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Water, Volume 16, Issue 14 (July-2 2024) – 136 articles

Cover Story (view full-size image): The thermal conditions of transitional (ranging from warm to cold) coldwater streams impact the range and availability of resources for the biota inhabiting these lotic systems. With ongoing climate change and an increase in the modification of land, thermal boundaries have shifted, altering thermal transition zones and their biotic communities. The objective of this study was to investigate the condition of trout across three forks of the Whitewater River catchment, located in southeastern Minnesota, and to investigate the factors influencing the composition and distribution of the fish community. In general, diversity increased, and trout were healthier but less abundant in the middle and headwater sections; however, in the lower reachers, diversity decreased slightly, the trout condition decreased, and the abundance of trout increased, with changes differing somewhat among forks. View this paper
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22 pages, 5676 KiB  
Article
Projections on the Spatiotemporal Bioclimatic Change over the Phytogeographical Regions of Greece by the Emberger Index
by Ioannis Charalampopoulos, Fotoula Droulia, Ioannis P. Kokkoris and Panayotis Dimopoulos
Water 2024, 16(14), 2070; https://doi.org/10.3390/w16142070 - 22 Jul 2024
Cited by 1 | Viewed by 910
Abstract
Unquestionably, the rapidly changing climate and, therefore, alterations in the associated bioclimate, constitute an alarming reality with implications for daily practice and natural capital management. This research displays the present and projected bioclimate evolution over Greece’s phytogeographical regions. For this purpose, ultrahigh-resolution computation [...] Read more.
Unquestionably, the rapidly changing climate and, therefore, alterations in the associated bioclimate, constitute an alarming reality with implications for daily practice and natural capital management. This research displays the present and projected bioclimate evolution over Greece’s phytogeographical regions. For this purpose, ultrahigh-resolution computation results on the spatial distribution of the Emberger index’s Q2 classes of bioclimatic characterization are analyzed and illustrated for the first time. The assessments are performed over the reference period (1970–2000) and two future time frames (2021–2040; 2041–2060) under the RCP4.5 and RCP8.5 emission scenarios. By 2060 and under the extreme RCP8.5, intense xerothermic trends are demonstrated owing to the resulting significant spatial evolution mainly of the Arid–Hot, Semi-Arid–Very Hot, Semi-Arid–Hot, and Semi-Arid–Temperate Q2 classes, respectively, over the phytogeographical regions of Kiklades (up to 29% occupation), Kriti and Karpathos (up to 30%), West Aegean Islands (up to 26%), North East (up to 56%), and North Central (up to 31%). The RCP8.5 long-term period exhibits the strongest impacts over approximately the right half of the Greek territory, with the bioclimate appearing more dry–thermal in the future. In conclusion, the Emberger index provides an in-depth view of the Greek area’s bioclimatic regime and the potential alterations due to climate change per phytogeographical region. Full article
(This article belongs to the Special Issue Impacts of Climate Change on Water Resources: Assessment and Modeling)
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28 pages, 3401 KiB  
Review
A Critical Review of Emerging Technologies for Flash Flood Prediction: Examining Artificial Intelligence, Machine Learning, Internet of Things, Cloud Computing, and Robotics Techniques
by Ghazi Al-Rawas, Mohammad Reza Nikoo, Malik Al-Wardy and Talal Etri
Water 2024, 16(14), 2069; https://doi.org/10.3390/w16142069 - 22 Jul 2024
Cited by 1 | Viewed by 2479
Abstract
There has been growing interest in the application of smart technologies for hazard management. However, very limited studies have reviewed the trends of such technologies in the context of flash floods. This study reviews innovative technologies such as artificial intelligence (AI)/machine learning (ML), [...] Read more.
There has been growing interest in the application of smart technologies for hazard management. However, very limited studies have reviewed the trends of such technologies in the context of flash floods. This study reviews innovative technologies such as artificial intelligence (AI)/machine learning (ML), the Internet of Things (IoT), cloud computing, and robotics used for flash flood early warnings and susceptibility predictions. Articles published between 2010 and 2023 were manually collected from scientific databases such as Google Scholar, Scopus, and Web of Science. Based on the review, AI/ML has been applied to flash flood susceptibility and early warning prediction in 64% of the published papers, followed by the IoT (19%), cloud computing (6%), and robotics (2%). Among the most common AI/ML methods used in susceptibility and early warning predictions are random forests and support vector machines. However, further optimization and emerging technologies, such as computer vision, are required to improve these technologies. AI/ML algorithms have demonstrated very accurate prediction performance, with receiver operating characteristics (ROC) and areas under the curve (AUC) greater than 0.90. However, there is a need to improve on these current models with large test datasets. Through AI/ML, IoT, and cloud computing technologies, early warnings can be disseminated to targeted communities in real time via electronic media, such as SMS and social media platforms. In spite of this, these systems have issues with internet connectivity, as well as data loss. Additionally, Al/ML used a number of topographical variables (such as slope), geological variables (such as lithology), and hydrological variables (such as stream density) to predict susceptibility, but the selection of these variables lacks a clear theoretical basis and has inconsistencies. To generate more reliable flood risk assessment maps, future studies should also consider sociodemographic, health, and housing data. Considering future climate change impacts, susceptibility or early warning studies may be projected under different climate change scenarios to help design long-term adaptation strategies. Full article
(This article belongs to the Section Hydrology)
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15 pages, 1615 KiB  
Article
Modelling the Fate of Linear Alkylbenzene Sulfonate in Agricultural Soil Columns during Inflow of Surfactant Pulses from Domestic Wastewaters
by María Dolores Saquete, Nuria Boluda-Botella, Vicente Cases and Ester Egea
Water 2024, 16(14), 2068; https://doi.org/10.3390/w16142068 - 22 Jul 2024
Viewed by 901
Abstract
Linear alkylbenzene sulfonate (LAS), a widely used anionic surfactant, is present in wastewater and can be discharged, causing environmental damage. When biodegradation is negligible, adsorption and desorption reactions play an important role, depending on the media characteristics (organic matter and clays) and hydrodynamic [...] Read more.
Linear alkylbenzene sulfonate (LAS), a widely used anionic surfactant, is present in wastewater and can be discharged, causing environmental damage. When biodegradation is negligible, adsorption and desorption reactions play an important role, depending on the media characteristics (organic matter and clays) and hydrodynamic parameters. Previously published laboratory column data are modelled with PHREEQC (version 2.18) in three scenarios of LAS input: spill (LAS pulse), continuous discharge (LAS adsorption step) and remediation (LAS desorption step). The distribution coefficients (0.1–4.9 × 10−3 L/g) in the sand columns are lower than those determined in this paper from batch tests and in columns of 25% and 50% agricultural soil mixtures (1–70 × 10−3 L/g). Considering the Freundlich constant parameters from the modelling, the results are similar to the distribution coefficients, but the linear isotherms are more consistent throughout. The mass transfer coefficient from the sand columns is lower than the agricultural soil columns (20–40 h−1), indicating longer elution times for the heavier homologues and a higher percentage of agricultural soil. For lighter homologues, fast migration could cause contamination of aquifers. The great persistence of LAS in the environment necessitates the development of mitigation strategies using reactive transport models, which predict longer times for the remediation of LAS homologues. Full article
(This article belongs to the Special Issue Physical–Chemical Wastewater Treatment Technologies)
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31 pages, 8433 KiB  
Article
Groundwater Dynamics in African Endorheic Basins in Arid to Semi-Arid Transition Zones: The Batha Aquifer System, NE Chad
by Abakar Bourma Arrakhais, Abderamane Hamit, Claude Fontaine, Fatima Abdelfadel, Moustapha Dinar and Moumtaz Razack
Water 2024, 16(14), 2067; https://doi.org/10.3390/w16142067 - 22 Jul 2024
Viewed by 1288
Abstract
This study investigates the Batha endorheic basin in Chad, situated east of the Lake Chad basin in the arid to semi-arid Sahelian zone. This region has not yet undergone comprehensive geological and hydrogeological studies. More broadly, the transition zone between semi-arid and arid [...] Read more.
This study investigates the Batha endorheic basin in Chad, situated east of the Lake Chad basin in the arid to semi-arid Sahelian zone. This region has not yet undergone comprehensive geological and hydrogeological studies. More broadly, the transition zone between semi-arid and arid climates has been minimally explored. This research aims to evaluate the resources and dynamics of this multi-layered system using a combined geology-hydrogeology-hydrochemistry-isotopes approach. The multilayer system includes sedimentary layers (Quaternary, Pliocene, and Eocene) over a crystalline basement. A piezometric investigation of the system shows a general SE–NW groundwater, indicating an interconnection between all layers. Hydrochemical analyses identifies four main facies (calcium-bicarbonate, sodium-bicarbonate, sulphate-sodium, and mixed), primarily controlled by water–rock interaction with secondary influences from base-exchange and evaporation. Saturation indices indicate that these waters are close to equilibrium with the calcite-Mg phases, gaylussite and gypsum. Stable isotopes (oxygen-18 and deuterium) categorize groundwater into three groups: ancient water, recent and older meteoric water mixtures affected by evaporation, and mixtures more heavily impacted by evaporation. Tritium contents reveal three groups: current rainwater, modern water, and sub-modern water. These results indicate that ionic and isotopic differentiations cannot be strictly linked to specific layers, confirming the interconnected nature of the Batha system. The observed heterogeneity is mainly influenced by lithological and climatic variations. This study, though still limited, enhances significantly the understanding of the basin’s functioning and supports the rational exploitation of its vital resources for the Batha area’s development. Future investigations to complete the present study are highlighted. Full article
(This article belongs to the Special Issue Water, Geohazards, and Artificial Intelligence, 2nd Edition)
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24 pages, 3169 KiB  
Review
Transformation and Mitigation of Tar and Related Secondary Pollutants during Sewage Sludge Pyrolysis
by Qingyuan Lin, Yongxiao Liu, Yimeng Jiao, Pengzhao Lv, Yanbo Liu, Wei Zuo, Yu Tian and Jun Zhang
Water 2024, 16(14), 2066; https://doi.org/10.3390/w16142066 - 22 Jul 2024
Viewed by 1048
Abstract
Sewage sludge has long been perceived as the bottleneck of wastewater treatment plants in China, restraining the healthy development of sewage treatment for decades. In recent years, pyrolysis as a promising multifunctional platform has attracted increasing interest for converting sludge into valuable resources. [...] Read more.
Sewage sludge has long been perceived as the bottleneck of wastewater treatment plants in China, restraining the healthy development of sewage treatment for decades. In recent years, pyrolysis as a promising multifunctional platform has attracted increasing interest for converting sludge into valuable resources. However, the generation and presence of pyrolysis tar, one of the key by-products during sludge pyrolysis, limit the wide application of pyrolysis product resources. The efficient and selective conversion of tar is complicated by the inherent complexity of sludge and various pollutants (e.g., N-, S-, and Cl-containing organic pollutants, heavy metals) in pyrolysis products, which may either migrate into tar or be released into the environment, complicating the in-depth treatment of tar and posing environmental risks. This review systematically examines the transformation and migration of tar and related secondary pollutants during sludge pyrolysis in order to optimize the pyrolysis process for resource recovery. We provide an overview of the research progress on tar generation, transformation, and secondary pollutants during pyrolysis; discuss potential control strategies for pollution abatement; and highlight the importance of understanding tar transformation during pyrolysis. Additionally, we offer insights into future development trends and research hotpots in this field. This review aims to deliver valuable information on the mechanism of tar formation, the conversion pathways of secondary pollutants, and corresponding control strategies, thus guiding the design and optimization of sludge pyrolysis processes to achieve higher efficiency and selectivity, with minimal environmental pollution. Full article
(This article belongs to the Special Issue Sustainable Water Treatment and Contaminants Control: Technologies and Strategies)
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14 pages, 2848 KiB  
Article
Exploring the Impact of Financial Development on Water–Energy Efficiency in Western China
by Jianqiang Wang and Zhongyun Zhang
Water 2024, 16(14), 2065; https://doi.org/10.3390/w16142065 - 22 Jul 2024
Viewed by 805
Abstract
The western region of China is a fundamental ecological protection barrier for China. The conflict between regional economic development and ecological environmental protection has always existed in the region. This study first evaluated the water–energy efficiency (WEE) of 11 provinces in western China [...] Read more.
The western region of China is a fundamental ecological protection barrier for China. The conflict between regional economic development and ecological environmental protection has always existed in the region. This study first evaluated the water–energy efficiency (WEE) of 11 provinces in western China from 2011 to 2019 using the super-slacks-based model with undesirable outputs and analyzed their spatiotemporal characteristics. It then investigated the influence of financial development level on WEE. The results indicate that (a) the WEE in Western China was at a relatively low level, showing an upward trend from 2011 to 2016 and fluctuating after 2016; (b) financial development levels had U-shaped impacts on the WEE of Western China, which reduced at first and then rose; (c) increasing technological innovation capabilities and trade openness had positive impacts on WEE in Western China, while urbanization level had a negative effect on WEE; and (d) an examination of robustness using two different methods showed that the test results are consistent with the above conclusions. Therefore, this study has robustness. We also put forward corresponding policy suggestions, such as increasing financial support for clean and low-carbon industries, increasing input in science and technology, vigorously developing cleaner and environmentally friendly foreign trade, and implementing a new type of urbanization strategy, to promote the WEE of Western China. Full article
(This article belongs to the Special Issue Advances in Water–Energy–Carbon–Economy–Health Relationships)
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13 pages, 1956 KiB  
Article
Changes in Runoff and Sediment Loads in the Tuhai River Basin and the Factors Influencing These Changes
by Qiqi Cao, Xianguo Zong, Chaozhen Qi, Chuanning Yu, Jianyao Guo, Jingxia Shen, Shoucai Wei, Dong Wang, Jun Zhang and Jiangbao Xia
Water 2024, 16(14), 2064; https://doi.org/10.3390/w16142064 - 22 Jul 2024
Viewed by 683
Abstract
In this study, rainfall, runoff, and sediment load data were collected from the Tuhai River Basin from 1972 to 2021. The Mann–Kendall test, runoff–sediment curve, and double mass curve were used to identify the characteristics and factors influencing runoff and sediment loads in [...] Read more.
In this study, rainfall, runoff, and sediment load data were collected from the Tuhai River Basin from 1972 to 2021. The Mann–Kendall test, runoff–sediment curve, and double mass curve were used to identify the characteristics and factors influencing runoff and sediment loads in the Tuhai River Basin. The results showed that the average annual runoff and sediment loads in the river basin were 4.03 × 108 m3 and 3.52 × 108 kg, respectively; furthermore, the flood season (June–September) accounted for 79.9% and 99.4% of these values, respectively. There were no apparent runoff trends in the annual, flood, and non-flood (October–May) stages, and the annual and flood season sediment loads decreased significantly. The abrupt change points of annual and flood season runoff in the Tuhai River Basin mainly occurred from 2003 to 2004 and from 2013 to 2014. Moreover, the abrupt change points of annual and flood season sediment load only occurred from 1978 to 1979. The runoff–sediment curve showed a clear power function relationship between runoff and sediment loads. The runoff in the Tuhai River Basin from 2003 to 2013 was mainly affected by precipitation. Additionally, the contributions of human activities to runoff and sediment load reduction in the Tuhai River Basin were 57.7–88.9% and 63.1–86.0%, respectively. The increase in human water consumption was the main reason for the decrease in runoff in the Tuhai River Basin. Furthermore, the measures taken in soil and water conservation and reservoir construction were the main factors behind a reduction in sediment loads in the Tuhai River Basin. Full article
(This article belongs to the Special Issue Research on Soil and Water Conservation and Vegetation Restoration)
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21 pages, 2685 KiB  
Article
Principles and Optimization of China’s Unconventional Water Management: From a Brand-New Perspective of Responsibility Allocation
by Ruifang Wang, Yingwen Ji and Chen Feng
Water 2024, 16(14), 2063; https://doi.org/10.3390/w16142063 - 22 Jul 2024
Viewed by 919
Abstract
Unconventional water includes reclaimed water, harvested rainwater, desalinated seawater, and mine water. Unconventional water use is considered more of a “mandatory responsibility” in China. The initial allocation of unconventional water emphasizes quantity-centered responsibility allocation while the minimum utilization reflects this responsibility. The unconventional [...] Read more.
Unconventional water includes reclaimed water, harvested rainwater, desalinated seawater, and mine water. Unconventional water use is considered more of a “mandatory responsibility” in China. The initial allocation of unconventional water emphasizes quantity-centered responsibility allocation while the minimum utilization reflects this responsibility. The unconventional water use responsibility (UWUR) should be tailored to the characteristics of each area, moving away from a ‘more is better’ mindset. However, there is a large research gap in this field. This paper first presented six fundamental principles for unconventional water allocation. Ensuring fairness in allocation involves aligning the allocated amount with urban water usage characteristics. Hence, based on four key features, this paper integrated various socioeconomic and environmental factors to build an initial allocation model. To enhance efficiency, an optimal allocation model was constructed using the zero-sum gains–data envelopment analysis (ZSG-DEA) method. The models were then applied to Jiangsu Province, China, to verify their applicability. The results showed that the projected minimum UWUR allocation (unit: 100 million m3) for each city in 2025 is 1.482 (Nanjing), 1.501 (Wuxi), 0.919 (Xuzhou), 1.029 (Changzhou), 2.977 (Suzhou), 1.497 (Nantong), 0.818 (Lianyungang), 0.766 (Huai’an), 0.875 (Yancheng), 0.920 (Yangzhou), 0.790 (Zhenjiang), 0.858 (Taizhou), and 0.766 (Suqian). The rational and feasible results indicated that the allocation framework proposed in this paper has a certain practicability. Lastly, this paper considered the differences in unconventional water utilization conditions across 13 cities and proposed corresponding measures to improve the utilization. This paper represents a tentative exploration of unconventional water allocation in China and offers theoretical and practical insights for policy-makers to improve territorial spatial planning and sustainable water management. Full article
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17 pages, 8806 KiB  
Article
Study on the Driving Mechanism of Ecohydrological Regime in the Wandering Section of the Lower Yellow River
by Yan Xie, Qing Yin, Siqi Jiang, Wenzhuo An, Jingyi Liao, Yanhui Liu and Yicheng Fu
Water 2024, 16(14), 2062; https://doi.org/10.3390/w16142062 - 22 Jul 2024
Viewed by 707
Abstract
Climate change and human activities exert significant impacts on runoff generation and convergence mechanisms. Understanding the evolution mechanisms and driving forces of runoff is crucial for the sustainable development of water resources. This study is based on the runoff data of the Huayuankou [...] Read more.
Climate change and human activities exert significant impacts on runoff generation and convergence mechanisms. Understanding the evolution mechanisms and driving forces of runoff is crucial for the sustainable development of water resources. This study is based on the runoff data of the Huayuankou (HYK), Jiahetan (JHT), and Gaocun (GC) stations in the lower reaches of the Yellow River from 1951 to 2019. The objectives are to identify and quantify the hydrological pattern and its driving mechanism of the three stations by the Mann–Kendall test, cumulative deviation method, wavelet analysis, the IHA-RVA method, SCRCO method, and the Budyko method. Our study revealed that the runoff disturbance points at all three stations occurred in 1985. During the two periods before and after the disturbance, the trends and periodicities within the year exhibited high consistency, showing an overall downward trend, with runoff increasing in October and decreasing in June and the primary cycles being 5 and 7 years. All three stations experienced high-degree changes in their hydrological situations, with the high-degree change occupying the largest proportion. At the HYK, JHT, and GC stations, human activities accounted for 66.05%, 71.94%, and 74.38% of runoff changes, respectively. Furthermore, we verified the attribution conclusion of runoff at HYK using the Budyko model, confirming that human activities are the primary factor influencing runoff. Finally, we explored the interactive relationships along the spatial trajectory of runoff at the three stations, analyzed 32 hydrological indicators, and detailed the land use changes in the Yellow River Basin. Our research findings complement the understanding of hydrological change mechanisms in the lower reaches of the Yellow River Basin and provide a scientific basis for future water resource management and flood prevention measures. Full article
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25 pages, 6434 KiB  
Article
Assessment of the Local Impact of Retention Reservoirs—A Case Study of Jagodno (Existing) and Sarny (Planned) Reservoirs Located in Poland
by Maksymilian Połomski and Mirosław Wiatkowski
Water 2024, 16(14), 2061; https://doi.org/10.3390/w16142061 - 22 Jul 2024
Viewed by 838
Abstract
The construction of retention reservoirs that cause permanent water damming is a complex subject and requires an interdisciplinary approach to environmental issues. The scope of the conducted study includes (1) a natural inventory of the area of Jagodno Reservoir in central Poland, which [...] Read more.
The construction of retention reservoirs that cause permanent water damming is a complex subject and requires an interdisciplinary approach to environmental issues. The scope of the conducted study includes (1) a natural inventory of the area of Jagodno Reservoir in central Poland, which has been in operation for almost a decade, (2) a natural inventory of the area where a reservoir of similar size could potentially be built (Sarny, in southwestern Poland), (3) an assessment of the local community’s attitudes toward the operation or construction of individual facilities, (4) analysis and use of the obtained results to predict the local impact of Sarny Reservoir. The results of this study indicate areas where the impact of Jagodno Reservoir should be considered negative, neutral, or positive and what effect can be expected during the construction of Sarny Reservoir. One of the more significant results for Jagodno Reservoir, we should point out, is the appearance of a few waterfowl breeding at the site (4 species), a substantial expansion of the ichthyofauna population (from 9 to 24 species, which does not apply only to native species), a local loss of 91E0 habitat (willow riparian forests) and the appearance of one species of an invasive plant (Canadian goldenrod), a favorable impact on the water quality of the River Wiązownica (reduction in total and nitrate nitrogen loads by an average of 43.4% and 58.2%, respectively), and a positive assessment of the reservoir’s impact on the development of the region by the local community (19 out of 26 village leaders expressed positive opinions with no unambiguously negative votes). Full article
(This article belongs to the Special Issue Freshwater Quality Challenges in Southern Europe under an Increasingly Warmer and Drier Climate Scenario)
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15 pages, 5192 KiB  
Article
Hydrochemical and Formation Mechanism Studies of Groundwater in Quaternary Aquifer in a Northern Plain of China: An Example of Beijing Plain
by Sarah Fatim Camara, Jinjun Zhou and Yongxiang Zhang
Water 2024, 16(14), 2060; https://doi.org/10.3390/w16142060 - 21 Jul 2024
Viewed by 1003
Abstract
Beijing Plain is a very active part of Beijing city regarding the socio-economic and human activities of the region. Over the past four decades, Beijing’s economic development and the continuous drought for nearly 10 years in the 2000s have negatively impacted the groundwater [...] Read more.
Beijing Plain is a very active part of Beijing city regarding the socio-economic and human activities of the region. Over the past four decades, Beijing’s economic development and the continuous drought for nearly 10 years in the 2000s have negatively impacted the groundwater quantity and quality. Therefore, it is necessary to investigate the present situation of groundwater chemistry in this region to develop a comprehensive database and orientation for future research on groundwater quality evaluation. Mathematical statistics, Piper’s trilinear diagram, Gibbs plots, the ion ratio method and PHREEQC software 3.7.3 were used to analyze the groundwater hydrogeochemical characteristics and formation mechanisms of the quaternary aquifers of the Beijing Plain area. Hydrogeochemical results indicated that the groundwater is slightly alkaline, with pH values ranging from 6.76 to 8.65 and an average value of 7.92. The order of major cations in groundwater was Ca2+ > Na+ > Mg2+ > K+ with average values of 66.54 mg/L, 50.58 mg/L, 23.78 mg/L, and 1.81 mg/L, respectively, while the order of major anions was HCO3− > SO42− > Cl− with average values of 284.89 mg/L, 52.1 mg/L and 35.5 mg/L, respectively. The groundwater chemical types are Mg-Ca-Cl-HCO3, Na-Ca-HCO3, Mg-Ca-HCO3 and Mg-Na-HCO3. Research on the main influencing factors and PHREEQC hydrogeochemical inverse simulations results along the four pathways selected confirmed that rock weathering with sulfate, silicate and carbonate rock mineral dissolution and Na+, Mg2+ and Ca2+ ion reaction exchange influenced groundwater hydrogeochemical characteristics of the quaternary aquifers of the Beijing Plain area. Understanding the formation mechanisms of hydrogeochemistry in quaternary plains provides guidance for future studies and, through suggestions and case studies, facilitates decision-making by policy-makers on the sustainable management of groundwater resources. Full article
(This article belongs to the Special Issue Effect of Climate Change and Anthropogenic Activities on Groundwater Resources)
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10 pages, 1335 KiB  
Article
Concentration and Distribution of Specific Siloxanes (D5 and D6) and PAHs in the Anacostia and Potomac Rivers, USA
by Olivia Ventresca, Ashley Acevedo, Kristina Nicholas, Jonathan Craig, Sophia Carpenter, Christia Fisher, Madeleine Danzberger, Cassidy Williams, Barbara Balestra and Stephen MacAvoy
Water 2024, 16(14), 2059; https://doi.org/10.3390/w16142059 - 20 Jul 2024
Viewed by 1036
Abstract
The waterways adjacent to Washington DC, USA have a history of contamination from heavy metals, nutrients, pesticides, and industrial chemicals. Among the chemicals of concern are PAHs, which are a historical contaminant but also have modern pyrogenic and petrogenic sources in the area’s [...] Read more.
The waterways adjacent to Washington DC, USA have a history of contamination from heavy metals, nutrients, pesticides, and industrial chemicals. Among the chemicals of concern are PAHs, which are a historical contaminant but also have modern pyrogenic and petrogenic sources in the area’s waterways. Another group of contaminants that are of emerging interest are siloxanes (silicones), which are widely used as lubricants, sealants, and cosmetics. Some lower-molecular-weight siloxanes are regulated by the EU in recognition of harm to aquatic life, but there are no restrictions in the United States. In fact, studies examining water pollutants do not typically test for siloxanes. Here, we present the concentrations of specific PAHs and siloxanes from surface sediments in the Potomac and Anacostia Rivers (including the Anacostia’s tributaries) collected between 2018 and 2023. Both D5 (decamethylcyclopentasiloxane) and D6 (dodecamethylcyclohexasiloxane) were found in most locations, with concentrations averaging 0.13 and 0.006 mg/g (dry mass), respectively. Pyrene, fluoranthene, bibenzyl, and phenanthrene were also found in the Anacostia and some of its tributaries, with concentrations increasing downstream. In the Potomac, concentrations were generally lower than those observed in the Anacostia. Based on ratios of pyrene to fluoranthene + pyrene, the likely source of PAHs was petrogenic. Full article
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20 pages, 7207 KiB  
Article
Multi-Source Remote Sensing Analysis of Yilong Lake’s Surface Water Dynamics (1965–2022): A Temporal and Spatial Investigation
by Ningying Bao, Weifeng Song, Jiangang Ma and Ya Chu
Water 2024, 16(14), 2058; https://doi.org/10.3390/w16142058 - 20 Jul 2024
Viewed by 766
Abstract
With the acceleration of global warming and the intensification of anthropogenic activities, numerous lakes worldwide are experiencing reductions in their water surface areas. Yilong Lake, a typical shallow plateau lake located on the Yunnan–Guizhou Plateau in China, serves as a crucial water resource [...] Read more.
With the acceleration of global warming and the intensification of anthropogenic activities, numerous lakes worldwide are experiencing reductions in their water surface areas. Yilong Lake, a typical shallow plateau lake located on the Yunnan–Guizhou Plateau in China, serves as a crucial water resource for local human production, daily life, and ecosystem services. Hence, long-term comprehensive monitoring of its dynamic changes is essential for its effective protection. However, previous studies have predominantly utilized remote sensing data with limited temporal resolution, thus failing to reflect the long-term variations in Yilong Lake’s water body. This study employs high temporal resolution monitoring, utilizing multi-source satellite data (e.g., KeyHole, Landsat, HJ-1 A/B) images spanning from 1965 to 2022 to investigate the changes in Yilong Lake’s surface area, analyzing the influencing factors and ecological impacts of these changes. The results indicate that from 1965 to 2022, Yilong Lake’s water surface area decreased by 8.33 km2, with a maximum surface area of 40.49 km2 on 7 January 1986, and a minimum surface area of 10.64 km2 on 20 April 2013. These changes are characterized by three significant phases: (1) a rapid shrinking phase (1965–1979); (2) a fluctuating shrinking period (1986–2016); and (3) an expanding recovery phase (2016–2022). Spatially, the most significant shrinkage was observed along the southern and southwestern shores of the lake. The driving factors varied across different periods: sunshine duration was the dominant influence during the rapid shrinking phase (1965–1979), accounting for 82% of the changes; population and cropland area were the main drive factors during the fluctuating shrinking period (1986–2016), accounting for 56% of the changes; and during the expanding recovery phase (2016–2022), the population accounted for 75% of the changes in the lake’s surface area. Currently, the protection of Yilong Lake depends on water supplementation and strict regulation of outflow, resulting in the lake exhibiting characteristics similar to a reservoir. This long-term investigation provides baseline information for future lake monitoring. Our research findings can also guide decision-makers in urban water resource management and environmental protection, ensuring the scientific and rational use of watershed water resources, effectively curbing the shrinkage of Yilong Lake, and achieving long-term sustainable restoration of the lake’s ecology. Full article
(This article belongs to the Section Hydrology)
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13 pages, 2678 KiB  
Article
Alkaline Pre-Fermentation Promotes Anaerobic Digestion of Enhanced Membrane Coagulation (EMC) Sludge: Performance and Microbial Community Response
by Qingshuang Kou, Quan Yuan, Song Chen, Heng Xu, Shanghui Wei and Kaijun Wang
Water 2024, 16(14), 2057; https://doi.org/10.3390/w16142057 - 20 Jul 2024
Viewed by 869
Abstract
Concentrating organic matter in sludge and converting it into methane through anaerobic bioconversion can improve resource recovery from domestic wastewater. Enhanced membrane coagulation (EMC) is highly efficient at concentrating organic matter, but residual coagulants (aluminum salts) can obstruct bioconversion by blocking microbial access. [...] Read more.
Concentrating organic matter in sludge and converting it into methane through anaerobic bioconversion can improve resource recovery from domestic wastewater. Enhanced membrane coagulation (EMC) is highly efficient at concentrating organic matter, but residual coagulants (aluminum salts) can obstruct bioconversion by blocking microbial access. Limited research exists on evaluating EMC sludge bioconversion performance and addressing coagulant inhibition. This study proposes alkaline pre-fermentation to break down HO-Al-P backbones in coagulated sludge flocs, thereby improving hydrolysis and organic acid production for anaerobic digestion. Among the tested alkaline conditions (pH 9, pH 10, pH 11), pre-fermentation at pH 11 released the most organic matter (4710.0 mg/L SCOD), 20.4 times higher than without alkaline treatment. At pH 11, phosphate (61 mg/L PO43−–P) and organic acid production (2728.1 mg COD/L, with nearly 50% acetic acid) peaked, resulting in superior volatile solids removal (65.2%) and methane production (185.8 mL/g VS) during anaerobic digestion. Alkaline pre-fermentation favored alkali-tolerant bacteria such as Firmicutes and Actinobacteria, especially at pH 11, while neutrophilic Proteobacteria were suppressed. Trichococcus and Bifidobacterium, known acid producers, dominated under all conditions, with their abundance increasing at higher pH levels. Anaerobic digestion enriched fermentative bacteria like Chloroflexi and Synergistota (e.g., Thermovirga), especially in high pH reactors. Methanothrix, an acetoclastic methanogen, became the dominant methanogenic archaeon, indicating that methane production from EMC sludge primarily followed the acetoclastic methanogenesis pathway. Our findings demonstrate that alkaline pre-fermentation at pH 11 significantly enhances the hydrolysis efficiency of EMC sludge for methane recovery. Full article
(This article belongs to the Special Issue Microbial Biotechnology for Water and Sludge Treatment)
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20 pages, 4691 KiB  
Article
Na-Kenyaite as Efficient Basic Blue-41 Dye Removal: Synthesis and Regeneration Studies
by Osama Y. Al-Madanat, Saheed A. Popoola, Hmoud Al Dmour, Rawan Al-Faze and Fethi Kooli
Water 2024, 16(14), 2056; https://doi.org/10.3390/w16142056 - 20 Jul 2024
Cited by 1 | Viewed by 802
Abstract
Na-kenyaite materials are available in nature and can easily be prepared in the laboratory. These materials exhibit interesting adsorption properties; therefore, they can be invested in the new wastewater treatment technologies. This study investigates the removal of basic blue-41 (BB-41) dye from artificially [...] Read more.
Na-kenyaite materials are available in nature and can easily be prepared in the laboratory. These materials exhibit interesting adsorption properties; therefore, they can be invested in the new wastewater treatment technologies. This study investigates the removal of basic blue-41 (BB-41) dye from artificially contaminated water using Na-kenyaite materials in batch mode. Firstly, Na-kenyaites were prepared by the hydrothermal process at a temperature of 150 to 170 °C for a period of 2 to 7 days using different silica sources and ratios of SiO2/NaOH/H2O. The prepared materials were characterized by different techniques such as XRD, FTIR, 29Si MAS NMR, TGA/DTA, SEM, and nitrogen adsorption isotherms. A pure Na-kenyaite phase was successfully obtained using a fumed silica source and 5SiO2/Na2O/122H2O ratio. The removal experiments of basic blue-41 estimated the effectiveness of Na-kenyaites in removing properties, investigating the influence of the solid dosage, initial basic blue-41 concentration, and solution pH or Na-kenyaite solid. Results showed optimal dye removal of around 99% at pH levels above 7. Furthermore, the estimated maximum removal capacity from the Langmuir isotherm was between 124 and 165 mg/g. The results demonstrated efficient removal by Na-kenyaites and its prominence for wastewater treatment. Finally, this study explored the regeneration and reuse of Na-kenyaites through seven cycles and reported a design of a batch adsorber system to reduce the initial concentration of 200 mg/L at different percentages. Full article
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17 pages, 13531 KiB  
Review
Applications of RIM-Based Flow Visualization in Fluid-Solid Interaction Problems: A Review of Formulations and Prospects
by Hanqi Zeng, Deping Cao, Hao Chen, Qi Chai and Tianze Lu
Water 2024, 16(14), 2055; https://doi.org/10.3390/w16142055 - 20 Jul 2024
Viewed by 802
Abstract
Over the past three decades, optical visualization measurements based on the Refractive Index Match (RIM) method have played a significant role in the experimental studies of fluid-solid interaction. The RIM method, which coordinates the refractive indices of the liquid and solid materials in [...] Read more.
Over the past three decades, optical visualization measurements based on the Refractive Index Match (RIM) method have played a significant role in the experimental studies of fluid-solid interaction. The RIM method, which coordinates the refractive indices of the liquid and solid materials in the experiment, dramatically reduces the observation error due to optical refraction. However, the existing literature on RIM has not systematically reviewed the various applications of this technique. This review aims to fill this gap by providing a comprehensive overview of the RIM technique, examining its role in material selection for fluid-solid interaction studies, and scrutinizing its applications across various engineering disciplines. The paper begins with a brief introduction to the RIM technique and then turns to material selection and its various applications in fluid-solid interaction. It also enumerates and analyzes specific RIM-based optical measurement techniques such as Laser Doppler Velocimetry (LDA), Particle Tracking Velocimetry (PTV), and Particle Image Velocimetry (PIV) from various research perspectives in previous studies. In addition, it summarizes RIM formulations categorized by different applications in liquid-solid interaction fields. RIM-based measurement techniques generally offer intuitive, non-intrusive, cost-effective, and convenient advantages over traditional methods. The paper also critically evaluates the strengths and limitations of different materials used in RIM experiments and suggests directions for future research, emphasizing the need to develop environmentally friendly and cost-effective RIM materials. Full article
(This article belongs to the Special Issue Wave–Structure Interaction: Research, Modeling and Future Application)
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16 pages, 6001 KiB  
Article
Coupling Imports of Dissolved Inorganic Nitrogen and Particulate Organic Matter by Aquaculture Sewage to Zhangjiang Estuary, Southeastern China
by Shuang He, Ta-Jen Chu, Zhiqiang Lu and Danyang Li
Water 2024, 16(14), 2054; https://doi.org/10.3390/w16142054 - 20 Jul 2024
Cited by 1 | Viewed by 833
Abstract
Estuary ecosystems serve as crucial connectors between terrestrial and marine environments, thus playing vital roles in maintaining the ecological balance of coastal marine ecosystems. In recent years, the eutrophication in estuaries caused by aquaculture sewage has been revealed, highlighting the necessity to understand [...] Read more.
Estuary ecosystems serve as crucial connectors between terrestrial and marine environments, thus playing vital roles in maintaining the ecological balance of coastal marine ecosystems. In recent years, the eutrophication in estuaries caused by aquaculture sewage has been revealed, highlighting the necessity to understand its influence on the nutrient conditions and carbon storage of estuaries. In this study, δ15N and δ18O were used to indicate the contribution of aquaculture-derived sewage to dissolved inorganic nitrogen in Zhangjiang Estuary, and δ13C and C:N ratio were used to reveal its effects on the particulate organic matter. The major results are as follows: (1) Aquaculture water contributed 62~86% and 60~100% of the total nitrate and ammonium in Zhangjiang Estuary, respectively, and the drainage periods of the cultured species has a great influence on the content and composition of dissolved inorganic nitrogen. (2) Aquaculture water was also the major source of particulate organic matter (24~33% of the total content) here, most of which may be derived from crab ponds. (3) The imports of nutrients by aquaculture water may potentially regulate particulate organic matter in Zhangjiang Estuary by promoting the growth of phytoplankton and zooplankton. Our study revealed the coupling effects of aquaculture activities on the nitrogen and carbon storage in an estuarine ecosystem. It also indicates that isotopes may be efficient in the monitoring of a coastal environment, which may further aid the management of inshore cultivation. Full article
(This article belongs to the Section Oceans and Coastal Zones)
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11 pages, 3237 KiB  
Article
Hydro–Solar Hybrid Plant Operation in a Hydropower Plant Cascade: Optimizing Local and Bulk System Benefits
by Mateus Henrique Balan, Luiz Armando Steinle Camargo, Dorel Soares Ramos, Roberto Castro, Lais Domingues Leonel, Eduardo Soares Pulcherio and Joaquin Melendez
Water 2024, 16(14), 2053; https://doi.org/10.3390/w16142053 - 20 Jul 2024
Viewed by 973
Abstract
A hydro–solar hybrid system is an important solution for expanding renewable generation capacity under the percepts of the energy transition. This type of association allows for the coordinated dispatch of solar and hydropower plants, resulting in operational benefits in terms of energy generation [...] Read more.
A hydro–solar hybrid system is an important solution for expanding renewable generation capacity under the percepts of the energy transition. This type of association allows for the coordinated dispatch of solar and hydropower plants, resulting in operational benefits in terms of energy generation and reservoir management, that is, the better use of available water and energy resources. As in this case, the operation of the hydropower plant is associated with the cascade in which it operates, when it is hybridized (for example, by associating with a solar power plant), in addition to local changes, there are impacts on the operating conditions of the other hydropower plants in the same cascade. From such a perspective, this study presents an energy system management model for hybrid power plants composed of hydro and solar sources, aiming to optimize the joint operation and measure the operational consequences at the local level and in the cascade. The results from a case study of a hydro–solar power plant hybridization in the Tietê River (Brazil) revealed increased energy production and improvement in the operating conditions of the cascade’s reservoirs, while the grid capacity was found to be an important constraint that limits the capture of synergies resulting from the generation sources complementarity and thus on the benefits to the cascade. Full article
(This article belongs to the Special Issue Advanced Research on Hydro-Wind-Solar Hybrid Power Systems)
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22 pages, 8964 KiB  
Article
Surface Flux Patterns of Nutrient Concentrations and Total Suspended Solids in Western Carpathian Stream within Agricultural, Forest, and Grassland Landscapes
by Wiktor Halecki and Dawid Bedla
Water 2024, 16(14), 2052; https://doi.org/10.3390/w16142052 - 19 Jul 2024
Viewed by 699
Abstract
The intricate processes of surface water erosion are vital for ecological systems and river-scale management; yet, understanding them comprehensively remains a challenge. Forested agricultural catchments, especially in the Carpathian region, face significant degradation, potentially leading to inorganic nutrient leaching and total suspended solid [...] Read more.
The intricate processes of surface water erosion are vital for ecological systems and river-scale management; yet, understanding them comprehensively remains a challenge. Forested agricultural catchments, especially in the Carpathian region, face significant degradation, potentially leading to inorganic nutrient leaching and total suspended solid (TSS) flux. Continuous rainwater inundation of soils in river valleys exacerbates this issue. Utilizing innovative tools like SWAT+, studies have revealed higher concentrations of inorganic nutrients in main watercourses from flysch catchments, with agricultural use linked to N-NO3− concentrations and pasture use linked to anion P-PO43−. Maintaining detailed records is crucial for researchers comparing data. SWAT+ proves valuable for studying TSS washing out and inorganic nutrient leaching, informing collaborative watershed management policies involving stakeholders from agriculture, conservation, and water management sectors. The insights on nutrient leaching, particularly phosphorus (P) and nitrogen (N), are instrumental for shaping policies targeting nutrient pollution within pasture land use for EU agriculture. These findings can guide policy frameworks focused on sustainable practices, especially for eco-schemes, and encourage collaborative watershed management efforts. Full article
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16 pages, 891 KiB  
Article
Influence of Temperature on the Toxic Effects of Carbamazepine on the Copepod Tigriopus fulvus: A Transgenerational Full Life Cycle Study
by Isabella Parlapiano, Ermelinda Prato, Giuseppe Denti and Francesca Biandolino
Water 2024, 16(14), 2051; https://doi.org/10.3390/w16142051 - 19 Jul 2024
Viewed by 851
Abstract
Coastal areas are increasingly exposed to global warming and emerging contaminants from anthropogenic activities; however, the interactive effects of these stress factors in shaping the offspring’s vulnerability to them are poorly understood. The present study aimed to assess the influence of temperature on [...] Read more.
Coastal areas are increasingly exposed to global warming and emerging contaminants from anthropogenic activities; however, the interactive effects of these stress factors in shaping the offspring’s vulnerability to them are poorly understood. The present study aimed to assess the influence of temperature on the toxicity of the pharmaceutical carbamazepine (CBZ) in the parental (F0) and in the first (F1) generation of Tigriopus fulvus, through a full life cycle study, measuring several biological parameters. At control temperature (20 °C), exposure to CBZ significantly inhibited larval development, especially in the F1 generation. In contrast, under warmer conditions (27 °C), even after exposure to CBZ, the development was stimulated, proving that temperature was the main factor influencing it. As regards the other investigated life traits (body length, sex ratio, and fecundity), both temperature and generation modulated toxic effects of CBZ, which is evidenced by the onset of higher alterations in F1 co-exposed copepods. Our findings suggest that temperature and contaminants could increase the long-term vulnerability to stressors of T. fulvus, potentially affecting the population structure over multiple generations of exposure. Full article
(This article belongs to the Special Issue Implementation of Biodiversity and Ecosystem Services in Marine Ecosystem Management, 3rd Edition)
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19 pages, 5153 KiB  
Article
Comparison of Hexavalent Chromium Adsorption Behavior on Conventional and Biodegradable Microplastics
by Zongzhi Fang, Zhenghua Wang, Han Tang and Andrew Hursthouse
Water 2024, 16(14), 2050; https://doi.org/10.3390/w16142050 - 19 Jul 2024
Viewed by 993
Abstract
Microplastics are omnipresent in aquatic environments and can act as vectors to carry other pollutants, modifying their pathway through the systems. In this study, the differences in the adsorption capacity and mechanism for Cr(VI) sorption with polyethylene (PE, a conventional microplastic) and polylactic [...] Read more.
Microplastics are omnipresent in aquatic environments and can act as vectors to carry other pollutants, modifying their pathway through the systems. In this study, the differences in the adsorption capacity and mechanism for Cr(VI) sorption with polyethylene (PE, a conventional microplastic) and polylactic acid (PLA, a biodegradable microplastic) were investigated via characterization of the MPs, the determination of kinetic behavior (pseudo-first- and second-order model, the Elovich model), and the degree of fit to Langmuir and Freundlich isothermal models; the adsorption behavior was also studied under different solution conditions. The results indicated that when the dose of MPs was 1 g/L, the adsorption capacity of Cr(VI) on MPs reached the highest value, the adsorption capacities were PLA(0.415 mg/g) > PE(0.345 mg/g). The adsorption of Cr(VI) on PE followed the Langmuir isotherm model, while PLA had a stronger fit with the Freundlich model. Sorption in both cases followed a pseudo-first-order kinetics model. The maximum adsorption capacity of Cr(VI) on PLA (0.54 mg/g) is higher than that on PE (0.38 mg/g). In addition, PLA could reach adsorption equilibrium in about 8 h and can adsorb 72.3% of the total Cr(VI) within 4 h, while PE required 16 h to reach equilibrium, suggesting that PLA adsorbs at a significantly faster rate than PE. Thus, biodegradable MPs like PLA may serve as a superior carrier for Cr(VI) in aquatic environments. When the pH increased from 2 to 6, the adsorption of Cr(VI) by PE and PLA decreased from 0.49 mg/g and 0.52 mg/g to 0.27 mg/g and 0.26 mg/g, respectively. When the concentration of sodium dodecyl sulfate in the Cr(VI) solution was increased from nil to 300 mg/L, the adsorption of Cr(VI) by PE and PLA increased by 3.66 and 3.05 times, respectively. In addition, a higher temperature and the presence of Cu2+ and photoaging promoted the adsorption of Cr(VI) by MPs, while higher salinity inhibited the adsorption. The desorption efficiencies of Cr(VI) on MPs were PLA(57.8%) > PE(46.4%). The characterization results further confirmed that the adsorption mechanism could be attributed to electrostatic attraction, hydrogen bonding, and surface complexation. In sum, PLA could potentially serve as better vectors for Cr(VI) than PE, but the risk associated with PLA might be higher than that with PE. Full article
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19 pages, 8980 KiB  
Article
Effect of Grain Size on the Uniaxial Compressive Strength of Ice Forming with Different Wind Speeds in a Cold Laboratory
by Yujia Zhang, Zuoqin Qian, Weilong Huang, Xiaodong Chen, Zhen Zhang and Jie Ren
Water 2024, 16(14), 2049; https://doi.org/10.3390/w16142049 - 19 Jul 2024
Cited by 1 | Viewed by 849
Abstract
This study investigated the uniaxial compressive strength of distilled water ice prepared in a low-temperature laboratory at −30 °C at varying wind speeds of 0 m/s, 1 m/s, 2 m/s, 4 m/s, 6 m/s, and 8 m/s. The crystal structure and grain size [...] Read more.
This study investigated the uniaxial compressive strength of distilled water ice prepared in a low-temperature laboratory at −30 °C at varying wind speeds of 0 m/s, 1 m/s, 2 m/s, 4 m/s, 6 m/s, and 8 m/s. The crystal structure and grain size of the ice were measured. The results indicated that, during the ice forming period, the higher the wind speed, the lower the grain size. Uniaxial compression tests were conducted parallel to the ice crystal long axis direction within a strain rate range of 10−6 s−1 to 10−2 s−1. The experimental temperature was controlled at −10 °C. Stress–strain curves were generated, elucidating the mechanical properties and failure modes of the ice. The results suggest that the uniaxial compressive strength of ice is related to the strain rate by a power–law function and shows a linear correlation with −1/2 power of grain size. The results explain the physical fact that the strength of ice is higher when the ice is formed in low-temperature and high-wind-speed environments. Additionally, this highlights how wind speed influences ice strength by controlling grain size during ice forming. Full article
(This article belongs to the Special Issue Cold Region Hydrology and Hydraulics)
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18 pages, 18389 KiB  
Article
Quantification Assessment of Winter Wheat Sensitivity under Different Drought Scenarios during Growth
by Shangming Jiang, Zheng Li, Hongwei Yuan, Juliang Jin, Chenguang Xiao and Yi Cui
Water 2024, 16(14), 2048; https://doi.org/10.3390/w16142048 - 19 Jul 2024
Cited by 1 | Viewed by 834
Abstract
To effectively reveal the disaster-causing mechanism between water stress and yield loss under different drought combinations during multiple growth periods of winter wheat, based on biennial wheat drought experiments, a crop growth analysis method was used to quantitatively identify and assess wheat yield [...] Read more.
To effectively reveal the disaster-causing mechanism between water stress and yield loss under different drought combinations during multiple growth periods of winter wheat, based on biennial wheat drought experiments, a crop growth analysis method was used to quantitatively identify and assess wheat yield loss sensitivity. The results showed that there was a significant negative correlation between the total dry matter relative growth rate (RGR) of wheat and the daily average degree of drought stress. The average determination coefficients of logarithmic fitting for 2017 and 2018 were 0.7935 and 0.7683, respectively. Wheat dry matter accumulation differed under the different drought combination scenarios. The yield loss sensitivity response relationship between the decrease in the RGR of wheat dry matter (relative to no drought stress) and the daily average degree of drought stress could be quantitatively identified by an S-shaped curve, and the 2017 and 2018 average coefficients of determination R2 were 0.859 and 0.849, respectively. Mild drought stress at the tillering stage stimulates adaptability and has little effect on yield. The soil water content (SWC) can be controlled to 65–75% of the field water holding capacity; the SWC at the jointing and booting stage can be controlled to be higher than the field water holding capacity of 55%. The SWC was maintained at a level higher than 75% of the field water holding capacity during the heading and flowering stages and the grain-filling and milky stages to achieve a harmonization of yields and water savings. In addition, during the production process, continuous severe drought during the jointing and booting stage and the heading and flowering stage should be avoided. This study elucidates the response relationship between drought intensity and drought-induced losses from the perspective of physical genesis, provides effective irrigation guidance for regional wheat planting, lays the foundation for the construction of quantitative agricultural drought loss risk curves, and provides technical support for predicting the trend of yield losses in wheat under different drought stresses. Full article
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14 pages, 6197 KiB  
Article
Experimental Study on Impedance Spectrum-Based Detection of Water Holdup in Two-Phase Flow under Complex Salinity Conditions
by Linfeng Cheng, Shizhen Ke, Hongwei Shi, Yuhang Zhang, Hu Luo and Hao Hu
Water 2024, 16(14), 2047; https://doi.org/10.3390/w16142047 - 19 Jul 2024
Viewed by 652
Abstract
In industrial production and water resource management involving fluid flows, two-phase flow measurement in complex environments has always been a research hotspot. In this study, a broadband detection device (40–110 MHz) suitable for two-phase flow in pipes was designed in a laboratory environment, [...] Read more.
In industrial production and water resource management involving fluid flows, two-phase flow measurement in complex environments has always been a research hotspot. In this study, a broadband detection device (40–110 MHz) suitable for two-phase flow in pipes was designed in a laboratory environment, the impedance response of two-phase flow was investigated under different salinity conditions and flow patterns, and a new impedance dispersion model suitable for two-phase flow in pipes was built. The experimental results show that the new model can better describe the rules of impedance dispersion in two-phase flow and is universally applicable, and that the equivalent solution resistance and interfacial polarization frequency have a stable functional relationship with water holdup. Based on the static experimental results, water holdup evaluation models for four flow patterns were established, and the dynamic detection results were predicted. The prediction results show that the new method proposed herein is not affected by changes in salinity and flow pattern when the flow pattern is known, and that its accuracy can meet the production requirements. This study expands the application range of traditional single-frequency conductivity detection techniques and provides a new idea for the development and improvement of systems for online detection of water holdup in two-phase flow. Full article
(This article belongs to the Special Issue Quantifying Groundwater Flow and Solute Transport Processes through Modelling and Experiments)
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15 pages, 8233 KiB  
Article
Investigation of the Deformation Behavior of Baffle Structures Impacted by Debris Flow Based on Physical Modelling
by Weizhi Chen, Bei Zhang, Na Xu and Yu Huang
Water 2024, 16(14), 2046; https://doi.org/10.3390/w16142046 - 19 Jul 2024
Viewed by 731
Abstract
The utilization of baffle structures as a highly effective strategy for mitigating debris flow has attracted significant scholarly attention in recent years. Although the predominant focus of existing research has been on augmenting the energy dissipation capabilities of baffle structures, their deformation behavior [...] Read more.
The utilization of baffle structures as a highly effective strategy for mitigating debris flow has attracted significant scholarly attention in recent years. Although the predominant focus of existing research has been on augmenting the energy dissipation capabilities of baffle structures, their deformation behavior under impact load has not been extensively investigated. Addressing this research gap, the current study systematically designs a series of physical model experiments, incorporating variables such as baffle height, shape, and various combinations of baffle types to comprehensively analyze the deformation characteristics of baffles subjected to debris flow impact. The experimental results reveal that the deformation of baffle group structures demonstrates a marked non-uniform spatial distribution and exhibits a latency effect. Additionally, distinct baffle configurations show considerable variations in peak strain, suggesting that combining different baffle shapes can not only optimize energy dissipation but also enhance resistance to deformation. Moreover, the relationship between baffle height and the development of deformation in relation to energy dissipation capacity is inconsistent, indicating that deformation must be a key consideration in the design of baffle structures. Consequently, this paper advocates for the formulation of a deformation-based design strategy for baffle structures, with the findings presented herein providing a foundational reference for future studies. Full article
(This article belongs to the Special Issue Flowing Mechanism of Debris Flow and Engineering Mitigation)
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14 pages, 4940 KiB  
Article
The Impact of the Three Gorges Reservoir Operations on Hydraulic Characteristics in the Backwater Region: A Comprehensive 2D Modeling Study
by Yaqian Xu, Shengde Yu, Defu Liu, Jun Ma and Mingying Chuo
Water 2024, 16(14), 2045; https://doi.org/10.3390/w16142045 - 19 Jul 2024
Cited by 1 | Viewed by 851
Abstract
The Three Gorges Reservoir (TGR), a landmark of human engineering, has significantly altered the hydrodynamics and ecology of its surrounding environment. Our research explores the hydrodynamic and ecological changes in the TGR, focusing on their implications for reservoir-induced water quality and water resource [...] Read more.
The Three Gorges Reservoir (TGR), a landmark of human engineering, has significantly altered the hydrodynamics and ecology of its surrounding environment. Our research explores the hydrodynamic and ecological changes in the TGR, focusing on their implications for reservoir-induced water quality and water resource issues. We designed a 2D hydrodynamic and water quality model and implemented 15 operational scenarios with an advanced dynamic storage capacity method for the TGR during flood season, drawdown and impoundment periods. Our simulations well reproduced and predicted water levels, discharge rates, and thermal conditions of the TGR, providing critical insights. The dynamic storage capacity method significantly improved the precision of water level simulations. This approach achieved modeling errors below 0.2 m when compared to real measurements from seven stations. We performed a detailed analysis of the sensitive, sub-sensitive, and insensitive areas during three reservoir operation periods. The drawdown period showed the most extensive impact range (468 km river channel), while the impoundment period had the least impact range (76 km river channel). Furthermore, we quantified the delay of temperature waves during these periods, observing a maximum delay of approximately 120 km and a minimum delay of less than 10 km, which underscores the variability in hydrodynamic responses under different operational scenarios. Our findings reveal the complex sensitivities of the TGR to varied operational modes, aiding in the development of eutrophication and water resources control strategies. Our modeling application provides different operational scenarios and insights for ecological management strategies in large dam systems globally, informing future water resource management and policy-making, ensuring sustainable and effective management of large reservoir systems. Full article
(This article belongs to the Special Issue Environmental Effects of Natural Processes and Human Activities on the Water Environment in Watershed)
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12 pages, 558 KiB  
Article
Estimation of the Soil–Water Characteristic Curve from Index Properties for Sandy Soil in China
by Shijun Wang, Xing Guo, Feng You, Zhong Zhang, Tianlun Shen, Yuhui Chen and Qian Zhai
Water 2024, 16(14), 2044; https://doi.org/10.3390/w16142044 - 19 Jul 2024
Viewed by 747
Abstract
The soil–water characteristic curve (SWCC) is an important parameter of unsaturated soil, and almost all the engineering characteristics of unsaturated soil are more or less related to the SWCC. The SWCC contains important information for geotechnical engineering, water engineering, hydrogeology modelling and climate [...] Read more.
The soil–water characteristic curve (SWCC) is an important parameter of unsaturated soil, and almost all the engineering characteristics of unsaturated soil are more or less related to the SWCC. The SWCC contains important information for geotechnical engineering, water engineering, hydrogeology modelling and climate modelling. It is noted that the experimental measurement of SWCC is costly and time consuming, which limits the implementation of principles of unsaturated soil mechanics in practical engineering. The indirect method, which estimates the SWCC from the index properties of soil, can provide the SWCC with the errors which are within tolerance in practical engineering. In addition, the indirect method can determine SWCC very fast and almost with no cost. In this paper, the domestic sandy soils are selected and the index properties of those sands are used to correlate the SWCC fitting parameters. Consequently, mathematical equations are proposed to estimate SWCC from index properties of domestic sands. The proposed models are trained from 44 sets of experimental data and verified with another independent 8 sets of experimental data from published literature. It is observed that the results from the proposed model agree well with the experimental data from literature. Full article
(This article belongs to the Special Issue Soil Dynamics and Water Resource Management)
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23 pages, 8137 KiB  
Article
SWAT-Driven Exploration of Runoff Dynamics in Hyper-Arid Region, Saudi Arabia: Implications for Hydrological Understanding
by Sajjad Hussain, Burhan Niyazi, Amro Mohamed Elfeki, Milad Masoud, Xiuquan Wang and Muhammad Awais
Water 2024, 16(14), 2043; https://doi.org/10.3390/w16142043 - 19 Jul 2024
Viewed by 929
Abstract
Hydrological modeling plays a vital role in water-resource management and climate-change studies in hyper-arid regions. In the present investigation, surface runoff was estimated by a Soil and Water Assessment Tool (SWAT) model for Wadi Al-Aqul, Saudi Arabia. The Sequential Uncertainty Fitting version 2 [...] Read more.
Hydrological modeling plays a vital role in water-resource management and climate-change studies in hyper-arid regions. In the present investigation, surface runoff was estimated by a Soil and Water Assessment Tool (SWAT) model for Wadi Al-Aqul, Saudi Arabia. The Sequential Uncertainty Fitting version 2 (SUFI-2) technique in SWAT-CUP was adopted for the sensitivity analysis, calibration, and validation of the SWAT model’s components. The observational runoff data were scarce and only available from 1979 to 1984; such data scarcity is a common problem in hyper-arid regions. The results show good agreement with the observed daily runoff, as indicated by a Pearson Correlation Coefficient (r) of 0.86, a regression (R2) of 0.76, and a Nash–Sutcliffe coefficient (NSE) of 0.61. Error metrics, including the Mean Absolute Error (MAE) and Root Mean Square Error (RMSE), were notably low at 0.05 and 0.58, respectively. In the daily validation, the model continued to perform well, with a correlation of 0.76 and regression of 0.58. As a new approach, fitted parameters of daily calibration were incorporated into the monthly simulation, and they demonstrated an even better performance. The correlation coefficient (regression) and Nash–Sutcliffe were found to be extremely high during the calibration period of the monthly simulation, reaching 0.97 (0.95) and 0.73, respectively; meanwhile, they reached 0.99 (0.98) and 0.63 in the validation period, respectively. The sensitivity analysis using the SUFI-2 algorithm highlighted that, in the streamflow estimation, the Curve Number (CN) was found to be the most responsive parameter, followed by Soil Bulk Density (SOL_BD). Notably, the monthly results showed a higher performance than the daily results, indicating the inherent capability of the model in regard to data aggregation and reducing the impact of random fluctuations. These findings highlight the applicability of the SWAT model in predicting runoff and its implication for climate-change studies in hyper-arid regions. Full article
(This article belongs to the Special Issue Climate Change Impact on Hydrological Cycle and Water Resources Management, 2nd Edition)
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16 pages, 4297 KiB  
Article
Development of an Explicit Water Level Pool Routing Method in Reservoirs
by Alfonso Arrieta-Pastrana, Oscar E. Coronado-Hernández and Vicente S. Fuertes-Miquel
Water 2024, 16(14), 2042; https://doi.org/10.3390/w16142042 - 19 Jul 2024
Viewed by 872
Abstract
Local regulations control the additional runoff produced by urbanization processes. Sustainable urban drainage systems can mitigate the issues associated with increased runoff by employing infiltration basins, detention ponds, wet ponds, and constructed wetlands. Traditionally, the Water Level Pool Routing Method, which relies on [...] Read more.
Local regulations control the additional runoff produced by urbanization processes. Sustainable urban drainage systems can mitigate the issues associated with increased runoff by employing infiltration basins, detention ponds, wet ponds, and constructed wetlands. Traditionally, the Water Level Pool Routing Method, which relies on an implicit calculation scheme, has been used to calculate outflow hydrographs in reservoirs. In this research, an explicit scheme for the Water Level Pool Routing Method has been developed. The proposed model is applied to a case study where the reservoir has a surface area of 9.12 hectares. The influence of weir width and the discharge coefficient is also analyzed. Additionally, the variation in time step does not significantly affect the response of the proposed model, demonstrating its adequacy as a novel method. The proposed model is compared to the traditional method, yielding similar results in an analyzed ornamental reservoir (low percentage reduction in peak flow). However, a case study with experimental data reveals that the proposed model provides better accuracy than the traditional method. In addition, the proposed model is more efficient as it reduces computational time compared to the implicit scheme (conventional method). Finally, the proposed model is simplified for small watersheds by applying the rational method for computing an inflow hydrograph. Full article
(This article belongs to the Section Hydrology)
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8 pages, 591 KiB  
Editorial
Groundwater Chemistry and Quality in Coastal Aquifers
by Guanxing Huang and Liangping Li
Water 2024, 16(14), 2041; https://doi.org/10.3390/w16142041 - 19 Jul 2024
Cited by 1 | Viewed by 1066
Abstract
Groundwater is the most abundant freshwater resource available on earth, and it accounts for more than 95% of all liquid freshwater [...] Full article
(This article belongs to the Special Issue Groundwater Chemistry and Quality in Coastal Aquifers)
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