Water

17 pages, 3613 KiB

Open AccessArticle

Analysis of Local Scour around Double Piers in Tandem Arrangement in an S-Shaped Channel under Ice-Jammed Flow Conditions

by Shihao Dong, Zhenhua Zhang, Zhicong Li, Pangpang Chen, Jun Wang and Guowei Li

Water 2024, 16(19), 2831; https://doi.org/10.3390/w16192831 (registering DOI) - 6 Oct 2024

Abstract

The stability of bridge foundations is affected by local scour, and the formation of ice jams exacerbates local scour around bridge piers. These processes, particularly the evolution of ice jams and local scour around piers, are more complex in curved sections than in [...] Read more.

The stability of bridge foundations is affected by local scour, and the formation of ice jams exacerbates local scour around bridge piers. These processes, particularly the evolution of ice jams and local scour around piers, are more complex in curved sections than in straight sections. This study, based on experiments in an S-shaped channel, investigates how various factors—the flow Froude number, ice–water discharge rate, median particle diameter, pier spacing, and pier diameter—affect the maximum local scour depth around double piers in tandem and the distribution of ice jam thickness. The results indicate that under ice-jammed flow conditions, the maximum local scour depth around double piers in tandem is positively correlated with the ice–water discharge rate, pier spacing, and pier diameter and negatively correlated with median particle diameter. The maximum local scour depth is positively correlated with the flow Froude number when it ranges from 0.1 to 0.114, peaking at 0.114. Above this value, the correlation becomes negative. In curved channels, the arrangement of double piers in tandem substantially influences ice jam thickness distribution, with increases in pier diameter and spacing directly correlating with greater ice jam thickness at each cross-section. Furthermore, ice jam thickness is responsive to flow conditions, escalating with higher ice–water discharge rates and decreasing flow Froude numbers. Full article

(This article belongs to the Special Issue Cold Region Hydrology and Hydraulics)

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13 pages, 5166 KiB

Open AccessArticle

Quality and Influences of Natural and Anthropogenic Factors on Drinking Water in Rural Areas of Southern Chile

by Norka Fuentes, Aldo Arriagada, Claudio Pareja and Mauricio Molina-Roco

Water 2024, 16(19), 2830; https://doi.org/10.3390/w16192830 (registering DOI) - 6 Oct 2024

Abstract

Water quality is a fundamental aspect of public health and environmental sustainability. In rural areas, the physicochemical and microbiological quality of drinking water depends not only on hydrogeological conditions but also on anthropogenic activities carried out on the surface of the basin. This [...] Read more.

Water quality is a fundamental aspect of public health and environmental sustainability. In rural areas, the physicochemical and microbiological quality of drinking water depends not only on hydrogeological conditions but also on anthropogenic activities carried out on the surface of the basin. This study aimed to identify natural and anthropogenic influences related to the quality of drinking water in rural areas of southern Chile. In order to perform this, six rural drinking water systems were evaluated. A total of two types of catchment sources (groundwater and surface water) that were located in a longitudinal gradient were used, where coverage and sequences of rocks and soils could be differentiated. The results show that the water delivered by the majority of rural drinking water systems studied was of good quality, meeting the standards of Chilean and international regulations. No fecal coliforms or Escherichia coli were recorded. In addition, we recorded that turbidity, color, pH, concentration of total dissolved solids and fecal coliforms showed significant differences between groundwater and surface water. We also recorded that in two groundwater systems, iron and manganese levels slightly exceeded the regulations, endangering the acceptability of the water. These increases can be related to the natural origins of the metals, linked to the presence of oxides in Andisol- and Utisol-type volcanic soils. Full article

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

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23 pages, 11503 KiB

Open AccessArticle

Novel Framework for Exploring Human–Water Symbiosis Relationship: Analysis, Quantification, Discrimination, and Attribution

by Xi Qin, Qiting Zuo, Qingsong Wu and Junxia Ma

Water 2024, 16(19), 2829; https://doi.org/10.3390/w16192829 (registering DOI) - 6 Oct 2024

Abstract

There is an interdependent symbiotic relationship between humans and water; scientific and effective assessment of the human–water symbiosis relationship is of great significance for the promotion of sustainable development. This study developed a novel framework of the human–water symbiosis relationship under an integrated [...] Read more.

There is an interdependent symbiotic relationship between humans and water; scientific and effective assessment of the human–water symbiosis relationship is of great significance for the promotion of sustainable development. This study developed a novel framework of the human–water symbiosis relationship under an integrated perspective, which included theoretical interpretation, quantitative assessment, pattern discrimination, and an attribution analysis. Based on the symbiosis theory, the theoretical analysis of the human–water relationship was carried out to analyze the three basic elements of the human–water system, and then the evaluation index system of the human–water symbiosis system was constructed to quantitatively assess the development level of the human system and the water system. The Lotka–Volterra model was used to identify the symbiotic pattern, and the human–water symbiosis index was calculated to characterize the health state of the human–water symbiosis system. The main influencing factors of the human–water symbiosis system were further identified through an attribution analysis. Finally, a case study was carried out with 18 cities in Henan Province. Results reveal that (a) the proposed method can effectively realize the quantitative characterization of the human–water symbiosis relationship, with good applicability and obvious advantages; (b) the human–water symbiosis pattern of cities in Henan Province is dominated by the “human system parasitizes water system (H⁺W⁻)” pattern, and more attention should be paid to the water system in the subsequent development of it; and (c) the main factors influencing the human system, the water system, and the human–water symbiosis system are the research and development (R&D) personnel equivalent full-time (H7), per capita water resources (W1), and proportion of water conservancy and ecological water conservancy construction investment (W6), respectively. The findings can provide theoretical and methodological support for the study of the human–water symbiosis relationship and sustainable development in other regions. Full article

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

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21 pages, 4354 KiB

Open AccessArticle

Transboundary Water Allocation under Water Scarcity Based on an Asymmetric Power Index Approach with Bankruptcy Theory

by Jianan Qin, Xiang Fu, Xia Wu, Jing Wang, Jie Huang, Xuxun Chen, Junwu Liu and Jiantao Zhang

Water 2024, 16(19), 2828; https://doi.org/10.3390/w16192828 (registering DOI) - 6 Oct 2024

Abstract

Cooperative and self-enforceable water allocation is a key instrument to manage geopolitical conflict induced by water scarcity, which necessitates the cooperative willingness of the agents and considers their heterogeneity in geography, climate, hydrology, environment and social economy. Based on a multi-indicator system that [...] Read more.

Cooperative and self-enforceable water allocation is a key instrument to manage geopolitical conflict induced by water scarcity, which necessitates the cooperative willingness of the agents and considers their heterogeneity in geography, climate, hydrology, environment and social economy. Based on a multi-indicator system that contains asymmetric information on water volume contribution, current water consumption, water economic efficiency and efforts for eco-environmental protection, this study proposed a water allocation framework by combining the asymmetric power index approach with bankruptcy theory for solving the transboundary water allocation problem under scarcity. The proposed method was applied to the Yellow River Basin in northern China, which is mainly shared by nine provincial districts and frequently suffers from severe water shortages, and its results were compared with six alternative methods. The results highlight the necessity of quantifying agents’ willingness to cooperate under the condition of asymmetric negotiation power when making decisions on transboundary water allocations. The proposed method allows for transboundary water allocations through simultaneous consideration of the agent’s willingness to cooperate and asymmetric negotiation power, as well as disagreement allocation points, which ensure the stability, fairness and self-enforceability of allocation results. Therefore, it can offer practical and valuable decision-making insights for transboundary water management under water scarcity. Full article

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

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13 pages, 545 KiB

Open AccessArticle

How Top-Down Water Regulation Affects the Financial Performance of Enterprises: The River Chief System in China as an Example

by Peipei Zhao, Jiawen Li and Xin Luo

Water 2024, 16(19), 2827; https://doi.org/10.3390/w16192827 (registering DOI) - 5 Oct 2024

Abstract

As a top-down type of water regulation, the River Chief System (RCS) in China has effectively enhanced urban water quality. Simultaneously, environmental control significantly impacts the financial performance of enterprises. In recent years, the tension between environmental protection and economic development has escalated, [...] Read more.

As a top-down type of water regulation, the River Chief System (RCS) in China has effectively enhanced urban water quality. Simultaneously, environmental control significantly impacts the financial performance of enterprises. In recent years, the tension between environmental protection and economic development has escalated, underscoring the undeniable economic ramifications of stringent water regulations. Enterprises are the fundamental agents of economic activities and environmental impact, thus becoming the primary targets of water environment regulatory policies. This study adopts the differences-in-differences (DID) method and uses a sample of listed enterprises in the Yangtze River Economic Belt region from 2010 to 2021 to study the impact of the RCS on the financial performance of enterprises. The results show that the RCS harms the financial performance of enterprises. This impact primarily manifests through increased environmental protection investments. Conversely, the RCS does not have a positive influence on enterprises’ technological innovation. This indicates the challenge of stringent top-down environmental regulations in stimulating short-term technological advancements and enhancing enterprise performance. Moreover, the adverse effects of the RCS on financial performance are notably pronounced for non-state-owned enterprises and those located in the upper Yangtze River Economic Belt. This suggests that private enterprises and those in less-developed regions exhibit lower resilience to top-down environmental regulations. Full article

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

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21 pages, 4678 KiB

Open AccessArticle

Quantifying the Impact of Rain-on-Snow Induced Flooding in the Western United States

by Brennan Lynn Bean and Emma Watts

Water 2024, 16(19), 2826; https://doi.org/10.3390/w16192826 - 4 Oct 2024

Abstract

The potentially destructive flooding resulting from rain-on-snow (ROS) events motivates efforts to better incorporate these events and their residual effects into flood-related infrastructure design. This paper examines relationships between measured streamflow surges at streamgages across the Western United States and the meteorological conditions [...] Read more.

The potentially destructive flooding resulting from rain-on-snow (ROS) events motivates efforts to better incorporate these events and their residual effects into flood-related infrastructure design. This paper examines relationships between measured streamflow surges at streamgages across the Western United States and the meteorological conditions preceding them at SNOTEL stations within the same water catchment. Relevant stream surges are identified using a peak detection algorithm via time series analysis, which are then labeled ROS- or non-ROS-induced based on the preceding meteorological conditions. Both empirical and model-derived differences between ROS- and non-ROS-induced stream surges are then explored, which suggest that ROS-induced stream surges are 3–20 percent larger than non-ROS-induced stream surges. Quantifying the difference between ROS and non-ROS-induced stream surges promises to aid the improvement of flood-related infrastructure design (such as culverts) to better guard against extreme flooding events in locations subject to ROS. Full article

(This article belongs to the Section Hydrology)

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28 pages, 5858 KiB

Open AccessArticle

Assessing the Impact of Climate Change on an Ungauged Watershed in the Congo River Basin

by Stephane Masamba, Musandji Fuamba and Elmira Hassanzadeh

Water 2024, 16(19), 2825; https://doi.org/10.3390/w16192825 - 4 Oct 2024

Abstract

This study assesses the impact of climate change on streamflow characteristics in the Lualaba River Basin (LRB), an important yet ungauged watershed in the Congo River Basin. Two conceptual hydrological models, HBV-MTL and GR4J, were calibrated using the reanalysis datasets and outputs of [...] Read more.

This study assesses the impact of climate change on streamflow characteristics in the Lualaba River Basin (LRB), an important yet ungauged watershed in the Congo River Basin. Two conceptual hydrological models, HBV-MTL and GR4J, were calibrated using the reanalysis datasets and outputs of Generalized Circulation Models (GCMs) under CMIP6 during the historical period. The hydrological models were fed with outputs of GCMs under shared socioeconomic pathways (SSPs) 2-45 and 5-85, moderate- and high-radiative future scenarios. The results demonstrate that hydrological models successfully simulate observed streamflow, but their performance varies significantly with the choice of climate data and model structure. Interannual streamflow (Q) percentiles (10, 50, 90) were used to describe flow conditions under future climate. Q10 is projected to increase by 33% under SSP2-45 and 44% under SSP5-85, suggesting higher flow conditions that are exceeded 90% of the time. Q50 is also expected to rise by almost the same rate. However, a considerably higher Q90 is projected to increase by 56% under the moderate- and 80% under the high-radiative scenario. These indicate the overall higher water availability in this watershed to be used for energy and food production and the need for flood risk management. Full article

(This article belongs to the Section Water and Climate Change)

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18 pages, 2579 KiB

Open AccessArticle

Assessing the Synergies of Photo-Fenton at Natural pH and Granular Activated Carbon as a Quaternary Treatment

by Paula Núñez-Tafalla, Irene Salmerón, Silvia Venditti and Joachim Hansen

Water 2024, 16(19), 2824; https://doi.org/10.3390/w16192824 - 4 Oct 2024

Abstract

The challenge of microcontaminants (MCs) in wastewater effluent has been addressed by using different technologies, including advanced oxidation processes (AOPs) and adsorption. This work evaluates the benefits and synergies of combining these two processes. The AOPs were photo-Fenton and UV/H₂O₂ [...] Read more.

The challenge of microcontaminants (MCs) in wastewater effluent has been addressed by using different technologies, including advanced oxidation processes (AOPs) and adsorption. This work evaluates the benefits and synergies of combining these two processes. The AOPs were photo-Fenton and UV/H₂O₂ operated under natural pH but with different reagents dosages, lamps, and chelating agents. Chelating agents were used at analytical (ethylenediamine-N,N-disuccinic acid and citric acid) and technical grade (citric acid) to simulate scaling-up conditions. The adsorption process was studied via granular activated carbon (GAC) filtration using fresh and regenerated GAC. Four AOP scenarios were selected and coupled with GAC filtration, showing benefits for both processes. AOP treatment time decreased from 10–15 min to 5 min, resulting in a reduction in energy consumption of between 50 and 66%. In the photo-Fenton process, it was possible to work with low reagent dosages (1.5 mg L⁻¹ iron and 20 mg L⁻¹ of H₂O₂). However, the use of UV/H₂O₂ showed close removal, highlighting it as a real alternative. An extension of the GAC lifetime by up to 11 times was obtained in all the scenarios, being higher for regenerated than for fresh GAC. Furthermore, the toxicity and phytotoxicity of the treated wastewater were evaluated, and no acute toxicity or slight variation in the phytotoxicity was observed in the combination of these processes. Full article

(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment III)

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20 pages, 4658 KiB

Open AccessArticle

Trend Stability Assessment for Hydrological Drought in Euphrates Basin (Türkiye) Using Triple Wilcoxon Test and Innovative Trend Analysis Methods

by İbrahim Halil Demirel, Erdal Kesgin, Yavuz Selim Güçlü, R. İlayda Tan and Büşra Başaran

Water 2024, 16(19), 2823; https://doi.org/10.3390/w16192823 - 4 Oct 2024

Abstract

This study investigates the stability of hydrological drought trends in the Euphrates Basin from 1960 to 2020 using three-dimensional (3D) graphical representations based on innovative trend analysis (ITA) and triple Wilcoxon test (WT) methods. Unlike traditional ITA and WT, which are widely used [...] Read more.

This study investigates the stability of hydrological drought trends in the Euphrates Basin from 1960 to 2020 using three-dimensional (3D) graphical representations based on innovative trend analysis (ITA) and triple Wilcoxon test (WT) methods. Unlike traditional ITA and WT, which are widely used for trend identification but do not inherently provide trend stability information, this study employs a novel approach to assess and visualize trend stability. The Triple WT method divides the data into three equal segments, examining differences without altering the time series. Drought indices are calculated for 3-month, 6-month, and 12-month time scales using historical streamflow data from five stations. The research identifies trends and their stabilities across three distinct periods: 1967–1984, 1985–2002, and 2003–2020. Results show that as the time scale increases, trend differences between extreme drought conditions diminish. One station consistently exhibits significantly decreasing trends, while three stations show unstable trends with notable variations in the standardized streamflow index (SSFI). The use of 3D-ITA and Triple WT effectively captures the dynamics and stability of drought trends, offering a deeper understanding of hydrological drought in the Euphrates Basin. These findings provide a reference for future studies on drought trend mechanisms in various climatic regions. Full article

(This article belongs to the Section Water and Climate Change)

15 pages, 11422 KiB

Open AccessArticle

Impact of Fluid Migration Conditions on Hydrate Accumulation in the Shenhu Area: Insights from Thermo-Flow-Chemical Simulation

by Zhaobin Zhang, Zhuoran Xie, Yuxuan Li, Tao Xu, Shouding Li and Xiao Li

Water 2024, 16(19), 2822; https://doi.org/10.3390/w16192822 - 4 Oct 2024

Abstract

Natural gas hydrates are a clean and efficient new energy source with the potential to replace conventional energy, holding significant production value. Studying hydrate accumulation systems is fundamental for hydrate resource evaluation and target reservoir selection. The Shenhu area of the South China [...] Read more.

Natural gas hydrates are a clean and efficient new energy source with the potential to replace conventional energy, holding significant production value. Studying hydrate accumulation systems is fundamental for hydrate resource evaluation and target reservoir selection. The Shenhu area of the South China Sea has abundant hydrate resources, and drilling data show that the hydrate distribution in this area exhibits noticeable heterogeneity. Aiming at this phenomenon, we used a novel thermo-flow/chemical coupled simulator to simulate the hydrate accumulation system based on the actual geological strata and provide a detailed depiction of the evolution of components in the process. The results indicate that favorable migration conditions can accelerate hydrate formation. However, to achieve the rapid formation of thick, high-saturation hydrate layers, the fluid migration conditions must be complemented by effective fluid aggregation conditions. Furthermore, a sensitivity analysis of the fault morphology was conducted, revealing that larger-scale faults are more conducive to rapid hydrate accumulation. In summary, this study provides a quantitative analysis of the hydrate accumulation process and its key influence factors using a novel simulator, offering theoretical support for resource evaluation and an exploration of hydrate distribution. Full article

(This article belongs to the Special Issue Advances in Marine Sedimentation and Geological Processes)

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26 pages, 2639 KiB

Open AccessArticle

Low Strength Wastewater Treatment Using a Combined Biological Aerated Filter/Anammox Process

by Wanying Xie, Ji Li, Tao Song, Yong Li, Zhenlin Wang and Xiaolei Zhang

Water 2024, 16(19), 2821; https://doi.org/10.3390/w16192821 - 4 Oct 2024

Abstract

To achieve the in situ capacity expansion of the post-denitrification biological aerated filter (BAF-DN), the integration of BAF with the anammox process (BAF/AX) was proposed. With the objective of maximizing retaining ammonia nitrogen, the operational optimization of BAF was achieved by two distinct [...] Read more.

To achieve the in situ capacity expansion of the post-denitrification biological aerated filter (BAF-DN), the integration of BAF with the anammox process (BAF/AX) was proposed. With the objective of maximizing retaining ammonia nitrogen, the operational optimization of BAF was achieved by two distinct strategies. The treatment performance of BAF demonstrated that the removal efficiencies of chemical oxygen demand (COD) and ammonia nitrogen () was 66.3~67.3% and 4~12%, respectively, under conditions of low aeration intensity (0.4 m³·m⁻²·h⁻¹) or a shortened empty bed residence time (EBRT) of 30 min. Residual in the BAF effluent served as the ammonia substrate for the subsequent anammox process, which was successfully launched by using ceramic particles and sponges as carriers. Notably, the sponge carrier facilitated a shorter start-up period of 41 to 44 days. Furthermore, the sponge-based anammox reactor exhibited a superior removal capacity (≥85.7%), under operations of a shorter EBRT of 40 min, low influent concentrations (≤30 mg/L), and COD levels of ≤67 mg/L. In addition, a comprehensive evaluation of the BAF/AX process was conducted, which considered performance, cost-effectiveness, and engineering feasibility. The performance results illustrated that the effluent quality met the standard well (with a COD level of ≤50 mg/L, and a TN of ≤3.1~10.5 mg/L). Following a comparison against the low aeration intensity operation, it was recommended to operate BAF at a low EBRT within the BAF/AX process. Consequently, the treated volume was double the volume of the standalone BAF-DN, synchronously achieving low costs (0.413 yuan/m³). Full article

(This article belongs to the Special Issue Advances in Biological Technologies for Wastewater Treatment)

19 pages, 2355 KiB

Open AccessArticle

Recovering Nitrogen from Anaerobic Membrane Bioreactor Permeate Using a Natural Zeolite Ion Exchange Column

by Jesús Godifredo, Laura Ruiz, Silvia Hernández, Joaquín Serralta and Ramón Barat

Water 2024, 16(19), 2820; https://doi.org/10.3390/w16192820 - 4 Oct 2024

Abstract

In the framework of a circular economy, wastewater treatment should be oriented toward processes that allow the recovery of the resources present in the wastewater while ensuring good effluent quality. Nitrogen recovery is usually carried out in streams concentrated in this nutrient because [...] Read more.

In the framework of a circular economy, wastewater treatment should be oriented toward processes that allow the recovery of the resources present in the wastewater while ensuring good effluent quality. Nitrogen recovery is usually carried out in streams concentrated in this nutrient because these high concentrations facilitate nitrogen valorization. On the other hand, the mainstream of a wastewater treatment plant (WWTP) has a high potential for nitrogen recovery, but it is not usually considered because it is hard to manage due to its low nitrogen concentration. To solve this problem and facilitate the recovery of nitrogen in the mainstream, this work proposes ion exchange with zeolites as a stage of ammonium concentration, to provide a nitrogen-concentrated stream that could be valorized by another technology, while obtaining a nitrogen-free effluent. The working stream, the permeate of an AnMBR process in the mainstream, has suitable characteristics to be treated in an ion exchange column (free of suspended solids and with very low organic matter content). To this end, the effect of the working flow rate (17.5 to 4.4 BV/h) and the ammonium concentration (54 to 17 mg NH₄-N/L) on the adsorption capacity of the zeolite in the loading phase was evaluated. The adsorption curves were fitted to three mathematical models: Thomas, Bohart–Adams, and Yoon–Nelson. The effect of the regeneration flow rate (from 8.7 to 2.2 BV/h) and the regenerant concentration (NaOH at 0.2, 0.1, and 0.05 M) on regeneration capacity and efficiency were also studied. A novel control strategy based on effluent conductivity was used in both phases to control the duration of the adsorption and regeneration phases. Full article

(This article belongs to the Special Issue Innovations in Anaerobic Digestion Technology)

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15 pages, 2953 KiB

Open AccessArticle

Evaluation of Straw Mulch as an Erosion Control Practice for Varying Soil Types on a 4:1 Slope

by John R. Cater, Wesley N. Donald, Michael Perez and Xing Fang

Water 2024, 16(19), 2819; https://doi.org/10.3390/w16192819 - 4 Oct 2024

Abstract

Construction sites rely on erosion control practices to protect bare slopes and prevent soil loss. The effectiveness of certain erosion controls is often under-evaluated if they are not a part of a product evaluation program. Furthermore, erosion controls in general are not fully [...] Read more.

Construction sites rely on erosion control practices to protect bare slopes and prevent soil loss. The effectiveness of certain erosion controls is often under-evaluated if they are not a part of a product evaluation program. Furthermore, erosion controls in general are not fully understood regarding how their performance can be affected by site specific variables, such as soil variations. This study used large-scale rainfall simulators to evaluate how a commonly used erosion control on construction sites, broadcasted straw mulch, performs on three common soil types in Alabama. The study at the Auburn University, Stormwater Research Facility (AU-SRF) used the industry standard testing method and three different soil types: sand, loam, and clay in accordance with ASTM D6459-19, the standard test method for testing rolled erosion control products’ (RECPs) performance in protecting hillslopes from rainfall-induced erosion. As required by ASTM D6459-19, the rainfall simulators simulated a storm of varying 20 min increments of 2 in./h (5.08 cm/h), 4 in./h (10.16 cm/h), and 6 in./h (15.24 cm/h). A total of nine bare soil tests on the 4:1 test plots was performed with an average total soil loss of 1977 lb (897 kg), 236.2 lb (107 kg), and 114.2 lb (51.8 kg) for sand, loam, and clay, respectively. The average erodibility K-factor for each soil type is calculated to be 0.37 (sand), 0.043 (loam), and 0.013 (clay). Nine straw tests were performed on the 4:1 plots, with an average total soil loss of 44.31 lb (20.1 kg), 6.74 lb (3.1 kg), and 17.13 lb (7.8 kg) for sand, loam, and clay, respectively. Straw testing indicated substantial soil loss reduction with average cover management C-factor values under the revised universal soil loss equation (RUSLE) method of 0.021, 0.047, and 0.193 for sand, loam, and clay applications, respectively. This variation in C-factor across the three soil types indicates that the single C-factor, often reported by product manufacturers, is not adequate to imply performance. Full article

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20 pages, 2971 KiB

Open AccessArticle

Enhanced TDS Modeling Using an AI Framework Integrating Grey Wolf Optimization with Kernel Extreme Learning Machine

by Maryam Sayadi, Behzad Hessari, Majid Montaseri and Amir Naghibi

Water 2024, 16(19), 2818; https://doi.org/10.3390/w16192818 - 4 Oct 2024

Abstract

Predictions of total dissolved solids (TDS) in water bodies including rivers and lakes are challenging but essential for the effective management of water resources in agricultural and drinking water sectors. This study developed a hybrid model combining Grey Wolf Optimization (GWO) and Kernel [...] Read more.

Predictions of total dissolved solids (TDS) in water bodies including rivers and lakes are challenging but essential for the effective management of water resources in agricultural and drinking water sectors. This study developed a hybrid model combining Grey Wolf Optimization (GWO) and Kernel Extreme Learning Machine (KELM) called GWO-KELM to model TDS in water bodies. Time series data for TDS and its driving factors, such as chloride, temperature, and total hardness, were collected from 1975 to 2016 to train and test machine learning models. The study aimed to assess the performance of the GWO-KELM model in comparison to other state-of-the-art machine learning algorithms. Results showed that the GWO-KELM model outperformed all other models (such as Artificial Neural Network, Gaussian Process Regression, Support Vector Machine, Linear Regression, Classification and Regression Tree, and Boosted Regression Trees), achieving the highest coefficient of determination (R²) value of 0.974, indicating excellent predictive accuracy. It also recorded the lowest root mean square error (RMSE) of 55.75 and the lowest mean absolute error (MAE) of 34.40, reflecting the smallest differences between predicted and actual values. The values of R², RMSE, and MAE for other machine learning models were in the ranges of 0.969–0.895, 60.13–108.939, and 38.25–53.828, respectively. Thus, it can be concluded that the modeling approaches in this study were in close competition with each other and, finally, the GWO-KELM model had the best performance. Full article

(This article belongs to the Special Issue Water Resource Management in Artificial Intelligence and Big Data Analytics)

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11 pages, 257 KiB

Open AccessCommunication

Achieving Responsible Reclaimed Water Reuse for Vineyard Irrigation: Lessons from Napa Valley, California and Valle de Guadalupe, Baja California

by Marc Beutel, Leopoldo Mendoza-Espinosa, Clara Medina, Jorge Andrés Morandé, Thomas C. Harmon and Josué Medellín-Azuara

Water 2024, 16(19), 2817; https://doi.org/10.3390/w16192817 - 4 Oct 2024

Abstract

Here we report on preliminary efforts to assess the potential to use reclaimed water from municipal wastewater treatment plants for irrigation of vineyards in Napa Valley, California, USA and Valle de Guadalupe, Baja California, Mexico. Vineyards in Napa Valley use a range of [...] Read more.

Here we report on preliminary efforts to assess the potential to use reclaimed water from municipal wastewater treatment plants for irrigation of vineyards in Napa Valley, California, USA and Valle de Guadalupe, Baja California, Mexico. Vineyards in Napa Valley use a range of source waters including 70 L/s of reclaimed water during the summertime irrigation season. Reclaimed water is secondary effluent that undergoes filtration and disinfection and meets stringent total coliform (<240 MPN/100 mL) and turbidity (10 NTU) requirements. Vineyards in Valle de Guadalupe currently use regional groundwater supplies of marginal quality, and there is interest in expanding source waters to include reclaimed water from nearby Ensenada or the more remote Tijuana. Valle de Guadalupe is drier than Napa Valley and has ongoing salinity management challenges, making the region more sensitive to using reclaimed water for irrigation. Several social and economic factors facilitated the implementation of reclaimed water reuse in Napa Valley for vineyard irrigation, including (1) formation of an assessment district by interested growers to help finance pipeline construction, (2) a long-term reclaimed water vineyard irrigation study by agricultural experts that confirmed the reclaimed water was safe, and (3) a well-defined and relatively low unit cost of reclaimed water. In Valle de Guadalupe, the federal government has approved a project to transport 1000 L/s of reclaimed water over 100 km from Tijuana to Valle de Guadalupe. Questions remain including financing of the project, reclaimed water quality, grower interest in using reclaimed water, and community concerns for such a large-scale program. In considering reclaimed water reuse in vineyards, a key issue is implementation of long-term studies showing that reclaimed water is effectively treated and is safe for irrigation, especially from the standpoint of salt content. In addition, the cost of reclaimed water needs to be comparable with traditional water sources. Finally, in addition to assessing economic constraints, social constraints and water user concerns should be comprehensively addressed in the context of a regional integrated water management framework. Full article

(This article belongs to the Special Issue Safe Application of Reclaimed Water in Agriculture)

15 pages, 1068 KiB

Open AccessReview

Occurrence and Speciation of Pollutants in Guilin Huixian Wetland: Nutrients, Microplastics, Heavy Metals, and Emerging Contaminants

by Hang Gao, Hao Chen, Yue Jin, Ruoting Gao, Chunzhong Wei, Chunfang Zhang and Wenjie Zhang

Water 2024, 16(19), 2816; https://doi.org/10.3390/w16192816 - 3 Oct 2024

Abstract

The Huixian Wetland is a natural ecosystem of immense ecological value, providing crucial ecosystem services such as water purification, water regulation, and a habitat for the region’s flora and fauna. Its karst peak forest landforms and surrounding environment also possess unique ecological and [...] Read more.

The Huixian Wetland is a natural ecosystem of immense ecological value, providing crucial ecosystem services such as water purification, water regulation, and a habitat for the region’s flora and fauna. Its karst peak forest landforms and surrounding environment also possess unique ecological and landscape value. However, with the ongoing socioeconomic development, including the rise of industrial, agricultural, and aquaculture activities in the wetland area, the nutrient composition of the Huixian Wetland has been altered. This paper reviews the current status of nitrogen, phosphorus, heavy metals, emerging pollutants, and biodiversity in various environmental media of the Huixian Wetland. It synthesizes the literature to identify the factors influencing these changes and projects future research directions for the wetland. This work is of significant practical importance, providing scientific foundations for the restoration and protection of the Huixian Wetland. Full article

(This article belongs to the Special Issue Water Treatment Technology for Emerging Contaminants)

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16 pages, 5515 KiB

Open AccessArticle

Field Demonstration of In Situ Slow-Release Oxygen Chemicals Coupled with Microbial Agents for Injection to Remediate BTEX Contamination

by Shuai Yang, Shucai Zhang, Shici Ma, Sheng Zhao and Zhengwei Liu

Water 2024, 16(19), 2815; https://doi.org/10.3390/w16192815 - 3 Oct 2024

Abstract

The global concern for risk control of organic contaminated sites is becoming more and more prominent. Traditional ex situ remediation techniques are costly and damage the site, seriously destroying the soil structure and ecological functions. Therefore, in situ means of combining material injection [...] Read more.

The global concern for risk control of organic contaminated sites is becoming more and more prominent. Traditional ex situ remediation techniques are costly and damage the site, seriously destroying the soil structure and ecological functions. Therefore, in situ means of combining material injection and microbial remediation have become a potential pathway for the green, economical, and efficient remediation of contaminated sites. In this work, a 200 m² test block was selected for the coupled injection of slow-release oxygen materials and microbial agents, and long-term monitoring of groundwater was carried out. The results showed that the slow-release materials could release oxygen for a period of 90 days, which provided an oxidizing environment for microorganisms to rapidly degrade BTEX. For the pre-adapted indigenous degradation bacterial agent test group, the degradation degree of BTEX was up to 98% after 40 days of injection. The results of the application on the field scale proved the feasibility of reinforcing biostimulation for remediation of underground organic contamination through the coupled injection of slow-release oxygen materials and microbial agents. The results provided theoretical and technical support for the in situ remediation of petroleum hydrocarbon-contaminated sites. Full article

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

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15 pages, 845 KiB

Open AccessArticle

Diffusion Mechanism of Variable-Rate Grouting in Water Prevention and Control of Coal Mine

by Chong Li, Cunjin Lu, Jinpeng Xu, Kai Zhang, Shiming Liu and Hui Zhao

Water 2024, 16(19), 2814; https://doi.org/10.3390/w16192814 - 2 Oct 2024

Abstract

Regional grouting treatment is an effective technical means to prevent mine water disasters, and the grouting effect is affected by many factors. In actual grouting engineering, the single constant-rate grouting method is often transformed into a variable-parameter grouting process. However, research on grouting [...] Read more.

Regional grouting treatment is an effective technical means to prevent mine water disasters, and the grouting effect is affected by many factors. In actual grouting engineering, the single constant-rate grouting method is often transformed into a variable-parameter grouting process. However, research on grouting rates has been insufficient. This investigation focused on the issue of “the diffusion law of variable-rate grouting slurry in regional governance”. Methods such as theoretical analysis, numerical simulation, and field verification were used to evaluate the diffusion mechanism of variable-rate fracture grouting. The results indicated that the key parameters of variable-rate grouting, such as slurry diffusion distance and grouting pressure, were affected by the grouting rate. The decrease in the grouting rate reduced the migration speed of the slurry and the grouting pressure. The time for constant-velocity grouting and variable-velocity grouting to reach the same diffusion distance was 60 s and 108 s, respectively, which can be achieved with lower grouting pressure. When the grouting rate was 7.5 L/min and 30 L/min, the maximum grout diffusion distance was 2.81 m and 5.64 m, respectively, which required greater grouting pressure. The slurry diffusion rate decreased with the reduction in the grouting rate. Under the same diffusion distance conditions, variable-rate grouting took longer than constant high-rate grouting. In variable-rate grouting, the grouting pressure decreased stepwise with the grouting rate, with a final pressure drop of 77.4%. In grouting practice, the innovative use of the rate-reducing grouting method can greatly reduce the final grouting pressure under the premise of changing the slurry diffusion distance less, which can not only ensure the stability of surrounding rock but also reduce the cost of high-pressure grouting and the risk of grouting operation. The investigation results can provide scientific guidance for ground grouting renovation projects in deep coal mine water hazard areas. Full article

14 pages, 1104 KiB

Open AccessArticle

The Spatial Evolution Characteristics of Phytoplankton and the Impact of Environmental Factors in a Harbor-Construction-Formed Reservoir

by Xiaokun Hu, Kuixuan Lin, Rui Wang, Shucong Lv, Yunlong Liu, Yu Wang, Yan Luo, Tianpeng Zhou and Lusan Liu

Water 2024, 16(19), 2813; https://doi.org/10.3390/w16192813 - 2 Oct 2024

Abstract

Phytoplankton are an important part of aquatic ecosystems and substantially contribute to primary productivity. Under certain conditions, phytoplankton can grow or cluster in large numbers, resulting in enormous economic losses and serious threats to human life and health. In this study, complex causative [...] Read more.

Phytoplankton are an important part of aquatic ecosystems and substantially contribute to primary productivity. Under certain conditions, phytoplankton can grow or cluster in large numbers, resulting in enormous economic losses and serious threats to human life and health. In this study, complex causative species of algal blooms were examined and regulatory factors were determined in a reservoir formed by harbor construction. The reservoir is isolated from the harbor by sluice gates, forming a separate water region. Twelve species of phytoplankton, including normally and abnormally blooming species, were identified to be causing blooms in this continuous water. Different from the areas where simple algae caused blooms, multiple bloom-causative species, which were completely different, occurred at several stations. In this study area, whereas the abundance of algal cells was above 10 million cells/L, the total phosphorus concentration was higher than 0.2 mg/L. When the total phosphorus concentration was lower than 0.2 mg/L, there was no algal bloom. In waters with total algal cell abundance over 10 million, the N/P ratios were all ˂8. This study indicates that the occurrence of algal blooms in this water was influenced by the concentrations of total nitrogen and phosphorus, and total phosphorus plays a more important role. Full article

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

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