Water Network Research Articles

Leveraging Urban Water Distribution Systems with Smart Sensors for Sustainable Cities

Optimizing urban water distribution systems is essential for reducing economic losses, minimizing water wastage, and addressing resource access gaps, particularly in drought-prone regions impacted by climate change. We apply advanced artificial intelligence (AI) techniques and the Internet of Things (IoT) to optimize water networks in Spain using simulation. By employing EPANET for hydraulic modeling and a linear regression-based algorithm for optimization, we achieved up to 96.62% system efficiency with a mean absolute error of 0.049. Our approach demonstrates the potential to conserve up to 648,000 L of water daily at high-demand nodes, contributing to substantial resource savings across urban water networks. We propose a global architecture utilizing Low Power Wide Area Network and Low Earth Orbit solutions for widespread deployment. This study underscores the potential of AI in water network optimization and suggests future research avenues for implementing the proposed architecture in real urban water systems.

Strong Replaces Weak: ​Hydrogen Bond‐Anchored Electrolyte Enabling Ultra‐Stable and Wide‐Temperature Aqueous Zinc‐Ion Capacitors

Despite aqueous electrolytes offer a great opportunity for large‐scale energy storage owing to their safety and cost‐effectiveness, their practical application suffers from the parasitic side reactions and poor temperature adaptability stemming from weak hydrogen‐bond (HB) network in free water. Here, we propose the guiding thought “strong replaces weak” to design hydrogen bond‐anchored electrolyte by introducing sulfolane (SL) for disrupting the regular weak HB network and contributing to superior temperature tolerance. Judiciously combined experimental characterization and theoretical calculation confirm that SL can remodel the primary solvation shell of metal ions, customize stable electrode interface chemistry and restrain the side reactions. Consequently, symmetric supercapacitor constructed by activated carbon (AC) electrodes is able to fully work within a voltage range of 2.4 V and reach high capacitance retention of 89.8% after 60000 cycles. Additionally, Zn anodes exhibit ultra‐stable Zn plating/stripping behaviors and a wide temperature range (‐20 ~ 60 °C), and zinc‐ion capacitor (Zn//AC) also delivers an excellent cycling stability with capacity retention of 99.7% after 55000 cycles, implying that the designed electrolyte has practical application potential in extreme environments. This work proposes a novel critical solvation strategy that paves the route for the construction of ultra‐stable and wide‐temperature aqueous energy storage devices.

Strong Replaces Weak: ​Hydrogen Bond-Anchored Electrolyte Enabling Ultra-Stable and Wide-Temperature Aqueous Zinc-Ion Capacitors.

Despite aqueous electrolytes offer a great opportunity for large-scale energy storage owing to their safety and cost-effectiveness, their practical application suffers from the parasitic side reactions and poor temperature adaptability stemming from weak hydrogen-bond (HB) network in free water. Here, we propose the guiding thought "strong replaces weak" to design hydrogen bond-anchored electrolyte by introducing sulfolane (SL) for disrupting the regular weak HB network and contributing to superior temperature tolerance. Judiciously combined experimental characterization and theoretical calculation confirm that SL can remodel the primary solvation shell of metal ions, customize stable electrode interface chemistry and restrain the side reactions. Consequently, symmetric supercapacitor constructed by activated carbon (AC) electrodes is able to fully work within a voltage range of 2.4 V and reach high capacitance retention of 89.8% after 60000 cycles. Additionally, Zn anodes exhibit ultra-stable Zn plating/stripping behaviors and a wide temperature range (-20 ~ 60 °C), and zinc-ion capacitor (Zn//AC) also delivers an excellent cycling stability with capacity retention of 99.7% after 55000 cycles, implying that the designed electrolyte has practical application potential in extreme environments. This work proposes a novel critical solvation strategy that paves the route for the construction of ultra-stable and wide-temperature aqueous energy storage devices.

Entropy Changes in Water Networks Promote Protein Denaturation.

For over a century, an explanation for how concentrated ions denature proteins has proven elusive. Here, we report a novel mechanism of protein denaturation driven by entropy changes in water networks. Experiments and simulations show that ion pairs like LiBr and LiCl localize water molecules and disrupt the water network's structure, while others exert a more global effect without compromising network integrity. This disruption reduces the entropy penalty when proteins sequester water molecules during unfolding, resulting in a peculiar yet universal "inverse hydrophobic effect" that potentiates protein denaturation. Through successful isolation and systematic study of indirect solute effects, our findings offer a universal approach to salt induced protein denaturation and provide a unified framework for the decoding of the protein-water-solute nexus.

Layered V10O24·nH2O as a new ammonium ion host material for aqueous and quasi-solid-state ammonium-ion hybrid capacitors

Aqueous ammonium-ion hybrid capacitors (AIHCs) emerge as a promising candidate for efficient and sustainable charge storage. Yet, a pivotal challenge lies in the development of an ammonium ion (NH4+) host material that possesses high capacity and prolonged cycle life. Herein, we explore the potential of layered V10O24·nH2O, synthesized via electrodeposition method, for use in high-capacity aqueous NH4+ storage. Our investigation, supported by both experimental observations and first-principles theoretical computations, has demonstrated that the layered V10O24·nH2O exhibits commendable electrochemical performance for aqueous NH4+ storage, which is attributed to the presence of certain amount of crystal water and unique nanowire network structure. This allows for a high specific capacity of 203.1 mAh g−1 at 0.3 A g−1, and the capacity retention is 97.6 % after 20,000 cycles. Ex-situ characterizations uncovered that the insertion and extraction of NH4+ in the V10O24·nH2O layers are reversible processes, accompanied by changes in the oxidation states of vanadium and the reversible contraction and expansion of the interlayer spacing. Furthermore, the as-assembled AIHCs device not only exhibits a voltage window of 1.8 V, surpassing other types of hybrid capacitors, but also retains 82.8 % capacitance after 10,000 cycles, showcasing its good flexibility and potential for series–parallel combinations. The study highlights the potential of layered V10O24·nH2O electrodes for sustainable energy storage applications and offers some insights for high-performance hybrid capacitors with non-metallic NH4+ as the charge carrier.

The effect of dilution on the energy dissipation in water interstellar ice analogues

Context. Interstellar ices and their energetic processing play an important role in advancing the chemical complexity in space. Interstellar ices covering dust grains are intrinsically mixed, and it is assumed that physicochemical changes induced by energetic processing – triggered by photons, electrons, and ions – strongly depend on the content of the ice. Yet, the modelling of these complex mixed systems in experiments and theory is complicated. Aims. In this paper, we investigate the effect of infrared irradiation on a series of different molecules mixed with porous amorphous solid water (pASW) to study the release of vibrational energy in the hydrogen-bonding network of water as a function of mixing ratio and ice content. Particularly, we select mixtures of 20:1 H2O:X and 5:1 H2O:X with X=CO2, NH3, or CH4. Methods. Infrared radiation was supplied by the intense and tunable free electron laser (FEL) 2 at the HFML-FELIX facility. We monitored the structural changes in the interstellar ice analogue after resonant infrared excitation using Fourier-transform reflection absorption infrared (FT-RAIR) spectroscopy. Results. We observed that on-resonance irradiation at the OH-stretching vibration of pASW results in quantitatively identical changes compared to pure pASW for all investigated mixtures. The structural changes we observed closely resemble the previously reported local reordering. The 5:1 mixtures show weaker changes compared to pure pASW, with a decrease in strength from NH3 to CO2. Conclusions. Since the hydrogen-bonding network of pASW restructures similarly upon FEL irradiation, regardless of the mixing component, treating ice layers in models that simulate energy dissipation in the hydrogen-bonding network as pure H2O ice layers can be a justified approximation. Hence, complex systems might not always be necessary to describe the infrared energetic processing of ices.

Modeling the health impact of wastewater contamination events in drinking water networks

Pathogen intrusion in drinking water systems can pose severe health risks. To better prepare in planning and responding to such events, computational models that capture the intrusion and health impact dynamics are needed. This study presents a novel benchmark testbed that integrates current knowledge on pathogen transport and fate in chlorinated systems and can assess infection risk from contamination events. The model considers organic matter degradation, chlorine decay mechanisms, pathogen inactivation kinetics, as well as stochastic water demands.We studied modeling of wastewater intrusion events that can occur anywhere within a chlorinated and non-chlorinated network. We applied the Quantitative Microbial Risk Assessment framework focusing on three pathogens: enterovirus, Campylobacter, and Cryptosporidium, and their respective dose-response models. Synthetic household-level water demand time series were used to model the individual water consumption timing and calculate the infection risk (exposure via ingestion).Model outcomes indicate that while chlorination aids mitigation, larger contaminations can still lead to infections due to chlorine resistance (for Cryptosporidium) and chlorine depletion at the contamination point. In our example scenarios, chlorine-susceptible pathogens infected of the downstream population, while chlorine-resistant ones infected the entire downstream population. Enterovirus infection risk is higher, despite the concentrations in the contamination source being lower, due to the lower susceptibility to chlorine than Campylobacter. In non-chlorinated networks, the modeled wastewater contamination events led to infection risk in the total population, depending on the contamination location. Hydraulic uncertainty had a limited influence on infection risk. Furthermore, Campylobacter’s infection risk is more sensitive to the initial concentration in the contamination source whereas enterovirus infection risk to the inactivation rate. The model further indicates that the time window for effective mitigation of the magnitude of a waterborne outbreak is short (within hours).

High-temperature heat pumps in industrial heating networks: A study on energy use, emissions, and economics

Industrial heat significantly contributes to global primary energy use and primarily relies on fossil-fuel combustion. Recovering residual heat in the industry offers a means to reduce overall energy use. However, the temperature and amount of residual heat available varies widely across industrial sites. Some may have a large amount of residual heat available at relatively high temperatures, while others may not have any residual heat available. Furthermore, for most industries, the residual heat available is at temperatures below 100 °C, while the heat demands are at higher temperatures. Hence, clustering these industries by industrial heating networks, using high-temperature heat pump integration, could offer a promising solution. Research on this concept regarding energy use, emissions and economics is however lacking in the literature. This study however distinguishes and subsequently compares three different heat network configurations in terms of their energy use, carbon emissions and financial appraisal. These configurations include a ‘consumer based heat upgrading network’, a ‘supplier based heat upgrading network’ and a ‘supplier based heat upgrading network with an additional hot water network’. For this purpose a generic methodology is developed, using first and second law principles completed with empirical data for performance and costs. The methodology is applied to data collected from ten companies clustered within the North Sea Port, Ghent (Belgium). The results indicate that the first configuration exhibits the most efficient use of energy and consequently also has the lowest carbon emissions. In addition it also has the lowest levelized cost of heat. This configuration shows, depending on maximum supply temperature of the heat pump, a potential reduction in carbon emissions ranging from 70 % to 80 % in comparison to natural gas boilers. Considering low gas prices, a positive financial appraisal is difficult without carbon taxation. On the other hand, an evaluation during the energy crisis of 2021–2022 indicates that the even without carbon taxation, the levelized cost of heat decreases by 19 % compared to a gas boiler at a maximum heat pump temperature of 160 °C. It was also found that in scenarios of dynamic energy prices a hybrid configuration of a consumer based heat upgrading network and a natural gas boiler could lower the LCOH compared to the individual solutions, by up to 7.6 % compared to the best individual solution. This is done by activating the technology with the lowest operational cost in each time frame.

Hydrogen Spillover-Bridged Interfacial Water Activation of WCx and Hydrogen Recombination of Ru as Dual Active Sites for Accelerating Electrocatalytic Hydrogen Evolution.

Tungsten carbide (WCx) is a promising alternative to platinum catalysts for hydrogen evolution reaction (HER). However, strong tungsten-hydrogen bond hinders hydrogen desorption while favoring H+ reduction, thus limiting HER kinetics. Inspired by the phenomenon of hydrogen spillover in heterogeneous catalysis, a ruthenium (Ru) doped-driven activated hydrogen migration from WCx surface to Ru is reported. This approach achieved high activity with an ultralow overpotential of 9.0mV at 10 mA·cm-2 and superior stability at an industrial-grade current density of 1.0 A·cm-2 @ 1.65V. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS)and operando electrochemical impedance spectra revealed that this exceptional hydrogen production-which surpasses that of previously reported Pt/C catalysts-is attributable to the outstanding ability of WCx to induce water dissociation and hydrogen spillover from WCx to Ru surface. During the HER process, the rigid interfacial water network negatively affected the HER efficiency under alkaline conditions. The WCx sites disrupted this rigid structure, facilitating the contact between activated hydrogen (H*) and WCx sites. Subsequently, H* migrates to Ru surface, where hydrogen recombination occurs to produce H2. This work paves a new avenue for the construction of coupled catalysts at the atomic scale to facilitate HER electrocatalysis.

Water Networks within Metal Organic Nanotubes: Assessment of Techniques to Understand Structure and Properties.

AbstractHybrid materials, such as metal organic nanotubes (MONTs) can possess nanoconfined water molecules within their pore space and the overall behavior of the water within the material may be tuned based upon interactions with the inner channel walls. We have previously developed a range of methods (electron density mapping, kinetic models, and water interaction enthalpies) to evaluate water behavior under nanoconfinement using a uranium‐based metal organic nanotube (UMONT) but have not explored their applicability across a range of materials. In the current study, we test our methodologies on two additional MONT materials (LaMONT and Cu‐LaMONT) to determine if the techniques can be utilized in other systems to predict behavior within complex hybrid materials. In addition, we explored how to use Hirshfeld surface maps generated by the CrystalExplorer software in the visualization and prediction of water behavior within complex hybrid materials.

Proton transfer driven by the fluctuation of water molecules in chitin film.

Proton-transfer mechanisms and hydration states were investigated in chitin films possessing the functionality of fuel-cell electrolytes. The absolute hydration number per chitin molecule (N) as a function of relative humidity (RH) was determined from the OH stretching bands of H2O molecules, and the proton conductivity was found to enhance above N = 2 (80%RH). The FIR spectrum at 500-900cm-1 for 20%RH (N < 1) together with first-principles calculations clearly shows that the w1 site has the same hydration strength as the w2 site. The molecular dynamics simulations for N = 2 demonstrate that H2O molecules with tiny fluctuations are localized on w1 and w2, and the hydrogen-bond (HB) network is formed via the CH2OH group of chitin molecules. Shrinkage of the O-O distance (dOO), which synchronizes with the barrier height, is required for proton transfer from H3O+ to adjacent CH2OH groups or H2O molecules. Nevertheless, dOO is hardly modulated for N = 2 because H2O molecules are strongly constrained on w1 and w2, and therefore, the transfer probability becomes small. For N = 3, novel HBs emerged between the additional H2O molecules broadly distributed on the w3 site and H2O molecules on w1 and w2. The transfer probability is enhanced because large fluctuations and diffusions in the whole H2O molecule yield large modulations of dOO. Consequently, long-range proton hopping is driven by the Zundel-type protonated hydrates in the water network.

Dissecting the hydrogen bond network of water: Charge transfer and nuclear quantum effects

The molecular structure of water is dynamic, with intermolecular (H)-bond interactions being modified by both electronic charge transfer and nuclear quantum effects (NQEs). Electronic charge transfer and NQEs potentially change under acidic / basic conditions, but such details have not been measured. Here, we developed correlated vibrational spectroscopy, a symmetry-based method that distinctively separates interacting from non-interacting molecules in self- and cross-correlation spectra, giving access to previously inaccessible information. We found that OH − donated ~8% more negative charge to the H-bond network of water and H 3 O + accepted ~4% less negative charge from the H-bond network of water. D 2 O had ~9% more H-bonds compared to H 2 O, and acidic solutions displayed more dominant NQEs than basic ones.

Evaluation of Water System Connectivity Based on Node Centrality in the Tarim River Basin, Xinjiang, China

Water system connectivity is an important measure to optimize the balanced spatial allocation of water resources and water security patterns. Inland river basins in arid zones are generally insufficiently connected, so the scientific evaluation of the current status of water system connectivity and the centrality of its nodes in the water system network has practical significance for the scientific construction of regional water networks. Taking the Tarim River Basin in Xinjiang, China, as an object, this study conducted a comprehensive evaluation of basin water system connectivity by constructing a water system connectivity evaluation system with a total of 12 indicators for the three aspects of pattern connectivity, structural connectivity and functional connectivity. Subsequently, the TOPSIS model, with combined weights of the analytic hierarchy process and the entropy weight method, was used to comprehensively evaluate the connectivity of the watershed’s water system. The research evaluated the node centrality of the water system network that was closely related to the basin water system connectivity by using complex network analyses. The study results indicated the following: (1) among the source streams in the Tarim River Basin, the connectivity of the Aksu Basin was the best and that of the Keriya Basin was the worst and (2) the distribution patterns of the eigenvector centrality and betweenness centrality of the basin hydrological network nodes were similar, with nodes of highest centrality concentrated in the vicinity of the mainstems and the source–mainstem intersections. This work provides a basis and reference for the construction of water system connectivity and the selection of key control sections for ecological flow in the Tarim River Basin.

Different Adaption Strategies of Abundant and Rare Microbial Communities in Sediment and Water of East Dongting Lake.

The dynamics of aquatic microbes is of great importance for comprehending the acclimatisation and evolution of microorganisms in lake ecology. However, little is known about the adaption strategies of microbial communities in East Dongting Lake, which had special and complexity geographical characteristics. A semi-enclosed lake area (A) and a waterway connected to Yangtze River (B) both existed in the lake zone. Here, we investigated bacterial and fungal community diversity, community network and community assembly processes in sediment and water. The results indicated that the proportion of OTU numbers and their relative abundance for rare and abundant taxa were different obviously between sediment and water, but not between bacteria and fungi. However, abundant subcommunities dominated the shifts of bacterial community diversity and structure in A region, while rare subcommunities for fungal community diversity. Compared to fungal community, bacterial network was more compact and more key stones were identified as rare taxa. In addition, stochastic processes (dispersal limitation) drove the community assembly of abundant and rare subcommunities, but the effects of deterministic processes (including variable and heterogeneous selections) affected more on rare rather than abundant taxa. Partial Mantel test further indicated that the effect of environmental factors was a stronger force in shaping abundant bacterial subcommunities (TOC, NH4+-N, TN, and ORP) and rare fungal subcommunities (ORP). Environmental factors explained more of the variation in bacterial community structure than that in fungal community structure, although they had additional effects on fungal community diversity and community assembly. Moreover, bacterial community affected the fungal community as a biotic factor in water. This research provided new insights into better understanding of microbial communities in the complex environment of the East Dongting Lake.

Principal Component Analysis (PCA) of MALDI-TOF for the Identification of Waterborne Pathogenic Bacteria

The study focuses on the application of Principal Component Analysis (PCA) combined with MALDI-TOF MS (Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry) for the identification of waterborne pathogenic bacteria in urban water networks. In this comprehensive research, 168 bacterial strains were meticulously isolated from the water networks of Abidjan, Côte d'Ivoire, a region known for its inadequate wastewater treatment infrastructure. The analysis aimed to rapidly and precisely identify these bacterial pathogens, leveraging the power of MALDI-TOF MS and the sophisticated data reduction capabilities of PCA. This approach not only accelerates the identification process but also enhances the accuracy of detecting various pathogens. The study identified a diverse range of pathogens, including Pseudomonas aeruginosa, Escherichia coli, Salmonella, Shigella, Vibrio cholerae, Morganella morganii, Proteus mirabilis, Acinetobacter baumannii, Klebsiella pneumoniae, Providencia rettgeri, Providencia stuartii, Aeromonas hydrophila, Bacillus cereus, Lysinibacillus fusiformis, Lysinibacillus sphaericus, and Staphylococcus aureus. These findings underscore the critical public health risks posed by microbial contamination in water networks, particularly in areas with deficient waste management systems. This study highlights the necessity for improved wastewater management practices, robust public health strategies, and regular monitoring to mitigate the risks associated with waterborne pathogens. Moreover, the integration of PCA with MALDI-TOF MS proves to be a powerful tool for enhancing the efficiency and accuracy of pathogen identification in environmental water samples, offering a promising solution for better public health protection and water quality management in urban settings.

Towards more realistic stochastic modelling of leakage in water distribution systems

ABSTRACT A new stochastic model is developed to predict leak types and sizes in water distribution systems. By linking records of actual failures in water networks with new tools for stochastic modelling, the study provides more accurate estimates of network leakage behaviour. District metered areas (DMAs) have been adopted internationally as best practice for monitoring and controlling leakage, with the infrastructure leakage index (ILI) as the main performance indicator. The leakage exponent (N1), which quantifies the relationship between leakage rate and pressure, is a key parameter in describing DMA leakage behaviour. After analysing thousands of stochastic networks for different combinations of pipe material and ILI, the study found that different pipe materials have distinct leakage exponent distributions. Iron and asbestos cement (AC) pipes display N1 values close to 0.5, polyvinyl chloride (PVC) pipes have the highest N1 values, and polyethylene (PE) lies between PVC and iron/AC. The study further showed that current guidelines linking ILI to N1 for different pipe materials depart substantially from the observed results, indicating that these guidelines may need to be updated. The study provides a tool for more realistic modelling of leakage that offers valuable insights into the behaviour of leakage in different pipe materials.

Smart Building Digital Twin for Interior Water Distribution System Management

Abstract. A smart campus integrates the Internet of Things, artificial intelligence, and real-time sensor data to optimize campus functions and create a context-aware decision-support platform for effective campus management. A crucial aspect of a smart campus is the water distribution system, which faces several challenges due to bursts, leaks, and water quality issues. This study uses Digital Twin technology to address these challenges through real-time monitoring, detection, and management of campus water distribution networks. A building-level digital twin is developed for the interior water networks of the Daphne Cockwell Complex at Toronto Metropolitan University. The major components include a 3D network model capable of analysis and simulations, a smart water management system, and real-time visualization. A 3D static model of the interior water utility network is created using the Industrial Foundation Class data. The semantic and topological models based on graph models are developed for network analysis. The models are integrated into the ESRI ArcGIS Pro to facilitate BIM-GIS integration. A dynamic model is created by incorporating automatic meter readings based on IoT. Combined with the 3D model of the utility network, the digital twin monitors and visualizes building water consumption, facilitating anomaly detection and real-time maintenance by the facilities management department. This study provides practical guidance for managing water distribution systems in university buildings, with potential applications in other complex environments. Future work aims to develop a system for detecting complex event processes by integrating different utilities.

Hydrogels Innovation: A Review on Recent Development, Characterization, and Applications

Hydrogels are special materials that can hold a large amount of water and form 3D networks. In the past few years, there have been exciting improvements in hydrogel technology, bringing new ideas to many different areas. By trying out new materials like smart hydrogels that can respond to different conditions, provided new ways to deliver medicine precisely, build tissues, and create wearable gadgets. Among the most significant developments is the creation of smart hydrogels, which can react dynamically to different environmental stimuli. With their ability to release therapeutic chemicals under regulated conditions in response to particular physiological cues, these intelligent materials have enormous potential for the administration of precision medicine. These kinds of customized drug delivery systems have the power to completely change how treatments are administered by reducing adverse effects and increasing therapeutic efficacy. Hydrogels are also useful in tissue engineering, where they are used as scaffolds to create biological tissues that function. Hydrogel-based tissue constructions, which imitate the extracellular matrix, offer a favorable microenvironment for cell proliferation and differentiation, promoting the healing of injured or ill tissues. With its enormous potential in regenerative medicine, this revolutionary strategy offers hope for the treatment of ailments including organ failure. this article gives a thorough look at the recent developments in hydrogels, characterization techniques, and the new application of hydrogels in various fields of science. In summary, new developments in hydrogel technology have opened up a plethora of opportunities in a variety of scientific fields. The adaptable properties of hydrogels continue to spur innovation in a variety of fields, including wearable technology, tissue engineering, and precision medicine. These applications offer revolutionary answers to urgent social issues.

Comparison of passive and manual chlorination in small piped water networks in rural Ghana: Technical performance, ease-of-use, and cost

Chlorination is the most common water treatment method globally and leads to proven health benefits. Yet, many rural water supplies in low-income settings are unchlorinated, exposing consumers to waterborne diseases. Insufficient technical and financial capacity of water suppliers in low-resource settings are common barriers to more widespread chlorination. We conducted a case study of two approaches to chlorinate small piped water supplies− passive (inline) chlorination and manual chlorination− and compared their technical performance, ease-of-use, and costs in rural Ghana. Based on 685 water quality measurements across two piped networks over three months, both methods provided adequate free chlorine residuals (i.e., 0.2–2.0 mg/L) most of the time (71% for manual chlorination and 86% for passive chlorination). Follow-up measurements five months later revealed a decline in chlorine levels with the manual approach (47% in the target range) and an increase with the passive (inline) approach (100% in the target range). We observed large fluctuations in chlorine levels over time, particularly with inline chlorination, that pH, temperature, conductivity, and turbidity variations did not fully explain. Temporal changes in chlorine demand and/or inconsistently implemented protocols possibly contributed to these fluctuations. Inline chlorination scored higher for ease-of-use (85%) than manual chlorination (70%) but was less financially viable: it represented an 11% increase in operational expenses, compared to 4% for manual chlorination. Initial equipment and installation cost approximately 6,000 USD for inline chlorination and about 260 USD for manual chlorination. Our results highlight the tradeoffs between passive (inline) and manual chlorination. Although less favorable for ease-of-use, manual chlorination is more viable financially and can achieve comparable performance with strict dosing protocol adherence, suggesting this approach deserves similar consideration as passive chlorination when evaluating options for low-resource settings. Both methods are susceptible to changes in operator behaviors and require external oversight plus support for troubleshooting and recalibration.

The Holocene evolution of the fluvial system of the southern Hessische Ried (Upper Rhine Graben, Germany) and its role for the use of the river Landgraben as a waterway during Roman times

Abstract. Intensive human intervention in the natural drainage system of the Hessische Ried (Upper Rhine Graben, Germany) resulted in the transformation of a large wetland into an intensively used cultural landscape. At least since the first century CE, when Romans conducted early river regulation and water management, the natural water network has experienced extensive anthropogenic re-organisation. The LandGraben project focuses on the reconstruction of the natural and anthropogenic watercourse systems along the river Landgraben, a tributary to the river Rhine in the northern Hessische Ried. Several rivers from the southern Hessische Ried could have fed the river Landgraben during Roman times via the meandering Palaeo-Neckar depression, thus increasing both length and discharge of the Roman waterway. In this study, we present results of our investigations within the southern Hessische Ried to reconstruct the former channel network that was used by Romans for the transportation of troops, wares and border security. Our approach integrates the use of high-resolution digital elevation models (DEMs) as a base for geophysical measurements (electrical resistivity tomography, ERT), direct push sensing and sediment coring in combination with sedimentological and geochemical analyses of the encountered sedimentary units. Local chronostratigraphies were established based on radiocarbon dating. Based on our results, we are able to differentiate a palimpsest of several abandoned fluvial channels throughout the southern Hessische Ried and to reconstruct the spatio-temporal development of the corresponding fluvial systems. Chronostratigraphic data show that the Palaeo-Neckar stopped flowing through the Hessische Ried around 10 000 cal BCE. Moreover, we found that the river Weschnitz, the largest of the possible Landgraben tributaries, stopped flowing through the Palaeo-Neckar depression at ca. 3000 cal BCE. Instead, it took a right-angled shortcut westwards to the river Rhine, north of the city of Lorsch. For the first time, we present geomorphological evidence that the river Weschnitz was not diverted by the Romans as speculated so far. This is corroborated by numerous wooden posts of human-made construction crossing an E–W running water course at the modern Weschnitz knee, with the oldest posts being dendrochronologically dated to the fourth and third millennia BCE. We further argue that the river Winkelbach/Lauter formed its knee towards the river Rhine and thus left the Palaeo-Neckar depression not later than the second century CE but most probably even contemporaneously with the formation of the Weschnitz diversion. In the case of the Winkelbach/Lauter, a high-energy flood event presumably related to strong rainfall and/or meltwater processes in the Odenwald Mountains is assumed to be responsible for the initiation of the new, diverted water course. With regard to the Landgraben and its use as a waterway within the Roman fluvioscape of the Hessische Ried, we therefore conclude that the Romans successfully collected water from several smaller rivers, such as from the rivers Modau and Darmbach and from even smaller tributaries, to make the river Landgraben a navigable waterway. The rivers Weschnitz and Winkelbach/Lauter, however, did not contribute any water to the Landgraben system during Roman times.