In water resources management, remote sensing data and techniques are essential in watershed characterization and monitoring, especially when no data are available. Water quality is usually assessed through in-situ measurements that require high cost and time. Water quality parameters help in decision making regarding the further use of water-based on its quality. Turbidity is an important water quality parameter and an indicator of water pollution. In the past few decades, remote sensing has been widely used in water quality research. In this study, we compare turbidity parameters retrieved from a high-resolution image with in-situ measurements collected from Borabey Lake, Turkey. Here, the use of RapidEye-3 images (5 m-resolution) allows for detailed assessment of spatio-temporal evaluation of turbidity, through the normalized difference turbidity index (NDTI). The turbidity results were then compared with data from 21 in-situ measurements collected in the same period. The actual water turbidity measurements showed high correlation with the estimated NDTI mean values with an R² of 0.84. The research findings support the use of remote sensing data of RadipEye-3 to estimate water quality parameters in small water areas. For future studies, we recommend investigating different water quality parameters using high-resolution remote sensing data. Full article

With the growing concerns over emerging contaminants in indirect potable reuse (IPR) applications, we investigate the impact on human health risk of emerging contaminants introduced into groundwater. Some emerging contaminants have potential endocrine-related health effects at a specific exposure range that is much lower than current guidelines. We start by analyzing Bisphenol A (BPA), which is one of the frequently detected emerging contaminants in groundwater. The objective of this study is to understand how the non-trivial toxicity of BPA affects the estimation of human health risks and, consequentially, aquifer resilience. Based on our results, we aim to provide indications on how to improve water resources management in BPA contaminated sites. We use numerical methods to model BPA contamination of a three-dimensional aquifer, and human health risks and aquifer resilience are estimated at a control plane representing an environmentally sensitive target. A Monte Carlo simulation is conducted to compute uncertainty associated with two levels of heterogeneity. In order to evaluate health risks due to BPA, two types of Dose-Response (DR) models are considered: the monotonic DR model for general exposure and the non-monotonic DR model for prenatal/postnatal exposure. The aquifer resilience is defined as the capacity to recover the state where groundwater is considered potable (i.e., negligible health risks due to BPA). When using the non-monotonic DR model, computational results indicate that the aquifer resilience reduces and its uncertainty increases as the aquifer heterogeneity increases. On the other hand, the aquifer resilience considering the monotonic DR model enhances, and its uncertainty increases relatively smaller than the one considering the non-monotonic DR model. In addition, the variability of the aquifer resilience is controlled by the residence time of the BPA plumes at the control plane, which is related to the volumetric flow rate at the front side of the contamination source. Finally, the decision-making strategy for BPA contaminated sites should be established in accordance with the heterogeneous structure of aquifer and land uses that determines which DR model of BPA is more important in estimating the aquifer resilience. Full article

The effluent of tanneries is a hazardous waste and a combination of physical-chemical and biological techniques is required for its treatment. As a result of the previous processes, a sludge with high chromium content is produced. So, the aim of this study is the hydrometallurgical recovery of chromium in the context of a circular economy. According to chemical characterization, the only form of metal that existed in the sludge was the trivalent, while its content was up to 14.8% w/w. Among the examined acids, the highest efficiency in Cr(III) leaching was achieved by the H₂SO₄ (93%), due to the formation of the soluble CrSO₄⁺. Regarding the step of precipitation, no significant varions were observed between the two alkaline medias that were tested, namely NaOH and Ca(OH)₂. Full article

The subsea transmission main (TM) of Trieste, Italy, plays a crucial role in the water supply system managed by AcegasApsAmga SpA (Hera Group). With the aim of implementing a systematic inspection procedure (at present divers are used for periodic surveys) AcegasApsAmga SpA decided to proceed with Transient Test-Based Techniques (TTBTs). In this paper, the results of preliminary transient tests generated by means of the existing devices (the first option to be considered within TTBTs) are discussed and possible alternatives are highlighted. Full article

According to a recent report by World Health Organization, the countries which still have limited access to water for drinking purposes are mainly those in the Sub-Saharan region. (Potential) water sources for drinking needs may contain different contaminants. In this context, the current study consists in an overview of the quality of surface water and groundwater in the Republic of South Africa (RSA) and Mozambique (MZ) and provides the variability ranges of the concentrations of the main pollutants in the two countries. Chemical and physical characteristics and concentrations of macropollutants, inorganic compounds (metals) and selected microorganisms were collected for surface water and groundwater and compared with the standards for drinking water set in the two countries. It was found that in surface water, microorganisms were always at very high concentrations. In addition, nickel (in RSA) and boron and chlorine (in MZ) were the most critical compounds. It emerged that in groundwater, arsenic, lead and chlorine (in RSA) and boron, sodium and chlorine (in MZ) were the main critical pollutants. Adequate treatments in the construction of new drinking water plants in rural areas should be selected on the basis of these most critical compounds and their observed variability over time. Full article

Wastewater treatment plants (WWTPs) are responsible for attenuating the environmental impact that waste in effluent discharged to receiving waters has. As a consequence of this, new techniques for an effective control are valuable, not just for minimising this impact, but also for minimising operational costs by using energy efficiently. Such kinds of problems, with several objectives to fulfil (and usually in conflict), are termed as multi-objective problems. Within this context, multi-objective optimisation techniques have been shown to be a valuable tool in the control engineering field to tune different kinds of controller for complex systems. To accomplish this, a simultaneous optimisation approach is carried out, in order to approximate a set of Pareto-optimal solutions. Such solutions differ in the level of trade-off exhibited in two (or more) conflicting objectives. The multi-objective approach for controller tuning in one-input/one-output processes is well documented in the literature. Nevertheless, that is not the case of multivariable control. This fact is mainly due to the quantity of design objectives required to evaluate the multi-objective performance of several outputs. In this work, we elaborate a proposal to handle multi-objective problems for multivariable processes. Performance evaluation is performed (via simulation) in a multivariable benchmark for the PI control of an activated sludge process with nitrification and denitrification. Full article

Recent development dynamics of urban centers forced administrations to deal more frequently with problems linked to the inability of traditional sewer systems to manage rainwater in a sustainable and effective manner. Currently, several laws require compliance with the quantitative and qualitative stormwater limits to be discharged into watercourses but, in parallel with a “regulatory” approach, integrated strategies are increasingly being developed. A fundamental role is carried out by Sustainable Drainage Systems (SuDS), whose basic principle is the management of rainwater at the source, through the implementation of prevention, mitigation and treatment strategies. This study, starting from a project proposal made by different Italian firms and funded by PoliS-Lombardia, aims to assess the benefits deriving from the widespread application of SuDS in the Sesto Ulteriano industrial area, through a comparison between a scenario that represents the current configuration of the drainage network, and an ideal scenario where SuDS are taken into consideration. SWMM5 software was used, in order to simulate the behavior of the drainage network in contexts without and with SuDS, after the construction of the synthetic rainfall data sets. Although only event scale simulations have been conducted so far, the encouraging results suggest that these systems really contribute can to mitigating the effects of flooding in urban areas. Full article

The importance of identifying the areas vulnerable for both floods and flash-floods is an important component of risk management. The assessment of vulnerable areas is a major challenge in the scientific world. Adaptation and mitigation have generally been treated as two separate issues, both in public politics and in practice, in which mitigation is seen as the attenuation of the cause, and studies of adaption look into dealing with the consequences of climate change. Studies on the impact of climate change on flood risk are mostly conducted at the river basin or regional scale. Remote sensing and GIS technologies, together with the latest modelling techniques, can contribute to our ability to predict and manage floods. Various methods are commonly used to map flood sensitivity. Recent methods such as multicriteria evaluation, decision tree analysis (DT), fuzzy theory, weight of samples (WoE), artificial neural networks (ANN), frequency ratio (FR) and logistic regression (LR) approaches have been widely used by many researchers. Full article

Green infrastructures can provide multiple benefits and play an important role in cities’ resilience to extreme stormwater events caused by climate change. Additionally, these techniques can contribute to the protection of transport infrastructures, averting major environmental and economical adversities. Stormwater can be treated through several processes, some processes being more effective than others for specific contaminants. A review of some of the most commonly used green infrastructures (GI) for stormwater management in urban environments was carried out, with emphasis on their efficiency in reducing peak flow rates, runoff volumes and the following pollutants: total suspended solids, heavy metals, total phosphorus and total nitrogen. The GI studied were green roofs, bioretention systems, filter strips, vegetated swales and trenches. In addition to the advantages in the urban water cycle, benefits of amenity and ecosystem services of these GI have also been identified. The discussion of the results and the comparative analysis of GI performance were carried out taking advantage of a table that summarizes the range of percentages of GI efficiency obtained in various studies for the different functions. Full article

The evolving climate conditions contribute to increase flooding risk in urban areas. Green roofs are effective tools for controlling and managing stormwater runoff. With the aim to prevent these damaging events, an accurate modelling of the response of green roofs to storm events becomes essential. The goal of this research is to compare the accuracy of two hydrological models in predicting the behavior of two green roof test beds in terms of runoff production. The test beds are located in the campus of University of Salerno, in a typical Mediterranean climate and they differ in the composition of the drainage layer. The selected models are the Storm Water management model (SWMM) model and the Nash model. They have been calibrated against hourly data of 25 rainfall-runoff events observed at the experimental site and compared using a number of goodness of fit indexes. The Nash cascade model aims to be a very simple but effective approach. No substantial differences were observed in the behavior of the two green roof plots, though they differ in their design characteristics. Finally, the existence of a relationship between the errors and the rainfall characteristics has been found. Full article

Over the last 30 years, constructed wetlands (CWs) have been used as an alternative, cost-efficient way of treating wastewater, often in combination with conventional wastewater technologies. When CWs are attached at the end of conventional wastewater treatment plants, they treat the effluent and thus provide a polishing step. However, recent studies have shown that when CWs are used as the main wastewater treatment method for the agricultural reuse of effluents, they perform poorly on meeting the accepted limit of microbial contamination. Moreover, CWs are increasingly used within the scope of the circular economy and water reuse applications. Therefore, there is a need for a comprehensive exploration of the performance of CWs on pathogen removal. This paper explores relevant case studies regarding pathogen removal from constructed wetlands to create a comprehensive dataset that provides a complete overview of CWs performance under various conditions. After a systematic literature review, a total of 48 case studies were qualified for both qualitative and quantitative analyses. From the dataset, the general performance, optimal conditions, and knowledge gaps were identified. The review confirmed that constructed wetlands (as a standalone treatment) cannot meet the accepted limits of pathogen removal. However, they can be a credible choice for wastewater polishing when they are combined with conventional wastewater treatment systems. Regarding the most common indicators that were recorded, the removal of Escherichia coli ranged between 0.01–5.6 log; the removal of total and fecal coliforms was 0.2–5.32 log and 0.07–6.08 log, respectively; while the removal of fecal streptococci was 0.2–5.2 log. The great variability of pathogen removal indicates that the complexity of CWs makes it difficult to draw robust conclusions regarding their removal efficiency. Potential correlations were identified between influent and effluent concentrations, as well as between log removal and hydraulic characteristics. Additionally, no correlations between pathogen removal and temperature/climatic zones were found since average pathogen removal per country showed high variation throughout the various climatic zones. The dataset can be used as a benchmark of CWs’ performance as a barrier against the spreading of pathogens in the environment. The knowledge gaps identified in this review can provide direction for further research. Finally, a potential meta-analysis of the dataset using statistical analysis can pave the way for a better understanding of the design and operational parameters of CWs in order to fine-tune and quantify the factors that influence the performance of these systems. Full article

Silica gel was used as an adsorbent for dyes in aqueous solutions. Afterwards, the silica gel with the adsorbed dye was heated to 600 °C, at which the dye combusted, leaving behind clean silica gel. This silica gel can be reused in the adsorption process. The operation leaves behind little waste products. It is an optimal procedure for educational and other research laboratories which are working with biological stains, food colorants and some non-commercial dyes. Full article

The current approach to stormwater management should focus on dealing with water on its source. The Sustainable Urban Drainage Systems (SuDS) promotes runoff peak flow and volume attenuation, load removal while providing amenites and biodiversities but can be difficult to apply in developed urban centers. An infiltration-exfiltration system (IES) placed on road gutters can function on receiving runoff from roads and directing them to the sewers system reducing peak flow and volume. This research follows up a full-scale test of an IES installed in São Paulo, Brazil. The IES has 49 × 1880 m dimension and a cross-section of 49 × 30 cm with a pervious concrete surface layer. The pervious concrete showed mechanical results acceptable for a low vehicular traffic and infiltration rate that allows water infiltration. Rainfall-runoff modeling showed that the proposed IES had a low effect on runoff peak flow and volume attenuation. A deeper gravel layers depth and outlet flow restrictor would improve performance. The proposed IES function on avoid ponding, promoting water treatment, and reducing inlet maintenance. Full article

Water pollution is a critical environmental issue nowadays. One major problem is the pollution of freshwaters by pollutants of low concentrations (ng/L–μg/L), known as micropollutants. The most promising techniques for micropollutants degradation are Advanced Oxidation Processes (AOPs). Heterogeneous catalytic ozonation is among them, and recent studies have shown that it can be an efficient water treatment technique. The aim of this study is to evaluate the catalytic activity of five minerals (anatase, dolomite, kaolin, talc and zeolite) on the ozonation of small concentrations of p-CBA at pH 7 by batch mode experiments. p-CBA was employed as a model compound for evaluation of single and catalytic ozonation performance, because it cannot be efficiently removed by direct ozonation (k_O3 < 0.15 M⁻¹s⁻¹), while it has high reactivity with hydroxyl radicals (k^·_OH = 5×10⁹ M⁻¹s⁻¹). It was found that all applied solid materials can be characterized as catalysts, except kaolin, theuse of which presented almost the same performance with single ozonation. The best results were obtained by zeolite and dolomite (>99.4%) within 15 min reaction/oxidation time. These materials were neutrally (PZC = 6.8) and positively (PZC = 8.9) charged, respectively, during the oxidation process (pH 7), favoring the contact of micropollutant and ozone with the catalysts’ surface. On the other hand, the addition of anatase and talc in the ozonation system resulted in 97.5% and 98.5% p-CBA degradation, respectively, due to their slightly negative surface charge throughout the reaction. Conclusively, the experimental results indicated that the performance of heterogeneous catalytic ozonation is strongly depending on the surface charge of the solid materials (catalysts). Full article

The success of the analysis and design of a Water Network (WN) is strongly dependent on the veracity of the data and a priori knowledge used in the model calibration of the network. This fact motivates this paper in which an off-line approach to verify datasets acquired from WN is proposed. This approach allows the data separation of abnormal and normal events without requiring high expertise for a large raw database. The core of the approach is an unsupervised classification tool that does not require the features of the different events to be identified. The proposal is applied to datasets acquired from a Mexican water management utility located in the center part of Mexico. The datasets are pre-processed to be synchronized since they were recorded and sent with different and irregular sampling times to a web platform. The pressures and flow-rate conforming the datasets correspond to the dates between 25 June 2019 @ 00:00 and 25 September 2019 @ 00:00. The District Metered Area (DMA) is formed by 90 nodes and 78 pipes, and it provides service to approximately 2000 consumers. The raw data identified as generated by abnormal events are validated with the reports of the DMA managers. The abnormal events identified are communication problems, sensor failures, and draining of the network reservoir. Full article

One of the most undesirable failures is water loss due to leaks in the supplying system; there are mainly two types of water losses: the visible and the non-visible. Within the non-visible we have those that are detectable by acoustic methods and those that are not. Here we decide to study new techniques for leak detection, since non-visible leaks are more difficult to find (detect). This is the aim of this paper. In a previous stage we have been studying the possibility of obtaining thermographic images to develop visualization techniques on pipes as an option for leak detection. Analyzing this possibility, with previous studies we have established conditions for taking images for later analysis, which has confirmed the benefits of the use of thermography as a tool. Here we present a case study where images were taken in a controlled atmosphere in a laboratory, using a physical model that contained a buried pipe with a simulated loss of water. During the entire duration of the test, images were taken at a certain interval of time and afterwards the images were analyzed. The results show the benefits and limitations of the technique, which should continue to be studied since thermal imaging cameras and computers to process the images are becoming more powerful and accessible by the day. Full article

The Water Framework Directive (WFD, EC, 2000) states that the “good” ecological status of natural water bodies must be based on their chemical, hydromorphological and biological features, especially under drastic conditions of floods or droughts. Phytoplankton is considered a good environmental bioindicator (WFD) and climate change has a strong impact on phytoplankton communities and water quality. The development of robust techniques to predict and control phytoplankton growth is still in progress. The aim of this study is to analyze the impact of the different stressors associated with the change in phytoplanktonic communities in small rivers in the center of the Iberian Peninsula (Southwestern Europe). A statistical study on the identification of the essential limiting variables in the phytoplankton growth and its seasonal variation by climate change was carried out. In this study, a new method based on the partial least-squares (PLS) regression technique has been used to predict the concentration of phytoplankton and cyanophytes from 22 variables usually monitored in rivers. The predictive models have shown a good agreement between training and test data sets in rivers and seasons (dry and wet). The phytoplankton in dry periods showed greatest similarities, these dry periods being the most important factor in the phytoplankton proliferation Full article

Spinel ferrite MFe₂O₄ (M = Cu, Ca, Mg, Ni, etc.) nanoparticles and their composites are a new promising materialbecause they have shown great interest in the field of sensing, optoelectronics, catalysis, and solar cells due to their unique physical and chemical properties that differ from their bulk structures. Today, lots of CuFe₂O₄ nanomaterials have been synthesized by different methods, such as hydrothermal route and sol-gel combustion methods. Nevertheless, there are hardly any results about photocatalytic activity. For this reason, we tried to increase optical properties by preparing a composite of CuFe₂O₄ nanomaterials with other oxides. In this paper, a CuFe₂O₄@CuO magnetic composite was synthesized via an ultrasound method. The samples prepared were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance spectrpscopy (DRS), field emission scanning electron microscopy (FESEM) images, vibrating sample magnetometer (VSM), and elemental analysis (energy-dispersive X-ray (EDX)). The catalytic activity of as-synthesized CuFe₂O₄@CuO was evaluated using the degradation of methylene blue. Furthermore, a possible reaction mechanism was discussed. Finally, the catalyst was used for effective degradation of methylene blue (MB) in its solution, which indicated a potential for practical applications in water pollutant removal and environmental remediation. Full article

A challenge to managing water resources is characterizing the heterogeneity created by the interactions among hydrological, ecological and anthropological processes. An option applied to other scientific disciplines includes identifying and analyzing emergent phenomena in complex systems, whose components self-organize into novel structures or processes via their collective interactions with each other and the environment. A new level of organization and complexity emerges that cannot be predicted from or attributed to the components alone. Predictions based on the functionally emergent properties of watershed systems (top-down) differ from predictions based on reductionist models (bottom-up). This presentation reviews the ways in which emergent properties may be applied to water resources and associated systems. Full article

The St. Johns River watershed, located in Florida, USA, is the focus of planning efforts to improve the resiliency and management of water resources infrastructure from current and future flood threats. These threats are driven by intense urbanization of the basin combined with increased frequency and intensity of coastal storms, made worse by sea level rise. Research efforts have begun to develop a comprehensive system of coupled numerical simulation models of the entire watershed in order to assess the current and long-term risks from flood inundation. This study provides a discussion of the system-wide model design and preliminary development. The study first outlines the project area and various numerical models to be coupled together. Then, the study discusses preliminary model development efforts and challenges. This initial study revealed the overall complexity and size of the undertaking. Overall, the study’s primary conclusion is that while an integrated system of coupled models is feasible and potentially very useful for long-term planning, the computational challenges for such an undertaking are extensive. Full article

Flushing plans within a water distribution network (WDN) provide a tool for improving disinfectant residuals and removing stagnant water. The problem of low disinfectant residuals occurs in areas of a WDN such as dead-end nodes, in which low flow conditions and long residence times lead to excessive decay of the disinfectant upstream from users. Here, a methodology is presented to maintain adequate disinfectant residuals in WDNs that have numerous dead-end nodes. The slight increase in nodal outflows at these sites, which can be obtained through the opening of a blow-off at the hydrant site, can help in tackling this problem. The methodology is based on the combined use of optimization and of flow routing/water quality modelling. The concentration of disinfectant at the source(s) and the values of nodal emitter coefficients at the critical dead-end nodes are the decisional variables to be optimized. Two objective functions are considered in the optimization, namely the total volume of water delivered in the network and the total mass of disinfectant injected into the network. The effectiveness of the methodology is proven on a real WDN, yielding an insight into the economic feasibility of the solution. Full article

Proper design of a pumping system requires the use of a pump curve and set-point curve system. Both have to be as close as possible to optimize energy use. This is achieved by control systems in which the type of control (flow or pressure) and the combination between fixed speed drive (FSD) pumps and variable speed drive (VSD) pumps are involved. The objective of this work is to determine the optimal number of FSD and VSD pumps for each flow rate range in order to discuss the classic design of pumping stations and their control systems. For this, a methodology is applied that defines the parametric form of the pump curve, efficiency curve, and set-point curve in relation to the most efficient point. In this way, dimensionless expressions are obtained and the influence of the set-point parameters on the design of the control system can be analyzed. Additionally, the method includes an expression that estimates the performance of the frequency inverter, which is based on the load and pump speed rotation. The application of the methodology to different case studies allows us to question many classic procedures for pumping stations. In summary, it can be concluded that the appropriate number of variable speed pumps for each control system cannot be established in advance but requires an in-depth study of different available options. Full article

Nutrients’ removal from residential and industrial wastewaters is essential for environmental and public health protection. Removal of nutrients from wastewater can be achieved chemically or biologically. Biological nutrient removal (BNR) uses a series of anaerobic, anoxic, and aerobic zones to provide conditions for the biomass to uptake the nitrogen and phosphorus species and comes in different configurations such as A/O, A2O, and five-stage Bardenpho^TM. However, BNR systems require a sufficient carbon source which most wastewaters lack. The goal of this study is to use a sustainable carbon source to optimize the five-stage Bardenpho^TM BNR systems and reduce the chemical cost. The experiments were carried out using two five-stage Bardenpho^TM BNR systems coupled with side-stream prefermenters. Glycerol, a biodiesel by-product, was used as a sustainable carbon source by direct addition or after fermentation. The results from both systems were beneficial to the BNR system and resulted in similar effluent quality. Both systems achieved complete denitrification and excellent phosphorus removal (82–89%). Co-fermentation of glycerol and primary solids resulted in a significant increase in the volatile fatty acid (VFA) loading beyond the estimated results, but did not correlate to better behavior between the two pilots since both systems achieved complete denitrification. Full article

Even though Ecuador is a country with one of the highest concentration of rivers per square kilometer, its water resources are of poor quality d there is a lack of drinking water and sewage systems for its population. In 2013, only 34% of the rural population had access to drinking water and 25% to sewerage services. This is because of a lack of infrastructure and the necessary budgets allocated to them. This paper deals with a proposal for water purification that consists of the use of the Moringa olifeira plant to facilitate the flocculation process, considering that its use reduces the costs associated with the water treatment and minimizes the concentration of metals in the residual sludge. The dosage effects of the plant seeds during the flocculation processes were explored with Jar tests using a solution in doses from 250 to 350 mg per liter of water and then evaluating Chemical Oxygen Demand (COD) and turbidity as selected response variables. The COD reduction goes from the 45% to 55% while the turbidity reduction goes from the 77% to 81%, making the use of the plant possible and feasible. Full article

Quantifying groundwater resources is important for effective water resource planning and management at the river basin scale, and it has to take into account all the natural and anthropogenic components of the water balance, i.e., rainfall and runoff processes, as well as mutual interactions between surface water and groundwater, but also artificial groundwater recharges (i.e., from irrigation) and groundwater extractions. In the present study, a reverse hydrogeological balance model was applied to estimate the active mean annual recharge of the northern Etna groundwater system within the Alcantara river basin in the Sicily region (Italy), based on precipitation, temperature, and potential evapotranspiration in the area. The main objective of this study was to quantify how the digital elevation model (DEM) resolution influences the groundwater resource estimation through the abovementioned methodology and how this is also influenced by the method for potential evapotranspiration assessment. Groundwater and surface flow for our case study have been evaluated for five different DEM resolutions (20, 60, 100, 300, 500 m) and with three different theoretical approaches for evapotranspiration calculation (Turc Method, Modified Turc Method, and Budyko Method). Results were validated against isochronous recorded data of river discharge at the Moio Alcantara cross-section and show how the reverse hydrogeological balance method shows better performance if implemented with the Budyko Method for estimating evapotranspiration and by using a DEM with a 60 × 60 m grid resolution. Full article

Pressure reducing valves (PRVs) effectiveness for water distribution networks’ (WDNs’) optimal pressure management is proven, but problems and operational limitations have been highlighted by some recent studies. In this work, the functioning of a piston-actuated pressure reducing valve (PA-PRV), subjected to low flow regimes, is investigated by means of a laboratory test set. The results obtained highlight that the PA-PRV tends not to respect the imposed set-point value, and can present an unstable behaviour, characterised by significant pressure oscillations under some flow-rate conditions. Full article

The Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) of the United Nations mentions that extreme rainfalls might increase their intensity and frequency in most mid-latitude locations and tropical regions by the end of this century, as a consequence of the rise of the average global surface temperature. Human action has given way to global warming which manifests with an increase in extreme rainfall. If these climatic conditions are added to the waterproofing that cities have been experiencing as a result of urban development, a scenario of growing concern for the managers of drainage systems is generated. The objective of drainage networks is preventing the accumulation of rainwater on the surface. Under the new conditions of climate change, these need to be modified and adapted to provide cities with the security they demand. The following article describes a method for flood control by using a rehabilitation model that connects the Storm Water Management Model (SWMM) 5 model with a genetic algorithm to find the best solutions to the flood problem. The final analysis is performed using the Pareto efficiency criteria. The innovation of this method is the inclusion of a local head loss in the drainage network, allowing the upstream flow to be retained by decreasing the downstream concentration time. These elements called hydraulic controls improve system performance and are installed in the initial part of some pipes coming out of storm tanks. As a case study, the developed method has been applied in a section of the drainage network of the city of Bogotá. Full article

Non-Newtonian fluid flow in a single fracture is a 3D nonlinear phenomenon that is often averaged across the fracture aperture and described as 2D. To capture key interactions between fluid rheology and spatial heterogeneity, we adopted a simplified geometric model to describe aperture variability, consisting of adjacent one-dimensional channels with constant aperture, each drawn from assigned aperture distribution. The flow rate was then derived under the lubrication approximation for the two limiting cases of an external pressure gradient that was parallel/perpendicular to the channels; these two arrangements provided an upper/lower bound to fracture conductance. Fluid rheology was described via the Prandtl–Eyring shear-thinning model. Novel closed-form results for flow rate and hydraulic aperture were derived and are discussed; different combinations of parameters describing the fluid rheology and variability of the aperture field were considered. In general, flow rate depends, in a nonlinear fashion, on the dimensionless pressure gradient and distribution parameters. Full article

To properly manage water resources, data acquisition through environmental monitoring is required. However, the cost of professional sophisticated hydrological monitoring equipment may be prohibitive for many locations around the world. This work aims to develop a low-cost data collection platform (L-DCP) to be used to densify the hydrological monitoring network for rainfall, small rivers level and water temperature. Low cost sensors were compared to professional ones and presented an excellent correlation, with the coefficient of determination higher than 0.99 for temperature. The L-DCP was kept activated and collecting data for over 150 days without major problems. The low-cost solution has approximately 9% of the cost of a professional solution. Full article

The increasing frequency of extreme storm events has implications for the operation of sewer systems, storm water, flood control monitoring and tide level variations. Accurate and continuous monitor water level monitoring is demanded in different environments. Piezoelectric sensors are widely used for water level monitoring and work submerged in waters subject to the presence of solid particles, biological fouling and saltwater oxidation. This work aimed to develop a simple, low-cost methodology to protect sensors over long-term deployment. The results show that simple actions, costing less than 2 EUR, can protect and extend the lifecycle of equipment worth over 2000 EUR, ensuring continuous monitoring and maintaining quality measurements. Full article