Sediment production is often intensified in peri-urban areas, due to the transition from predominantly rural to urbanized landscapes. Although sediment dynamics in urbanizing areas remain complex and poorly understood, urban development can generate significant fine sediment, emphasizing the importance of monitoring the impacts of each stage of urban development. We monitored suspended solids concentration and loads in six stormwater drainage systems with small, street-scale catchments for 6 months using low-cost automatic monitoring stations in southeast Australia. The study was conducted in a peri-urban area undergoing urbanization, where different stages of urban development were observed, ranging from bulk earthworks and road construction to fully urbanized sites. The results showed that during urbanization, event mean suspended solids concentrations commonly exceed 5 g/L ( 100× more than fully urbanized sites). Suspended solids yields (SSY) in early-stage urbanization areas can be up to 30 times higher than in fully developed areas. The median particle size of sediments in early development stages was up to six times finer than those in the later development stages. The results highlight that early urbanization stages contribute significantly to fine sediment production, presenting a high risk to sensitive water bodies. The findings highlight the value of combining innovative IoT (Internet of Things) monitoring technologies, with geospatial and time series analysis to better understand sediment dynamics in a complex and rapidly urbanizing landscape. Additionally, the findings underscore that erosion and sediment control measures are vital, particularly during the early stages of urbanization, requiring proactive management throughout this process to mitigate fine sediment impacts and protect downstream waterbodies.

Historically, humans learned to swim in natural bodies of water, and river bathing was a popular leisure activity for centuries in Europe. However, the Industrial Revolution caused water pollution and conflicting river usage, ultimately leading to the prohibition of urban river bathing in major European cities during the 20th century, a ban that remains in effect in many places today. In recent years, a grassroots movement has been emerging in across Europe, advocating for the revival of river bathing, fuelled by the growing demand for natural interactions during hot summers and a renewed connection between cities and rivers. This article presents a pioneering synthesis of urban river bathing in the European context, developed under the auspices of the interdisciplinary Consortium on Urban Bathing. It draws on multidisciplinary literature review, policy analysis, fieldwork conducted in 11 European cities, and interviews with 26 stakeholders. The study identifies two types of urban river bathing designs: designated river pools and free river bathing zones, each with distinct regulations and management approaches. The analysis critically examines current management practices, addressing water microbial quality and health risks under EU Directive guidance, alongside river drowning prevention and safety protocols in case study cities. Finally, it discusses the sustainability potential of developing urban river bathing by proposing strategies for collaborative river governance and responding to the growing impacts of climate change, emphasizing the ignored ecological consideration. These findings serve as the foundation for an interdisciplinary framework to understand the evolution, management, and sustainability of this globally emerging subject.

Human alterations have disrupted sediment dynamics in European rivers, leading to sediment starvation, channel incision, and excessive deposition of fine sediments within gravel bed interstices. This interstitial infilling, when intensified by anthropogenic pressures, promotes hyporheic clogging and degrades habitat quality. Yet, the spatial and temporal dynamics of fine sediment storage in dam-associated bypassed reaches remain poorly documented, particularly where sediment replenishment is implemented. To fill this knowledge gap, we conducted a three-year multi-site study along 329 km of the Rhone River (France), encompassing armoured, gravel-replenished, and dynamic reference reaches. Sampling stations were restricted to riffles in order to minimize hydraulic variability linked to differences among geomorphic units. Interstitial fine sediment content was quantified using a cylinder core sampler. Results indicate that the variability in interstitial fine sediments is mainly driven by station-scale factors related to hydraulic conditions (i.e., grain size distribution of the bed and flow velocity). By minimizing station-scale effects using a quantile regression model, inter-station variability exceeds intra-station variability (over time), highlighting the strong influence of reach type. Armoured reaches, characterised by a coarse-grained fixed bed, has higher fine sediment contents than replenished reaches and reference reaches, the latter exhibiting the lowest fine sediment content. At two armoured stations, fine sediment contents exceed 25%, suggesting potential ecological impairment of the hyporheic zone. Temporal variability was limited, even after periods of high-flow conditions. These findings emphasize the need for multi-scale monitoring to disentangle station, reach and catchment-scale drivers, and for complementary methods to assess clogging potential more directly.

The deployment of low-cost network sensors (LCNS) for environmental monitoring has become increasingly prevalent in recent years, offering a cost-effective solution for enhancing spatial sensor coverage while minimizing financial constraints. This study presents LevelWAN, a water level monitoring system specifically designed for highly dynamic aquatic environments such as rivers, ponds or lakes. LevelWAN is an open-source, robust, and cost-effective Internet of Things (IoT)-based monitoring solution incorporating an ultrasonic sensor. The electronic components were carefully selected for their affordability, reliability, and performance. The system underwent a fully autonomous, long-term (3-year) field test in a challenging and highly dynamic environment - a sewer system - to validate its robustness. Its accuracy was assessed against a high-precision professional device, demonstrating an error margin of less than 1 cm. Additionally, LevelWAN was developed with a user-friendly design to facilitate accessibility for non-experts, aligning with the needs of citizen science initiatives and educational applications.

Urban river bathing is re-emerging across Europe, driven by social demand and climate change impacts. The Urban Bathing Consortium, an interdisciplinary and intersectoral consortium initiated at the University of Lyon (France), is at the forefront of studying the challenges and opportunities of creating and managing healthy, safe, and accessible river bathing spaces. Through interdisciplinary collaboration among researchers and stakeholders, the consortium proposed an analytical framework, identifying seven critical dimensions for urban river bathing: the history and revival of city-river relationships, legal and regulatory frameworks, bathing water quality, river drowning risks, river ecosystems, social perspectives, and urban planning. By examining these dimensions with state-of-the-art approaches and drawing on Lyon's experiences, the study provides scientific insights and practical recommendations for future sustainable urban river bathing development. These include revitalizing historical city-river connections, aligning local regulations with EU guidance, advancing holistic microbial water quality control, enhancing safety measures, incorporating ecological considerations, balancing competing river uses in urban planning, and addressing social needs for inclusive river governance.

Among the Maasai group ranches surrounding Amboseli National Park in southern Kenya, perennial springwater from the foothills of Mt. Kilimanjaro generates an oasis effect in an otherwise water-scarce landscape; it underpins pastoral livelihoods, agricultural productivity, and wildlife conservation economics. This resource, however, is increasingly under pressure from these competing interests. Based on semi-structured interviews, waterscape mapping workshops with Maasai pastoralists, field observations, and visual interpretations of highresolution satellite images, we map, describe and analyse how 70 years of uncoordinated proliferation of water extraction, conveyance, and storage features across the semi-arid savanna rangelands has altered the local water cycle and changed power dynamics around water resources. A succession of externally driven rural development, land reform and conservation policies has contributed to the reshaping of patterns and regimes of access to water by modifying land ownership and attracting new activities such as crop irrigation and safari tourism. As a result, the status of water is shifting from a common-property resource with a tradition of sharing, to a commodified resource that is controlled privately and redistributed according to individualistic strategies. Our focus on three hydrosocial territories from a Maasai perspective examines how high densities of private structures such as wells and small runoff- and pipeline-fed storage reservoirs are pushing the livestock-based, semi-nomadic economy towards intensive, sedentary agriculture. Inequalities in access to water have deepened, with water users associations and other water management organisations also experiencing or generating new forms of conflict between resident communities.

eLogUp! is a low-cost, modular, and open-source data logger designed to support both research and operational environmental monitoring applications requiring accurate data recording and storage, efficient power management, and reliable data transmission. It serves as a key component for the implementation of effective Low-Cost Network Sensor (LCNS) systems, enhancing environmental observation capabilities. eLogUp! consists of a custom-designed PCB integrated with an Arduino® MKR microcontroller, enabling data acquisition from a wide range of analog and digital sensors, such as temperature, water level, and humidity probes, with user-defined sampling intervals. A distinctive feature of eLogUp! is its auto-wake-up function, which powers down the system between measurements to optimize energy consumption. It also integrates several electronic components (e.g. RTC) to minimize the overall footprint of the system. The system can thus operate on a small LiPo battery and solar panel. Data transmission can be carried out using different protocols (e.g., WiFi, GSM, or LoRaWAN). Developed as an alternative to commercial environmental data loggers, which are often expensive, overly specialized, proprietary, or limited to a narrow set of parameters, eLogUp! offers an affordable, adaptable, and open-source solution. This makes it a versatile tool for environmental researchers, field practitioners, and citizen science initiatives, providing a scalable and accessible approach to long-term environmental data collection.

Sound urban water management relies on extensive and reliable monitoring of water infrastructure. As low-cost sensors and networks have become increasingly available for environmental monitoring, urban water researchers and practitioners must consider the benefits and disadvantages of such technologies. In this perspective paper, we highlight six technical and socio-technological considerations for low-cost monitoring technology to reach its full potential in the field of urban water management, including: technical barriers to implementation, complementarity with traditional sensing technologies, low-cost sensor reliability, added value of produced information, opportunities to democratize data collection, and economic and environmental costs of the technology. For each consideration, we present recent experiences from our own work and broader literature and identify future research needs to address current challenges. Our experience supports the strong potential of low-cost monitoring technology, in particular that it promotes extensive and innovative monitoring of urban water infrastructure. Future efforts should focus on more systematic documenting of experiences to lower barriers to designing, implementing, and testing of low-cost sensor networks, and on assessing the economic, social, and environmental costs and benefits of low-cost sensor deployments.

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The use of low-cost sensors, with open-source code, facilitates greater spatial resolution and flexibility of environmental monitoring, thus generating more information and overcoming limitations of traditional commercial sensors. Measurement of water turbidity using submerged sensors can be problematic in that rapid biofouling requires frequent site visits to remove, clean, calibrate and replace the sensor. We therefore designed an automated system using low-cost commercially-available sensors that pumps water from the stream, samples it for turbidity and purges remaining water, leaving the turbidity sensor dry between measurements, thus greatly reducing the biofouling problem and minimizing operation costs. Our station was able to estimate suspended sediment concentrations between 0 and 6 g/L with a root mean square error (RMSE) around 5 % of the total range, which meets typical research and operational study requirements. The results showed that the monitoring station is capable of monitoring water level and turbidity for long periods without the need of cleaning the turbidity sensor, due to its purge function. We demonstrated that spatially intense measurement of turbidity within catchments and drainage networks can be achieved at a relatively low cost, which allows a better understanding of the main sources of suspended sediments and their spatial and temporal variability.

The result of work of an interdisciplinary group of researchers of the French Workshop Zone Network (Réseau des Zones Ateliers, CNRS), this article focuses on the implementation of restoration projects aiming to restore ecological connectivity of rivers. These projects are at the center of an important controversy taking place in the French public space since several years. Thus certain actors put into question the pertinence of the public policy aiming at removal of hydraulic structures contributing to connectivity interruption. Here, we first synthesize the currently known effects of the connectivity interruption in its longitudinal, lateral and vertical dimensions on a row of biophysical and socio-economic processes. Spotlighting the complexity of processes linked to river connectivity, the variablity of territorial contexts and the associated uncertainties, our analysis reveals the necessity of inscribing restoration projects within a larger project of water ressource management conducted at the scale of a territory and rooted in a participatory decision process. The decision to restore or not restore connectivity cannot be based exclusively on science and technical expertise. With this in mind, we propose an action strategy to address challenges related to river connectivity restoration. We identify ten critical points to take into account for implementing restoration projects that would be both supported by different stakeholders, and efficient in regard to their defined objectives.

This study presents the process of design and development of a low-cost turbidimeter for monitoring water quality, facilitating rigorous spatial-temporal variability analysis within large-scale hydrological systems. We propose a low-cost optical turbidimeter, modifying the existent SEN0189 turbidity sensor, Arduino boards, and additional sensors for temperature compensation. We compared a low-cost system with high-tech sensors, modifying the original low-cost SEN0189 probe for enhanced environmental performance. The three-step methodological framework involved prototype development, compensation for environmental factors, and preparation for future field deployment. Calibration equations with a high coefficient of determination and a temperature correction equation were established. We made adaptations to overcome field deployment challenges, including a 3-D printed sensor case, defining the relationship between measurement uncertainty and energy consumption, and specifying field installation guidelines. In summary, this study presents a comprehensive approach to a low-cost optical turbidity system, demonstrating its potential for accurate and affordable field deployment. We aim to address the critical need for sustainable inland water management tools, making this system a valuable contribution to environmental monitoring practices. We also aim to inspire similar development of open-source monitoring systems within our community.

Monitoring bedload transport in rivers is a challenging research domain teeming with technical innovations and methodological developments aimed at improving our knowledge and models of bedload processes at different spatial–temporal scales. Radio frequency identification (RFID) technology has improved sediment tracking, allowing the characterisation of transport processes of individual particles at flood‐event scales. Meanwhile, geophone sensors have enabled the long‐term continuous monitoring of seismic signals that can provide surrogate measures of bedload fluxes at local scales, during flood events and at sediment‐pulses. The combination of these two techniques could allow sediment transport processes to be linked with both flood events and sediment pulses. In this study, we used a combination of active ultra‐high frequency RFID technology and geophone monitoring stations to link the virtual velocity of tracers with seismic activity, hydraulic forcing, and the properties of the tracked particles. Single and multiple regression models show that seismic activity best explained the observed variance (81%) of the virtual velocity of particles, in comparison with discharge (58%) and stream power (63%). Furthermore, when several control variables (seismic activity and particle properties) were combined in an empirical model, the model explained 89% of the variance and allowed quantification of the portions of the variance explained by hydraulic forcing, geophonic activity and tracked particles. These results show the high potential of these combined monitoring techniques for future in‐field experiments to investigate bedload processes at different spatiotemporal scales in rivers of different morphologies.

Combined sewer overflows (CSO) are used to avoid overloading unitary sewers and wastewater treatment plants. Following the European Council Directive on Urban Wastewater Treatment (UWT), CSO discharges are regulated using guidelines that aim to reduce their ecological impact on aquatic systems. A model CSO, which is part of a long-term experimental field observatory, was modified according to these guidelines and used to evaluate the benefits of compliance through analyses of the bacteriological and chemical states of the receiving intermittent stream. The benthic and hyporheic sediments of similar geomorphic units located upstream and downstream of a monitored CSO outlet were compared before and after changes in CSO regimes. Hydrological, pollutants (Metal Trace Elements, MTE; Polycyclic Aromatic Hydrocarbons, PAH; fecal indicator bacteria, FIB), and tpm-based DNA meta-barcoding datasets resolving the occurrences of >700 bacterial species of nearly 200 genera were studied. The frequency of overflow was confirmed to have significantly decreased following the application of the UWT guidelines. Overflows became almost limited to periods of heavy summer thunderstorm events. These changes were not associated with a significant decrease in most of the surveyed MTE, PAH, and FIB among stream sediments, except for chromium. Ecological benefits were highlighted by significant changes in tpm-based meta-barcoding community patterns between the UWT compliant sampling period and the previous one. Bacterial community change point analyses confirmed this segregation in the meta-barcoding dataset according to hydrological indices such as the number of CSO events and discharged volumes. A significant decline in CSO bacterial taxa in the benthic and hyporheic sediments was observed. Thirty-four CSO indicator species were identified, including Aeromonas caviae, Aeromonas media, and Pseudomonas oleovorans. These indicators, often documented as opportunistic pathogens (to humans, animals or plants) and/or pollutant degraders, were proposed as ecological sentinels for the assessment of CSO impacts.