentrations (0, 50, 100 and 200 μM) on the energy balance of the bivalve Corbicula fluminea in the Rhine River. Bivalves were collected at four sampling sites which were contaminated by La to different degrees, thereby allowing to understand the degree of their potential acclimation. With increasing exposure dose, shell and somatic growth (the most energetically expensive biological processes) decreased significantly in clams inhabited the control (uncontaminated) habitat; while less pronounced impacts were evident in all three contaminated sites. In particular, the latter showed virtually unaffected energy (glycogen and protein) reserves. An elucidation of shifts in the organismal energy budget may shed light on such improvement of growth performance. Irrespective of sampling sites, short-term exposure to La caused significant increases of oxygen consumption and ammonia excretion, indicating that the clams promoted their energy metabolism and thereby allocated more energy to essential physiological processes. Noteworthily, the clams originating from contaminated sites displayed virtually unaffected clearance rate, thereby being able to partially fulfill the increased energy demand and eventually alleviating the La-induced physiological interference. Taken together, findings of the present study demonstrate that whether, and to what extent, C. fluminea is able to sustain its energy homeostasis play a central role in the phenotypic plasticity and/or genetic adaptation in the face of anthropogenic La contamination in the Rhine River. [ABSTRACT FROM AUTHOR]