Water

34 pages, 1283 KiB

Open AccessArticle

Upgrading Maize Cultivation in Bosnia and Herzegovina from Rainfed to Irrigated Systems: Use of Remote Sensing Data and the Dual Crop Coefficient Approach to Estimate Evapotranspiration

by Sabrija Čadro, Zuhdija Omerović, Daniela Soares, Benjamin Crljenković, Wilk S. Almeida, Milan Šipka, Merima Makaš, Mladen Todorović and Teresa A. Paço

Water 2024, 16(13), 1797; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131797 (registering DOI) - 25 Jun 2024

Abstract

A two-year experiment was conducted with a local maize hybrid under full (F) and deficit (D) drip irrigation and rainfed conditions (R) to estimate maize evapotranspiration in Bosnia and Herzegovina (BiH). Three approaches, namely, A&P, SIMDualKc (SD), and vegetation index (VI), to estimate [...] Read more.

A two-year experiment was conducted with a local maize hybrid under full (F) and deficit (D) drip irrigation and rainfed conditions (R) to estimate maize evapotranspiration in Bosnia and Herzegovina (BiH). Three approaches, namely, A&P, SIMDualKc (SD), and vegetation index (VI), to estimate the actual crop coefficient (K_{c act}), the actual basal crop coefficient (K_{cb act}), and the actual crop evapotranspiration (ET_{c act}), were applied with the dual crop coefficient method and remote sensing (RS) data for the first time. While K_{cb act} from all approaches matched FAO56 tabulated values, SD showed differences in comparison to A&P of up to 0.24 in D and R conditions, especially in the initial and mid-season stages. VI demonstrated very good performance in all treatments. In F, the obtained K_{c act} for all approaches during the initial and end stages were higher than the tabulated values, ranging from 0.71 to 0.87 for the K_{c ini act} and from 0.80 to 1.06 for the K_{c end act}, while the mid-season period showed very good agreement with the literature. The maize crop evapotranspiration range is 769–813 mm, 480–752 mm, and 332–618 mm for F, D, and R, respectively. The results confirmed the suitability of both approaches (SD and VI) to estimate maize crop evapotranspiration under F, with the VI approach demonstrating an advantage in calculating K_{cb act}, K_{c act}, and ET_{c act} values under water stress conditions. The higher observed yields (67.6%) under irrigation conditions emphasize the need to transition from rainfed to irrigation-dependent agriculture in BiH, even for drought-resistant crops like maize. Full article

(This article belongs to the Topic Application of Smart Technologies in Water Resources Management)

18 pages, 1898 KiB

Open AccessArticle

Process Energy and Material Consumption Determined by Reaction Sequence: From AAO to OHO

by Xuguang He, Xiong Ke, Tuo Wei, Yao Chen, Zhi Qin, Acong Chen, Heng Zhang, Hua Huang, Yudi Yang, Guanglei Qiu, Haizhen Wu and Chaohai Wei

Water 2024, 16(13), 1796; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131796 (registering DOI) - 25 Jun 2024

Abstract

The anaerobic-anoxic-oxic (AAO) process is one of the most widely used processes for treating industrial organic wastewater, and it has shown significant effectiveness in the removal of organic compounds, as well as denitrification and phosphorus removal. However, for the treatment of industrial organic [...] Read more.

The anaerobic-anoxic-oxic (AAO) process is one of the most widely used processes for treating industrial organic wastewater, and it has shown significant effectiveness in the removal of organic compounds, as well as denitrification and phosphorus removal. However, for the treatment of industrial organic wastewater, this anaerobic preposition and aerobic postposition process has exposed various limitations. Therefore, for this type of wastewater, the oxic-hydrolytic and denitrification-oxic (OHO) treatment process has been proposed and developed based on the principles of three-sludge separation and fluidization. This study integrated operational data from 203 coking wastewater treatment plants worldwide, and the two-step nitrification-denitrification activated sludge model No.3 (TCW-ASM3) was used for comparative analysis of the pollutant removal efficiency and total operating cost of the AAO process and the OHO process in the face of characteristic pollutants in coking wastewater. The results indicate that the full-scale OHO process achieved removal efficiencies of up to 3784 mg/L for chemical oxygen demand (COD) and 297 mg/L for total nitrogen (TN). The theoretical total cost for OHO and AAO were 9.75 and 14.38 CNY/m³, respectively. The pre-treatment aerobic process effectively reduces the biological toxicity of high-toxicity and refractory industrial wastewater, and the three-sludge system provides a stable living space for functional microorganisms, the combination of multi-mode denitrification processes offers new possibilities for treating similar types of industrial wastewater. Full article

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

18 pages, 1614 KiB

Open AccessArticle

Structural Evolution of Mn-Substituted FeOOH and Its Adsorption Mechanism for U(Ⅵ): Effect of the Mole Ratio of Mn/(Fe + Mn)

by Mengxue Li, Lanbao Zhu, Jing Wang, Li Ma, Zhengwei Pan, Wenwei Ji, Xiaoyu Sun, Ruping Li, Xia Li, Shilong Duan and Yule Tao

Water 2024, 16(13), 1795; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131795 (registering DOI) - 25 Jun 2024

Abstract

Mn-substituted FeOOH with different Mn/(Mn + Fe) molar ratios are synthesized, and characterized using FESEM, XRD, FTIR, ICP-OES, BET, Zeta potential, TG-DSC, XPS, and VSM. The results show that the actual doping amounts of Mn are 0%, 3.05%, 6.13%, 9.04%, 12.70%, and 15.14%, [...] Read more.

Mn-substituted FeOOH with different Mn/(Mn + Fe) molar ratios are synthesized, and characterized using FESEM, XRD, FTIR, ICP-OES, BET, Zeta potential, TG-DSC, XPS, and VSM. The results show that the actual doping amounts of Mn are 0%, 3.05%, 6.13%, 9.04%, 12.70%, and 15.14%, respectively. The substitution of Mn promotes the transformation of goethite from FeOOH to MnFe₂O₄, resulting in a saturation magnetization intensity of up to 14.90 emu/g for G-Mn15%, laying a theoretical foundation for magnetic recovery. The specific surface area of Mn-substituted FeOOH increases from 57.15 m²/g to 315.26 m²/g with an increasing Mn substitution amount. Combined with the abundant oxygen-containing functional groups such as -OH, Fe-O, and Mn-O on the surface, sufficient active sites are provided for the efficient adsorption of U(VI). The TG-DSC analysis results indicate that the substitution of Mn improves the thermal stability of goethite. In addition, XPS analysis results indicate that the substitution of Mn leads to the conversion of Fe³⁺ to Fe²⁺ in goethite, and the conversion of Mn²⁺ to Mn³⁺ replaces Fe³⁺ in the structure of goethite. Fe-O and Mn-O coordinate participate in the adsorption and reduction process of U(VI). The batch experiment results show that the substitution of Mn promotes the adsorption performance of goethite for U(VI). When T = 303 K, pH = 4.0, m/V = 0.5 g/L, and I = 0.01 mol/L NaCl, the maximum adsorption capacity of G-Mn15% for U(VI) is 79.24 mg/g, indicating the potential value of Mn substitution for goethite in the treatment of uranium-containing wastewater. Full article

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

21 pages, 1655 KiB

Open AccessArticle

Operation Status and Effective Operation Management Model for On-Site Swine Wastewater Treatment Facilities

by Jae-Hong Park, Eu-Gene Chung, Eun-Hye Na and Yong-Seok Kim

Water 2024, 16(13), 1794; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131794 (registering DOI) - 25 Jun 2024

Abstract

This study was conducted to examine the operation statuses of on-site swine wastewater treatment facilities through surveys and field surveys on pig farms and to propose effective operation models. Field analyses and surveys of pig farms indicate that technical and financial support systems [...] Read more.

This study was conducted to examine the operation statuses of on-site swine wastewater treatment facilities through surveys and field surveys on pig farms and to propose effective operation models. Field analyses and surveys of pig farms indicate that technical and financial support systems are required for both farms and on-site swine wastewater treatment facilities. Public environmental services have been proposed as an effective support system, in which private sewage treatment facilities are entrusted to professional environmental management agencies, and the costs are shared by local governments and facility owners. However, securing a stable budget represents a challenge to implementing public environmental services. Thus, this study proposes a collaborative manure management model composed of individual farms, professional environmental management agencies, and local governments to address the shortcomings of public environmental services. To effectively manage pig manure, the flexible application of discharge standards, diversification of pollutant reduction management techniques (e.g., feed management), and periodic review of permits must be considered. Additionally, the reinforcement of discharge standards for individual purification facilities, control of the livestock density and number, and impacts of livestock manure discharge on riverine ecosystems must be considered. Full article

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

30 pages, 1705 KiB

Open AccessArticle

Predicting Urban Water Consumption and Health Using Artificial Intelligence Techniques in Tanganyika Lake, East Africa

by Alain Niyongabo, Danrong Zhang, Yiqing Guan, Ziyuan Wang, Muhammad Imran, Bertrand Nicayenzi, Alemayehu Kabeta Guyasa and Pascal Hatungimana

Water 2024, 16(13), 1793; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131793 (registering DOI) - 25 Jun 2024

Abstract

Water quality has significantly declined over the past few decades due to high industrial rates, rapid urbanization, anthropogenic activities, and inappropriate rubbish disposal in Lake Tanganyika. Consequently, forecasting water quantity and quality is crucial for ensuring sustainable water resource management, which supports agricultural, [...] Read more.

Water quality has significantly declined over the past few decades due to high industrial rates, rapid urbanization, anthropogenic activities, and inappropriate rubbish disposal in Lake Tanganyika. Consequently, forecasting water quantity and quality is crucial for ensuring sustainable water resource management, which supports agricultural, industrial, and domestic needs while safeguarding ecosystems. The models were assessed using important statistical variables, a dataset comprising six relevant parameters, and water use records. The database contained electrical conductivity, pH, dissolved oxygen, nitrate, phosphates, suspended solids, water temperature, water consumption records, and an appropriate date. Furthermore, Random Forest, K-nearest Neighbor, and Support Vector Machine are the three machine learning methodologies employed for water quality categorization forecasting. Three recurrent neural networks, namely long short-term memory, bidirectional long short-term memory, and the gated recurrent unit, have been specifically designed to predict urban water consumption and water quality index. The water quality classification produced by the Random Forest forecast had the highest accuracy of 99.89%. The GRU model fared better than the LSTM and BiLSTM models with values of R² and NSE, which are 0.81 and 0.720 for water consumption and 0.78 and 0.759 for water quality index, in the prediction results. The outcomes showed how reliable Random Forest was in classifying water quality forecasts and how reliable gated recurrent units were in predicting water quality indices and water demand. It is worth noting that accurate predictions of water quantity and quality are essential for sustainable resource management, public health protection, and ecological preservation. Such promising research could significantly enhance urban water demand planning and water resource management. Full article

(This article belongs to the Section Urban Water Management)

19 pages, 427 KiB

Open AccessEssay

Toward a Sociology of Water: Reconstructing the Missing “Big Picture” of Social Water Research

by Peter Schulz and Alexis Gros

Water 2024, 16(13), 1792; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131792 (registering DOI) - 25 Jun 2024

Abstract

In recent years, significant advancements have been made in the field of social water research. This is especially reflected in the emergence and consolidation of three influential theoretical approaches in hydrology, human geography, and anthropology: socio-hydrology, hydrosocial theory, and the multiple ontologies of [...] Read more.

In recent years, significant advancements have been made in the field of social water research. This is especially reflected in the emergence and consolidation of three influential theoretical approaches in hydrology, human geography, and anthropology: socio-hydrology, hydrosocial theory, and the multiple ontologies of water, respectively. While the present paper acknowledges the great merits of each of these perspectives, it starts from the identification of two important shortcomings in current social water research: the dispersion of the literature in distinct disciplinary sub-fields and the lack of specifically sociological approaches to hydrosocial issues. Accordingly, the aim of this paper is twofold: to offer a “big picture” of current social water research from a sociological–theoretical perspective and to initiate a fruitful conversation between sociologists and social water researchers from other disciplines. Full article

20 pages, 3969 KiB

Open AccessArticle

Innovative Adaptive Multiscale 3D Simulation Platform for the Yellow River Using Sphere Geodesic Octree Grid Techniques

by Bingxuan Li, Jinxin Wang, Yan Zhang and Yongkang Sun

Water 2024, 16(13), 1791; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131791 (registering DOI) - 25 Jun 2024

Abstract

Earth system simulation technology is fundamental for ecological protection and high-quality development in the Yellow River Basin. To address the lack of a Yellow River simulation platform, this study proposes an adaptive multiscale true 3D crust simulation platform using the Sphere Geodesic Octree [...] Read more.

Earth system simulation technology is fundamental for ecological protection and high-quality development in the Yellow River Basin. To address the lack of a Yellow River simulation platform, this study proposes an adaptive multiscale true 3D crust simulation platform using the Sphere Geodesic Octree Grid (SGOG). Twelve models in four categories were designed: single fine-scale models, geomorphic zone-based models, and models using both top-down and bottom-up approaches. The models were evaluated based on terrain feature representation and computational efficiency. The results show that single fine-scale models preserve detailed terrain features but are computationally intensive. They are suitable for the precise simulation of surface processes. Top-down and bottom-up models balance terrain detail and efficiency, and are thereby widely applicable. Geomorphic zone-based models provide detailed focal area representation and higher computational efficiency, being more targeted. Various methods offer flexible scale transformations, each with its own strengths, allowing researchers to select a method according to practical application needs. Consequently, this research demonstrates that spherical discrete grids offer reliable support for constructing basin simulation platforms, providing new technological and scientific insights for the Yellow River Basin’s ecological protection and development. Full article

(This article belongs to the Special Issue Yellow River Basin Management under Pressure: Present State, Restoration and Protection III)

10 pages, 1058 KiB

Open AccessArticle

Impact of Gas-to-Water Ratio on Treatment Efficiency of Submerged-Macrophyte Constructed Wetland Systems

by Hongming Mao, Shiwen Lu, Guiying Huang, Xianle Jia, Chenqian Bao, Xinyi Yan, Xiangyong Zheng, Min Zhao and Zhan Jin

Water 2024, 16(13), 1790; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131790 (registering DOI) - 25 Jun 2024

Abstract

Abstract: Constructed wetland systems employing submerged macrophytes are increasingly utilized for treating municipal and industrial wastewater, as well as odoriferous and eutrophic water bodies. However, the pollutant removal efficiency of these systems needs further enhancement. In this study, we examined the impact of [...] Read more.

Abstract: Constructed wetland systems employing submerged macrophytes are increasingly utilized for treating municipal and industrial wastewater, as well as odoriferous and eutrophic water bodies. However, the pollutant removal efficiency of these systems needs further enhancement. In this study, we examined the impact of the gas-to-water ratio on the treatment efficiency of the constructed wetland of Vallisneria. We also examined the extracellular polymeric substances (EPSs) of the floating biofilm and the structure of the microbial community in this system. Our findings showed that the gas-to-water ratio significantly affects the total nitrogen (TN) removal rate within the Vallisneria wetlands, with an optimum removal at a gas-to-water ratio of 15:1, while the removal efficiencies for chemical oxygen demand (COD), NH₄⁺-N, and total phosphorus (TP) remain relatively unaffected. Increased gas-to-water ratios corresponded to a notable decrease in biofilm EPSs. High-throughput sequencing analysis demonstrated a shift in biofilm-denitrifying bacteria from anoxic heterotrophic to aerobic denitrifiers, alongside a significant rise in the abundance of denitrifying bacteria, whereas excessively high gas-to-water ratios inhibited the growth of these bacteria. A gas-to-water ratio of 15:1 constituted the optimal condition for ecological restoration of the water body within the Vallisneria wetland systems. These results could contribute to the optimization of submerged-macrophyte constructed wetland system design and the enhancement of treatment efficiency. Full article

(This article belongs to the Special Issue Constructed Wetlands as a Sustainable Technology for Wastewater Treatment: Current Trends and Future Potential)

29 pages, 5484 KiB

Open AccessArticle

Rainwater Harvesting Site Selection for Drought-Prone Areas in Somali and Borena Zones, Oromia Regional State, Ethiopia: A Geospatial and Multi-Criteria Decision Analysis

by Amanuel Kumsa Bojer, Desta Jula Bekalo, Taye Girma Debelee, Saralees Nadarajah and Ayad M. Fadhil Al-Quraishi

Water 2024, 16(13), 1789; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131789 (registering DOI) - 25 Jun 2024

Abstract

Rainwater collection systems play a crucial role in enhancing water availability in regions with low precipitation. This study focused on identifying potential rainwater harvesting (RWH) locations in drought-prone areas, specifically the Borena zone of Oromia and the regional states of Somali. This research [...] Read more.

Rainwater collection systems play a crucial role in enhancing water availability in regions with low precipitation. This study focused on identifying potential rainwater harvesting (RWH) locations in drought-prone areas, specifically the Borena zone of Oromia and the regional states of Somali. This research leveraged geospatial techniques and a multi-criteria decision analysis (MCDA) to assess feasible RWH sites. The dataset comprises essential factors such as rainfall, drainage density, slope, soil texture type, and land use/land cover. These thematic layers serve as inputs for analysis, with each factor being weighted using the Analytical Hierarchy Process (AHP) method based on its significance. Reclassifying factors into subclasses facilitates suitability analysis. The weighted linear combination (WLC) technique is applied to identify and prioritize potential rainwater harvesting (PRWH) locations based on four suitability classes: highly suitable, moderately suitable, low suitability, and unsuitable. Our findings reveal that 1% of the study area, covering approximately 3288 km², is highly suitable for RWH. Areas with moderate suitability constitute approximately 12% (37,498 km²), while regions with low suitability, representing the majority, encompass about 75% (242,170 km²). Additionally, 13% (41,000 km²) of the study area is deemed unsuitable for RWH. The proposed technique for identifying suitable RWH sites is adaptable to other low-precipitation regions. However, before implementing RWH structures, further research is imperative. This study proposed the exploration of socioeconomic variables in future research and urged for an in-depth examination of various aspects of environmental sustainability. Our research paves the way for adapting rainwater harvesting systems to align with community needs and life cycles while also exploring the socio-economic and environmental dimensions of sustainability for future study. The insights offer promising solutions to address the urgent issues associated with water scarcity. This should include comprehensive site depictions, an exploration of social and economic activities, and the meticulous preparation of a cost-benefit analysis. Full article

(This article belongs to the Section Urban Water Management)

22 pages, 1318 KiB

Open AccessArticle

Integrated Struvite Precipitation and Fenton Oxidation for Nutrient Recovery and Refractory Organic Removal in Palm Oil Mill Effluent

by Yi Fen Sea, Adeline Seak May Chua, Gek Cheng Ngoh and Mohamad Fairus Rabuni

Water 2024, 16(13), 1788; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131788 (registering DOI) - 25 Jun 2024

Abstract

Anaerobically treated palm oil mill effluent (AnT-POME), containing a high concentration of ammoniacal-nitrogen (NH₄⁺-N) and soluble chemical oxygen demand (sCOD) was subjected to sequential processes of struvite precipitation to recover NH₄⁺-N and Fenton oxidation for sCOD removal. [...] Read more.

Anaerobically treated palm oil mill effluent (AnT-POME), containing a high concentration of ammoniacal-nitrogen (NH₄⁺-N) and soluble chemical oxygen demand (sCOD) was subjected to sequential processes of struvite precipitation to recover NH₄⁺-N and Fenton oxidation for sCOD removal. The optimization of treatment was conducted through response surface methodology (RSM). Under optimized struvite precipitation conditions (Mg²⁺/NH₄⁺, PO₄³⁻/NH₄⁺ molar ratios: 1; pH 8.2 ± 0.1), NH₄⁺-N concentration decreased to 41 ± 7.1 mg L⁻¹from an initial 298 ± 41 mg L⁻¹(78.8 ± 1.6 % removal). Field emission scanning electron microscopy (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDX) confirmed NH₄⁺-N was recovered as struvite. Subsequent Fenton oxidation under the optimized conditions (H₂O₂ dosage: 2680 mg L⁻¹; molar ratio of Fe²⁺/H₂O₂: 0.8; reaction time: 56 min) reduced sCOD concentration to 308 ± 46 mg L⁻¹ from an initial 1350 ± 336 mg L⁻¹ (76.0 ± 1.0 % removal). The transparent appearance of treated AnT-POME validated the removal of sCOD responsible for the initial brownish appearance. Models derived from RSM demonstrated significance, with high coefficients of determination (R² = 0.99). Overall, integrated struvite precipitation and Fenton oxidation effectively removed NH₄⁺-N and sCOD from AnT-POME, contributing to nutrient recovery and environmental sustainability. Full article

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

26 pages, 3540 KiB

Open AccessArticle

Future Wave Climate-Driven Longshore Sediment Transport and Shoreline Evolution along the Southwestern Black Sea

by Büşra Başaran and H. Anıl Arı Güner

Water 2024, 16(13), 1787; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131787 (registering DOI) - 25 Jun 2024

Abstract

This study investigates the future wave climate-driven longshore sediment transport (LST) and shoreline change on the Karasu Coast, situated on the southwestern coast of the Black Sea, under the RCP4.5 and RCP8.5 wave climate scenarios. Within the scope of this study, hourly deep [...] Read more.

This study investigates the future wave climate-driven longshore sediment transport (LST) and shoreline change on the Karasu Coast, situated on the southwestern coast of the Black Sea, under the RCP4.5 and RCP8.5 wave climate scenarios. Within the scope of this study, hourly deep sea wave data between 2021 and 2100, according to the RCP4.5 and RCP8.5, were used in order to predict future LST processes. Net and gross LST rates were computed using various empirical and numerical methods based on hourly wave parameters. By the conclusion of the study period after 80 years, the average net LST rates were obtained as 48,000 and 51,500 m³/year in the RCP4.5 and RCP8.5, respectively, while the gross LST rates were 250,000 and 255,000 m³/year. Due to the increase in wave height and period in both climate scenarios compared to the historical data, the average gross LST rates are projected to rise in the future. The reduction in swell wave heights, coupled with an increase in wind wave heights, compared to the past has led to a reduction in net LST. The results show that, after 80 years, LST will have increased 2.5 times more in the near future in comparison with the middle future for both scenarios. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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17 pages, 1092 KiB

Open AccessArticle

Investigate the Spatiotemporal Evolution of Drought and Its Interaction with Atmospheric Circulation in the Yellow River Middle Basin

by Yuanxin Dai, Jinlong Dong, Yingnan Wei, Mengyuan Xu, Tehseen Javed, Olusola Olaitan Ayantobo, Ning Yao and Bao Hu

Water 2024, 16(13), 1786; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131786 - 24 Jun 2024

Viewed by 110

Abstract

Global warming contributes to an increased frequency and severity of droughts. Drought emerges as a highly prevalent natural calamity, distinguished by its formidable disruptive impact and the capacity to trigger considerable economic setbacks. Understanding the spatiotemporal characteristics of droughts and clarifying the driving [...] Read more.

Global warming contributes to an increased frequency and severity of droughts. Drought emerges as a highly prevalent natural calamity, distinguished by its formidable disruptive impact and the capacity to trigger considerable economic setbacks. Understanding the spatiotemporal characteristics of droughts and clarifying the driving role of atmospheric circulation on droughts is vital for agricultural, hydrological, ecological, and socio-economic systems. Leveraging meteorological data from 36 stations in the middle reaches of the Yellow River Basin from 1961 to 2020, we employed the Standardized Precipitation Evapotranspiration Index (SPEI) to calculate drought occurrence. Concurrently, we explored the influence of atmospheric circulation on the SPEI. The findings of our study underscore a concerning trend of worsening drought conditions within the study area. We discovered a significant correlation between the duration and severity of drought (R = 0.83, p < 0.001); longer durations often corresponded to higher levels of severity. Turning our attention to atmospheric dynamics, the Nino Eastern Pacific index (NE) emerged as a critical driver of SPEI dynamics (the contribution of NE to SPEI was 0.22), significantly impacting drought patterns. In conclusion, the study significantly contributes to our comprehension of the evolving drought patterns under the influence of global warming. The findings can provide valuable information for water resource management and drought disaster control. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

15 pages, 13165 KiB

Open AccessArticle

Numerical Study of Low-Specific-Speed Centrifugal Pump Based on Principal Component Analysis

by Yangyang Wei, Han Zhu, Quanwang Fan, Ning Qiu, Jie Wu and Weibin Zhang

Water 2024, 16(13), 1785; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131785 - 24 Jun 2024

Viewed by 129

Abstract

The characteristics of pressure pulsations in centrifugal pumps have attracted considerable attention. In this study, principal component analysis is used to discuss the pressure pulsations in a centrifugal pump with a low specific speed, and the primary causes for these pressure pulsations are [...] Read more.

The characteristics of pressure pulsations in centrifugal pumps have attracted considerable attention. In this study, principal component analysis is used to discuss the pressure pulsations in a centrifugal pump with a low specific speed, and the primary causes for these pressure pulsations are analyzed in conjunction with experimental results. The results indicate that principal component analysis effectively separates the primary modes that influence the flow field characteristics. An excessive wrap angle results in the formation of a backflow vortex on the working face of the blade. Obvious stratification of the zero-order modal pressure indicates that the geometric structure of the impeller is rational and that the transient flow field is stable. The second- and third-order modes are conjugates, and their dominant frequency coincides with the dominant rotating frequency of the impeller, indicating that the pulsations of a single channel are the primary component of the pressure pulsations. The primary frequency (148.54 Hz) of the pressure pulsations at monitoring points distributed across the volute is three times the rotational frequency (49.51 Hz) of the impeller. The different positions and sub-frequencies of the monitoring points mean that the principal component analysis can effectively identify the impeller-induced sub-frequency difference. Full article

(This article belongs to the Special Issue Hydrodynamics in Pumping and Hydropower Systems)

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26 pages, 7190 KiB

Open AccessArticle

Interactive Changes in Climatic and Hydrological Droughts, Water Quality, and Land Use/Cover of Tajan Watershed, Northern Iran

by Mohammadtaghi Avand, Hamid Reza Moradi and Zeinab Hazbavi

Water 2024, 16(13), 1784; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131784 - 24 Jun 2024

Viewed by 146

Abstract

In response to novel and complex uncertainties, the present research is conducted to characterize the most significant indicators of watershed health including drought, water quality, and vegetation for the Tajan watershed, Mazandaran, Iran. The Standardized Precipitation Index (SPI) and Streamflow Drought Index (SDI) [...] Read more.

In response to novel and complex uncertainties, the present research is conducted to characterize the most significant indicators of watershed health including drought, water quality, and vegetation for the Tajan watershed, Mazandaran, Iran. The Standardized Precipitation Index (SPI) and Streamflow Drought Index (SDI) are, respectively, used to quantify the meteorological and hydrological droughts in the present (1993–2020) and future (2023–2050) employing optimistic RCP2.6 and pessimistic RCP8.5 scenarios. To concoct discharge data for the future, IHACRES v1.0 software is used with a Nash–Sutcliffe coefficient (NSE) of 0.48 and a coefficient of determination (R²) of 0.58. Maps of land use and Normalized Difference Vegetation Index (NDVI) are also prepared using Landsat images. Subsequently, the surface water quality is assessed using AqQA v1.1.0 software. The results show the difference in the severity of future meteorological droughts in different stations. In addition, the predominance of non-drought (SDI≥0) or mild drought (−1 ≤ SDI < 0) is indicated for future hydrology. The land use changes show a decrease in rangeland (−5.47%) and an increase in residential land (9.17%). The water quality analysis also indicates an increase in carbonate ions in the watershed outlet. Communicating the relationships between study indicators, which is a big gap in the current watershed management approach, avoids future failures and catastrophes. Full article

(This article belongs to the Special Issue Hydroclimate Extremes: Causes, Impacts, and Mitigation Plans)

24 pages, 14077 KiB

Open AccessArticle

Spatio-Temporal Variation in Suspended Sediment during Typhoon Ampil under Wave–Current Interactions in the Yangtze River Estuary

by Jie Wang, Cuiping Kuang, Daidu Fan, Wei Xing, Rufu Qin and Qingping Zou

Water 2024, 16(13), 1783; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131783 - 24 Jun 2024

Viewed by 193

Abstract

Suspended sediment plays a major role in estuary morphological change and shoal erosion and deposition. The impact of storm waves on sediment transport and resuspension in the Yangtze River Estuary (YRE) was investigated using a 3D coupling hydrodynamic-wave model with a sediment transport [...] Read more.

Suspended sediment plays a major role in estuary morphological change and shoal erosion and deposition. The impact of storm waves on sediment transport and resuspension in the Yangtze River Estuary (YRE) was investigated using a 3D coupling hydrodynamic-wave model with a sediment transport model during Typhoon Ampil. This model has been validated in field observations of water level, current, wave, and sediment concentration. The model was run for tide only, tide + wind, tide + wind and wave forcing conditions. It was found that: (1) typhoons can increase the suspended sediment concentration (SSC) by enhancing bed shear stress (BSS), especially in the offshore area of the YRE, and there is hysteresis between SSC and BSS variation; (2) exponential and vertical-line types are the main vertical profile of the SSC in the YRE and typhoons can strengthen vertical mixing and reconstruct the vertical distribution; and (3) waves are the dominating forcing factor for the SSC in the majority of the YRE through wave-induced BSS which releases sediment from the seabed. This study comprehensively investigates the spatio-temporal variation in SSC induced by Typhoon Ampil in the main branch of the YRE, which provides insights into sediment transport and resuspension during severe storms for estuaries around the world. Full article

(This article belongs to the Special Issue Hydrodynamics and Sediment Transport in the Coastal Zone)

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16 pages, 1098 KiB

Open AccessArticle

Retention, Degradation, and Runoff of Plastic-Coated Fertilizer Capsules in Paddy Fields in Fukushima and Miyagi Prefectures, Japan: Consistency of Capsule Degradation Behavior and Variations in Carbon Weight and Stable Carbon Isotope Abundance

by Shigeki Harada, Itsuki Yajima, Keitaro Fukushima and Youji Nitta

Water 2024, 16(13), 1782; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131782 - 23 Jun 2024

Viewed by 313

Abstract

Paddy field runoff containing plastic capsules that are used to coat fertilizers has been receiving increased attention. However, the behavior of these capsules, especially their degradation behavior, has not been extensively investigated. We divided the capsules in runoff into two categories: “floating capsules [...] Read more.

Paddy field runoff containing plastic capsules that are used to coat fertilizers has been receiving increased attention. However, the behavior of these capsules, especially their degradation behavior, has not been extensively investigated. We divided the capsules in runoff into two categories: “floating capsules after ploughing” and “floating capsules discharged via pipes at the exits of paddy fields”. The behaviors of the capsules in both types of runoff were monitored in 2022 and 2023 at four paddy fields in Fukushima and Miyagi prefectures in northern Japan. Sampling of capsules in paddy biomass and soil, and comparisons of capsule weight to biomass weight showed that a decrease in plastic capsule weight reflected a decrease in capsule runoff. However, the emergence of clear effects showed a delay of 2 to 3 years, as explained by carbon isotopic analyses. The decrease in the weight of the plastic capsules could be attributed to a combination of capsule degradation and the release of urea inside the capsules, which was also explained by carbon isotopic analyses. Three types of degraded capsules were found: shrunken, broken, and spherical. Statistically significant differences among the weights of each type found. Full article

(This article belongs to the Topic Microplastics Pollution)

23 pages, 14609 KiB

Open AccessArticle

Overflow Simulation and Optimization of a Drainage System in an Urban Area in the Northern Anhui Plain

by Yun Wan, Mingjun Li, Nan Zhang, Yuxuan Li, Peiqing Huang, Houkuan Zhang, Hao Huang, Wei Wei and Shuguang Zhu

Water 2024, 16(13), 1781; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131781 - 23 Jun 2024

Viewed by 293

Abstract

Quantitative simulation of urban waterlogging using computer models is an effective technical means for urban storm water management, especially for predicting and preventing waterlogging. In this study, a city in the northern Anhui Plain, China, was selected as the study site. The Storm [...] Read more.

Quantitative simulation of urban waterlogging using computer models is an effective technical means for urban storm water management, especially for predicting and preventing waterlogging. In this study, a city in the northern Anhui Plain, China, was selected as the study site. The Storm Water Management Model was applied to simulate the dynamic changes in the pipeline overload, node overflow, and discharge port runoff characteristics from three perspectives: surface runoff, pipe network transmission, and flow control of low-impact development. The operation of the rainwater pipe network under different return periods and the real-time operation of the rainwater pipe network were simulated to seek solutions to urban waterlogging problems caused by flat terrain and slow drainage. The results revealed that surface runoff is the primary source of rainfall in the study area, with a runoff coefficient of 0.599. The drainage pipe network was optimized by expanding the diameter of the pipe from ≤1.5 mm to ≥2 mm. The water reduction rate was more than 50%, and overload did not occur after optimization. Therefore, sinking green space technology and optimization methods for expanding a pipe diameter can reduce urban waterlogging. Full article

18 pages, 2267 KiB

Open AccessArticle

Tracking the Dynamics of Spartina alterniflora with WorldView-2/3 and Sentinel-1/2 Imagery in Zhangjiang Estuary, China

by Di Dong, Huamei Huang and Qing Gao

Water 2024, 16(13), 1780; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131780 - 23 Jun 2024

Viewed by 255

Abstract

The invasion of Spartina alterniflora (S. alterniflora) has posed serious threats to the sustainability, quality and biodiversity of coastal wetlands. To safeguard coastal ecosystems, China has enacted large-scale S. alterniflora removal projects, which set the goal of effectively controlling S. alterniflora [...] Read more.

The invasion of Spartina alterniflora (S. alterniflora) has posed serious threats to the sustainability, quality and biodiversity of coastal wetlands. To safeguard coastal ecosystems, China has enacted large-scale S. alterniflora removal projects, which set the goal of effectively controlling S. alterniflora throughout China by 2025. The accurate monitoring of S. alterniflora with remote sensing is urgent and requisite for the scientific eradication, control and management of this invasive plant. In this study, we combined multi-temporal WorldView-2/3 (WV-2/3) and Sentinel-1/2 imagery to monitor the S. alterniflora dynamics before and after the S. alterniflora removal projects in Zhangjiang Estuary. We put forward a new method for S. alterniflora detection with eight-band WV-2/3 imagery. The proposed method first used NDVI to discriminate S. alterniflora from water, mud flats and mangroves based on Ostu thresholding and then used the red-edge, NIR1 and NIR2 bands and support vector machine (SVM) classifier to distinguish S. alterniflora from algae. Due to the contamination of frequent cloud cover and tidal inundation, the long revisit time of high-resolution satellite sensors and the short-term S. alterniflora removal projects, we combined Sentinel-1 SAR time series and Sentinel-2 optical imagery to monitor the S. alterniflora removal project status in 2023. The overall accuracies of the S. alterniflora detection results here are above 90%. Compared with the traditional SVM method, the proposed method achieved significantly higher identification accuracy. The S. alterniflora area was 115.19 hm² in 2015, 152.40 hm² in 2017 and 15.29 hm² in 2023, respectively. The generated S. alterniflora maps clearly show the clonal growth of S. alterniflora in Zhangjiang Estuary from 2015 to 2017, and the large-scale S. alterniflora eradication project has achieved remarkable results with a removal rate of about 90% in the study area. With the continuous implementation of the “Special Action Plan for the Prevention and Control of Spartina alterniflora (2022–2025)” which aims to eliminate more than 90% of S. alterniflora in all provinces in China by 2025, the continual high-spatial resolution monitoring of S. alterniflora is crucial to control secondary invasion and restore coastal wetlands. Full article

(This article belongs to the Special Issue Conservation and Monitoring of Marine Ecosystem)

25 pages, 5616 KiB

Open AccessArticle

Enhancing Hydrodynamic Performance of Floating Breakwaters Using Wing Plates

by Fares Ali Al-Sairafi, Jisheng Zhang, Chaohua Jiang, Abdullah I. Almansour and Bassiouny Saleh

Water 2024, 16(13), 1779; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131779 - 23 Jun 2024

Viewed by 225

Abstract

Understanding the dynamic response of floating breakwaters to wave forces is essential for optimizing their design and improving coastal protection. The response amplitude operator serves as a key parameter in accurately predicting the structural response amplitudes at different frequencies and wave angles. By [...] Read more.

Understanding the dynamic response of floating breakwaters to wave forces is essential for optimizing their design and improving coastal protection. The response amplitude operator serves as a key parameter in accurately predicting the structural response amplitudes at different frequencies and wave angles. By incorporating this knowledge, adjustments can be made to enhance the effectiveness of floating breakwaters. In this study, a comprehensive 3D model of the mooring system is developed to simulate its behavior under various wave and current conditions. The model takes into account critical design factors such as pontoon shapes, anchor types, placements, and configurations. Through simulations, valuable insights are obtained regarding the performance of the wing-plate floating breakwater mooring system across different operational settings. These findings contribute to the optimization of floating breakwaters and their ability to protect coastlines from wave impacts. Full article

(This article belongs to the Section Oceans and Coastal Zones)

16 pages, 2518 KiB

Open AccessArticle

Tequila Vinasse Treatment in Two Types of Vertical Downflow Treatment Wetlands (with Emergent Vegetation and Ligninolytic Fungi)

by Anderson A. Ramírez-Ramírez, Juan A. Lozano-Álvarez, Melesio Gutiérrez-Lomelí and Florentina Zurita

Water 2024, 16(13), 1778; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131778 - 23 Jun 2024

Viewed by 218

Abstract

The aim of this study was to evaluate and compare the efficiency of two types of vertical downflow wetlands (VDFWs) (with the presence of ligninolytic fungus Trametes versicolor and planted with Iris sibirica) for the treatment of tequila vinasses (TVs) as a secondary [...] Read more.

The aim of this study was to evaluate and compare the efficiency of two types of vertical downflow wetlands (VDFWs) (with the presence of ligninolytic fungus Trametes versicolor and planted with Iris sibirica) for the treatment of tequila vinasses (TVs) as a secondary treatment; control systems with only a filter medium were also included. The systems operated with a 7-day run/resting mode of operation. Various water quality parameters were analyzed in both the influent and the effluents, namely total suspended solids (TSS), chemical oxygen demand (COD), biological oxygen demand (BOD₅), total organic carbon (TOC), pH, electrical conductivity (EC), true color and turbidity, total phosphorus (TP), total nitrogen (TN), etc. The two types of VDFWs as well as the control treatment were effective in reducing the different pollutants (p < 0.05); however, planted systems showed a tendency toward higher efficiencies. With an influent concentration of 49,000 mg L⁻¹ and an organic loading rate of 4942 g COD m⁻²d⁻¹, the COD reduction was around 40% in the planted systems, while in the other two, the reduction was 35%. Furthermore, TSS removals were 36, 20 and 16% in the VDFWs with vegetation, ligninolytic fungus and control systems, respectively. These results suggest that the fungus Trametes versicolor did not develop the desirable enzymatic expression for pollutant removal, probably as a result of the absence of aerobic conditions in the systems. Therefore, more research is needed to achieve a better fungal performance in VDFWs. Full article

(This article belongs to the Special Issue Advanced Processes for Industrial Wastewater Treatment)

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24 pages, 4946 KiB

Open AccessArticle

Water Level Prediction and Forecasting Using a Long Short-Term Memory Model for Nam Ngum River Basin in Lao PDR

by Choong-Soo Kim, Cho-Rong Kim, Kah-Hoong Kok and Jeong-Min Lee

Water 2024, 16(13), 1777; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131777 - 22 Jun 2024

Viewed by 311

Abstract

The process of implementing neural networks in a computer system is known as deep learning. In this study, a deep learning model, namely long short-term memory (LSTM), was established to predict and forecast water levels for stations located at the Nam Ngum River [...] Read more.

The process of implementing neural networks in a computer system is known as deep learning. In this study, a deep learning model, namely long short-term memory (LSTM), was established to predict and forecast water levels for stations located at the Nam Ngum River Basin in Lao PDR. Water levels are predicted and forecasted based on the rainfall and water level data observed at previous time steps. It is proposed that the optimal sequence length for modeling should be determined based on the threshold of the correlation coefficient obtained from the water level and rainfall time series. The trained LSTM models in this study can be considered fair and adequate for water level prediction, as NSE values from 0.5 to 0.7 were mostly obtained from the model validations in the testing periods. The results showed that the autocorrelation and cross-correlation analysis did help in determining the optimal sequence length in an LSTM model. The performance levels of the LSTM model in forecasting future water levels in the Nam Ngum River Basin varied; the forecasted water level hydrographs for the Pakkayoung station generally corresponded with the observed ones, while the forecasted water level hydrographs for the other stations deviated significantly from the observed hydrographs. Full article

21 pages, 1855 KiB

Open AccessArticle

A Comparative Performance Assessment of the Integrated Upflow and Surface Flow-Based Constructed Wetlands Dosed with Landfill Leachate: Electrode Coupling and Input Load Variation

by Tanveer Saeed

Water 2024, 16(13), 1776; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131776 - 22 Jun 2024

Viewed by 404

Abstract

This study reports organic, nutrient, and coliform removal performances of two integrated wetlands designed to treat landfill leachate. Each integrated system included two components: a normal or electrode-integrated upflow-based wetland and a surface flow wetland (with internal baffle walls). The components were fully [...] Read more.

This study reports organic, nutrient, and coliform removal performances of two integrated wetlands designed to treat landfill leachate. Each integrated system included two components: a normal or electrode-integrated upflow-based wetland and a surface flow wetland (with internal baffle walls). The components were fully or partially filled with stone dust media and planted with Canna indica. Two hydraulic loading rates, i.e., 15 L and 60 L (per day), were applied. The integrated wetlands achieved a mean biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and coliform removal efficiency ranges of 89–94%, 95–97%, 85–91%, 91–98%, and 70–88%, respectively, within the applied loading ranges. The electrode-dependent system achieved better pollutant removal performances due to the influence of electrochemical-based bioreactions that fostered microbial decomposition. Nitrogen accumulation percentage (with respect to observed removal) in plant tissues ranged between 0.6 and 25%; phosphorus accumulation percentage was negligible, i.e., ≤0.009%. The chemical composition of the stone dust media supported nutrient adsorption. Stable nutrient removal performance was observed with both systems despite variable loading ranges due to pollutant removal in the upflow-based wetlands followed by controlled flow direction (induced by baffle walls) in the surface flow wetlands that triggered chemical and biological removals. Mean power density production ranged between 235 and 946 mW/m³ with the electrode-based integrated wetland system. In summary, this study demonstrates the application of integrated wetland systems to treat landfill leachate and the associated factors to achieve stable removal under variable loading ranges. Full article

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

20 pages, 11380 KiB

Open AccessArticle

Changing Soil Water Content: Main Trigger of the Multi-Phase Mobilization and Transformation of Petroleum Pollution Components—Insights from the Batch Experiments

by Mingxing Yang, Bing Wang, Yubo Xia, Yan Qiu, Chunling Li and Zhendong Cao

Water 2024, 16(13), 1775; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131775 - 22 Jun 2024

Viewed by 391

Abstract

Soil moisture content continuously alters the types and forms of petroleum organic pollutants in the soil through processes such as dissolution, convection, and dilution, forming complex migration and transformation in a water–air–soil–NAPL system. Field investigations and traditional indoor simulation experiments have difficulty in [...] Read more.

Soil moisture content continuously alters the types and forms of petroleum organic pollutants in the soil through processes such as dissolution, convection, and dilution, forming complex migration and transformation in a water–air–soil–NAPL system. Field investigations and traditional indoor simulation experiments have difficulty in terms of accurately diagnosing the state of different petroleum pollutants due to the influence of environmental factors and the difficulty of controlling single factors. Batch experiments were conducted to simulate the mobilization and differentiation processes of petroleum pollutants under the influence of soil water content. The results show that (1) the residual content of components is the lowest in coarse sand and the highest in clay, which is mainly affected by soil particles; meanwhile, the residual saturation value of octanoic acid is the largest, and that of toluene is the smallest, as determined in terms of their viscosity and volatility. (2) The infiltration processes of the components are affected by their properties and medium characteristics. Due to its small particle size and strong adsorption, clay has the highest residual saturation of petroleum pollutants (28.8%). This can even be more than twice that of coarse sand (13.3%). For different components, the residual saturations of octanoic acid and toluene are the highest and lowest, respectively (taking fine sand as an example: 25.3% and 13.2%), with a relatively large difference, as determined in terms of viscosity and solubility. (3) As the free phase can migrate freely, it is transformed most rapidly in the pores. The changes in the dissolved phase of each component are relatively small and tend to be gentle. The changes in the residual phase are mainly affected by volatility, viscosity, soil particles, and pore and cosmid content; the degree of change is ordered as follows: toluene > cyclohexane > hexadecane > octanoic acid. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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12 pages, 10608 KiB

Open AccessArticle

Effect of Median Soil–Particle Size Ratio on Water Storage Capacity of Capillary Barrier

by Honghua Liu, Jie Dong, Qiang Liu, Lin Geng, Zhongsheng Wang and Chong Sun

Water 2024, 16(13), 1774; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131774 - 22 Jun 2024

Viewed by 216

Abstract

Capillary barriers are widely used as a cover system to enhance the upper-soil-layer water storage capacity and reduce water infiltrate into the lower soil layer. In this paper, the effects of the median soil–particle size ratio on the water storage capacity of capillary [...] Read more.

Capillary barriers are widely used as a cover system to enhance the upper-soil-layer water storage capacity and reduce water infiltrate into the lower soil layer. In this paper, the effects of the median soil–particle size ratio on the water storage capacity of capillary barriers were studied using a series of indoor one-dimensional soil column infiltration tests. The results show that the water storage capacity rises with an increase in the median soil–particle size ratio until it exceeds 10. The variation in the total water storage capacity is related to not only the median soil–particle size ratio but also the particle size of coarse-grained soil or fine-grained soil. When the fine-grained soil-layer particle size is constant, the total water storage first increases, then decreases, and finally remains constant after increasing the median soil–particle size ratio. In contrast, when the coarse-grained soil layer particle size is constant, the relationship between the capillary barrier’s total water storage and median soil–particle size ratio can be defined as a power function. Using the capillary barrier can increase coarse-grained sand by 90% in water storage capacity and can only increase fine-grained sand by 7% in water storage capacity. The breakthrough time increases with the increase in the median soil–particle size ratio. The presence of the coarse and fine-grained soil layer interface in the capillary barrier can affect the fine-grained soil layer infiltration rate. Full article

(This article belongs to the Topic Advances in Environmental Hydraulics)

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20 pages, 8057 KiB

Open AccessArticle

Molecular Fingerprinting of the Biodegradation of Petroleum Organic Pollutants in Groundwater and under Site-Specific Environmental Impacts

by Mingxing Yang, Yuesuo Yang, Xinyao Yang, Xiaoming Song, Xinqiang Du and Ying Lu

Water 2024, 16(13), 1773; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131773 - 22 Jun 2024

Viewed by 259

Abstract

A quantitative and qualitative assessment using molecular markers derived from compound-specific indices for indicating groundwater impacted by petroleum spills in an oil field was recently undertaken and demonstrated serious contamination, with both high total petroleum hydrocarbons (TPH) (3.68–7.32 mg/L) and hazardous compounds in [...] Read more.

A quantitative and qualitative assessment using molecular markers derived from compound-specific indices for indicating groundwater impacted by petroleum spills in an oil field was recently undertaken and demonstrated serious contamination, with both high total petroleum hydrocarbons (TPH) (3.68–7.32 mg/L) and hazardous compounds in the groundwater. A petroleum source was identified, and the analysis revealed a decreasing trend of fresh petroleum input, along with groundwater advection and an increasing trend of biodegradation potential at locations farther from the source. This was confirmed via microbial analysis with both biodegrading microorganisms and diversity indices (Shannon, Simpson, and Pielou) and the principal component analysis (PCA) modeling approach, which classified the field samples into three types according to the distribution correlations between different organic compounds. Biodegradation was believed to be the dominant sink of hydrocarbons due to the increasing Pr/C17 and Ph/C18 values with seasonal changes. Raised temperatures activated the microbial degradation process; specifically, low-weight hydrocarbons degraded more rapidly than high-weight hydrocarbons, resulting in the accumulation of an unresolved complex mixture of bioproducts at locations that were farther away. Spatially, the Pr/C17 and Ph/C18 values increased from the upstream to the downstream areas, showing substantial biodegradation. The relationships between the molecular markers and chemical indices were quantified via canonical correlation analysis (CCA) to visually explain the interactive reaction processes. It was also demonstrated that the biodegradation of petroleum organics can be characterized by the consumption of dissolved oxygen and a decreasing Pr/Ph ratio, due to system reduction. These results demonstrate that compound-specific molecular markers, coupled with biochemical parameters, can effectively support a better understanding and effective fingerprinting of the fate and transport of petroleum organic contaminants, thus offering valuable technical support for a cost-effective remediation strategy. Full article

(This article belongs to the Special Issue Persistent and Emerging Organic Contaminants in Natural Environments)

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19 pages, 10467 KiB

Open AccessArticle

Using MODFLOW to Model Riparian Wetland Shallow Groundwater and Nutrient Dynamics in an Appalachian Watershed

by Bidisha Faruque Abesh, James T. Anderson and Jason A. Hubbart

Water 2024, 16(13), 1772; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131772 - 22 Jun 2024

Viewed by 287

Abstract

Simulating shallow groundwater (SGW) flow dynamics and stream–SGW interactions using numerical modeling tools is necessary to develop a mechanistic understanding of water flow systems and improve confidence in water resource management practices. A three-dimensional (3D) SGW flow model was developed for a riparian [...] Read more.

Simulating shallow groundwater (SGW) flow dynamics and stream–SGW interactions using numerical modeling tools is necessary to develop a mechanistic understanding of water flow systems and improve confidence in water resource management practices. A three-dimensional (3D) SGW flow model was developed for a riparian wetland in a mixed forest and agricultural catchment in West Virginia (WV), Appalachia, USA, using a Modular 3D Groundwater Model (MODFLOW). The MODFLOW simulation was calibrated in steady (R² = 0.98, ME = −0.21, and RMSE = 0.77), transient state (R² = 0.97, ME = −0.41, and RMSE = 1.28) and validated (R² = 0.97, ME = −0.28, and RMSE = 1.05) using observed SGW levels from thirteen nested piezometers under steady and transient states. An experimental MT3D transport scenario was developed to show the lateral transport of NO₃-N from the aquifer to stream cells. Relatively stable SGW head distribution was observed. In the downstream reach, SGW discharge varied from 948 m³/day to 907 m³/day in 2020, with creek seepage ranging from 802 m³/day to 790 m³/day. Similarly, SGW input to the stream ranged from 891 m³/day to 978 m³/day, while creek seepage ranged from 796 m³/day to 800 m³/day in 2021. In upstream reaches, losing stream conditions were observed in January, June, and September 2020 and January to April 2021, while gaining stream conditions prevailed during other months. Thus, an approximately monthly alternating gaining–losing stream condition was observed in the upstream area. An experimental MT3D transport scenario resulted in an advection–dispersion scenario, showing a cumulative loss of 947 g of NO₃-N from SGW to the stream. Denitrification accounted for the cumulative loss of 1406 g of NO₃-N from SGW, surpassing 639 g of nitrate from the SGW to the stream during the study period. Additionally, particle tracking using MODPATH indicated a long residence time for SGW nutrients, affirming the efficiency of nitrogen transformation through denitrification. This study is among the first to simulate hydrologic and nutrient interactions in riparian wetlands of a mixed land use catchment in the Appalachian region of the northeastern United States. The results better inform water resource management decisions and modeling efforts in the Appalachian region and similar physiographic regions globally. Full article

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23 pages, 26729 KiB

Open AccessArticle

Analyzing the Mitigation Effect of Urban River Channel Flood Diversion on Waterlogging Disasters Based on Deep Learning

by Qingzhen Sun, Dehua Zhu, Zhaoyang Zhang and Jingbo Xu

Water 2024, 16(13), 1771; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131771 - 21 Jun 2024

Viewed by 453

Abstract

In recent years, urban waterlogging disasters have become increasingly prominent. Physically based urban waterlogging simulation models require considerable computational time. Therefore, rapid and accurate simulation and prediction of urban pluvial floods are important for disaster prevention and mitigation. For this purpose, we explored [...] Read more.

In recent years, urban waterlogging disasters have become increasingly prominent. Physically based urban waterlogging simulation models require considerable computational time. Therefore, rapid and accurate simulation and prediction of urban pluvial floods are important for disaster prevention and mitigation. For this purpose, we explored an urban waterlogging prediction method based on a long short-term memory neural network model that integrates an attention mechanism and a 1D convolutional neural network (1DCNN–LSTM–Attention), using the diversion of the Jinshui River in Zhengzhou, China, as a case study. In this method, the 1DCNN is responsible for extracting features from monitoring data, the LSTM is capable of learning from time-series data more effectively, and the Attention mechanism highlights the impact of features on input effectiveness. The results indicated the following: (1) The urban waterlogging rapid prediction model exhibited good accuracy. The Pearson correlation coefficient exceeded 0.95. It was 50–100 times faster than the InfoWorks ICM model. (2) Diversion pipelines can meet the design flood standard of a 200-year return period, aligning with the expected engineering objectives. (3) River channel diversion significantly reduced the extent of inundation. Under the 30-year return period rainfall scenario, the maximum inundation area decreased by 1.46 km², approximately equivalent to 205 international standard soccer fields. Full article

(This article belongs to the Special Issue Hydrological Simulation and Forecasting Based on Artificial Intelligence)

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22 pages, 2668 KiB

Open AccessReview

Review of the Water–Land–Food–Carbon Nexus Focused on Regional Low-Carbon and High-Quality Agricultural Development

by Caiyun Deng, Tianhe Xu, Li Zhang, Siqi Yang, Huiying Yin, Jian Guo, Lulu Si, Ran Kang and Hermann Josef Kaufmann

Water 2024, 16(13), 1770; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131770 - 21 Jun 2024

Viewed by 324

Abstract

To overcome the multiple challenges of water scarcity, agricultural land conversion, food security, and carbon emissions, an optimal collaborative management scheme for food production is urgently needed, especially in high food-production and food-consumption countries such as China. The water–land–food–carbon (WLFC) nexus provides a [...] Read more.

To overcome the multiple challenges of water scarcity, agricultural land conversion, food security, and carbon emissions, an optimal collaborative management scheme for food production is urgently needed, especially in high food-production and food-consumption countries such as China. The water–land–food–carbon (WLFC) nexus provides a new perspective, but its interactions are complex, dynamic, and spatially heterogeneous; the coupling mechanism is not fully understood; and the driving forces and regulation strategies remain uncertain. Therefore, in this study, the WLFC nexus centered on low-carbon and high-quality agricultural development was systematically reviewed. The main contributions are as follows: (1) A framework of the regional agricultural WLFC nexus was proposed based on bibliographic analysis. (2) The main internal and external factors influencing the WLFC nexus in agriculture were identified by reevaluating meta-analysis review studies. The results showed that changes in the amount and type of irrigation water, the amount and planting activities of agricultural land, and climate change (temperature, precipitation, and CO₂ concentration) affected food (rice, wheat, and maize) yields and carbon emissions to varying degrees. Moreover, population, technological innovation, trade, and polices were important external factors impacting food production and carbon emissions. (3) The common methods and tools for assessing, simulating, and optimizing the WLFC nexus in agriculture were summarized from the perspectives of its status, physical links, and embodied links. Integrated indices, complex system thinking, and process-based and data-driven methods were applied in the studies of the WLFC nexus. (4) Strategies and programs for collaborative WLFC management in agriculture within 10 global river basins were compiled. These findings could help us better understand the WLFC nexus in agriculture and identify the optimal cooperative management scheme, thereby realizing low-carbon and high-quality agricultural development. Full article

(This article belongs to the Special Issue Studies on Water Resource and Environmental Policies)

24 pages, 8500 KiB

Open AccessArticle

Application of Variable Weight Theory in the Suitability Evaluation of Regional Shallow Geothermal Energy Development

by Ruifeng Wang, Mingchuan Shi, Yanliang Zhai, Ke Zhu, Lei Zhao, Chenhui Liu, Guohong Yan and Zhiqiang Yin

Water 2024, 16(13), 1769; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131769 - 21 Jun 2024

Viewed by 380

Abstract

Blindly developing shallow geothermal energy (SGE) may lead to difficulties in reinjection, a low coefficient of performance (COP), and the waste of funds. In order to avoid these problems and improve development efficiency, it is necessary to scientifically conduct a development suitability evaluation [...] Read more.

Blindly developing shallow geothermal energy (SGE) may lead to difficulties in reinjection, a low coefficient of performance (COP), and the waste of funds. In order to avoid these problems and improve development efficiency, it is necessary to scientifically conduct a development suitability evaluation and classify the suitability levels before development. This article takes Chengde City, Hebei Province, China as an example and constructs an evaluation index system based on the analysis of regional basic conditions. The Analytic Hierarchy Process (AHP) was used to calculate the constant weight. A Fuzzy C-means Clustering (FCM) analysis was used to determine the critical value of evaluation index classification and the interval threshold of variable weights. The parameters of the variable-weight model were calculated using the method of model backcalculation. Based on the constructed variable-weight model, the suitability of SGE development for groundwater sources in the study area was evaluated, and it was divided into five levels: most suitable area, suitable area, relatively suitable area, less suitable area, and unsuitable area. Through a verification analysis of engineering examples and a comparison with the evaluation results under traditional constant-weight models, it was found that the evaluation results based on variable weight theory have better data discreteness and a higher accuracy. Research has shown that variable-weight models can adjust the weight of each index based on its state value. Through this study, the accuracy of the suitability evaluation for regional SGE development can be improved. This can provide a certain reference for the suitability evaluation of SGE development in other regions. Full article

(This article belongs to the Special Issue Water-Related Geoenvironmental Issues, 2nd Edition)

23 pages, 5177 KiB

Open AccessArticle

Novel Implications of the PARAFAC Model for Characterizing and Distributing DOM in Groundwater Networks by Using Spectroscopic Techniques

by Yousef Alhaj Hamoud, Abdullah Maqsood, Muhammad Zia-ur-Rehman, Hiba Shaghaleh, Amna Sahar, Muhammad Usman, Muhammad Rizwan, Hesham F. Alharby, Refaat A. Abohassan and Awatif M. Abdulmajeed

Water 2024, 16(13), 1768; https://0-doi-org.brum.beds.ac.uk/10.3390/w16131768 - 21 Jun 2024

Viewed by 354

Abstract

Groundwater, a primary source of freshwater on Earth, is rapidly declining due to natural and anthropogenic activities. This study aimed to investigate the spatial distribution of dissolved organic matter (DOM) and heavy metals (HMs) in two municipal groundwater networks (A and B) from [...] Read more.

Groundwater, a primary source of freshwater on Earth, is rapidly declining due to natural and anthropogenic activities. This study aimed to investigate the spatial distribution of dissolved organic matter (DOM) and heavy metals (HMs) in two municipal groundwater networks (A and B) from tube wells to taps in an industrial city, Faisalabad. The results showed that parameters such as color, turbidity, pH, EC, TDS, Ca²⁺, Mg²⁺, CO₃²⁻, HCO₃⁻, Cl^-, CaCO₃, Na+, and NO₃⁻ were within the permissible limits set by the World Health Organization (WHO) and Pakistan Environmental Quality Standards (PEQSs). However, parameters like DO and COD exceeded standard values along the routes. Odor, taste, temperature, BOD, NH₄⁺, T. coli, and F. coli surpassed acceptable levels at the tap end of both networks. Fluorescence EEM-PARAFAC spectra were analyzed at an excitation wavelength of 220–500 nm and emission wavelength of 240–550 nm, revealing UVA-humic-like (C1–C2) and UVC-humic-like (C3) components in the DOM. Based on fluorescence intensity, DOM was dominated by C2 > C1 > C3 compounds in both networks. The mean concentrations of HMs, including Cu, Zn, and Fe, fell below the prescribed limits in both networks. However, concentrations of Pb (A: 0.015–0.028 mg/L), (B: 0.013–0.027 mg/L), and Cd (A: 0.004–0.006 mg/L), (B: 0.005–0.008 mg/L) exceeded permissible limits from tube wells to taps. Moreover, C1 demonstrated a significant positive correlation with Cd and Cu in networks A and B, respectively. Furthermore, C2 displayed a significant positive correlation with Cd in network A. This study concludes that the groundwater in both networks (A and B) is contaminated by agricultural runoff, industrial and sewage water, plumbing materials, and eroded pipelines. As a result, the water is unsafe for cooking and drinking, posing risks of kidney, lung, and bladder cancers. Therefore, this study urgently recommends pipeline reconstruction and the implementation of proper groundwater remediation approaches before these sources are used for drinking. Full article

(This article belongs to the Section Urban Water Management)

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Water, Volume 16, Issue 13 (July-1 2024) – 39 articles

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