Water

14 pages, 12543 KiB

Open AccessArticle

Evaluation of Various Forms of Geothermal Energy Release in the Beijing Region, China

by Zebin Luo, Mingbo Yang, Xiaocheng Zhou, Guiping Liu, Jinlong Liang, Zhe Liu, Peixue Hua, Jingchen Ma, Leyin Hu, Xiaoru Sun, Bowen Cui, Zhiguo Wang and Yuxuan Chen

Water 2024, 16(4), 622; https://doi.org/10.3390/w16040622 - 19 Feb 2024

Viewed by 1277

Abstract

The energy inside the Earth can not only be released outward through earthquakes and volcanoes but also can be used by humans in the form of geothermal energy. Is there a correlation between different forms of energy release? In this contribution, we perform [...] Read more.

The energy inside the Earth can not only be released outward through earthquakes and volcanoes but also can be used by humans in the form of geothermal energy. Is there a correlation between different forms of energy release? In this contribution, we perform detailed seismic and geothermal research in the Beijing area. The results show that the geothermal resources in Beijing belong to typical medium-low temperature geothermal resources of the sedimentary basin, and some areas are controlled by deep fault activities (e.g., Xiji geothermal well (No. 17)). The heat sources are upper mantle heat, radioactive heat in granite, and residual heat from magma cooling. The high overlap of earthquakes and geothermal field locations and the positive correlation between the injection water and earthquakes indicate that the exploitation and injection water will promote the release of the earth’s energy. The energy releases are partitioned into multiple microearthquakes, avoiding damaging earthquakes (M_L ≥ 5) due to excessive energy accumulation. Therefore, the exploitation of geothermal resources may be one way to reduce destructive earthquakes. Furthermore, the use of geothermal resources can also reduce the burning of fossil energy, which is of great significance in dealing with global warming. Full article

(This article belongs to the Topic Advances in Hydro-Geological Research in Arid and Semi-Arid Areas)

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24 pages, 27091 KiB

Open AccessArticle

Projected Increase in Compound Drought and Hot Days over Global Maize Areas under Global Warming

by Yan He, Yanxia Zhao, Yihong Duan, Xiaokang Hu and Jiayi Fang

Water 2024, 16(4), 621; https://doi.org/10.3390/w16040621 - 19 Feb 2024

Viewed by 1538

Abstract

Compound drought and hot events can lead to detrimental impacts on crop yield with grave implications for global and regional food security. Hence, an understanding of how such events will change under unabated global warming is helpful to avoid associated negative impacts and [...] Read more.

Compound drought and hot events can lead to detrimental impacts on crop yield with grave implications for global and regional food security. Hence, an understanding of how such events will change under unabated global warming is helpful to avoid associated negative impacts and better prepare for them. In this article, we comprehensively analyze the projected changes in compound drought and hot days (CDHDs) occurring within the maize-growing season of 2015–2100 over dynamic global maize areas using 10 downscaled Coupled Model Intercomparison Project Phase 6 (CMIP6) models and four socio-economic scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5). The results demonstrate a notable increase in the frequency and severity of CDHDs over global maize areas under all four SSPs, of which SSP5-8.5 has the fastest rise, followed by SSP3-7.0, SSP2-4.5 and SSP1-2.6. By the end of 21st century, the global average frequency and severity of CDHDs will reach 18~68 days and 1.0~2.6. Hotspot regions for CDHDs are mainly found in southern Africa, eastern South America, southern Europe and the eastern USA, where drought and heat show the most widespread increases. The increase in CDHDs will be faster than general hot days so that almost all increments of hot days will be accompanied by droughts in the future; therefore, compound dry and hot stresses will gradually become the predominant form of dry and heat stress on maize growth. The results can be applied to optimize adaptation strategies for mitigating risks from CDHDs on maize production worldwide. Full article

(This article belongs to the Topic Hydro-Meteorological Hazards: Forecasting, Assessment and Risk Management)

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16 pages, 4355 KiB

Open AccessArticle

Systematic Assessment on Waterlogging Control Facilities in Hefei City of Anhui Province in East China

by Hao Hu, Yankun Liu, Jiankang Du, Rongqiong Liu, Banglei Wu and Qingwei Zeng

Water 2024, 16(4), 620; https://doi.org/10.3390/w16040620 - 19 Feb 2024

Viewed by 1142

Abstract

Both the renovation of rainwater pipes and the addition of sponge city facilities in the low-terrain residences of urban fringes were rarely systematically simulated using the Storm Water Management Model (SWMM). With the waterlogging prevention project in an old residential quarter at a [...] Read more.

Both the renovation of rainwater pipes and the addition of sponge city facilities in the low-terrain residences of urban fringes were rarely systematically simulated using the Storm Water Management Model (SWMM). With the waterlogging prevention project in an old residential quarter at a fringe of Hefei city being an example, this study used the SWMM to simulate the effect of the renovation of rainwater pipes and sponge city facilities under different return periods. The results showed the key nodes on the main pipes met the drainage requirements based on water depth analysis after renovation below the 20-year return period, and the reduction rate of the maximum water depth at the key node J5 was the greatest, with 87.7%. The four flow parameters (the average flow rate, the peak flow rate, the total discharge, and the percentage of water flow frequency) for the two outlets (PFK1 and PFK2) all improved after renovation under five return periods (2, 5, 10, 20, and 50 years [a]). The addition of sponge city facilities effectively reduced the amount of rainwater runoff from 28.68% to 14.78% during 2 a to 50 a, and the maximum reduction rate of water depth, being 61.15%, appeared in J5 under 20 a. The curve integral area of the depth over the elapsed time was innovatively used to indirectly express the accumulated rainwater volume through the rainwater well. This study verified that the SWMM model can be well applied to old low-terrain residential quarters in urban fringes and broadened the application scenario of the model. Full article

(This article belongs to the Special Issue Urban Flood Mitigation and Sustainable Stormwater Management)

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17 pages, 1360 KiB

Open AccessArticle

Extensive Study of Electrocoagulation-Based Adsorption Process of Real Groundwater Treatment: Isotherm Modeling, Adsorption Kinetics, and Thermodynamics

by Forat Yasir AlJaberi

Water 2024, 16(4), 619; https://doi.org/10.3390/w16040619 - 19 Feb 2024

Cited by 2 | Viewed by 1453

Abstract

In this study, several adsorption models were studied to predict the adsorption kinetics of turbidity on an electro-generated adsorbent throughout the electrocoagulation remediation of real groundwater. A new design for an electrocoagulation reactor consisting of a finned anode positioned concentrically in a tube-shaped [...] Read more.

In this study, several adsorption models were studied to predict the adsorption kinetics of turbidity on an electro-generated adsorbent throughout the electrocoagulation remediation of real groundwater. A new design for an electrocoagulation reactor consisting of a finned anode positioned concentrically in a tube-shaped cathode was fabricated, providing a significant active area compared to its immersed volume. This work completed a previous electrochemical study through a deep investigation of adsorption technology that proceeded throughout the electrocoagulation reactor under optimal operating conditions, namely a treatment period of 2–30 min, a 2.3-Ampere current, and a stirring speed of 50 rpm. The one-, two-, and three-parameter adsorption models investigated in this study possess significant regression coefficients: Henry (R² = 1.000), Langmuir (R² = 0.9991), Freundlich (R² = 0.9979), Temkin (R² = 0.9990), Kiselev (R² = 0.8029), Harkins–Jura (R² = 0.9943), Halsey (R² = 0.9979), Elovich (R² = 0.9997), Jovanovic (R² = 0.9998), Hill–de Boer (R² = 0.8346), Fowler–Guggenheim (R² = 0.8834), Dubinin–Radushkevich (R² = 0.9907), Sips (R² = 0.9834), Toth (R² = 0.9962), Jossens (R² = 0.9998), Redlich–Peterson (R² = 0.9991), Koble–Carrigan (R² = 0.9929), and Radke–Prausnitz (R² = 0.9965). The current behavior of the adsorption–electrocoagulation system follows pseudo-first-order kinetics (R² = 0.8824) and the Bangham and Burt mass transfer model (R² = 0.9735). The core findings proved that an adsorption-method-based electrochemical cell has significant outcomes, and all the adsorption models could be taken into consideration, along with other kinetic and thermodynamics investigations as well. Full article

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

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15 pages, 5201 KiB

Open AccessArticle

Daily Runoff Prediction with a Seasonal Decomposition-Based Deep GRU Method

by Feifei He, Qinjuan Wan, Yongqiang Wang, Jiang Wu, Xiaoqi Zhang and Yu Feng

Water 2024, 16(4), 618; https://doi.org/10.3390/w16040618 - 19 Feb 2024

Cited by 4 | Viewed by 1759

Abstract

Accurately predicting hydrological runoff is crucial for water resource allocation and power station scheduling. However, there is no perfect model that can accurately predict future runoff. In this paper, a daily runoff prediction method with a seasonal decomposition-based-deep gated-recurrent-unit (GRU) method (SD-GRU) is [...] Read more.

Accurately predicting hydrological runoff is crucial for water resource allocation and power station scheduling. However, there is no perfect model that can accurately predict future runoff. In this paper, a daily runoff prediction method with a seasonal decomposition-based-deep gated-recurrent-unit (GRU) method (SD-GRU) is proposed. The raw data is preprocessed and then decomposed into trend, seasonal, and residual components using the seasonal decomposition algorithm. The deep GRU model is then used to predict each subcomponent, which is then integrated into the final prediction results. In particular, the hyperparameter optimization algorithm of tree-structured parzen estimators (TPE) is used to optimize the model. Moreover, this paper introduces the single machine learning model (including multiple linear regression (MLR), back propagation (BP), long short-term memory neural network (LSTM) and gate recurrent unit (GRU)) and a combination model (including seasonal decomposition–back propagation (SD-BP), seasonal decomposition–multiple linear regression (SD-MLR), along with seasonal decomposition–long-and-short-term-memory neural network (SD-LSTM), which are used as comparison models to verify the excellent prediction performance of the proposed model. Finally, a case study of the Qingjiang Shuibuya test set, which considers the period 1 January 2019 to 31 December 2019, is conducted. Case studies of the Qingjiang River show the proposed model outperformed the other models in prediction performance. The model achieved a mean absolute error (MAE) index of 38.5, a Nash-Sutcliffe efficiency (NSE) index of 0.93, and a coefficient of determination (R²) index of 0.7. In addition, compared to the comparison model, the NSE index of the proposed model increased by 19.2%, 19.2%, 16.3%, 16.3%, 2.2%, 2.2%, and 1.1%, when compared to BP, MLR, LSTM, GRU, SD-BP, SD-MLR, SD-LSTM, and SD-GRU, respectively. This research can provide an essential reference for the study of daily runoff prediction models. Full article

(This article belongs to the Special Issue Advanced Technologies for Water Quality Monitoring and Prediction)

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20 pages, 9212 KiB

Open AccessArticle

Case Study of Contaminant Transport Using Lagrangian Particle Tracking Model in a Macro-Tidal Estuary

by Bon-Ho Gu, Seung-Buhm Woo, Jae-Il Kwon, Sung-Hwan Park and Nam-Hoon Kim

Water 2024, 16(4), 617; https://doi.org/10.3390/w16040617 - 19 Feb 2024

Cited by 1 | Viewed by 1321

Abstract

This study presents a comprehensive analysis of contaminant transport in estuarine environments, focusing on the impact of tidal creeks and flats. The research employs advanced hydrodynamic models with irregular grid systems and conducts a detailed residual current analysis to explore how these physical [...] Read more.

This study presents a comprehensive analysis of contaminant transport in estuarine environments, focusing on the impact of tidal creeks and flats. The research employs advanced hydrodynamic models with irregular grid systems and conducts a detailed residual current analysis to explore how these physical features influence the movement and dispersion of contaminants. The methodology involves simulating residual currents and Lagrangian particle trajectories in both ‘Creek’ and ‘No Creek’ cases, under varying tidal conditions. The results indicate that tidal creeks significantly affect particle retention and transport, with notable differences observed in the dispersion patterns between the two scenarios. The ‘Creek’ case demonstrates enhanced material retention along the creek pathways, while the ‘No Creek’ case shows broader dispersion, potentially leading to increased sedimentation in open sea areas. The discussion highlights the implications of these findings for sediment dynamics, contaminant transport, and estuarine ecology, emphasizing the role of tidal creeks in modulating flow and material transport. The research underlines the necessity of incorporating detailed environmental features in estuarine models for accurate contaminant transport prediction and effective estuarine management. This study contributes to a deeper understanding of estuarine hydrodynamics and offers valuable insights for environmental policy and management in coastal regions. Full article

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

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16 pages, 21151 KiB

Open AccessArticle

Comprehensive Risk Assessment Framework for Flash Floods in China

by Qing Li, Yu Li, Lingyun Zhao, Zhixiong Zhang, Yu Wang and Meihong Ma

Water 2024, 16(4), 616; https://doi.org/10.3390/w16040616 - 19 Feb 2024

Viewed by 2001

Abstract

Accurately assessing the risk of flash floods is a fundamental prerequisite for defending against flash flood disasters. The existing methods for assessing flash flood risk are constrained by unclear key factors and challenges in elucidating disaster mechanisms, resulting in less-than-ideal early warning effectiveness. [...] Read more.

Accurately assessing the risk of flash floods is a fundamental prerequisite for defending against flash flood disasters. The existing methods for assessing flash flood risk are constrained by unclear key factors and challenges in elucidating disaster mechanisms, resulting in less-than-ideal early warning effectiveness. This article is based on official statistics of flash flood disaster data from 2017 to 2021. It selects eight categories of driving factors influencing flash floods, such as rainfall, underlying surface conditions, and human activities. Subsequently, a geographical detector is utilized to analyze the explanatory power of each driving factor in flash flood disasters, quantifying the contribution of each factor to the initiation of flash flood; the flash flood potential index (FFPI) was introduced to assess the risk of flash flood disasters in China, leading to the construction of a comprehensive assessment framework for flash flood risk. The results indicate that (1) Flash floods are generally triggered by multiple factors, with rainfall being the most influential factor, directly causing flash floods. Soil type is the second most influential factor, and the combined effects of multiple factors intensify the risk of flash floods. (2) The southeastern, southern, and southwestern regions of China are considered high-risk areas for flash floods, with a high danger level, whereas the northwestern, northern, and northeastern plain regions exhibit a lower danger level. The above research results provide reference and guidance for the prevention and control of flash flood disasters. Full article

(This article belongs to the Special Issue Advances in Flood and Drought Disaster Forecasting and Early Warnings through Integrating Hydrological and Hydrodynamic Models)

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15 pages, 5078 KiB

Open AccessArticle

The Impact of Tides and Monsoons on Tritium Migration and Diffusion in Coastal Harbours: A Simulation Study in Lianyungang Haizhou Bay, China

by Yangxin Zhang, Jiangmei Zhang, Tuantuan Liu, Xinghua Feng, Tengxiang Xie and Haolin Liu

Water 2024, 16(4), 615; https://doi.org/10.3390/w16040615 - 19 Feb 2024

Cited by 1 | Viewed by 1194

Abstract

Many nuclear power plants have been built along China’s coasts, and the migration and diffusion of radioactive nuclides in coastal harbours is very concerning. In this study, considering the decay and free diffusion of radioactive nuclides, a local hydrodynamic model based on the [...] Read more.

Many nuclear power plants have been built along China’s coasts, and the migration and diffusion of radioactive nuclides in coastal harbours is very concerning. In this study, considering the decay and free diffusion of radioactive nuclides, a local hydrodynamic model based on the FVCOM was built to investigate the migration and diffusion of the radioactive nuclide tritium in Haizhou Bay, China. This model was calibrated according to the observed tidal level and flow velocity and direction, which provide an accurate background. This study aimed to evaluate the impact of tides and monsoons on the migration path and concentration variations in tritium over time. The results demonstrated that the simulated flow field can reflect real-life receiving waters. The distribution of the tritium concentration is affected by the flow field, which is related to the tides. Moreover, more severe radioactive contamination was exhibited in winter than in summer because monsoons may have hindered the migration and diffusion of tritium within the harbour. Given the poor hydrodynamic conditions and slow water exchange in the open ocean in Haizhou Bay, the diffusion rate of radioactive nuclides outside the bay area was higher than that within it. Full article

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

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20 pages, 6650 KiB

Open AccessArticle

Seasonal Study of the Kako River Discharge Dynamics into Harima Nada Using a Coupled Atmospheric–Marine Model

by Valentina Pintos Andreoli, Hikari Shimadera, Hiroto Yasuga, Yutaro Koga, Motoharu Suzuki and Akira Kondo

Water 2024, 16(4), 614; https://doi.org/10.3390/w16040614 - 19 Feb 2024

Viewed by 1153

Abstract

This study developed a coupled atmospheric–marine model using the COAWST model system for the Harima Nada area between spring 2010 and winter 2011 to evaluate the seasonal influence of the Kako River’s discharge in the sea. The Kako River is one of the [...] Read more.

This study developed a coupled atmospheric–marine model using the COAWST model system for the Harima Nada area between spring 2010 and winter 2011 to evaluate the seasonal influence of the Kako River’s discharge in the sea. The Kako River is one of the largest rivers in southwest Japan, contributing almost half of the freshwater discharged in the Harima Nada region in the Seto Inland Sea. Validation was conducted for the entire period, showing a good performance for the atmospheric and marine variables selected. Multiple experiments injecting an inert tracer in the Kako River estuary were performed to simulate the seasonal river water distribution from the estuary into the sea and to analyze the seasonal differences in concentration patterns and mean residence times in Harima Nada. Because the study area is shallow, the results were evaluated at the surface and 10 m depth layers and showed significant seasonal differences in tracer distribution, circulation patterns, and mean residence times for the region. On the other hand, differences seemed to not be significant during the same season at different depths. The obtained results also agreed with the area’s natural water circulation, showing that the Kako River waters tend to distribute towards the west coast of Harima Nada in the warmer seasons but shift towards the east in winter. The influence of the Kako River in the center of the study area is seasonal and strongly dependent on the direction of the horizontal velocities more than their magnitude. The mean residence times varied seasonally from approximately 30 days in spring to 12 days in fall. The magnitude of the horizontal velocity was found to be maximum during summer when circulation patterns at the surface and 10 m depth in the central part of Harima Nada also seem to promote the strongest horizontal and vertical mixes. Full article

(This article belongs to the Special Issue Hydrodynamics in Coastal Areas)

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Calculation domains for WRF and ROMS (a) and Harima Nada region (b). JMA stations selected for SSH evaluation are (A) Takamatsu, (B) Kobe, (C) Sumoto, (D) Osaka, (E) Matsuyama, and (F) Kochi. Full article ">Figure 2
Coupled model layout and flowchart. Full article ">Figure 3
Calculated and observed meteorological average values in the Harima Nada area. Full article ">Figure 4
Salinity and temperature at four different observatories in Harima Nada. Full article ">Figure 5
Comparison of relative SSH values with respect to the annual average and their correlation (R) and mean average errors (MAEs) in different JMA coastal observatories inside the ROMS domain. Full article ">Figure 6
Seasonal ((A) spring, (B) summer, (C) autumn, and (D) winter) tracer distribution and average horizontal velocity in Harima Nada at the surface (1) and 10 m layers (2). The white areas in the 10 m layer correspond to places of lower bathymetry. Full article ">Figure 7
Tracer concentration and remain fraction values at the surface layer for different points of the control domain. Full article ">

15 pages, 4881 KiB

Open AccessArticle

Experimental Study on the Morphology of Snow Crystal Particles and Its Influence on Compacted Snow Hardness

by Shengbo Hu, Zhijun Li, Peng Lu, Qingkai Wang, Jie Wei and Qiuming Zhao

Water 2024, 16(4), 613; https://doi.org/10.3390/w16040613 - 19 Feb 2024

Viewed by 1264

Abstract

In their natural state, snow crystals are influenced by the atmosphere during formation and multiple factors after landing, resulting in varying particle sizes and unstable particle morphologies that are challenging to quantify. The current research mainly focuses on the relationship between the porosity [...] Read more.

In their natural state, snow crystals are influenced by the atmosphere during formation and multiple factors after landing, resulting in varying particle sizes and unstable particle morphologies that are challenging to quantify. The current research mainly focuses on the relationship between the porosity of compacted snow samples or qualitatively describes snow crystals and their macroscopic physical properties, ignoring that the significant differences in the morphology of snow crystals also affect their physical properties. To quantitatively evaluate the morphology of snow crystals, we employed optical microscopy to obtain digital images of snow crystals in Harbin, utilizing the Sobel and Otsu algorithms to determine the equivalent particle size and fractal dimension of individual snow particles. In addition, the hardness of snow with a density of 0.4 g/cm³ was measured through a penetration test, with an analysis of its correlation relative to particle size and fractal dimension. The results indicated the fractal dimension as an effective parameter for characterizing particle shape, which decreased rapidly over time and then fluctuated within the range of 1.10 to 1.15. During the initial period, natural snow crystals broke down rapidly, leading to an increase in the percentage of natural snow crystals with an equivalent particle size of 0.2–0.4 mm up to 51.86%. After three days, the sintering effect between snow crystals was enhanced, resulting in an even distribution of the equivalent particle size. Finally, multiple linear regression analysis showed a positive correlation between compacted snow hardness and fractal dimension, with a negative correlation between compacted snow hardness and equivalent particle size. These findings offer valuable technical support and data reference for exploring the relationship between snow’s mechanical properties and its microscopic particle shape. Full article

(This article belongs to the Section New Sensors, New Technologies and Machine Learning in Water Sciences)

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Snow and test equipment. (a) Diagram of the stored natural snow waiting to metamorphose; (b) Microscope; (c) Electronically controlled penetrometer. Full article ">Figure 2
Extraction of snow crystal edge contour lines. The original images of (a) a plate-like snow crystal, (b) a dendritic snow crystal, and (c) a hexagonal dendritic snow crystal. Automatically extracted images of (d) a plate-like snow crystal, (e) a dendritic snow crystal, and (f) a hexagonal dendritic snow crystal. Manual extraction of (g) a plate-like snow crystal, (h) a dendritic snow crystal, and (i) a hexagonal dendritic snow crystal. In (g–i), only the single required snow crystal was extracted manually. Full article ">Figure 3
Equivalent particle size distribution. (a) Equivalent particle size distribution of natural snow crystals in different periods; snow crystal equivalent particle size distribution on (b) day 1, (c) day 3, (d) day 15. Full article ">Figure 4
Grading curves of snow crystals. In different periods, (a) the relationships between equivalent particle size and cumulative mass percentage of natural snow crystals, and (b) the uniformity coefficients and curvature coefficients of snow crystals. In (b), the red area represented Cu > 5 and the blue area represented Cc = 1–3. A good distribution of particle size was indicated when Cu > 5 and Cc = 1–3. Full article ">Figure 5
Comparative weight distribution of particles. (a) The grading curve of snow crystal on the 10th day and its corresponding well-graded curve; (b) The weight distribution of snow crystal on the 10th day. Full article ">Figure 6
Variation curves of snow crystal morphology parameters. The curves of (a) equivalent particle size and (b) fractal dimension of snow crystals. Full article ">Figure 7
The curves of snow hardness, equivalent particle size, and the fractal dimension of a compacted snow crystal. Full article ">Figure 8
The composite correlation plot of compacted snow hardness with fractal dimension, equivalent particle size, and its fitted surface. Full article ">

14 pages, 3225 KiB

Open AccessCommunication

Metabolic Rates of Rainbow Trout Eggs in Reconstructed Salmonid Egg Pockets

by Rudy Benetti, Tobia Politi, Marco Bartoli and Nerijus Nika

Water 2024, 16(4), 612; https://doi.org/10.3390/w16040612 - 19 Feb 2024

Viewed by 1188

Abstract

In situ evaluations of the metabolic rates (i.e., respiration and excretion) of salmonid eggs are mostly indirect, focusing on the sampling of hyporheic water from wild or artificial nests. Comparatively, experimental studies carried out under controlled, laboratory conditions are less abundant due to [...] Read more.

In situ evaluations of the metabolic rates (i.e., respiration and excretion) of salmonid eggs are mostly indirect, focusing on the sampling of hyporheic water from wild or artificial nests. Comparatively, experimental studies carried out under controlled, laboratory conditions are less abundant due to methodological difficulties. This study presents a novel experimental setup aimed to address this issue and enable the measurement of oxygen and dissolved inorganic nitrogen fluxes in simulated rainbow trout (O. mykiss) egg pockets. The experimental setup consists of reconstructed egg pockets in cylindrical cores under flow-through conditions. Live and dead eyed-stage eggs were incubated in a natural, sterilised gravel substrate. Hyporheic water circulation was ensured using peristaltic pumps, with the possibility to collect and analyse inflowing and outflowing water for chemical analyses. Microcosm incubations, with closed respirometry of eggs in water alone, were also carried out in order to infer the importance of microbial respiration in the simulated egg pockets. The results show an increasing trend in oxygen demand, due to the development of biofilm in the reconstructed egg pockets and increased egg respiration rates. Moreover, egg pockets showed positive ammonium net fluxes connected with the advancing developmental egg stage, while nitrate removal peaked during the last phase of the experiment, mainly due to the formation of oxic-hypoxic interfaces, leading to couple nitrification–denitrification processes. The suggested approach enables to test a number of in situ situations, including the effects of extreme hydrological conditions, sediment clogging and sudden changes in water chemistry or temperature on the survival and metabolic performances of nests, at different egg development stages. Full article

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

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The photos summarise the sequence of actions for the mesocosm apparatus and the measurements: (a) preparation of the cores with spawning gravel, (b) egg pocket construction and laying of eggs, (c) falcon tube sampled with the needle oxygen logger, and (d) chamber used to incubate eggs for the microcosm assay. Full article ">Figure 2
Mesocosm setup in which reconstructed trout nests were incubated. The aquarium was laid in one pool of the RAS. Arrows indicate the water circulation direction. Full article ">Figure 3
Boxplot portraying the (a) DO demand (mg O2 egg−1 h−1) and (b) N-NH4+ excretion rates (μg N-NH4+ egg−1 h−1) of rainbow trout eggs at the three main developmental stages: eyed egg (294–310 dd), nearly hatched alevin with yolk sack (350–358 dd) and prior to the emergence time (swim up, 454–462 dd). The three eggs stages were incubated in closed glass chambers (see the text for more details). Full article ">Figure 4
Line plots depicting the (a) oxygen (mg O2 mesocosm−1 h−1) demand, (b) ammonium (mg N-NH4+ mesocosm−1 h−1) and (c) nitrates fluxes (mg N-NO3− mesocosm−1 h−1) for the simulated salmonid egg pockets (cores), for the whole incubation period until the complete alevin yolk sack absorption. Different colours represent the two main stages “eyed egg” and “alevin”, while different geometries stand for the live (L) and live and dead (L + D) setups and the control (bare sediments). Boxplots of 100-egg respiration and excretion data from the microcosm incubation are inserted for comparison. Please note that the boxplot position along the degree day axis is representative of the degree day intervals in which fluxes were measured from the microcosm experiments. Full article ">

4 pages, 169 KiB

Open AccessEditorial

Pathogen Detection and Identification in Wastewater

by Guangming Jiang, Ryo Honda and Sudipti Arora

Water 2024, 16(4), 611; https://doi.org/10.3390/w16040611 - 19 Feb 2024

Viewed by 1817

Abstract

The COVID-19 pandemic has renewed research needs for the detection and monitoring of various pathogens in urban wastewater systems including sewerage systems and wastewater treatment or recycling plants [...] Full article

(This article belongs to the Special Issue Pathogen Detection and Identification in Wastewater)

30 pages, 410 KiB

Open AccessReview

Challenges to Water Resource Management: The Role of Economic and Modeling Approaches

by Ariel Dinar

Water 2024, 16(4), 610; https://doi.org/10.3390/w16040610 - 18 Feb 2024

Cited by 8 | Viewed by 7270

Abstract

The field of water management is continually changing. Water has been subject to external shocks in the form of climate change and globalization. Water management analysis is subject to disciplinary developments and inter-disciplinary interactions. Are these developments well-documented in the literature? Initial observations [...] Read more.

The field of water management is continually changing. Water has been subject to external shocks in the form of climate change and globalization. Water management analysis is subject to disciplinary developments and inter-disciplinary interactions. Are these developments well-documented in the literature? Initial observations in the interdisciplinary literature suggest that results are fragmented, implying that a state-of-the-art review is needed. This paper aims to close such a gap by reviewing recent developments in water economics that address increasing perceptions of water scarcity by looking first at changes in the supply and quality of water and then at the impacts of climate change on water supply extremes. Among responses to such challenges, this paper identifies changes to water use patterns by including and co-managing water from different sources, including surface and groundwater, reclaimed wastewater, and desalinated water. Technological advancements are also among the resources that address water challenges. Water challenges are also reflected in the management of internationally shared water. A recent surge in scientific work identified international treaties as a significant contributor to international water management. This paper reviews recently employed economic approaches, such as experimental economics, game theory, institutional economics, and valuation methods. And, finally, it explores modeling approaches, including hydro-economic and computable general equilibrium models, that are being used to deal with water challenges. Full article

21 pages, 10109 KiB

Open AccessArticle

Design of a Seawater Desalination System with Two-Stage Humidification and Dehumidification Desalination Driven by Wind and Solar Energy

by Kaijie Huang, Chengjun Qiu, Wenbin Xie, Wei Qu, Yuan Zhuang, Kaixuan Chen, Jiaqi Yan, Gao Huang, Chao Zhang and Jianfeng Hao

Water 2024, 16(4), 609; https://doi.org/10.3390/w16040609 - 18 Feb 2024

Viewed by 1808

Abstract

The paper presents a wind–photovoltaic-thermal hybrid-driven two-stage humidification and dehumidification desalination system for remote island regions lacking access to electricity and freshwater resources. By conducting an analysis of the wind and solar energy resources at the experimental site, a suitable wind power station [...] Read more.

The paper presents a wind–photovoltaic-thermal hybrid-driven two-stage humidification and dehumidification desalination system for remote island regions lacking access to electricity and freshwater resources. By conducting an analysis of the wind and solar energy resources at the experimental site, a suitable wind power station and photovoltaic power station are constructed. The performance of the wind–solar complementary power generation system is then evaluated based on factors such as output power, seawater desalination load power, battery compensation output, system energy consumption, and water production costs. A variable step gradient disturbance method based on the power–duty ratio is proposed for tracking the maximum power point (MPPT) of wind power generation. The output power of the photovoltaic power generation system is optimized, employing a fuzzy logic control (FLC) method to track the MPPT of photovoltaic power generation. This approach effectively addresses the issues of slow speed and low accuracy encountered by traditional MPPT algorithms in tracking the maximum power point (MPP) of both photovoltaic and wind power generations. In order to ensure that the desalination system can operate stably under different weather conditions, eight working modes are designed, and a programmable logic controller (PLC) is used to control the system, which provides a guarantee for stable water production. Experimental results demonstrate that the system exhibits stable performance, achieving a maximum water output of 80.63 Kg/h and daily water yield is 751.32 Kg, the cost of desalination equipment is 1.4892 USD/t. Full article

(This article belongs to the Special Issue Water–Energy Nexus in the Era of Smart Water Revolution and Energy Transition)

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20 pages, 3088 KiB

Open AccessArticle

Assessment of Effluent Wastewater Quality and the Application of an Integrated Wastewater Resource Recovery Model: The Burgersfort Wastewater Resource Recovery Case Study

by Sekato Maremane, Gladys Belle and Paul Oberholster

Water 2024, 16(4), 608; https://doi.org/10.3390/w16040608 - 18 Feb 2024

Cited by 2 | Viewed by 1767

Abstract

Rivers in Africa have experienced dire pollution as a result of the poor management of wastewater effluent emanating from water resource recovery facilities (WRRFs). An integrated wastewater resource recovery model was developed and applied to identify ideal wastewater resource recovery technologies that can [...] Read more.

Rivers in Africa have experienced dire pollution as a result of the poor management of wastewater effluent emanating from water resource recovery facilities (WRRFs). An integrated wastewater resource recovery model was developed and applied to identify ideal wastewater resource recovery technologies that can be used to recover valuable resources from a mixture of wastewater effluents in a case study in the Burgersfort WRRF in the Limpopo province, South Africa. This novel model incorporates the process of biological nutrient removal (BNR) with an extension of conventional methods of resource recovery applicable to wastewater. The assessment of results of effluent quality from 2016 to 2022 revealed that ammonia, chemical oxygen demand, total coliform, fecal coliform, and Escherichia coli levels were critically non-compliant with the permissible effluent guidelines, indicating a stable upward trend in terms of concentrations, and scored a very bad wastewater quality index rating. All variables assessed showed a significant loading, except for orthophosphates, and significant correlations were observed among the variables. The results of the integrated wastewater resource recovery model revealed a high probability of reclaiming recoverable resources such as nutrients, sludge, bioplastics, biofuel, metals, and water from wastewater, which have economic, environmental, and social benefits, thereby improving the effluent quality of a WRRF. Full article

(This article belongs to the Special Issue Advances in Wastewater Treatment: Resources Recovery, Energy Neutralization and Water Reuse, 2nd Edition)

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22 pages, 4184 KiB

Open AccessArticle

A Transfer Learning Approach Based on Radar Rainfall for River Water-Level Prediction

by Futo Ueda, Hiroto Tanouchi, Nobuyuki Egusa and Takuya Yoshihiro

Water 2024, 16(4), 607; https://doi.org/10.3390/w16040607 - 18 Feb 2024

Cited by 1 | Viewed by 1713

Abstract

River water-level prediction is crucial for mitigating flood damage caused by torrential rainfall. In this paper, we attempt to predict river water levels using a deep learning model based on radar rainfall data instead of data from upstream hydrological stations. A prediction model [...] Read more.

River water-level prediction is crucial for mitigating flood damage caused by torrential rainfall. In this paper, we attempt to predict river water levels using a deep learning model based on radar rainfall data instead of data from upstream hydrological stations. A prediction model incorporating a two-dimensional convolutional neural network (2D-CNN) and long short-term memory (LSTM) is constructed to exploit geographical and temporal features of radar rainfall data, and a transfer learning method using a newly defined flow–distance matrix is presented. The results of our evaluation of the Oyodo River basin in Japan show that the presented transfer learning model using radar rainfall instead of upstream measurements has a good prediction accuracy in the case of torrential rain, with a Nash–Sutcliffe efficiency (NSE) value of 0.86 and a Kling–Gupta efficiency (KGE) of 0.83 for 6-h-ahead forecast for the top-four peak water-level height cases, which is comparable to the conventional model using upstream measurements (NSE = 0.84 and KGE = 0.83). It is also confirmed that the transfer learning model maintains its performance even when the amount of training data for the prediction site is reduced; values of NSE = 0.82 and KGE = 0.82 were achieved when reducing the training torrential-rain-period data from 12 to 3 periods (with 105 periods of data from other rivers for transfer learning). The results demonstrate that radar rainfall data and a few torrential rain measurements at the prediction location potentially enable us to predict river water levels even if hydrological stations have not been installed at the prediction location. Full article

(This article belongs to the Topic Advances in Hydrogeological Research)

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19 pages, 3518 KiB

Open AccessArticle

Study on the Influence of Water Erosion on the Bearing Capacity and Function of the High Pile Foundation of the Wharf

by Yashi Yang, Peng Zhang, Lingjun Wu and Qian Zhang

Water 2024, 16(4), 606; https://doi.org/10.3390/w16040606 - 18 Feb 2024

Viewed by 1259

Abstract

High-pile foundation is a common form of deep foundation commonly used in ocean environments, such as docks and bridge sites. Aiming at the problem of bearing capacity of high pile foundations, this paper proposes the calculation of bearing capacity and the analysis of [...] Read more.

High-pile foundation is a common form of deep foundation commonly used in ocean environments, such as docks and bridge sites. Aiming at the problem of bearing capacity of high pile foundations, this paper proposes the calculation of bearing capacity and the analysis of scour depth of high pile foundations under the action of scour based on the modified p-y curve. In this paper, three kinds of scour mechanisms—natural evolution scour, general scour, and local scour—are described; and the calculation methods of scour widely used at present are compared and analyzed. The solution of the vertical stress of soil around the pile under local scour is solved and applied to the β method to solve the lateral resistance of the pile under local scour. The local erosion is equivalent to the whole erosion, and the expression of the ultimate soil resistance before and after the equivalent is calculated, respectively, according to the principle that the ultimate soil resistance at a certain point above the equivalent pile end remains unchanged. The distance from the equivalent soil surface to the pile end can be obtained simultaneously, and then the equivalent erosion depth, p-y curve of sand at different depths, and high pile bearing capacity can be obtained. Finally, it is found that the bending moment of a single pile body varies along the pile body in the form of a parabola, and the maximum bending moment of the pile body is below the mud surface and increases with the increase in horizontal load. When the scouring depth is 30 m, the horizontal load is 25 KN, and the maximum bending moment of the pile body is about 150 N·m. The data with a relative error greater than 10% accounted for only 16.6% of the total data, and the error between the calculated value and the measured value was small. The formula can predict the erosion depth more accurately. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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18 pages, 7770 KiB

Open AccessArticle

An Optimization Study of Advanced Fenton Oxidation Methods (UV/Fenton–MW/Fenton) for Treatment of Real Epoxy Paint Wastewater

by Esra Billur Balcioglu Ilhan, Fatih Ilhan, Ugur Kurt and Kaan Yetilmezsoy

Water 2024, 16(4), 605; https://doi.org/10.3390/w16040605 - 18 Feb 2024

Cited by 3 | Viewed by 1893

Abstract

The use of various advanced oxidation methods in the treatment of wastewater has become the subject of many studies published in recent years. In particular, it is exceedingly significant to compare these treatment methods for industrial wastewater to reduce environmental effects and optimize [...] Read more.

The use of various advanced oxidation methods in the treatment of wastewater has become the subject of many studies published in recent years. In particular, it is exceedingly significant to compare these treatment methods for industrial wastewater to reduce environmental effects and optimize plant operations and economics. The present study is the first to deal with the treatability of real epoxy paint wastewater (EPW) using MW- and UV-assisted Fenton processes within an optimization framework. A three-factor, three-level Box–Behnken experimental design combined with response surface methodology (RSM) was conducted for maximizing the chemical oxygen demand (COD) and color removal efficiencies of ultraviolet (UV)/Fenton and microwave (MW)/Fenton processes in the treatment of the real epoxy paint wastewater (EPW, initial COD = 4600 ± 90 mg/L, initial color = 114 ± 4 Pt-Co), based on 15 different experimental runs. Three independent variables (reaction time ranging from 20 to 60 min (UV) and from 5 to 15 min (MW), power ranging from 20 to 40 W (UV) and from 300 to 600 W (MW), and H₂O₂/Fe²⁺ ratio ranging from 0.2 to 0.6 (for both UV and MW)) were consecutively coded as A, B, and C at three levels (−1, 0, and 1), and four second-order polynomial regression equations were then derived to estimate the responses (COD and color removals) of two distinct systems. The significance of the independent model components and their interrelations were appraised by means of a variance analysis with 99% confidence limits (α = 0.01). The standardized differences of the independent variables and the consistency between the actual and predicted values were also investigated by preparing normal probability residual plots and experiment-model plots for all processes. The optimal operating conditions were attained by solving the quadratic regression models and analyzing the surface and contour plots. UV/Fenton and MW/Fenton processes, which constitute combined Fenton processes, were performed using advanced oxidation methods, while Fenton processes were utilized as the standard method for wastewater treatment. When UV/Fenton and MW/Fenton processes were applied separately, the COD removal efficiencies were determined to be 96.4% and 95.3%, respectively. For the color parameter, the removal efficiencies after the application of both processes were found to exceed 97.5%. While these efficiencies were achieved in 1 h with a 38 W UV unit, they were achieved in 15 min with a MW power of 570 W. According to the RSM-based regression analysis results, the R² values for both processes were greater than 0.97 and p values were less than 0.003. Full article

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

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Pictorial diagram of the treatment process used for the advanced oxidation of EPW. Full article ">Figure 2
Normal probability residual plot and predicted vs. actual plot based on chemical oxygen demand (COD) removal efficiency values for the UV/Fenton process. Full article ">Figure 3
Normal probability residual plot and predicted vs. actual plot based on color removal efficiency values for the UV/Fenton process. Full article ">Figure 4
Surface and contour plots generated to illustrate the removal of pollutants, specifically addressing COD and color, through the UV/Fenton process. Full article ">Figure 5
Normal probability residual plot and predicted vs. actual plot based on chemical oxygen demand (COD) removal efficiency values for the MV/Fenton process. Full article ">Figure 6
Normal probability residual plot and predicted vs. actual plot based on color removal efficiency values for the MV/Fenton process. Full article ">Figure 7
Surface and contour plots generated to illustrate the removal of pollutants, specifically addressing COD and color, through the MW/Fenton process. Full article ">

23 pages, 18125 KiB

Open AccessArticle

Stability Analysis of a Rocky Slope with a Weak Interbedded Layer under Rainfall Infiltration Conditions

by Yizhou Zhuang, Xiaoyao Hu, Wenbin He, Danyi Shen and Yijun Zhu

Water 2024, 16(4), 604; https://doi.org/10.3390/w16040604 - 18 Feb 2024

Cited by 3 | Viewed by 1595

Abstract

Landslides not only cause great economic and human life losses but also seriously affect the safe operation of infrastructure such as highways. Rainfall is an important condition for inducing landslides, especially when a fault and weak interlayer exist on the slope, which can [...] Read more.

Landslides not only cause great economic and human life losses but also seriously affect the safe operation of infrastructure such as highways. Rainfall is an important condition for inducing landslides, especially when a fault and weak interlayer exist on the slope, which can easily transform into a landslide and cause instability under the action of rainfall. To explore the effects of a soft interlayer, a fault, and extreme rainfall on slope stability, this paper takes the landslide on the right side of the G104 Jinglan Line in Shengzhou City, Shaoxing City, Zhejiang Province, China, as an example. The cause, failure mechanism, and characteristics of the landslide are analyzed through field investigation and borehole exploration in the landslide area. The slope is simulated by numerical analysis, and the stability of the landslide under natural conditions and extreme rainstorm conditions is calculated using the strength reduction method. The stability of the slope before and after treatment is compared, and the effectiveness of the treatment measures is verified by combining the field monitoring data. At the same time, the complex geological structure and rainfall are considered to have been the main factors leading to the G104 landslide. Near the fault, the weak interlayer of the landslide was easily disturbed, the deformation trend of the deep displacement was consistent with rainfall, and the axial force of the anti-slide piles at the weak interlayer was correspondingly large. For a wedge rock slope, “excavation unloading” and “prestressed anchor + prestressed anchor cable + anti-slide pile” are effective treatments. This paper reveals the effects of a weak interlayer, a fault, and strong rainfall on a rocky high slope, providing predictions of instability modes and time evolution patterns for similar complex geological slopes under rainfall infiltration conditions and providing references for their treatment measures. Full article

(This article belongs to the Section Urban Water Management)

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25 pages, 24325 KiB

Open AccessArticle

The Investigation of the Response Mechanism of SST and Chlorophyll to Super Typhoon “Rey” in the South China Sea

by Shichao Wang, Jun Song, Junru Guo, Yanzhao Fu, Yu Cai and Linhui Wang

Water 2024, 16(4), 603; https://doi.org/10.3390/w16040603 - 18 Feb 2024

Viewed by 1399

Abstract

As one of the most significant disturbance sources in the upper marine environment of the South China Sea, tropical cyclones (typhoons) serve as a typical research subject for investigating the energy transfer process between the ocean and atmosphere. Utilizing satellite remote sensing data [...] Read more.

As one of the most significant disturbance sources in the upper marine environment of the South China Sea, tropical cyclones (typhoons) serve as a typical research subject for investigating the energy transfer process between the ocean and atmosphere. Utilizing satellite remote sensing data and focusing on Typhoon Rey No. 22’s transit event in 2021, this study quantitatively analyzes typhoon-induced energy input through heat pumping and cold suction at both surface and subsurface levels of the ocean. Additionally, it explores the response characteristics and feedback mechanisms of sea surface temperature (SST) and chlorophyll-a concentration (Chl-a) in the South China Sea to typhoon events. The research results show that the SST variation along the typhoon track displayed an asymmetric pattern, with a more pronounced warming on the right side and a cold anomaly lasting for 3–5 days on the left side. The subsurface warm anomaly dominated on the right side, showing a maximum temperature difference of 1.54 °C, whereas Ekman suction-induced upwelling led to cooling effects both at the subsurface and surface level on the left side, resulting in a maximum temperature difference of −3.28 °C. During the typhoon event, there was a significant decrease in sea surface heat flux, reaching 323.36 W/m², accompanied by corresponding changes in SST due to processes such as upwelling, seawater mixing, and air–sea heat transfer dynamics where anomalies arising from oceanic dynamic processes and exchange through sea surface heat flux contributed equally. Furthermore, strong suction-induced upwelling during the typhoon influenced chlorophyll concentration within the central and western regions of the South China Sea (13.5° N–16.5° N, 111° E–112.5° E), resulting in significant enhancement and reaching its peak value at approximately 0.65 mg/L. The average chlorophyll concentration increased by approximately 0.31 mg/L. Full article

(This article belongs to the Special Issue Application of Smart Technologies in Integrated Water Quality Modeling)

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31 pages, 5658 KiB

Open AccessArticle

Artificial Neural Network for Forecasting Reference Evapotranspiration in Semi-Arid Bioclimatic Regions

by Ahmed Skhiri, Ali Ferhi, Anis Bousselmi, Slaheddine Khlifi and Mohamed A. Mattar

Water 2024, 16(4), 602; https://doi.org/10.3390/w16040602 - 18 Feb 2024

Cited by 1 | Viewed by 1284

Abstract

A correct determination of irrigation water requirements necessitates an adequate estimation of reference evapotranspiration (ETo). In this study, monthly ETo is estimated using artificial neural network (ANN) models. Eleven combinations of long-term average monthly climatic data of air temperature (min and max), wind [...] Read more.

A correct determination of irrigation water requirements necessitates an adequate estimation of reference evapotranspiration (ETo). In this study, monthly ETo is estimated using artificial neural network (ANN) models. Eleven combinations of long-term average monthly climatic data of air temperature (min and max), wind speed (WS), relative humidity (RH), and solar radiation (SR) recorded at nine different weather stations in Tunisia are used as inputs to the ANN models to calculate ETo given by the FAO-56 PM (Penman–Monteith) equation. This research study proposes to: (i) compare the FAO-24 BC, Riou, and Turc equations with the universal PM equation for estimating ETo; (ii) compare the PM method with the ANN technique; (iii) determine the meteorological parameters with the greatest impact on ETo prediction; and (iv) determine how accurate the ANN technique is in estimating ETo using data from nearby weather stations and compare it to the PM method. Four statistical criteria were used to evaluate the model’s predictive quality: the determination coefficient (R²), the index of agreement (d), the root mean square error (RMSE), and the mean absolute error (MAE). It is quite evident that the Blaney–Criddle, Riou, and Turc equations underestimate or overestimate the ETo values when compared to the PM method. Values of ETo underestimation ranged from 1.9% to 66.1%, while values of overestimation varied from 0.9% to 25.0%. The comparisons revealed that the ANN technique could be adeptly utilized to model ETo using the available meteorological data. Generally, the ANN technique performs better on the estimates of ETo than the conventional equations studied. Among the meteorological parameters considered, maximum temperature was identified as the most significant climatic parameter in ETo modeling, reaching values of R and d of 0.936 and 0.983, respectively. The research showed that trained ANNs could be used to yield ETo estimates using new data from nearby stations not included in the training process, reaching high average values of R and d values of 0.992 and 0.997, respectively. Very low values of MAE (0.233 mm day⁻¹) and RMSE (0.326 mm day⁻¹) were also obtained. Full article

(This article belongs to the Special Issue Water Management in Arid and Semi-arid Regions)

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22 pages, 42889 KiB

Open AccessArticle

Hydrogeochemistry and Water Quality Index for Groundwater Sustainability in the Komadugu-Yobe Basin, Sahel Region

by Abdulrahman Shuaibu, Robert M. Kalin, Vernon Phoenix, Limbikani C. Banda and Ibrahim Mohammed Lawal

Water 2024, 16(4), 601; https://doi.org/10.3390/w16040601 - 18 Feb 2024

Cited by 4 | Viewed by 1873

Abstract

The assessment of hydrochemical characteristics and groundwater quality is crucial for environmental sustainability in developing economies. This study employed hydrogeochemical analysis, geospatial analysis, and groundwater quality index to assess hydrogeochemical processes and quality of groundwater in the Komadugu-Yobe basin. The pH, total dissolved [...] Read more.

The assessment of hydrochemical characteristics and groundwater quality is crucial for environmental sustainability in developing economies. This study employed hydrogeochemical analysis, geospatial analysis, and groundwater quality index to assess hydrogeochemical processes and quality of groundwater in the Komadugu-Yobe basin. The pH, total dissolved solids (TDS), and electrical conductivity (EC) were assessed in situ using a handheld portable electrical conductivity meter. The concentrations of the major cations (Na⁺, Ca²⁺, Mg²⁺, and K⁺), were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). The major anions (chloride, fluoride, sulfate, and nitrate) were analyzed via ion chromatography (IC). Total alkalinity and bicarbonate were measured in situ using a HACH digital alkalinity kit by the titrimetric method. Hydrochemical results indicate some physicochemical properties of the groundwater samples exceeded the maximum permissible limits as recommended by the World Health Organization guidelines for drinking water. Gibbs diagrams indicate rock–water interaction/rock weathering processes are the dominant mechanisms influencing the groundwater chemistry. Groundwater is predominantly Ca²⁺-Mg²⁺-HCO⁻₃ water type, constituting 59% of the groundwater samples analyzed. The groundwater quality index (GWQI) depicted 63 and 27% of the groundwater samples as excellent and good water types for drinking purposes, respectively. This study further relates the interaction between geology, hydrochemical characteristics, and groundwater quality parameters. The results are essential to inform a sustainable management strategy and protection 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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8 pages, 7483 KiB

Open AccessCommunication

Water Supply and Firefighting: Early Lessons from the 2023 Maui Fires

by Robert B. Sowby and Braxton W. Porter

Water 2024, 16(4), 600; https://doi.org/10.3390/w16040600 - 18 Feb 2024

Cited by 1 | Viewed by 2658

Abstract

Even though drinking water utilities are not meant to fight wildfires, they quickly become stakeholders, if not first responders, when their resources are needed for firefighting. The August 2023 wildfires on the island of Maui, Hawaii, USA, have highlighted weaknesses at this intersection. [...] Read more.

Even though drinking water utilities are not meant to fight wildfires, they quickly become stakeholders, if not first responders, when their resources are needed for firefighting. The August 2023 wildfires on the island of Maui, Hawaii, USA, have highlighted weaknesses at this intersection. While attention has focused on the wildfire causes or water quality impacts afterward, few studies have analyzed the response. We review this extreme case to support disaster-response lessons for water utilities and to guide further research and policy. First, emergency water releases were not available in a timely manner. Second, fire and wind toppled power lines, causing power outages that inhibited pumping water. Third, many structures were a total loss despite water doused on them, consuming valuable water. Finally, water was lost through damaged premise plumbing in burned structures, further reducing system pressure. These conditions emphasize that water utilities need to access emergency water supplies quickly, establish reliable backup electricity, coordinate with firefighters on priority water uses, and shut valves in burned areas to preserve water. While further research will certainly follow, we present these early lessons as starting points. Full article

(This article belongs to the Topic Natural Hazards and Environmental Challenges in the Anthropocene Age)

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17 pages, 4996 KiB

Open AccessArticle

Advantages of the Event Method for the Simulation of Water Quality in Pressurised Water Systems

by Marta Hervás, Fernando Martínez-Alzamora, Pilar Conejos and Joan Carles Alonso

Water 2024, 16(4), 599; https://doi.org/10.3390/w16040599 - 18 Feb 2024

Cited by 1 | Viewed by 1073

Abstract

In this paper, several methods for the calculation of water quality evolution in drinking water distribution networks are analysed. The Lagrangian Time-Driven method has been implemented in the Epanet simulation software since version 2.0. In version 2.2, some improvements were implemented to deal [...] Read more.

In this paper, several methods for the calculation of water quality evolution in drinking water distribution networks are analysed. The Lagrangian Time-Driven method has been implemented in the Epanet simulation software since version 2.0. In version 2.2, some improvements were implemented to deal with mass imbalances (Lagrangian Time-Driven improved method). However, it sometimes presents inaccuracies in calculations, especially when there are short-length pipes. To solve this problem, the implementation of the Lagrangian Event-Driven method is proposed, which provides more accurate quality results. In order to detail the differences and similarities of the results of the different methods and to determine under what conditions the results provided by Epanet are sufficiently adjusted, two practical examples have been carried out, one of them on a hydraulic model of a real network. Full article

(This article belongs to the Section Urban Water Management)

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21 pages, 6364 KiB

Open AccessFeature PaperArticle

Making Rivers, Producing Futures: The Rise of an Eco-Modern River Imaginary in Dutch Climate Change Adaptation

by Lotte de Jong, Gert Jan Veldwisch, Lieke Anna Melsen and Rutgerd Boelens

Water 2024, 16(4), 598; https://doi.org/10.3390/w16040598 - 18 Feb 2024

Cited by 1 | Viewed by 1890

Abstract

In the field of climate change adaptation, the future matters. River futures influence the way adaptation projects are implemented in rivers. In this paper, we challenge the ways in which dominant paradigms and expert claims monopolise the truth concerning policies and designs of [...] Read more.

In the field of climate change adaptation, the future matters. River futures influence the way adaptation projects are implemented in rivers. In this paper, we challenge the ways in which dominant paradigms and expert claims monopolise the truth concerning policies and designs of river futures, thereby sidelining and delegitimising alternative river futures. So far, limited work has been performed on the power of river futures in the context of climate change adaptation. We conceptualised the power of river futures through river imaginaries, i.e., collectively performed and publicly envisioned reproductions of riverine socionatures mobilised through truth claims of social life and order. Using the Border Meuse project as a case study, a climate change adaptation project in a stretch of the river Meuse in the south of the Netherlands, and a proclaimed success story of climate adaptation in Dutch water management, we elucidated how three river imaginaries (a modern river imaginary, a market-driven imaginary, and an eco-centric river imaginary) merged into an eco-modern river imaginary. Importantly, not only did the river futures merge, but their aligned truth regimes also merged. Thus, we argue that George Orwell’s famous quote, “who controls the past, controls the future: who controls the present, controls the past” can be extended to “who controls the future, controls how we see and act in the present, and how we rediscover the past”. Full article

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Front covers of the river’s future plans demonstrate a romantic view that represents a wild and natural river as it presumably was in the past. The vegetation is an eye-catching feature. The illustrations were made by (a) Natuur en Milieu Gelderland [<a href="#B39-water-16-00598" class="html-bibr">39</a>] and (b) Bureau Stroming and reused with the owner’s permission [<a href="#B41-water-16-00598" class="html-bibr">41</a>,<a href="#B45-water-16-00598" class="html-bibr">45</a>]. Full article ">Figure 2
Pictures shared internally and posted by the Anglers Association on their Facebook account and to create allies for a more fish-friendly river and to visualise a lack of focus on fish ecology around the Grensmaas. The photo on the left (a) was taken by Henk Houben and reused with the permission of the owner David Vertegaal, Sportvisserij Nederland. The photo on the right (b) was taken by Thijs Belgers and reused with the owner’s permission [<a href="#B49-water-16-00598" class="html-bibr">49</a>]. Full article ">Figure 3
Visualisation of a living river with thriving underwater life in the new living river vision of the World Wildlife Foundation. This vision includes fish as an important indicator of life and indicates that, in addition to fish, macro- and microfauna in the river exist and are considered to be valuable for the underwater reserves. The rewilding image is extended from only having trees on land in the original plans (<a href="#water-16-00598-f001" class="html-fig">Figure 1</a>) to including underwater wildlife in this image. The illustration includes tekst in Dutch arguing why river wood is crucial for underwater life and was made by Jeroen Helmer, ARK Rewilding Nederland and reused with the owner’s permission [<a href="#B51-water-16-00598" class="html-bibr">51</a>]. Full article ">Figure 4
Timeline of visions, studies, and events that shaped an eco-modern river imaginary. Full article ">Figure 5
Illustration of the dynamics of the river imaginaries over time, highlighting important events in the Border Meuse. In the floods of 1993 and 1995, three imaginaries moved toward each other and started negotiating toward an eco-modern river imaginary. Yet, during this time, the fish-friendly imaginary split from the eco-centric imaginary. After the 2021 floods, the eco-centric imaginary split off from the modern and market-driven imaginaries. Full article ">

26 pages, 6287 KiB

Open AccessArticle

Superiority of Dynamic Weights against Fixed Weights in Merging Multi-Satellite Precipitation Datasets over Pakistan

by Nuaman Ejaz, Aftab Haider Khan, Muhammad Shahid, Kifayat Zaman, Khaled S. Balkhair, Khalid Mohammed Alghamdi, Khalil Ur Rahman and Songhao Shang

Water 2024, 16(4), 597; https://doi.org/10.3390/w16040597 - 17 Feb 2024

Viewed by 1770

Abstract

Satellite precipitation products (SPPs) are undeniably subject to uncertainty due to retrieval algorithms and sampling issues. Many research efforts have concentrated on merging SPPs to create high-quality merged precipitation datasets (MPDs) in order to reduce these uncertainties. This study investigates the efficacy of [...] Read more.

Satellite precipitation products (SPPs) are undeniably subject to uncertainty due to retrieval algorithms and sampling issues. Many research efforts have concentrated on merging SPPs to create high-quality merged precipitation datasets (MPDs) in order to reduce these uncertainties. This study investigates the efficacy of dynamically weighted MPDs in contrast to those using static weights. The analysis focuses on comparing MPDs generated using the “dynamic clustered Bayesian averaging (DCBA)” approach with those utilizing the “regional principal component analysis (RPCA)” under fixed-weight conditions. These MPDs were merged from SPPs and reanalysis precipitation data, including TRMM (Tropical Rainfall Measurement Mission) Multi-satellite Precipitation Analysis (TMPA) 3B42V7, PERSIANN-CDR, CMORPH, and the ERA-Interim reanalysis precipitation data. The performance of these datasets was evaluated in Pakistan’s diverse climatic zones—glacial, humid, arid, and hyper-arid—employing data from 102 rain gauge stations. The effectiveness of the DCBA model was quantified using Theil’s U statistic, demonstrating its superiority over the RPCA model and other individual merging methods in the study area The comparative performances of DCBA and RPCA in these regions, as measured by Theil’s U, are 0.49 to 0.53, 0.38 to 0.45, 0.37 to 0.42, and 0.36 to 0.43 in glacial, humid, arid, and hyper-arid zones, respectively. The evaluation of DCBA and RPCA compared with SPPs at different elevations showed poorer performance at high altitudes (>4000 m). The comparison of MPDs with the best performance of SPP (i.e., TMPA) showed significant improvement of DCBA even at altitudes above 4000 m. The improvements are reported as 49.83% for mean absolute error (MAE), 42.31% for root-mean-square error (RMSE), 27.94% for correlation coefficient (CC), 40.15% for standard deviation (SD), and 13.21% for Theil’s U. Relatively smaller improvements are observed for RPCA at 13.04%, 1.56%, 10.91%, 1.67%, and 5.66% in the above indices, respectively. Overall, this study demonstrated the superiority of DCBA over RPCA with static weight. Therefore, it is strongly recommended to use dynamic variation of weights in the development of MPDs. Full article

(This article belongs to the Section Hydrology)

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17 pages, 4457 KiB

Open AccessArticle

Environmental Impact Analysis and Carbon Emission Reduction Pathways by Upgrading Wastewater Treatment Plant: A Case Study of Upgrading Project at a Wastewater Treatment Plant in Dongguan, China

by Yunxia Lu, Hao An, Chao Li and Changmin Liu

Water 2024, 16(4), 596; https://doi.org/10.3390/w16040596 - 17 Feb 2024

Cited by 1 | Viewed by 2514

Abstract

The potential environmental impact and increased operational costs associated with the upgrading and renovation of sewage treatment plants are acknowledged. This study employs the upgrading and expansion project of a municipal sewage plant in Dongguan City, Guangdong Province, as a case study. Utilizing [...] Read more.

The potential environmental impact and increased operational costs associated with the upgrading and renovation of sewage treatment plants are acknowledged. This study employs the upgrading and expansion project of a municipal sewage plant in Dongguan City, Guangdong Province, as a case study. Utilizing the principles and methods of the Life Cycle Assessment (LCA), a comprehensive assessment of the environmental benefits during the upgrading and renovation process of the sewage treatment plant, is conducted and targeted solutions are proposed. The research findings indicate that upgrading and renovating sewage treatment plants can significantly augment the adverse environmental effects of such facilities. Therefore, this study strategically proposes measures such as the utilization of clean energy, sludge resource utilization, and recycled water use as carbon emission reduction pathways. Through calculations, it is demonstrated that the utilization of clean energy and sludge resource can respectively reduce electricity consumption by 12.41% and 59.06%. Concurrently, recycled water use can lead to a reduction of 68.65% in carbon emissions, thereby markedly enhancing positive environmental outcomes. Full article

(This article belongs to the Special Issue Control and Treatment of Emerging Contaminants in Water Ecosystems)

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17 pages, 7506 KiB

Open AccessArticle

Study on the Hydrodynamic Performance of Swing-Type Flapping Hydrofoil Bionic Pumps Affected by Foil Camber

by Qizong Sun, Ertian Hua, Liying Sun, Linfeng Qiu, Yabo Song and Mingwang Xiang

Water 2024, 16(4), 595; https://doi.org/10.3390/w16040595 - 17 Feb 2024

Viewed by 1113

Abstract

The flapping hydrofoil bionic pump is an innovative hydrodynamic device that utilizes flapping hydrofoil technology. Flapping hydrofoil bionic pumps are crucial in addressing issues like inadequate river hydropower and limited water purification capabilities in flat river network regions. Optimizing the foil characteristics is [...] Read more.

The flapping hydrofoil bionic pump is an innovative hydrodynamic device that utilizes flapping hydrofoil technology. Flapping hydrofoil bionic pumps are crucial in addressing issues like inadequate river hydropower and limited water purification capabilities in flat river network regions. Optimizing the foil characteristics is essential for enhancing the hydrodynamic efficiency of the flapping hydrofoil bionic pump. This study investigates the impact of foil camber parameters on the hydrodynamic performance of swing-type asymmetric flapping bionic pumps. The NACA series standard foils with varying cambers are analyzed using the overlapping grid technology and finite volume method. The thrust coefficient, flow rate, pumping efficiency, and flow field structure of the flapping hydrofoil bionic pump are examined under pressure inlet conditions with the foil camber. The findings indicate that increasing the foil’s curvature within a specific range can greatly enhance the maximum values of thrust coefficient, propulsive efficiency, and pumping efficiency of the flapping hydrofoil bionic pump. Specifically, when the foil curvature is 6%c, the maximum value of the instantaneous thrust coefficient of the flapping hydrofoil bionic pump is significantly improved by 31.25% compared to the symmetric foil type under the condition of an oscillating frequency of f = 1 HZ. The flapping hydrofoil bionic pump achieves its maximum pumping efficiency when the oscillation frequency is within the range of f ≤ 2.5 Hz. This efficiency is 11.7% greater than that of the symmetric foil, and it occurs when the foil curvature is 8%c. Within the frequency range of f > 2.5 Hz, the flapping hydrofoil bionic pump that has a foil curvature of 6%c exhibits the highest enhancement in pumping efficiency. It achieves a maximum increase of 12.8% compared to the symmetric foil type. Nevertheless, the average head was less than 0.4 m, making it suitable for ultra-low-head applications. Full article

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16 pages, 6673 KiB

Open AccessArticle

Correlation between Turbidity and Inherent Optical Properties as an Initial Recognition for Backscattering Coefficient Estimation

by Kamila Haule, Maria Kubacka, Henryk Toczek, Barbara Lednicka, Bogusław Pranszke and Włodzimierz Freda

Water 2024, 16(4), 594; https://doi.org/10.3390/w16040594 - 17 Feb 2024

Viewed by 1450

Abstract

Seawater turbidity is a common water quality indicator measured in situ and estimated from space on a regular basis. However, it is rarely correlated with the inherent optical properties of seawater, which convey information about seawater composition. In this study, we show a [...] Read more.

Seawater turbidity is a common water quality indicator measured in situ and estimated from space on a regular basis. However, it is rarely correlated with the inherent optical properties of seawater, which convey information about seawater composition. In this study, we show a simple application of the turbidimeter’s weighting function in the estimation of the backscattering coefficient of a model inorganic suspension in seawater. First, we introduce a method to measure the instrument’s weighting function which describes the sensor’s angular response in terms of scattering angles. The determination of the sensor-specific weighting function led us to characterize its angular sensitivity to the presence of suspended particles. The highest sensitivity for the Seapoint turbidimeter is in the range of 114°–128° (containing 25% of the total signal). Next, we describe the correlations between turbidity and the scattering and backscattering coefficients on the example of the model of inorganic particle suspension using the calculations based on Mie theory. The correlations are analyzed for narrow size fractions of the particle size distribution of silica in the range of 0.59–190 µm. We established that there is a good linear correlation (characterized by the coefficient of determination r² = 0.979) between the part of the scattering coefficient measured by the turbidimeter and the backscattering coefficient of all size fractions of the model inorganic suspension. Full article

(This article belongs to the Special Issue Applications of In-Situ Research for Remote Sensing Algorithms in Estuarine and Coastal Waters)

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12 pages, 1731 KiB

Open AccessArticle

Monthly Streamflow Prediction of the Source Region of the Yellow River Based on Long Short-Term Memory Considering Different Lagged Months

by Haibo Chu, Zhuoqi Wang and Chong Nie

Water 2024, 16(4), 593; https://doi.org/10.3390/w16040593 - 17 Feb 2024

Cited by 3 | Viewed by 1211

Abstract

Accurate and reliable monthly streamflow prediction plays a crucial role in the scientific allocation and efficient utilization of water resources. In this paper, we proposed a prediction framework that integrates the input variable selection method and Long Short-Term Memory (LSTM). The input selection [...] Read more.

Accurate and reliable monthly streamflow prediction plays a crucial role in the scientific allocation and efficient utilization of water resources. In this paper, we proposed a prediction framework that integrates the input variable selection method and Long Short-Term Memory (LSTM). The input selection methods, including autocorrelation function (ACF), partial autocorrelation function (PACF), and time lag cross-correlation (TLCC), were used to analyze the lagged time between variables. Then, the performance of the LSTM model was compared with three other traditional methods. The framework was used to predict monthly streamflow at the Jimai, Maqu, and Tangnaihai stations in the source area of the Yellow River. The results indicated that grid search and cross-validation can improve the efficiency of determining model parameters. The models incorporating ACF, PACF, and TLCC with lagged time are evidently superior to the models using the current variable as the model inputs. Furthermore, the LSTM model, which considers the lagged time, demonstrated better performance in predicting monthly streamflow. The coefficient of determination (R²) improved by an average of 17.46%, 33.94%, and 15.29% for each station, respectively. The integrated framework shows promise in enhancing the accuracy of monthly streamflow prediction, thereby aiding in strategic decision-making for water resources management. Full article

(This article belongs to the Section Hydrology)

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Water, Volume 16, Issue 4 (February-2 2024) – 111 articles

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