Water

24 pages, 3066 KiB

Open AccessArticle

Modelling Current-State N- and P-Fluxes into Surface Waters in Germany

by Björn Tetzlaff, Ralf Kunkel, Max Eysholdt, Hong Hanh Nguyen, Markus Venohr, Tim Wolters, Maximilian Zinnbauer and Frank Wendland

Water 2024, 16(13), 1872; https://doi.org/10.3390/w16131872 (registering DOI) - 29 Jun 2024

Abstract

For the first time, the AGRUM model consortium—consisting of the agro-economic model RAUMIS, the water balance model mGROWA, the hydrological nutrient transport models DENUZ, WeKu and MEPhos, and the urban emission model MONERIS—was jointly set up throughout Germany (357,000 km²). This [...] Read more.

For the first time, the AGRUM model consortium—consisting of the agro-economic model RAUMIS, the water balance model mGROWA, the hydrological nutrient transport models DENUZ, WeKu and MEPhos, and the urban emission model MONERIS—was jointly set up throughout Germany (357,000 km²). This provided a nationwide consistent nutrient model to capture the current status of N and P inputs to surface waters from diffuse sources and urban areas. Diffuse nutrient emissions were quantified in high spatial resolution for the input pathways’ groundwater, drainage runoff, and natural interflow (100 m × 100 m), as well as for water erosion and wash-off (25 m × 25 m). The sum of diffuse nutrient inputs to surface waters is about 385,000 metric tons N/yr and ca. 11,530 metric tons P/yr. Urban emissions were quantified either as point source inputs (wastewater treatment plants, industrial direct dischargers) or at municipality scale for different collection and treatment systems, e.g., rainwater sewers or decentralized treatment plants, and sum up to ca. 95,000 t N/yr and 7500 t P/yr. As modelled, total N and P inputs into surface waters correspond well with observed N and P loads in rivers. The model results represent valuable information for water managers, being responsible for the preparation of management plans for the third management cycle of the EC Water Framework Directive spanning from 2021 to 2027. Full article

(This article belongs to the Special Issue Agricultural Water Protection in Europe under Pressure: Current State of Nutrient Flux Modeling and Assessment of the Impact of Mitigation Measures at National Level)

19 pages, 3869 KiB

Open AccessArticle

Enhanced Adsorption of Aqueous Pb(II) by Acidic Group-Modified Biochar Derived from Peanut Shells

by Yumeng Wu, Ci Li, Zhimiao Wang, Fang Li, Jing Li, Wei Xue and Xinqiang Zhao

Water 2024, 16(13), 1871; https://doi.org/10.3390/w16131871 (registering DOI) - 29 Jun 2024

Abstract

Using peanut shells, a sustainable agricultural waste product, as its raw material, the acid group-modified biochar (AMBC) was prepared through phosphoric acid activation, partial carbonization, and concentrated sulfuric acid sulfonation for efficient removal of lead ion from aqueous solutions. Characterization techniques such as [...] Read more.

Using peanut shells, a sustainable agricultural waste product, as its raw material, the acid group-modified biochar (AMBC) was prepared through phosphoric acid activation, partial carbonization, and concentrated sulfuric acid sulfonation for efficient removal of lead ion from aqueous solutions. Characterization techniques such as N₂ isothermal adsorption–desorption, SEM, XRD, FT-IR, TG-DTA, and acid–base titration were utilized to fully understand the properties of the AMBC. It was found that there were high densities of acidic oxygen-containing functional groups (-SO₃H, -COOH, Ph-OH) on the surface of the AMBC. The optimal adsorption performance of the AMBC for Pb(II) in water occurred when the initial concentration of Pb(II) was 100 mg/L, the pH was 5, the dosage of the adsorbent was 0.5 g/L, and the contact time was 120 min. Under the optimal conditions, the removal ratio of Pb(II) was 76.0%, with an adsorption capacity of 148.6 mg/g. This performance far surpassed that of its activated carbon precursor, which achieved a removal ratio of 39.7% and an adsorption capacity of 83.1 mg/g. The superior adsorption performance of AMBC can be caused by the high content of acidic oxygen-containing functional groups on its surface. These functional groups facilitate the strong binding between AMBC and Pb(II), enabling effective removal from water solutions. Full article

(This article belongs to the Special Issue Sustainable Water Treatment and Contaminants Control: Technologies and Strategies)

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17 pages, 5481 KiB

Open AccessArticle

Reach-Scale Mapping of Surface Flow Velocities from Thermal Images Acquired by an Uncrewed Aircraft System along the Sacramento River, California, USA

by Paul J. Kinzel, Carl J. Legleiter and Christopher L. Gazoorian

Water 2024, 16(13), 1870; https://doi.org/10.3390/w16131870 (registering DOI) - 29 Jun 2024

Abstract

An innovative payload containing a sensitive mid-wave infrared camera was flown on an uncrewed aircraft system (UAS) to acquire thermal imagery along a reach of the Sacramento River, California, USA. The imagery was used as input for an ensemble particle image velocimetry (PIV) [...] Read more.

An innovative payload containing a sensitive mid-wave infrared camera was flown on an uncrewed aircraft system (UAS) to acquire thermal imagery along a reach of the Sacramento River, California, USA. The imagery was used as input for an ensemble particle image velocimetry (PIV) algorithm to produce near-continuous maps of surface flow velocity along a reach approximately 1 km in length. To assess the accuracy of PIV velocity estimates, in situ measurements of flow velocity were obtained with an acoustic Doppler current profiler (ADCP). ADCP measurements were collected along pre-planned cross-section lines within the area covered by the imagery. The PIV velocities showed good agreement with the depth-averaged velocity measured by the ADCP, with

R^{2}

values ranging from 0.59–0.97 across eight transects. Velocity maps derived from the thermal image sequences acquired on consecutive days during a period of steady flow were compared. These maps showed consistent spatial patterns of velocity vector magnitude and orientation, indicating that the technique is repeatable and robust. PIV of thermal imagery can yield velocity estimates in situations where natural water-surface textures or tracers are either insufficient or absent in visible imagery. Future work could be directed toward defining optimal environmental conditions, as well as limitations for mapping flow velocities based on thermal images acquired via UAS. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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18 pages, 5408 KiB

Open AccessArticle

Effective Removal of Malachite Green Dye from Water Using Low-Cost Porous Organic Polymers: Adsorption Kinetics, Isotherms, and Reusability Studies

by Saad Melhi, Ayoub Abdullah Alqadami, Eid H. Alosaimi, Gehan M. Ibrahim, Belal El-Gammal, Mahmoud A. Bedair and Elsayed M. Elnaggar

Water 2024, 16(13), 1869; https://doi.org/10.3390/w16131869 (registering DOI) - 29 Jun 2024

Abstract

In this study, triphenylaniline-based porous organic polymers (TPA-POPs) were successfully prepared by the Friedel–Crafts reaction and applied to adsorb malachite green (MG) dye from water. The TPA-POP was characterized using TEM, SEM, FTIR, ¹³C (CP/MAS) NMR, BET surface area, and XRD analysis. [...] Read more.

In this study, triphenylaniline-based porous organic polymers (TPA-POPs) were successfully prepared by the Friedel–Crafts reaction and applied to adsorb malachite green (MG) dye from water. The TPA-POP was characterized using TEM, SEM, FTIR, ¹³C (CP/MAS) NMR, BET surface area, and XRD analysis. The results exhibited that the TPA-POP has a high surface area (1625.14 m²/g) with pore volume (0.353 cm³/g) and pore radius (1.57 nm) that reflect the high quantity of MG adsorbed on the TPA-POP. The polymer was evaluated as an excellent adsorbent for MG adsorption from water using the batch method. MG dye removal was optimized as 99.60% (at pH: 6.0, adsorbent dosage (m): 0.01 g, temperature (T): 45 °C, and contact time (t): 300 min). The kinetic data follow the Elovich model, while the isotherm data fit the Langmuir model well with uptake capacity (755.72 mg/g) at T: 45 °C. According to thermodynamic parameters, the adsorption process was endothermic and spontaneous. The adsorption of MG on the TPA-POP occurred via different mechanisms (π–π interaction, electrostatic attraction, and hydrogen bonding). Reusability experiments exhibited that the TPA-POP still maintained high removal efficiency (82.12%) after five cycles. In conclusion, the TPA-POP is a promising adsorbent owing to its cost-effectiveness, high adsorption capacity, high surface area, excellent reusability, and efficient MG removal from aqueous media. Full article

(This article belongs to the Section Wastewater Treatment and Reuse)

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28 pages, 3636 KiB

Open AccessArticle

A Novel Artificial Intelligence Prediction Process of Concrete Dam Deformation Based on a Stacking Model Fusion Method

by Wenyuan Wu, Huaizhi Su, Yanming Feng, Shuai Zhang, Sen Zheng, Wenhan Cao and Hongchen Liu

Water 2024, 16(13), 1868; https://doi.org/10.3390/w16131868 (registering DOI) - 29 Jun 2024

Abstract

Deformation effectively represents the structural integrity of concrete dams and acts as a clear indicator of their operational performance. Predicting deformation is critical for monitoring the safety of hydraulic structures. To this end, this paper proposes an artificial intelligence-based process for predicting concrete [...] Read more.

Deformation effectively represents the structural integrity of concrete dams and acts as a clear indicator of their operational performance. Predicting deformation is critical for monitoring the safety of hydraulic structures. To this end, this paper proposes an artificial intelligence-based process for predicting concrete dam deformation. Initially, using the principles of feature engineering, the preprocessing of deformation safety monitoring data is conducted. Subsequently, employing a stacking model fusion method, a novel prediction process embedded with multiple artificial intelligence algorithms is developed. Moreover, three new performance indicators—a superiority evaluation indicator, an accuracy evaluation indicator, and a generalization evaluation indicator—are introduced to provide a comprehensive assessment of the model’s effectiveness. Finally, an engineering example demonstrates that the ensemble artificial intelligence method proposed herein outperforms traditional statistical models and single machine learning models in both fitting and predictive accuracy, thereby providing a scientific and effective foundation for concrete dam deformation prediction and safety monitoring. Full article

(This article belongs to the Special Issue Remote Sensing, Artificial Intelligence and Deep Learning in Hydraulic Structure Safety Monitoring)

20 pages, 22990 KiB

Open AccessArticle

Enhancing Ecological Security in Ili River Valley: Comprehensive Approach

by Ruyi Pan, Junjie Yan, Qianqian Xia and Xufan Jin

Water 2024, 16(13), 1867; https://doi.org/10.3390/w16131867 (registering DOI) - 29 Jun 2024

Abstract

The growing tension between economic development and ecological preservation in the Ili River Valley underscores the need for advanced analytical methods to effectively balance these interests. In this study, we utilized the InVEST model to quantify ecosystem services, combined with an analysis of [...] Read more.

The growing tension between economic development and ecological preservation in the Ili River Valley underscores the need for advanced analytical methods to effectively balance these interests. In this study, we utilized the InVEST model to quantify ecosystem services, combined with an analysis of ecological sensitivity, to comprehensively assess the ecological health of the region. By applying circuit theory, the research identified key ecological components such as sources, corridors, and critical nodes, alongside barriers; thus, mapping an ecological security pattern tailored specifically for the wetland oasis of the Ili River Valley. The analysis identified 15 ecological source sites covering 43,221.17 km², 31 ecological corridors totaling 782 km in length, and 32 vital ecological nodes each exceeding 1 km². Notably, 81.8% of these ecological source areas exhibited high ecological resilience, thus emphasizing their crucial role in maintaining the region’s ecological balance. The findings provide essential guidance for the ecological stewardship and management of the Ili River Valley and underscore the importance of incorporating ecological considerations within economic planning frameworks in arid regions. Full article

(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)

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19 pages, 5632 KiB

Open AccessArticle

Rate Transient Analysis for Multi-Fractured Wells in Tight Gas Reservoirs Considering Multiple Nonlinear Flow Mechanisms

by Yonghui Wu, Lidong Mi, Liqiang Ma, Rongchen Zheng and Xiujuan Feng

Water 2024, 16(13), 1866; https://doi.org/10.3390/w16131866 (registering DOI) - 29 Jun 2024

Abstract

Making rate transient analysis (RTA) and formation evaluation for multi-fractured tight gas wells has always been a difficult problem. This is because the fluid flow in the formation has multiple nonlinear flow mechanisms, including gas-water two-phase flow, gas slippage, low-velocity non-Darcy flow, and [...] Read more.

Making rate transient analysis (RTA) and formation evaluation for multi-fractured tight gas wells has always been a difficult problem. This is because the fluid flow in the formation has multiple nonlinear flow mechanisms, including gas-water two-phase flow, gas slippage, low-velocity non-Darcy flow, and stress-dependent permeability. In this paper, a novel RTA method is proposed for multi-fractured wells in tight gas reservoirs incorporating nonlinear flow mechanisms. The RTA method is based on an analytical model, which is modified from the classical trilinear flow model by considering all the nonlinear flow mechanisms. The concept of material balance time and normalized rate is used to process the production data for both water and gas phases. The techniques of approximate solutions in linear/bilinear flow regimes and type curve fitting are combined in the proposed RTA method. After that, the rate transient behaviors and influencing factors of multi-fractured tight gas wells are analyzed. A field case from Northwestern China is used to test the efficiency and practicability of the proposed RTA method. The results show that six flow regimes for both gas and water production performances are exhibited on the log-log plots of normalized production rate against material balance time. The rate transient responses are sensitive to the nonlinear flow mechanisms, and formation and fracture properties. The medium flow regimes are significantly affected by fracture number, fracture conductivity, fracture half-length, stress-dependent permeability, gas-water two-phase flow, and formation permeability, which should be considered in making RTA of fractured tight gas wells. The field case shows that both gas and water production performances can be well-fitted using the proposed RTA method. The major innovation of this paper is that a novel RTA method is proposed for fractured tight gas wells considering multiple nonlinear flow mechanisms, and it can be used to make reasonable formation and fracturing evaluations in the field. Full article

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21 pages, 6501 KiB

Open AccessArticle

Irrigation and Agricultural Opportunities: Evaluating Hemp (Cannabis sativa L.) Suitability and Productivity in Lebanon

by Rhend Sleiman, Jocelyne Adjizian Gerard, Salim Fahed, Mladen Todorovic, Mohamed Houssemeddine Sellami, Rossella Albrizio and Marie Therese Abi Saab

Water 2024, 16(13), 1865; https://doi.org/10.3390/w16131865 (registering DOI) - 28 Jun 2024

Viewed by 46

Abstract

Within the prevalent challenges posed by climate change and decreasing resources, this research underscores the importance of adopting sustainable agricultural practices combined with efficient water resource management. Employing comprehensive climate and soil suitability analyses, this research analyzed the capacity of hemp (Cannabis [...] Read more.

Within the prevalent challenges posed by climate change and decreasing resources, this research underscores the importance of adopting sustainable agricultural practices combined with efficient water resource management. Employing comprehensive climate and soil suitability analyses, this research analyzed the capacity of hemp (Cannabis sativa L.) to adapt to Lebanon’s heterogeneous environmental landscapes across two distinct growing seasons (autumn and spring). Both climate and edaphic suitability mapping were conducted to study hemp’s suitability. AquaCrop v.7.1 was used to simulate seed yield, biomass production, irrigation needs and yield water productivity in the different agro-homogeneous zones of Lebanon for the two considered seasons. The findings revealed that approximately 30% and 19% of Lebanon’s land exhibit suitability for hemp cultivation during the spring and autumn seasons, respectively. According to AquaCrop model simulations, under the prevailing climatic conditions, the predicted seed yield will range from 3.7 to 5.6 t ha⁻¹ under rainfed conditions and will reach 11.1 t ha⁻¹ for irrigated cultivation. Moreover, employing efficient irrigation techniques during the spring season showed a significant improvement in both yield and biomass of hemp. The enhancement was evident, with notable increases of 112.22% in yield and 96.43% in biomass compared to rainfed conditions. This research highlights the importance of identifying suitable regions within Lebanon capable of supporting hemp cultivation in a sustainable manner. Such research not only promises economic development but also aligns with broader global sustainability objectives. Full article

(This article belongs to the Special Issue Improved Irrigation Management Practices in Crop Production)

27 pages, 7434 KiB

Open AccessArticle

Dual Domain Decomposition Method for High-Resolution 3D Simulation of Groundwater Flow and Transport

by Hao Deng, Jiaxin Li, Jixian Huang, Yanhong Zou, Yu Liu, Yuxiang Chen, Yang Zheng and Xiancheng Mao

Water 2024, 16(13), 1864; https://doi.org/10.3390/w16131864 (registering DOI) - 28 Jun 2024

Viewed by 55

Abstract

The high-resolution 3D groundwater flow and transport simulation problem requires massive discrete linear systems to be solved, leading to significant computational time and memory requirements. The domain decomposition method is a promising technique that facilitates the parallelization of problems with minimal communication overhead [...] Read more.

The high-resolution 3D groundwater flow and transport simulation problem requires massive discrete linear systems to be solved, leading to significant computational time and memory requirements. The domain decomposition method is a promising technique that facilitates the parallelization of problems with minimal communication overhead by dividing the computation domain into multiple subdomains. However, directly utilizing a domain decomposition scheme to solve massive linear systems becomes impractical due to the bottleneck in algebraic operations required to coordinate the results of subdomains. In this paper, we propose a two-level domain decomposition method, named dual-domain decomposition, to efficiently solve the massive discrete linear systems in high-resolution 3D groundwater simulations. The first level of domain decomposition partitions the linear system problem into independent linear sub-problems across multiple subdomains, enabling parallel solutions with significantly reduced complexity. The second level introduces a domain decomposition preconditioner to solve the linear system, known as the Schur system, used to coordinate results from subdomains across their boundaries. This additional level of decomposition parallelizes the preconditioning of the Schur system, addressing the bottleneck of the Schur system solution while improving its convergence rates. The dual-domain decomposition method facilitates the partition and distribution of the computation to be solved into independent finely grained computational subdomains, substantially reducing both computational and memory complexity. We demonstrate the scalability of our proposed method through its application to a high-resolution 3D simulation of chromium contaminant transport in groundwater. Our results indicate that our method outperforms both the vanilla domain decomposition method and the algebraic multigrid preconditioned method in terms of runtime, achieving up to 8.617× and 5.515× speedups, respectively, in solving massive problems with approximately 108 million degrees of freedom. Therefore, we recommend its effectiveness and reliability for high-resolution 3D simulations of groundwater flow and transport. Full article

(This article belongs to the Special Issue Contaminant Transport Modeling in Aquatic Environments)

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14 pages, 1128 KiB

Open AccessArticle

Characteristics and Mechanism of Downflow in Front of a Cylindrical Pier with Clear-Water Local Scour

by Weizheng Wang, Song Wei, Dayong Zhu, Jun Wang and Haipeng Duan

Water 2024, 16(13), 1863; https://doi.org/10.3390/w16131863 (registering DOI) - 28 Jun 2024

Viewed by 66

Abstract

Local scour often causes pier instability; however, the characteristics and mechanism of downflow, representing one of the crucial flow structures, are still unclear. In this paper, the interaction between the downflow and the horseshoe vortex system and the role of the downflow under [...] Read more.

Local scour often causes pier instability; however, the characteristics and mechanism of downflow, representing one of the crucial flow structures, are still unclear. In this paper, the interaction between the downflow and the horseshoe vortex system and the role of the downflow under clear-water local scour conditions are discussed, based on the stress distribution obtained via experiments and simulations. In the present experiment, more accurate data are measured by installing suitable sensors on 3D-printed models that reproduce the scour hole conditions at various times. The obtained results reveal that the downflow exhibits a strong interaction with the horseshoe vortex system. From the perspective of flow structures, the flow structures collide and rub against each other, which weakens the effect of the downflow. From the perspective of energy transfer, the horseshoe vortex system absorbs the energy carried by the downflow to develop and reduce the energy introduced into the sediment. In addition, shear stress is a crucial factor in maintaining a high tangent slope. When the shear stress is down to a minimum and is stable, the tangent slope rises with the growth of the pressure stress, which means that the downflow is able to promote scour depth development. Full article

23 pages, 3360 KiB

Open AccessArticle

Future Water: A Multi-University International Web Seminar

by Michael Pointl, João Marques, Frances C. Pick, Camilo Salcedo, Ina Vertommen, Mohamad Zeidan, Joby Boxall, Maria C. Cunha, Daniela Fuchs-Hanusch, Donghwi Jung, Avi Ostfeld, Juan Saldarriaga and Kevin E. Lansey

Water 2024, 16(13), 1862; https://doi.org/10.3390/w16131862 (registering DOI) - 28 Jun 2024

Viewed by 60

Abstract

Historically, water utilities have relied on tried-and-true practices in the design and operation of their infrastructure, tapping new resources and expanding networks as needed. However, as the effects of climate change and/or urbanization increasingly impact both water supply and demand, utilities need new, [...] Read more.

Historically, water utilities have relied on tried-and-true practices in the design and operation of their infrastructure, tapping new resources and expanding networks as needed. However, as the effects of climate change and/or urbanization increasingly impact both water supply and demand, utilities need new, holistic planning and management approaches. Integrated planning approaches must account for changing policies, technological progress, and unique, setting-specific operating conditions. Based on this notion, an international web seminar with faculty, researchers, and students from nine universities across five continents was conducted. In the 3-month seminar, participants were split into groups and tasked with developing future-proof, sustainable water management solutions for fictitious settings with unique resource availability, climate change predictions, demographic, and socioeconomic constraints. The goal of the seminar was to combine participants’ unique perspectives to tackle challenges in developing future water infrastructure, while forming lasting relationships. Water management concepts became more daring or “out-of-the-box” as the seminar progressed. Most groups opted for a holistic approach, optimizing existing infrastructure, integrating decentralized water management, furthering digitization, and fostering the adoption of innovative policy and planning strategies. To gauge their impact on the evolution of ideas, group dynamics and communication were observed throughout the seminar. As a result, the findings serve not only as a compendium of ideas and concepts for holistic design in the water sector, but also facilitate international collaboration, improve communication in cross-cultural teams or guide the development of training programs in water management for researchers, professional engineers, or water utilities. Full article

(This article belongs to the Section Urban Water Management)

17 pages, 3694 KiB

Open AccessArticle

Research on Internal Flow and Pressure Fluctuation Characteristics of Centrifugal Pumps as Turbines with Different Blade Wrap Angles

by Haibo Xu, Weizheng An, Erqinhu Ke, Yingyi Ma, Linlin Geng, Gang Yang and Desheng Zhang

Water 2024, 16(13), 1861; https://doi.org/10.3390/w16131861 (registering DOI) - 28 Jun 2024

Viewed by 85

Abstract

The use of pumps as turbines has been gaining more and more attention in recent years. The present work mainly investigates the influence of blade wrap angle on the internal flow and pressure fluctuation characteristics of centrifugal pumps as turbines. Five different wrap [...] Read more.

The use of pumps as turbines has been gaining more and more attention in recent years. The present work mainly investigates the influence of blade wrap angle on the internal flow and pressure fluctuation characteristics of centrifugal pumps as turbines. Five different wrap angles (35°,45°, 55°, 65°, and 75°) for a forward-curved impeller were numerically analyzed under multiple operating conditions. The accuracy of numerical simulation was validated by experimental results. The results show that maximum efficiency is achieved with a blade wrap angle of 35°, and the highest efficiency flow point gradually decreases as the blade wrap angle increases. It is found by conducting entropy production theory analysis that the high-entropy production rate regions in PATs are concentrated in the volute tongue and impeller blade inlet regions, and that the entropy production rate at the impeller inlet region increases and then decreases as the blade wrap angle decreases. In addition, pressure pulsation was affected not only by dynamic and static interference but also by an irregular vortex around the impeller; its magnitude under Q_t is higher than 0.8Q_t for blade wrap angles of 55° and 75°. The primary frequency of pressure pulsation within the impeller is the axial frequency fn and its multiples, and the frequency with the largest amplitude is 3fn. The periodicity of vortices is closely related to the periodicity of pressure pulsation. And it is suggested that a PAT with a 35° blade wrap angle is advantageous for improving the stability of a turbine. Full article

(This article belongs to the Special Issue Design and Optimization of Fluid Machinery, 2nd Edition)

18 pages, 7713 KiB

Open AccessArticle

CTAB Surfactant Promotes Rapid, Efficient, and Simultaneous Removal of Cationic and Anionic Dyes through Adsorption on Glycerol/Citrate Polyester

by Andrés F. Chamorro, Tulio A. Lerma and Manuel Palencia

Water 2024, 16(13), 1860; https://doi.org/10.3390/w16131860 (registering DOI) - 28 Jun 2024

Abstract

The discharge of dye waste by industries has caused environmental impacts on water properties, aquatic species, and human life. The production of eco-friendly materials for dye removal from wastewater has gained increasing interest, particularly through adsorption, as it is an efficient method for [...] Read more.

The discharge of dye waste by industries has caused environmental impacts on water properties, aquatic species, and human life. The production of eco-friendly materials for dye removal from wastewater has gained increasing interest, particularly through adsorption, as it is an efficient method for removing pollutants. However, the selectivity and limited adsorption capacity of materials for simultaneously adsorbing cationic and anionic dyes make it challenging to address the prevailing dye effluent issue. In this work, a poly(glycerol citrate) polyester was prepared without a solvent, using microwave heating, and was combined with cetyltrimethylammonium bromide (CTAB) to modulate the simultaneous adsorption of cationic (Rhodamine B, RB) and anionic dyes (acid blue 113, AB and acid red 27, AR). The formation of the polyester was successfully confirmed by ATR-FTIR and the thermal properties were evaluated by TGA and DCS. In the presence of CTAB 5 mM, the material removes almost 100% of the dyes, reaching the kinetics equilibrium in 30 min following the Pseudo-second order model. Additionally, dye adsorption on the polyester in the presence of CTAB was described by the Freundlich isotherm model, indicating a heterogeneous polyester surface that promotes a multi-layer adsorption driven by electrostatic interaction and hydrogen bonds. The material showed an adsorption capacity of 73.7 ± 3.2, 82.1 ± 4.4, and 21.2 ± 0.6 mg/g for RB, AB, and AR, respectively. Our results provide evidence that the poly(glycerol citrate)/CTAB has a higher potential for application in wastewater treatment to remove both anionic and cationic dyes. Full article

(This article belongs to the Topic Advanced Processes and Technologies for Wastewater: Collection, Treatment, and Resource)

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15 pages, 1922 KiB

Open AccessArticle

Preliminary Experiences in Determining the Soil–Water Characteristic Curve of a Sandy Soil Using Physical Slope Modeling

by Josip Peranić, Martina Vivoda Prodan, Rea Škuflić and Željko Arbanas

Water 2024, 16(13), 1859; https://doi.org/10.3390/w16131859 (registering DOI) - 28 Jun 2024

Viewed by 79

Abstract

Relating soil moisture content to soil suction, the soil–water characteristic curve (SWCC) represents an essential feature in unsaturated soil mechanics that enables estimation of different unsaturated soil property functions and modeling of the macro-scale soil behavior. However, depending on the soil and processes [...] Read more.

Relating soil moisture content to soil suction, the soil–water characteristic curve (SWCC) represents an essential feature in unsaturated soil mechanics that enables estimation of different unsaturated soil property functions and modeling of the macro-scale soil behavior. However, depending on the soil and processes under consideration, proper hydraulic characterization of a soil through direct laboratory measurements can be difficult, time-consuming, and involve many uncertainties. In the case of uniformly graded sands, there is a highly nonlinear and steep shape of the SWCC, with only a few kPa of soil suction separating saturated and residual soil moisture conditions, which makes measurements for determinations of SWCC especially challenging. This study encompasses an investigation of the sandy type of soil’s behavior and presents some preliminary results and experiences on the determination of SWCC through the use of physical slope model tests. The 30 cm deep slope, inclined at 35 degrees and instrumented with soil moisture and pore water pressure sensors, was exposed to series of rainfall intensities, ranging from 37 up to 300 mm/h. The results indicated that the data on hydraulic response in monitored points are not only useful for the determination of SWCC, but that the approach is useful for investigation of hydraulic hysteresis phenomena, as well as its effects on soil moisture and pore water pressure conditions, which also affects the stability conditions of a slope. In particular, the best-fit parameters of the van Genuchten model suggested air entry values of 1.6 and 1.1 kPa for the drying and the wetting curves of the SWCC, respectively, with the two branches shifted by about 1 kPa of soil suction. Full article

(This article belongs to the Special Issue Research Advances in Hydraulic Structure and Geotechnical Engineering)

23 pages, 971 KiB

Open AccessArticle

Bacterioplankton Community Diversity of a Portuguese Aquifer System (Maciço Calcário Estremenho)

by Daniela R. de Figueiredo, Maria T. Condesso de Melo, Pedro P. Saraiva, Joana Oliveira, Ana M. M. Gonçalves, Ana Sofia P. S. Reboleira, Ana R. M. Polónia, Nelson Abrantes and Daniel F. R. Cleary

Water 2024, 16(13), 1858; https://doi.org/10.3390/w16131858 (registering DOI) - 28 Jun 2024

Viewed by 81

Abstract

Climate change may increase the vulnerability of aquifers to contamination through extreme precipitation and extended drought periods. Therefore, the understanding of groundwater ecosystem dynamics is crucial, with bacterial assemblages playing a major role in biogeochemical cycles. The present research describes a geospatial study [...] Read more.

Climate change may increase the vulnerability of aquifers to contamination through extreme precipitation and extended drought periods. Therefore, the understanding of groundwater ecosystem dynamics is crucial, with bacterial assemblages playing a major role in biogeochemical cycles. The present research describes a geospatial study targeting the bacterial community structure of groundwaters from the largest karst aquifer in Portugal (the Maciço Calcário Estremenho), integrating hydrogeochemical and bacterial diversity data. A total of 22 samples were analyzed from a set of 11 geographically sparsely distributed groundwater sources in dry vs. wet seasons. The 16S rRNA gene barcoding data revealed bacterial community variability across samples in space and time. The phylum Proteobacteria was dominant across all samples (from 44 to 92% of total sequence reads), mainly represented by the classes Alphaproteobacteria (orders Sphingomonadales, BD7–3, Rhizobiales and Rhodospirillales), Betaproteobacteria (orders Burkholderiales, Rhodocyclales, Nitrosomonadales), Gammaproteobacteria (orders Pseudomonadales, Xanthomonadales, Alteromonadales, Legionellales) and Deltaproteobacteria (orders Myxococcales, Spirobacillales). Variation in the bacterial community was primarily attributed to parameters such as redox conditions (DO, ORP), Fe, Mn, SO₄, PO₄, Sr and Cl, but also some minor and trace elements (Al, V, Cr, Cu, Pb). Our results provide novel insights into bacterial diversity in relation to groundwater hydrogeochemistry. The strong dominance of OTUs related to bacterial taxa associated with nitrification/denitrification also highlights a potentially important role of these assemblages on nutrients (nitrogen sources) and groundwater quality dynamics at this karstic aquifer system. Moreover, the integration of bacterial assemblages information is emphasized as central for water quality monitoring programs. Full article

(This article belongs to the Special Issue Freshwater Quality Challenges in Southern Europe under an Increasingly Warmer and Drier Climate Scenario)

15 pages, 2861 KiB

Open AccessArticle

Spatial–Temporal and Risk Assessment of Microplastics in the Surface Water of the Qinhuai River during Different Rainfall Seasons in Nanjing City, China

by Luming Wang, Juan Huang, Yufeng Wu, Xuan Chen, Ming Chen, Hui Jin, Jiawei Yao and Xinyue Wang

Water 2024, 16(13), 1857; https://doi.org/10.3390/w16131857 (registering DOI) - 28 Jun 2024

Viewed by 74

Abstract

Microplastics (MPs) are increasingly becoming recognized as worldwide environmental contaminants, exerting a substantial impact on the safety of city rivers. This study explored the temporal variance in MPs in different rainfall seasons, including spring, plum, and autumn rains. The Qinhuai River has large [...] Read more.

Microplastics (MPs) are increasingly becoming recognized as worldwide environmental contaminants, exerting a substantial impact on the safety of city rivers. This study explored the temporal variance in MPs in different rainfall seasons, including spring, plum, and autumn rains. The Qinhuai River has large spatial fluctuations in MPs at six sampling sites, with an average concentration of 466.62 ± 153.69 items/L, and higher MP abundance was found downstream of spring rain and upstream of autumn rain. Among the different rainfall seasons, the variations in microplastics at various sampling sites were more stable in the plum rain season, with an average concentration of 473.67 ± 105.17 items/L, while the concentrations of TP and TN in the plum rain season were higher than those in other rain seasons. Transparent MPs had the highest abundance at many sampling sites in all seasons, and large-sized MPs (270–5000 μm) occurred more in the autumn rain season. PVC was more prevalent in autumn, but PET decreased in the plum rain season. Interestingly, more fibers, PET, and large-sized MPs were found in the autumn rain. The index of hazard scores of plastic polymers (

H

) revealed that the studied river was at a severe pollution level (IV), which was highly influenced by PVC and PC. In addition, the pollution load index (

P L I

) value in different rain seasons indicated slight pollution (I). At the same time, it was higher in autumn rains than in other seasons due to the higher variance in MPs. Therefore, the ecological risk of microplastics in the Qinhuai River should be seriously considered, along with seasonal variance and the PVC and PC polymers. Our research is expected to provide valuable assistance in improving the management of urban rivers. Full article

(This article belongs to the Section Water Quality and Contamination)

28 pages, 9347 KiB

Open AccessReview

A Review of Stability of Dam Structures in Coal Mine Underground Reservoirs

by Yan Wang, Fei Liu, Miaomiao Kou and Mingfei Li

Water 2024, 16(13), 1856; https://doi.org/10.3390/w16131856 (registering DOI) - 28 Jun 2024

Viewed by 79

Abstract

Coal has remained the primary component of China’s energy structure, and high-intensity extraction has continued in the central and western coal-producing regions of China. In contrast to the abundant coal resources, water resources have become extremely scarce in these regions, creating a conflict [...] Read more.

Coal has remained the primary component of China’s energy structure, and high-intensity extraction has continued in the central and western coal-producing regions of China. In contrast to the abundant coal resources, water resources have become extremely scarce in these regions, creating a conflict between coal resource extraction and water resource conservation. The coal mine underground reservoir (CMUR), as a typical technology for combined coal and water extraction and water-preserving coal mining, has been applied in numerous mines in central and western China. This effectively alleviates water resource shortages and achieves the goal of water resource conservation. The CMURs utilizes the goaf created by longwall mining as the water storage space. The reservoir dam structure comprises coal pillars, which serve as protective coal pillars in the mining area, and artificial dam structures that filled the gaps between these coal pillars. The stability of the dam structure under the complex stress effects of hydraulic coupling has been identified as the key to maintaining the safe operation of the CMUR. The mechanical properties, stress field, fracture field, and seepage field (“three fields”) change mechanisms, as well as the research results on size optimization of coal pillar dams and artificial dams in CMURs, were systematically reviewed. The core content included the instability and failure mechanisms of dam structures under the comprehensive coupling effects of factors such as dry–wet cycles of mine water, long-term immersion, chemical effects of high-salinity water, dynamic and static loads, and cyclic loads. This paper is considered to have certain reference value for the study of the stability of dam structures in CMURs and to provide some guidance for the safe operation of CMURs. Full article

(This article belongs to the Special Issue Remote Sensing, Artificial Intelligence and Deep Learning in Hydraulic Structure Safety Monitoring)

16 pages, 1862 KiB

Open AccessArticle

Modeling the Hydraulic Fracturing Processes in Shale Formations Using a Meshless Method

by Ziru Xiang, Shuyang Yu and Xiangyu Wang

Water 2024, 16(13), 1855; https://doi.org/10.3390/w16131855 (registering DOI) - 28 Jun 2024

Viewed by 95

Abstract

Complex bedding properties and in situ stress conditions of shale formation lead to complex hydraulic fracturing morphologies. However, due to the limitations of traditional numerical methods, the simulation of hydraulic fracturing in shale formation still needs further development. Based on this, the liquid–solid [...] Read more.

Complex bedding properties and in situ stress conditions of shale formation lead to complex hydraulic fracturing morphologies. However, due to the limitations of traditional numerical methods, the simulation of hydraulic fracturing in shale formation still needs further development. Based on this, the liquid–solid interaction modes and the SPH governing equations considering liquid–solid interaction force have been introduced. The smoothing kernel function in the traditional SPH method is improved by introducing the fracture mark ξ, which can realize the simulation of rock hydraulic fracturing processes. The stress boundary of the SPH method is applied by stress mapping of “stress particles”, and the feasibility and correctness of the method are verified by two numerical examples. Then, the simulation of hydraulic fracturing processes of bedding shale formations are carried out. With the increase of horizontal stress ratio, the total number of damaged particles decreases, but the initiation and extension pressure increase gradually. The initiation stress of small bedding dip angles (θ < 45°) is larger than that of big bedding dip angles (θ > 45°). The hydraulic fracture propagation range at low horizontal stress ratio is wider and the fracture is along the direction of maximum principal stress, while the hydraulic fracture propagation range at high horizontal stress ratio is limited to the perforation. The hydraulic fracture will propagate through the bedding with small dip angles. However, when the bedding dip angle is larger, the hydraulic fracture will propagate along the bedding direction. Full article

15 pages, 1293 KiB

Open AccessArticle

Hydraulic Conductivity Estimation: Comparison of Empirical Formulas Based on New Laboratory Experiments

by Mohammad Reza Goodarzi, Majid Vazirian and Majid Niazkar

Water 2024, 16(13), 1854; https://doi.org/10.3390/w16131854 (registering DOI) - 28 Jun 2024

Viewed by 104

Abstract

Hydraulic conductivity (K) is one of the most important characteristics of soils in terms of groundwater movement and the formation of aquifers. Generally, it indicates the ease of infiltration and penetration of water in the soil. It depends on various factors, [...] Read more.

Hydraulic conductivity (K) is one of the most important characteristics of soils in terms of groundwater movement and the formation of aquifers. Generally, it indicates the ease of infiltration and penetration of water in the soil. It depends on various factors, including fluid viscosity, pore size, grain size, porosity ratio, mineral grain roughness, and soil saturation level. Each of the empirical formulas used to calculate K includes one or more of the influencing parameters. In this study, pumping tests from an aquifer were performed by using a hydrology apparatus. Laboratory experiments were conducted on six types of soil with different grain sizes, ranging from fine sand to coarse sand, to obtain K. The experimental-based K values were compared with that of empirical formulas. The results demonstrate that Breyer and Hazen (modified) formulas adequately fit the laboratory values. The novelty of the present study is the comparison of the experimental formulas in completely similar conditions of the same sample, such as porosity, viscosity, and grain size, using the pumping test in a laboratory method, and the results show that the Hazen and the Breyer formulas provide the best results. The findings of this work will help in better development of groundwater resources and aquifer studies. Full article

22 pages, 4785 KiB

Open AccessArticle

Analysis of the Hydrogeochemical Characteristics and Origins of Groundwater in the Changbai Mountain Region via Inverse Hydrogeochemical Modeling and Unsupervised Machine Learning

by Yi Liu, Mingqian Li, Ying Zhang, Xiaofang Wu and Chaoyu Zhang

Water 2024, 16(13), 1853; https://doi.org/10.3390/w16131853 (registering DOI) - 28 Jun 2024

Viewed by 105

Abstract

This study employed hydrochemical data, traditional hydrogeochemical methods, inverse hydrogeochemical modeling, and unsupervised machine learning techniques to explore the hydrogeochemical traits and origins of groundwater in the Changbai Mountain region. (1) Findings reveal that predominant hydrochemical types include HCO₃⁻Ca·Mg, HCO [...] Read more.

This study employed hydrochemical data, traditional hydrogeochemical methods, inverse hydrogeochemical modeling, and unsupervised machine learning techniques to explore the hydrogeochemical traits and origins of groundwater in the Changbai Mountain region. (1) Findings reveal that predominant hydrochemical types include HCO₃⁻Ca·Mg, HCO₃⁻Ca·Na·Mg, HCO₃⁻Mg·Na, and HCO₃⁻Na·Mg. The average metasilicic acid content was found to be at 49.13 mg/L. (2) Rock weathering mechanisms, particularly silicate mineral weathering, primarily shape groundwater chemistry, followed by carbonate dissolution. (3) Water‒rock interactions involve volcanic mineral dissolution and cation exchange adsorption. Inverse hydrogeochemical modeling, alongside analysis of the widespread volcanic lithology, underscores the complexity of groundwater reactions, influenced not only by water‒rock interactions but also by evaporation and precipitation. (4) Unsupervised machine learning, integrating SOM, PCA, and K-means techniques, elucidates hydrochemical types. SOM component maps reveal a close combination of various hydrochemical components. Principal component analysis (PCA) identifies the first principal component (PC1), explaining 48.15% of the variance. The second (PC2) and third (PC3) principal components, explain 13.2% and 10.8% of the variance, respectively. K clustering categorized samples into three main clusters: one less influenced by basaltic geological processes, another showing strong igneous rock weathering characteristics, and the third affected by other geological processes or anthropogenic factors. Full article

(This article belongs to the Special Issue New Application of Isotopes in Hydrology and Hydrogeology)

19 pages, 827 KiB

Open AccessArticle

The Factors Affecting Stability and Durability of Flow Diversion Simple Weirs in Muchinga Province of Zambia

by Alex Lushikanda Kabwe, Masahiro Hyodo, Hidehiko Ogata, Yoshihiro Sagawa, Yoshinao Adachi and Masayuki Ishii

Water 2024, 16(13), 1852; https://doi.org/10.3390/w16131852 (registering DOI) - 28 Jun 2024

Viewed by 112

Abstract

The effectiveness of simple weirs and the ability of rural farmers to construct durable weirs are still areas of concern in rural areas in Zambia. The objective of this study is to investigate the factors contributing to the varying levels of durability of [...] Read more.

The effectiveness of simple weirs and the ability of rural farmers to construct durable weirs are still areas of concern in rural areas in Zambia. The objective of this study is to investigate the factors contributing to the varying levels of durability of the simple weir structures used for the diversion of river flows. This study was conducted in five districts where 33 simple weirs located in similar geographical zones were analyzed for their longevity. The research delved into catchment and climatic variables, as well as the social and psychological perception of simple weirs. This study conducted interviews with key informants who were familiar with the use of simple weirs in Muchinga Provinces between 26 December 2023 and 15 January 2024 using semi-structured questions. The findings of this study indicated that simple weirs constructed on relatively square-shaped catchments and narrow-shaped catchment areas were less vulnerable to damage and easy to operate and maintain. The study also found that climatic factors such as storm rainfall events had little impact on the operation and maintenance of these weirs in Muchinga province, as most sites are in the rainfall shadow while farmers’ views about the structures varied from site to site. Overall, planning is necessary for implementing small or large irrigation structures. Full article

(This article belongs to the Special Issue Exploring Progress in Agricultural Water Management under Changing Environments: Monitoring, Modelling, Performances, and Optimization with Applications)

19 pages, 13586 KiB

Open AccessArticle

Monitoring of the Icing Process and Simulation of Its Formation Mechanism in the Cut Slope of Beihei Highway

by Wei Shan, Peijie Hou, Guangchao Xu, Helong Du, Ying Guo and Chengcheng Zhang

Water 2024, 16(13), 1851; https://doi.org/10.3390/w16131851 (registering DOI) - 28 Jun 2024

Viewed by 102

Abstract

Icing in cut slopes is a serious risk to transportation safety in cold regions. Research on the occurrence process and mechanism of icing is a prerequisite for proposing effective management measures. We took the cut slopes of the K162 section of the Beihei [...] Read more.

Icing in cut slopes is a serious risk to transportation safety in cold regions. Research on the occurrence process and mechanism of icing is a prerequisite for proposing effective management measures. We took the cut slopes of the K162 section of the Beihei Highway as the research object. We used a combination of field investigation, geological exploration, monitoring, and simulation to study and analyze the power source, occurrence process, and triggering mechanism of icing in cut slopes. The results show that the geologic type of this cut slope is a mudstone–sandstone interaction stratum. Abundant shallow groundwater is the source of water for icing. The excavation of cut slopes extends the effect of negative temperatures on groundwater flow during the winter period. The process of ice formation in cut slopes can be described as follows: As the environmental temperature drops, the surface soil begins to freeze, resulting in a gradual narrowing of the water channel; then, the groundwater flow is blocked, so that the internal pressure begins to rise. When the internal pressure of the pressurized groundwater exceeds the strength of the frozen soil, groundwater overflows from the sandstone layer to the surface, forming icing. The high pore water pressure inside the cut slope is the precursor for the occurrence of icing. The dynamic pressure of the pore water pressure is the main driving force for the formation of icing in cut slopes. The obstruction of the water channel due to ground freezing is the triggering condition for ice formation in cut slopes. Full article

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17 pages, 4040 KiB

Open AccessArticle

Prediction of Settling Velocity of Microplastics by Multiple Machine-Learning Methods

by Zequan Leng, Lu Cao, Yun Gao, Yadong Hou, Di Wu, Zhongyan Huo and Xizeng Zhao

Water 2024, 16(13), 1850; https://doi.org/10.3390/w16131850 - 28 Jun 2024

Viewed by 139

Abstract

The terminal settling velocity of microplastics plays a vital role in the physical behavior of microplastics, and is related to the migration and fate of these microplastics in the ocean. At present, the terminal settling velocity is mostly calculated by formulae, which also [...] Read more.

The terminal settling velocity of microplastics plays a vital role in the physical behavior of microplastics, and is related to the migration and fate of these microplastics in the ocean. At present, the terminal settling velocity is mostly calculated by formulae, which also leads to a fewer studies on the use of machine-learning models to predict its settling velocity in this field. This study fills this gap by studying the prediction of the settling velocity by machine-learning models and compares it with the traditional formula calculation method. This study evaluates three machine-learning models, namely, random forest, linear regression, and the back propagation neural network. The results of this study show that the prediction results of the three machine-learning models are more accurate than those of traditional formula calculations, with an accuracy increase of 12.79% (random forest), 9.3% (linear regression), and 13.92% (back propagation neural network), respectively. At the same time, according to the results of this study, random forest is better than the other models in the mean absolute error and root mean square error evaluation indicators, which are only 0.0036 and 0.0047. This paper proposes three machine-learning methods to prove that the prediction effect of machine learning is much better than traditional formula calculations, thereby improving the shortcomings in this field. At the same time, it also provides reliable data support for studying the migration behavior of microplastics in water bodies. Full article

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20 pages, 3761 KiB

Open AccessArticle

Multi-Objective Ecological Long-Term Operation of Cascade Reservoirs Considering Hydrological Regime Alteration

by Changjiang Xu, Di Zhu, Wei Guo, Shuo Ouyang, Liping Li, Hui Bu, Lin Wang, Jian Zuo and Junhong Chen

Water 2024, 16(13), 1849; https://doi.org/10.3390/w16131849 - 28 Jun 2024

Viewed by 121

Abstract

Constructing and operating cascade reservoirs significantly contribute to comprehensive basin water resource management, while altering natural hydrological regimes of rivers, which imposes negative impacts on riverine ecology. The main aim of this study is to synergistically optimize the objectives of increasing hydropower generation [...] Read more.

Constructing and operating cascade reservoirs significantly contribute to comprehensive basin water resource management, while altering natural hydrological regimes of rivers, which imposes negative impacts on riverine ecology. The main aim of this study is to synergistically optimize the objectives of increasing hydropower generation and alleviating hydrological regime alteration for cascade reservoirs. This study first proposed a dynamic time warping scenario backward reduction (DTW-SBR) framework to extract streamflow scenarios from the historical streamflow series regarded as benchmarks for calculating deviation degrees of hydrological regimes. Then a multi-objective long-term operation model considering the hydrological regime and hydroelectricity was formed for minimizing the deviation degrees of hydrological regimes at the downstream section (O1) and maximizing the hydropower generation of cascade reservoirs (O2). The non-dominated sorting genetic algorithm-II (NSGA-II) combined with the long-term conventional operation (CO) rules of cascade reservoirs was adopted to produce the Pareto-front solutions to derive the recommended policies for guiding the long-term operation of cascade reservoirs. The six large reservoirs in the middle reaches of the Jinsha River, China with a 10-day runoff dataset spanning from 1953 to 2015 constitute a case study. The results showed that nine streamflow scenarios were extracted for calculating the O1 by the DTW-SBR framework, which could reflect the intra- and inter- annual variability of hydrological regimes at the Panzhihua hydrological station. The Pareto-front solutions obtained by the NSGA-II revealed competitive relationships between the O1 and O2. As compared to the long-term CO rules of cascade reservoirs, the O1 value could be reduced by up to 42,312 (corresponding rate of 10.51%) and the O2 value could be improved by up to 1752 × 10⁸ kW·h (corresponding rate of 5.14%). Based on the inclination to be dominated by different objectives, three typical operation schemes, A, B and C, were chosen from the Pareto-front solutions; Scheme A could be considered as the recommended solution, which simultaneously reduced the O1 value by 23,965 with the rate of 5.95% and increased the O2 value by 1752 × 10⁸ kW·h with the rate of 5.14%, as compared to the long-term CO rules. This study can provide references on boosting the synergies of hydropower production and hydrological regime restoration for the long-term ecological operation of cascade reservoirs. Full article

(This article belongs to the Special Issue Advances in Water Conservancy and Hydropower Engineering: Modelling, Performances, Optimization Application and Environmental Effects)

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16 pages, 1040 KiB

Open AccessReview

Research Progress on the Removal of Contaminants from Wastewater by Constructed Wetland Substrate: A Review

by Liyan Wang, Leihui Ma, Junke Wang, Xia Zhao, Yushu Jing, Changqing Liu, Yihua Xiao, Cang Li, Chen Jiao and Mengchen Xu

Water 2024, 16(13), 1848; https://doi.org/10.3390/w16131848 - 28 Jun 2024

Viewed by 117

Abstract

Constructed wetlands (CWs) primarily achieve efficient wastewater purification through synergistic interactions among substrates, plants, and microorganisms. Serving as the structural foundation of the entire wetland system, substrates not only provide a growth medium for plants, but also serve as adhesive carriers for microorganisms [...] Read more.

Constructed wetlands (CWs) primarily achieve efficient wastewater purification through synergistic interactions among substrates, plants, and microorganisms. Serving as the structural foundation of the entire wetland system, substrates not only provide a growth medium for plants, but also serve as adhesive carriers for microorganisms and habitats for animal activities. Research on substrates has attracted considerable attention; however, in practical engineering applications, the selection of substrates often depend on personal experience, which may lead to significant gaps in the effectiveness of wetland systems in treating different characteristic contaminants. Therefore, it is of great significance to investigate the influence of substrates on the removal of contaminants in sewage and identify substrate materials with good physical and chemical properties to optimize the design and operation of CWs-based sewage-treatment systems and improve their purification efficiency. In this review, bibliometric analysis was conducted to using the Web of Science database and VOSviewer_1.6.20 software to assess the progress of research on CWs. This article provides a comprehensive overview of substrate types and characteristics based on recent research advancements in the field. Additionally, it discusses removal methods and the influence of factors related to conventional contaminants (COD, nitrogen, and phosphorus), heavy metals (HMs), fluorinated compounds, pharmaceuticals, personal care products (PPCPs), and microplastics. A thorough evaluation was conducted on the economic costs of various substrates and their ability to remove major contaminants from water bodies, providing a reference for the further development of wetland technology. Full article

(This article belongs to the Special Issue Science and Technology for Water Purification)

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14 pages, 2673 KiB

Open AccessArticle

Evaluation of Coal-Seam Roof-Water Richness Based on Improved Weight Method: A Case Study in the Dananhu No.7 Coal Mine, China

by Jie Xu, Qiqing Wang, Yuguang Zhang, Wenping Li and Xiaoqin Li

Water 2024, 16(13), 1847; https://doi.org/10.3390/w16131847 - 28 Jun 2024

Viewed by 148

Abstract

The safety of mines is a top priority in the mining industry, and a precise assessment of aquifer water levels is crucial for conducting a risk analysis of water-related disasters. Among them, the GIS-based water abundance index method is widely used in water-richness [...] Read more.

The safety of mines is a top priority in the mining industry, and a precise assessment of aquifer water levels is crucial for conducting a risk analysis of water-related disasters. Among them, the GIS-based water abundance index method is widely used in water-richness evaluation. However, the existing research lacks sufficient determination of evaluation indicator weights, specifically in the following aspects: (1) failure to consider the information differences between indicators and (2) inadequate differentiation of the relative importance of each indicator and their importance to the evaluation target. Taking the No.3 coal roof of Dananhu No.7 coal mine as the research object, six factors are selected as the main indexes for evaluating water richness. The weights were calculated using an improved entropy method and the scatter degree method, with the principle of information entropy used to reconcile the competitive and consistent relationship between the two evaluation methods. This approach resulted in the determination of combination weights for each influencing factor, highlighting the information differences between indicators and the importance of each indicator. Finally, the evaluation of aquifer water richness is partitioned by combining the GIS analysis function. The findings suggest that the Ⅰ division has low water richness, while the Ⅱ division is primarily medium-to-high water rich. The accuracy of the evaluation results exceeds 80%, providing valuable insights for hydrophobic programs for other coal-seam roofs. Full article

(This article belongs to the Special Issue The Research on Effects of Mining on Groundwater Environment)

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22 pages, 1345 KiB

Open AccessArticle

Residents’ Perception of Urban Water System-Based Environmental Issues

by Zerrin Kenanoğlu, Emine Malkoç True, Çiğdem Kılıçaslan Deniz, Bülent Deniz and Merve Özeren Alkan

Water 2024, 16(13), 1846; https://doi.org/10.3390/w16131846 - 28 Jun 2024

Viewed by 118

Abstract

The present study aims to investigate the level of awareness among residents living around an urban stream regarding the issues arising from the stream and the degree to which they are affected by these problems. To achieve this goal, a face-to-face questionnaire-based survey [...] Read more.

The present study aims to investigate the level of awareness among residents living around an urban stream regarding the issues arising from the stream and the degree to which they are affected by these problems. To achieve this goal, a face-to-face questionnaire-based survey was conducted with 270 randomly selected individuals using a proportional sampling method. We measured the awareness of residents about the issues arising from the urban stream, as well as their level of impact. The research determined that the inhabitants of the region were aware of and affected by various ecological, socio-cultural, land use, technical engineering, and management issues. The most important problems of which participants were aware included the low water quality, public order problems, the existence of unsafe, unused, and abandoned parts of the city on the stream banks and in the immediate vicinity of the stream, and the presence of a foul odor. Water pollution, public order problems, visual pollution, and the presence of a foul odor were identified as the problems most affecting the participants. Solution recommendations were developed under the five main headings of the identified problems. Full article

(This article belongs to the Special Issue Urban Water Systems: Challenges in Current Environment)

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17 pages, 5577 KiB

Open AccessArticle

Game Theory Applications in Equilibrium Water Pricing of Multiple Regional Sources and Users

by Shiwu Wang, Shangbin Liu, Shuiping Yao, Xi Guo, Shan-e-hyder Soomro, Chaojie Niu, Liyu Quan and Caihong Hu

Water 2024, 16(13), 1845; https://doi.org/10.3390/w16131845 - 28 Jun 2024

Viewed by 195

Abstract

China has been facing a contradiction between its water supply and demand for a long time, and it is urgent that it builds a “water-saving society”. Previous research on water pricing mainly focused on the policy level, only considering the supply and demand [...] Read more.

China has been facing a contradiction between its water supply and demand for a long time, and it is urgent that it builds a “water-saving society”. Previous research on water pricing mainly focused on the policy level, only considering the supply and demand sides and ignoring the participation of local governments. Due to the inconsistent approval mechanisms, different times of cost formation, and lack of a scientific pricing relationship between multiple water sources and multiple users, with the current water pricing in China, it is difficult to solve the complex problem of water resource allocation. This study aimed to promote the qualitative supply of water and the reuse of reclaimed water, achieve a high-quality and low-cost water supply, and explore the role of water-pricing mechanisms in the regulation of multi-source water supply configurations. The mechanism of regulation is constructed for the complex, multi-source, multi-user water resource system, and a three-party game model is established among local governments, water supply enterprises, and water users. A reasonable pricing system with a rational price relationship is obtained, and Pinghu City in Zhejiang Province is taken as the research area. The prices of the external water supply to residential users, non-resident users, and special users are 4.48 CNY/m³, 6.28 CNY/m³, and 7.12 CNY/m³. The external supply prices for resident users, non-resident users, and special users are 3.81 CNY/m³, 5.25 CNY/m³, and 6.05 CNY/m³. The external supply price for non-resident users is 2.62 CNY/m³ for reclaimed water. The results of the study showed that when the government’s contribution did not exceed the amount that it would have been without the inclusion of recycled water and the annual payment of water users did not exceed their ability to pay, the income of water suppliers increased by 69%. The three balanced objectives of rational water resource configuration by the local government, reasonable profit for the water supply enterprise, and reasonable payment by water users have been achieved. This study provides theoretical and methodological support for the implementation of water pricing for multi-source and multi-user water supplies in water-scarce areas. Full article

(This article belongs to the Topic Hydrology and Water Resources Management)

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19 pages, 4509 KiB

Open AccessArticle

Assessment of Flood Hazard Mapping Using a DEM-Based Approach and 2D Hydrodynamic Modeling

by Omayma Amellah, Paolo Mignosa, Federico Prost and Francesca Aureli

Water 2024, 16(13), 1844; https://doi.org/10.3390/w16131844 - 28 Jun 2024

Viewed by 156

Abstract

DEM-based approaches for assessing flood-prone areas have recently gained extensive attention due to their parsimony and cost-effectiveness. This work aims to test the capability of the Geomorphic Flood Index (GFI) to delineate flood-prone areas and the results performances while downscaling the calibration map. [...] Read more.

DEM-based approaches for assessing flood-prone areas have recently gained extensive attention due to their parsimony and cost-effectiveness. This work aims to test the capability of the Geomorphic Flood Index (GFI) to delineate flood-prone areas and the results performances while downscaling the calibration map. The accuracy was tested by examining the sensitivity to the exponent of the power function linking the flow depth in the river network and the upslope contributing area. Two approaches were selected: the first consisted of calibrating the GFI using a flood map generated through a 2D-SWE hydrodynamic model. The second consisted of correlating water depths with their corresponding upslope areas. The geomorphological model is able to effectively delineate flood susceptibility areas which, although on average larger than that obtained using the hydrodynamic model, provide a good starting point for any subsequent in-depth analysis. After calibration, an Objective Function of 0.21 and an Area Under the ROC Curve AUC = 92%, which is among the highest if compared with other cases in the literature, were obtained. Positive feedback was also obtained using a calibration map that covers only a rather limited portion of the basin. However, the small values of the scaling exponent obtained after calibration with the first method indicate substantial independence of the river depths from the upslope contributing areas. This leads to the belief that a simple power function is not particularly suitable for describing the relationships between these two variables. Full article

(This article belongs to the Special Issue Hydrometeorological Hazard and Risk Assessment)

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13 pages, 10207 KiB

Open AccessArticle

Removal of Glyphosate with Nanocellulose for Decontamination Purposes in Aquatic Systems

by Suzan da Silva Lessa, Blenda Lopes Orsi, Luciana Camargo de Oliveira, Wander Gustavo Botero, Paulo Sergio Tonello and Danielle Goveia

Water 2024, 16(13), 1843; https://doi.org/10.3390/w16131843 - 28 Jun 2024

Viewed by 145

Abstract

(1) The excessive and incorrect use of agricultural pesticides has caused environmental pollution, with a final destination in aquatic environments. Among the widely used agricultural pesticides, glyphosate stands out for weed control, which according to the World Health Organization (WHO) is potentially carcinogenic [...] Read more.

(1) The excessive and incorrect use of agricultural pesticides has caused environmental pollution, with a final destination in aquatic environments. Among the widely used agricultural pesticides, glyphosate stands out for weed control, which according to the World Health Organization (WHO) is potentially carcinogenic in humans. Once in an aquatic environment, decontamination aimed at removing the pesticide is not always a simple task. In this sense, it is necessary to develop low-cost, sustainable procedures with a high remediation capacity. (2) In this context, a nanocellulose-based biopolymer was developed to removal glyphosate from aquatic environments. Nanocellulose was obtained from a cellulose sample from eucalyptus wood and was characterized by scanning and double-beam electron microscopy, scanning microscopy with an energy dispersive detector and Fourier transform infrared (FTIR) spectroscopy. Adsorption studies were carried out to evaluate the retention of glyphosate by nanocellulose. (3) Nanocellulose showed a value of 4.7 mg of glyphosate per gram of nanocellulose, and organomodified nanocellulose showed the removal of 6.1 mg of glyphosate per gram of nanocellulose, as evaluated in pseudo-first-order kinetic models. (4) The biomaterial has a sustainable and renewable origin, has potential for contaminant removal and can be applied to contaminated aquatic systems. Full article

(This article belongs to the Special Issue Sustainable Novel Processes for the Removing of Heavy Metals and Other Pollutants from Aqueous Solutions)

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