Multi-objective evolutionary algorithms (MOEAs) are widely used to optimize multi-purpose reservoir operations. Considering that most outcomes of MOEAs are Pareto optimal sets with a large number of incomparable solutions, it is not a trivial task for decision-makers (DMs) to select a compromise solution for application purposes. Due to the increasing popularity of data-driven decision-making, we introduce a clustering-based decision-making method into the multi-objective reservoir operation optimization problem. Traditionally, solution selection has been conducted based on trade-off ranking in objective space, and solution characteristics in decision space have been ignored. In our work, reservoir operation processes were innovatively clustered into groups with unique properties in decision space, and the trade-off surfaces were analyzed via clustering in objective space. To attain a suitable performance, a new similarity measure, referred to as the Mei–Wang fluctuation similarity measure (MWFSM), was tailored to reservoir operation processes. This method describes time series in terms of both their shape and quantitative variation. Then, a compromise solution was selected via the joint use of two clustering results. A case study of the Three Gorges cascade reservoirs system under small and medium floods was investigated to verify the applicability of the proposed method. The results revealed that the MWFSM effectively distinguishes reservoir operation processes. Two more operation patterns with similar positions but different shapes were identified via MWFSM when compared with Euclidean distance and the dynamic time warping method. Furthermore, the proposed method decreased the selection range from the whole Pareto optimal set to a set containing relatively few solutions. Finally, a compromise solution was selected. Full article

Sulphide build-up in pressure sewers has been identified as the main cause for the occurrence of odour and corrosion in sewer systems. Despite the efforts to optimize commonly used control technologies such as nitrate and iron salts to reduce sulphide emission, continuous addition of these chemicals is still required. A biocidal agent such as free nitrous acid can be added intermittently, less frequently, and in smaller quantities whilst achieving total sulphide control. So far, laboratory and field studies in Australia and the USA have successfully proven and applied the use of this control technology, exhibiting its strong biocidal effects during intermittent addition. In this study, nine trials were made to assess the application of the free nitrous acid (FNA) as an alternative sulphide control technology in Germany. The sewer pilot plant of the Berlin Water Utility Company was used to perform the trials at a technical scale using a supply of raw sewage. FNA exposure times ranging from 5 to 24 h in varying concentrations were investigated. The effectiveness of the FNA treatment was monitored using the online hydrogen sulphide (H₂S) gas and dissolved-sulphide sensors installed in the sewer pilot plant. Effective sulphide control was only possible during dosing periods, with rapid resumption of sulphide production for the trials with exposure times of <12 h and concentrations ranging from 0.08 to 0.56 mg HNO₂-N L⁻¹ suggesting a slight inhibitory effect. A more pronounced biocidal effect was observed for the trials exposed to FNA treatment for 24 h at concentrations >0.29 mg HNO₂-N L⁻¹. Overall, the trials of this study demonstrated that the biofilms were FNA resistant and that the concentrations and exposure times used were inadequate to develop an effective intermittent dosing strategy. Full article

This study takes Taiwan’s Sun Moon Lake Reservoir as the research object to discuss the sustainable development decision-making of the reservoir water source area in the island area. The grounded theory was adopted to construct the framework; 835 questionnaires were analyzed by statistical test; 10 interviewees’ feelings were collected through interviews and discussions, and multiple verification methods were used for exploration. Conclusion: The study found that the current development of the reservoir water source area of the outlying islands has brought much garbage; affecting the quality of the natural environment; lake; and water source; caused the disappearance of distinctive culture and architecture. The poor interaction between businesses and communities has led to an overlap in the types of industries, consumer goods, attractions and a lack of transportation and medical facilities, affecting people’s desire to travel. The government’s future decisions include: Increasing the variety of consumer goods; improving medical and transportation facilities; preserving unique culture and architecture; linking foreign-invested enterprises with community interactivity; enhancing local people’s interaction; and compensating for the deficiencies in human resources for industrial development are the key points for future improvement of the reservoir water source area of the outlying islands. Full article

This paper estimates the prevalence and severity of dental fluorosis among participants in the first wave of The Aguascalientes Longitudinal Study of Child Development (EDNA). The analytical sample includes 1052 children in 100 public elementary schools. Dental fluorosis is determined using the Modified Dean’s Index. There is a 43% general dental fluorosis prevalence, and the estimated Community Fluorosis Index is 0.99. Five municipalities report average groundwater fluoride concentrations above the official Mexican guideline value of 1.5 mg/L. In those municipalities, there is a 50% average dental fluorosis prevalence. An ordered logistic regression analysis indicates that obesity in participants increases the likelihood of suffering more severe dental fluorosis symptoms compared with normal-weight participants (OR = 1.62, p < 0.05). Households consuming tap water are more likely to have children suffering more severe dental fluorosis symptoms (OR = 1.63, p < 0.05). Children aged 8 years are more likely to present more severe dental fluorosis symptoms than their peers aged 7 years (OR = 1.37, p < 0.05). Dental fluorosis will persist as a public health problem in Aguascalientes State unless appropriate technologies for fluoride removal from water are installed and operated. Full article

One of the last wild populations of the critically endangered stellate sturgeon (Acipenser stellatus) survives in the Danube River. Limited knowledge about the genetic structure, ecology, and evolution of this species led to poor and inconsistent management decisions with an increased risk for species extinction in the wild. Here we show the results of genetic structure screening of the Danube River wild population over 12 years timespan. Our research does not bring evidence of population recovery. No genetic structuring was identified at the mitochondrial level concerning spawning migration timing, sampling locations, and developmental stages. Eleven maternal lineages were revealed based on restriction fragment lengths analysis of the D-loop region, with one haplotype as the most frequent. While this could be the result of a massive restocking activity using a reduced number of spawners, our data does not support it. The selection of mitochondrial haplotypes under the pressure of habitat contraction and the narrower range of temperature variation since dams’ construction on the river could explain the observed distribution. Several factors of managerial concern are discussed. Our results provide baseline data on the mtDNA diversity in a critically endangered species of exceptionally high socioeconomic and conservation interest. Full article

This study aims to develop the relational equation between the color and chemical composition of discolored seawater around a submarine volcano, and to examine its relation to the volcanic activity at Nishinoshima Island, Japan, in 2020, using the model applied by atmospheric corrected reflectance 8 day composite of GCOM-C SGLI. To achieve these objectives, the relational equation between the RGB value of the discolored seawater in the submarine volcano and the chemical composition summarized in past studies was derived using the XYZ colorimetric system. Additionally, the relationship between the volcanic activity of the island in 2020 and the chemical composition was compared in chronological order using the GCOM-C SGLI data. The following findings were obtained. First, a significant correlation was observed between the seawater color (x) calculated by the XYZ colorimetric system and the chemical composition such as (Fe + Al)/Si. Second, the distribution of (Fe + Al)/Si in the island, estimated from GCOM-C SGLI data, fluctuated significantly just before the volcanic activity became active (approximately one month prior). These results suggest that the chemical composition estimation of discolored seawater using SGLI data may be a powerful tool in predicting submarine volcanic activity. Full article

The efficiency of a fishway is determined by the ability of immigrating fish to follow its attraction flow (i.e., its jet) to locate and enter the fishway entrance. The hydraulic characteristics of fishway entrance jets can be simplified using findings from widely investigated surface jets produced by shaped nozzles. However, the effect of the different boundary conditions of fishway entrance jets (characterized by vertical entrance slots) compared to nozzle jets must be considered. We investigate the downstream propagation of attraction jets from the vertical slot of a fishway entrance into a quiescent tailrace, considering the following boundary conditions not considered for nozzle jets: (1) slot geometry, (2) turbulence characteristics of the approach flow to the slot, and (3) presence of a lateral wall downstream of the slot. We quantify the effect of these boundary conditions using three-dimensional hydrodynamic-numeric flow simulations with DES and RANS turbulence models and a volume-of-fluid method (VoF) to simulate the free water surface. In addition, we compare jet propagation with existing analytical methods for describing jet propagations from nozzles. We show that a turbulent and inhomogeneous approach flow towards a vertical slot reduces the propagation length of the slot jet in the tailrace due to increased lateral spreading compared to that of a jet produced by a shaped nozzle. An additional lateral wall in the tailrace reduces lateral spreading and significantly increases the propagation length. For highly turbulent flows at fishway entrances, the RANS model tends to overestimate the jet propagation compared to the transient DES model. Full article

The Vega Baja region lays on the lower course of the Segura River (southeastern Spain). It is one of the six traditional “huerta” European landscapes and has an ancient, extensive, and complex network of irrigation and drainage channels. The accumulation of floating waste causes numerous economic, environmental, and landscape problems in its irrigation infrastructures, hindering farmers’ water management practices. This work classifies and estimates the total volume of floating waste at various points along the Segura River and its irrigation channels as a first systematic approach to define and quantify the problem of floating waste accumulation. Aerial images taken by a drone were analyzed over time and a manual count of residues was performed on selected points. The results obtained show that reeds and residues of riparian vegetation represent more than 95% of the floating debris volume measured on the riverbed. Anthropogenic waste, which represents less than 5% of debris volume, was characterized, finding that plastics of domestic sources are the most abundant by count (14.9%) and only a reduced part of the floating waste can be attributed to agricultural activities (3.8%). Assessing the type and origin of the floating waste is essential to inform the actions required in order to avoid the floating waste reaching the Mediterranean Sea. Full article

The Romans were well aware of the strategic importance of Crete and tried, by any means possible, its final conquest. The island was under Roman rule over four centuries (ca 67 BC–330 AD). Under Roman rule, Crete witnessed a growth of its population and prosperity and an increase in its connectivity with other parts of the Empire. In addition, Gortys, Chersonisos, Elyros, Lyttos, Kissamos and other cities flourished under their rule. At that prosperous time, several luxurious infrastructures, such as hydraulic works, were developed. In this paper, we wish to examine the principles and the technical characteristics of major aqueducts built at that time. They constructed impressive hydro-works, such as aqueducts, by using the knowledge gained from earlier Greek civilizations in Minoan and Classical and Hellenistic times. However, they mainly increased the scale of applied technologies to support the increased population water demand. Water is a common need of humankind and several ancient civilizations developed simple but practical techniques, such as the aqueduct, especially during Roman times. We can gain from their experience and knowledge to develop a sustainable water supply, presently and in the future, both in developed and developing countries. Full article

This study aims to investigate the influence of treated wastewater (TWW) on the hydraulic performance of drip irrigation emitters. A field experiment was conducted in order to test two types of online emitters, a low pressure (LP) and a standard pressure (SP), at different working pressures (0.25 bar, 0.50 bar, and 1.00 bar) using TWW. The emitters were initially evaluated in the laboratory and the field for the discharge exponent (X), discharge coefficient (Kd), average emitter discharge (Q_avg), coefficient of variation (CV), distribution uniformity (DU), the mean discharge ratio (Dra), and the main degree of clogging (DC). The main effect of the emitters on the hydraulic parameters of irrigation performance was not significant, while the operational pressure and operational time of irrigation had a significant effect. For the LP emitter, the average emitter discharge was 7.6, 7.7, and 7.8 Lh⁻¹ at 0.25, 0.50, and 1.00 bar, respectively. For the SP emitter, the average emitter discharge was 7.6, 7.8, and 7.8 Lh⁻¹ at 0.25, 0.50, and 1.00 bar, respectively. The EU values for the LP and SP emitters varied from low to moderate at 0.25 bar, as the EU values at 0.50 and 1.00 bar were considered high for both emitter types. Full article

Small streams in urbanized rural areas receive loads of P from various, often episodic, sources. This paper addresses, through a tracer test with ${}^{32}$P, retention and transport of a pulse input of phosphorus in a 2.6 km long stretch of a channelized second-order lowland stream. Tritiated water was introduced alongside the ${}^{32}$P-labelled ortophosphate in order to isolate the influence of the hydrodynamic factors on P behavior. Tracer concentrations in unfiltered water samples were measured by liquid scintillation counting. Four in-stream and five hyporheic breakthrough curves were collected at four points along the stream, two of which encompass a beaver dam impoundment. The overall retention efficiency of ${}^{32}$P along the studied reach was 46%. The transient storage transport model OTIS-P provided reasonable fits for in-stream breakthrough curves (BTCs) but failed at reproducing the hyporheic BTCs. The overall small effect of transient storage on solute transport was higher in the stretch with a more pronounced surface storage. Transient storage and phosphorus retention were not enhanced in the beaver dam impoundment. Full article

Irrigation is an important factor affecting the change of terrestrial water storage (TWS), especially in grain-producing areas. The Northeast China Plain (NECP), the Huang-Huai-Hai Plain (HHH) and the middle and lower reaches of the Yangtze River Basin Plain (YRB) are major grain-producing regions of China, with particular climate conditions, crops and irrigation schemes. However, there are few papers focusing on the different variation pattern of water storage between NECP, HHH and YRB. In this paper, the characteristics of terrestrial water storage anomaly (TWSA) and groundwater storage in the three regions mentioned above from 2003 to 2014 were analyzed, and the main reasons for water storage variations in the three regions were also discussed. The result shows that although effective irrigated areas increased in all three regions, TWSA only decreased in HHH and TWSA in the other two regions have shown an increasing trend. Spatially, the water storage deficit was more serious in middle and south NECP and HHH. In the three regions, water storage variations were impacted by meteorological condition and anthropogenic stress (e.g., irrigation). However, irrigation water consumption has a greater impact on water storage deficit in HHH than the other two regions, and water storage variation in YRB was mainly impacted by meteorological conditions. In this case, we suggest that the structure of agricultural planting in HHH should be adjusted to reduce the water consumption for irrigation. Full article

This paper focuses on the legal and institutional framework of urban water services in Spain, emphasizing water sanitation by using proposals that would positively contribute to wastewater management in Brazil. The recent Brazilian Federal Law No. 14,026/20 aims to encourage investment in water sanitation, promoting public-private collaboration formulas so that service management is viable even in economically less-favored regions. In Spain, sanitation policies are aimed at fulfilling the set of obligations and objectives imposed by European Union Directives within the environmental policies of the Union. From an economic point of view, supply and sanitation water services are classified at European legal framework as “services of general economic interest” (SGEI), not subject to harmonized regulation and open to a natural monopoly provision regime, which they admit various types of management formulas, public and private, based on the ownership and public intervention of the service, both at national and European level. We believe that the Spanish experience in this field, beyond its singularities, can serve as a useful reference for Brazilian’s urban wastewater new regulation for several reasons: (1) Because of the decentralized political scheme that both countries share and the need to articulate an adequate system of competencies in consequence; (2) Because of the international experience that Spanish companies have at the sector’s technological forefront, they are very competitive; (3) Due to the adequate functioning of the Spanish legal and organizational framework since, despite its shortcomings, as we later will comment, it has managed to develop successful financing formulas and management models that, in general terms, have allowed to ensure with reasonable efficiency, continuity, stability and sustainability in the provision of urban water services. Full article

Climate warming can alter the thermal conditions of reservoirs. However, some hydraulic interventions can be explored to mitigate this impact. This study investigates the long-term effects of climate on the temperature and thermal structure of a monomictic reservoir that has had varying operations from 1959 to 2016. Reservoir progressively operated through three distinct periods, namely, (A) deep penstock withdrawal (DPW; 1959–1991), (B) purely selective withdrawal (SW; 1992–2001), and (C) combination of SW and vertical curtain (VC; 2002–2016). Although annual air temperatures are increasing (+0.15 °C decade⁻¹) in the long term, the reservoir’s surface water temperatures have been found to be decreasing (−0.06 °C decade⁻¹). Periods B and C produced colder profiles and exhibited lower heat content and higher potential energy anomaly than Period A. Furthermore, stronger thermoclines, as indicated by Brunt–Vaisala frequency, were observed in the two latter periods. The results of this study show that varying operations bear a stronger influence on the reservoir’s temperature and thermal structure than climate change itself. Mitigating the thermal impacts of climate warming in reservoirs appears promising with the use of SW and VC. Full article

A key principle of agricultural best management practices (BMPs) is to improve water quality by reducing agricultural-sourced nutrients and associated eutrophication. Long-term (1998–2016) lake summer trophic state index (TSI) trends of an agricultural watershed with agricultural best management practices (BMPs) were assessed. Structural BMPs included vegetative buffers, conservation tillage, conservation reserve, a constructed wetland, and a sediment retention pond. TSI included Secchi visibility (SD), chlorophyll a (Chl), total phosphorus (TP), and total nitrogen (TN). Summer TSI 1977 was >80 in 1998–1999 (hypertrophic) and decreased over the first 10 years to TSI 1977 ≈ 75 (eutrophic). TSI 1977 decrease and changing TSI deviations coincided with vegetative buffers, conservation tillage, and conservation reserve. The TSI(SD) decrease (>90 to <70) coincided with vegetative buffers and TSI(TP) decrease (>90 to <75) coincided primarily with conservation tillage and the sediment retention pond. TSI(Chl) increase (<60 to >70) coincided with conservation tillage and vegetative buffer. Results indicate watershed-wide BMPs can modestly decrease summer trophic state through increased water transparency and decreased TP, but these changes are off-set by increases in chlorophyll a to reach a new stable state within a decade. Future research should assess algal nutrient thresholds, internal nutrient loading, and climate change effects. Full article