Water

27 pages, 16928 KiB

Open AccessFeature PaperArticle

Spatial and Temporal Variability of Rainfall Trends in Response to Climate Change—A Case Study: Syria

by Martina Zeleňáková, Hany F. Abd-Elhamid, Katarína Krajníková, Jana Smetanková, Pavol Purcz and Ibrahim Alkhalaf

Water 2022, 14(10), 1670; https://doi.org/10.3390/w14101670 - 23 May 2022

Cited by 9 | Viewed by 3714

Abstract

Recent climate changes have prompted changes in the hydrological cycle at a global scale, creating instability when predicting future climate conditions and related changes. Perturbations in global climate models have created the need to concentrate consequent changes in hydro climatic factors to comprehend [...] Read more.

Recent climate changes have prompted changes in the hydrological cycle at a global scale, creating instability when predicting future climate conditions and related changes. Perturbations in global climate models have created the need to concentrate consequent changes in hydro climatic factors to comprehend the regional and territorial impacts of climate and environmental changes. Syria, as a Middle East country, is exposed to extreme climate events such as drought and flood. The aim of this study is to analyze rainfall trends in Syria in response to the likely climate change. The analysis was conducted for rainfall data collected from 71 stations distributed all over the country for the period (1991–2009). The trend analysis was performed in monthly and seasonal scales using Mann–Kendall non-parametric statistical tests. The results attained from Mann–Kendall trend analysis revealed decreasing trends at most of the stations. Additionally, rainfall analysis was conducted for the stations with significant trends for wet and dry periods, which also revealed decreasing trends at almost all the stations. From the analysis of the results, it is obvious that slight increasing trends in rainfall in Syria occurred in the fall period. However, in the winter and spring periods, significant decreasing trends have been observed at almost all the stations. This reveals that the country will suffer from shortage of water, because most rainfall occurs in the winter and spring, infrequently in fall and rarely in summer. The results are consistent with the IPCC’s fifth report that predicted a decrease in rainfall in the Mediterranean and southern Asia. The results of this paper could help the management of water resources in Syria considering future climate changes. Full article

(This article belongs to the Special Issue Assessment and Management of Hydrological Risks Due to Climate Change)

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22 pages, 4683 KiB

Open AccessArticle

Deploying a GIS-Based Multi-Criteria Evaluation (MCE) Decision Rule for Site Selection of Desalination Plants

by Mehdi Gholamalifard, Bonyad Ahmadi, Ali Saber, Sohrab Mazloomi and Tiit Kutser

Water 2022, 14(10), 1669; https://doi.org/10.3390/w14101669 - 23 May 2022

Cited by 7 | Viewed by 3073

Abstract

Water supply is one of the most critical infrastructures for development, and by desalinating the water of the Persian Gulf, water demands may be satisfied. The countries of the Persian Gulf basin have applied this technology and compensated for the country’s water shortage, [...] Read more.

Water supply is one of the most critical infrastructures for development, and by desalinating the water of the Persian Gulf, water demands may be satisfied. The countries of the Persian Gulf basin have applied this technology and compensated for the country’s water shortage, whereas because of Iran’s unlimited access to water, desalination has only been applied on a local scale. Due to serious hydrological stress and periodic water shortages in Iran’s southern coastal area, seawater desalination may be necessary as an optional solution for water supply. Site selection for desalination plants is difficult as it may have a direct influence on the territorial and water environment, as well as disrupt biological systems, hence, the objective of this study was to identify desalination sites across the coastline of Hormozgan. To choose a suitable site, a multi-criteria evaluation (MCE) design was applied, with three scenarios evaluated in the constraints part and two scenarios considered in the criteria weight section. Altogether, out of 21 determination criteria considered for the construction of desalination facilities, 14 were associated to the inland and coastal segment, six with the marine zone, and one with the water quality phase. The results showed that about 33,584 ha in the optimal scenario, or when minimum and maximum constraints were applied, approximately 109,553 and 7182 ha, respectively, of the region, including a total of 11 zones, were suitable for the building of desalination facilities. In conclusion, this study was the first to consider MCE with many criteria and different scenarios for developing a decision rule for the installation of desalination facilities based on environmental and marine factors. Full article

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

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21 pages, 5298 KiB

Open AccessArticle

Improving the Prediction of Soil Organic Matter in Arable Land Using Human Activity Factors

by Lixin Ning, Changxiu Cheng, Xu Lu, Shi Shen, Liang Zhang, Shaomin Mu and Yunsheng Song

Water 2022, 14(10), 1668; https://doi.org/10.3390/w14101668 - 23 May 2022

Cited by 5 | Viewed by 2148

Abstract

Detailed spatial distribution of soil organic matter (SOM) in arable land is essential for agricultural management and decision making. Based on digital soil mapping (DSM) theory, much attention has been focused on the selection of environmental covariates. However, the importance of human activity [...] Read more.

Detailed spatial distribution of soil organic matter (SOM) in arable land is essential for agricultural management and decision making. Based on digital soil mapping (DSM) theory, much attention has been focused on the selection of environmental covariates. However, the importance of human activity factors in SOM prediction has not received enough attention, especially in arable soil. Moreover, due to the insufficient amount of soil sampling data used to train and validate the DSM model, the prediction results may be questionable, and some even contradictory. This paper explores the effectiveness of the human footprint, amount of fertilizer application, agronomic management level, crop planting type, and irrigation guarantee degree in SOM mapping of arable land in Heilongjiang Province. The results show that the model only including environmental covariates accounts for 41% of the variation in SOM distribution. The model combining the five human activity factors increases the SOM spatial prediction by 39% in terms of R² (coefficient of determination), 12% in terms of RMSE (root mean square error), 15% in terms of MAE (mean absolute error), and 11% in terms of LCCC (Lin’s concordance correlation coefficient), showing better prediction accuracy and performance. This indicates that human activity factors play a crucial role in determining SOM distribution in arable land. In the SOM prediction, soil moisture is the most important environmental covariate, and the amount of fertilizer application with a relative importance of 11.36% (ranking 3rd) is the most important human activity factor, higher than the annual average precipitation and elevation. From a spatial point of view, the Sanjiang Plain is a difficult area for prediction. Full article

(This article belongs to the Special Issue Application of Various Hydrological Modeling Techniques and Methods in River Basin Management)

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19 pages, 3779 KiB

Open AccessArticle

Socio-Economic Aspects of Centralized Wastewater System for Rural Settlement under Conditions of Eastern Poland

by Aleksandra Brzusek, Marcin K. Widomski and Anna Musz-Pomorska

Water 2022, 14(10), 1667; https://doi.org/10.3390/w14101667 - 23 May 2022

Cited by 8 | Viewed by 3257

Abstract

This paper presents a case study concerning multivariate analysis, including social and financial aspects, as well as environmental impacts, of the organized sanitation development under conditions of the selected rural settlement in Poland. Three technologically up-to-date variants of sanitary sewerage network concepts with [...] Read more.

This paper presents a case study concerning multivariate analysis, including social and financial aspects, as well as environmental impacts, of the organized sanitation development under conditions of the selected rural settlement in Poland. Three technologically up-to-date variants of sanitary sewerage network concepts with the different assumed sewage transport, i.e., pressure, pressure-gravity and gravity, were proposed together with the investment and operation and maintenance costs estimation. The willingness-to-accept (WTA) and willingness-to-pay (WTP) survey was used to analyze the level of social acceptance and involvement. The financial analysis covered two economic and cost-efficiency dynamic indicators, benefits–costs ratio (BCR) and dynamic generation cost (DGC), commonly used to support the decision-making process. The environmental aspects were assessed by the possible anthropopressure caused by sewerage leakage and odor emissions. Results of the WTA and WTP survey presented a significant level of acceptance and involvement of the local population to sustain the improved sanitation. The determined values of DGC indicated low cost-efficiency of the gravity system, while obtained values of BCR for all variants and the actual regional sewage fees showed the low profitability of improved sanitation, i.e., BCR < 1.0. All studied sanitation systems were assessed positively due to their environmental impacts. The performed studies showed that, despite the declared willingness to accept the organized sanitation and to pay the sewage fees, the economical sustainability of the proposed designs is doubtful over the longer time duration due to the significant capital and operation costs affecting the sewerage payment value. Full article

(This article belongs to the Special Issue Integrated Water Resources Management (IWRM), a Holistic Approach to Sustainable Water Management)

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29 pages, 3563 KiB

Open AccessArticle

Development of Monthly Reference Evapotranspiration Machine Learning Models and Mapping of Pakistan—A Comparative Study

by Jizhang Wang, Ali Raza, Yongguang Hu, Noman Ali Buttar, Muhammad Shoaib, Kouadri Saber, Pingping Li, Ahmed Elbeltagi and Ram L. Ray

Water 2022, 14(10), 1666; https://doi.org/10.3390/w14101666 - 23 May 2022

Cited by 13 | Viewed by 2939

Abstract

Accurate estimation of reference evapotranspiration (ET_o) plays a vital role in irrigation and water resource planning. The Penman–Monteith method recommended by the Food and Agriculture Organization (FAO PM56) is widely used and considered a standard to calculate ET_o. However, [...] Read more.

Accurate estimation of reference evapotranspiration (ET_o) plays a vital role in irrigation and water resource planning. The Penman–Monteith method recommended by the Food and Agriculture Organization (FAO PM56) is widely used and considered a standard to calculate ET_o. However, FAO PM56 cannot be used with limited meteorological variables, so it is compulsory to choose an alternative model for ET_o estimation, which requires fewer variables. This study built ten machine learning (ML) models based on multi-function, neural network, and tree-based structure against the FAO PM56 method. For this purpose, time series temperature data on a monthly scale are only used to train ML models. The developed ML models were applied to estimate ET_o at different test stations and the obtained results were compared with the FAO PM56 method to verify and validate their performance in ET_o estimation for the selected stations. In addition, multiple statistical indicators, including root-mean-square error (RMSE), coefficient of determination (R²), mean absolute error (MAE), Nash–Sutcliffe efficiency (NSE), and correlation coefficient (r) were calculated to compare the performance of each ML model on ET_o estimation. Among the applied ML models, the ET_o tree boost (TB) ML model outperformed the other ML models in estimating ET_o in diverse climatic conditions based on statistical indicators (R², NSE, r, RMSE, and MAE). Moreover, the observed R², NSE, and r were the highest for the TB ML model, while RMSE and MAE were found to be the lowest at the study sites compared to other applied ML models. Lastly, ET_o point data yielded from the TB ML model was used in an interpolation process to create monthly and annual ET_o maps. Based on the ET_o maps, this study suggests mainly a focus on areas with high ET_o values and proper irrigation scheduling of crops to ensure water sustainability. Full article

(This article belongs to the Special Issue Projection of Groundwater Levels, Spring Flows, Lake Dynamics, Extreme Drought Events, and Floods under Future Climates Using Artificial Intelligence Models)

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22 pages, 3036 KiB

Open AccessArticle

Contaminant Fate and Transport Modeling in Distribution Systems: EPANET-C

by Gopinathan R. Abhijith and Avi Ostfeld

Water 2022, 14(10), 1665; https://doi.org/10.3390/w14101665 - 23 May 2022

Cited by 8 | Viewed by 3023

Abstract

Typically, computer-based tools built on mathematical models define the time-series behavior of contaminants, in dissolved or colloidal form, within the spatial boundaries of water distribution systems (WDS). EPANET-MSX has become a standard tool for WDS quality modeling due to its collaboration with EPANET. [...] Read more.

Typically, computer-based tools built on mathematical models define the time-series behavior of contaminants, in dissolved or colloidal form, within the spatial boundaries of water distribution systems (WDS). EPANET-MSX has become a standard tool for WDS quality modeling due to its collaboration with EPANET. The critical challenges in applying EPANET-MSX include conceptualizing the exchanges among multiple reacting constituents within the WDS domain and developing the scientific descriptions of these exchanges. Moreover, due to its complicated user interface, the EPANET-MSX application demands programming skills from a software engineering viewpoint. The present study aims to overcome these challenges by developing a novel computer-based tool, EPANET-C. Via built-in and customizable conceptual and mathematical models’ directories, EPANET-C simplifies WDS water quality modeling for users, even those lacking programming expertise. Due to its flexibility, EPANET-C can become a de facto standard tool in WDS quality modeling study both for the industry and the academia. Full article

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

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16 pages, 2720 KiB

Open AccessArticle

Salt Accumulation during Cropping Season in an Arid Irrigation Area with Shallow Water Table Depth: A 10-Year Regional Monitoring

by Chaozi Wang, Yuanyuan Luo, Zailin Huo, Zhongyi Liu, Geng Liu, Shuai Wang, Yifan Lin and Peijin Wu

Water 2022, 14(10), 1664; https://doi.org/10.3390/w14101664 - 23 May 2022

Cited by 7 | Viewed by 2061

Abstract

Nowadays, irrigation takes up about 35% of agricultural water consumption worldwide, and irrigation induced secondary soil salinizationsalinization affects the crop production and sustainable development of arid irrigation areas globally. However, the regular pattern of salt accumulation in the root zone during the cropping [...] Read more.

Nowadays, irrigation takes up about 35% of agricultural water consumption worldwide, and irrigation induced secondary soil salinizationsalinization affects the crop production and sustainable development of arid irrigation areas globally. However, the regular pattern of salt accumulation in the root zone during the cropping season and the contributions of its attribute factors are still unclear. Therefore, a 10-year monitoring was conducted in the Hetao Irrigation District to reveal the soil salt accumulation during the cropping season and to relate it to influential factors, including potential crop evapotranspiration, water input (field irrigation + precipitation) and water table depth. It was found that under the climate conditions and water-saving irrigation measures of the investigated 10-year period, (1) the salt accumulated during the cropping season could be effectively leached by autumn irrigation and the root zone soil could remain suitable for crop germination, (2) the cropping season water deficit (potential crop evapotranspiration − field irrigation − precipitation) showed strong correlation with the cropping season salt accumulation, and (3) maintaining the cropping season average water table depth larger than a critical depth (roughly 3 m) might be the most economical way to alleviate salt accumulation. Therefore, it is recommended to balance the salt leaching and the water table depth controlling in the future water-saving irrigation management practices. Full article

(This article belongs to the Topic Water and Soil Management in Adaptation to Climate Change)

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15 pages, 1865 KiB

Open AccessArticle

Characteristics of Plant Community and Its Relationship with Groundwater Depth of the Desert Riparian Zone in the Lower Reaches of the Ugan River, Northwest China

by Tianju Zhang, Yaning Chen, Wanrui Wang, Yongjin Chen and Xigang Liu

Water 2022, 14(10), 1663; https://doi.org/10.3390/w14101663 - 23 May 2022

Cited by 4 | Viewed by 2262

Abstract

The vegetation in the desert riparian zone represents a critical barrier in the maintenance of the ecosystem’s balance. However, in recent years, the vegetation degradation of the riparian zone has seriously hindered economic development and ecological environment conservation. Based on a field investigation [...] Read more.

The vegetation in the desert riparian zone represents a critical barrier in the maintenance of the ecosystem’s balance. However, in recent years, the vegetation degradation of the riparian zone has seriously hindered economic development and ecological environment conservation. Based on a field investigation and literature, the mechanisms of vegetation degradation in the lower reaches of the Ugan River are discussed in this study through the analysis of plant coverage, diversity, substitution rate, distribution pattern, grey correlation analysis, and the relationship with groundwater depth. The results showed that the vegetation coverage in this region is relatively low when the water depth exceeds 4 m. Furthermore, the Shannon–Wiener index, the Simpson index, and the Pielou index all decreased with increases in water depth. Woody plants are the main species maintaining the ecological balance of the region with an aggregation distribution pattern. The degradation of vegetation is the result of the lack of water sources and the intense water consumption caused by human activities (especially agricultural). To promote ecological balance and vegetation restoration, the relative optimal water depth range should be maintained within 2 to 5 m as well as proper control of human activities. In addition, the degraded vegetation can gradually be restored using point and surface (i.e., flowering in the center and spreading to the surrounding areas). The results can provide a scientific basis for vegetation restoration and ecological conservation in the lower reaches of China’s Ugan River. Full article

(This article belongs to the Special Issue Advances in Studies on Ecohydrological Processes in the Arid Area)

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14 pages, 2380 KiB

Open AccessArticle

Detection and Stability of Cyanogen Bromide and Cyanogen Iodide in Drinking Water

by Fuyang Jiang, Yuefeng Xie, Kun Dong, Dunqiu Wang and Haixiang Li

Water 2022, 14(10), 1662; https://doi.org/10.3390/w14101662 - 23 May 2022

Cited by 1 | Viewed by 2021

Abstract

This study systematically summarized the factors affecting the stability of CNXs, providing a reference for better control and elimination of CNXs. A method for the detection of CNBr and CNI in solution was established using a liquid–liquid extraction/gas chromatography/electron capture detector. Specifically, the [...] Read more.

This study systematically summarized the factors affecting the stability of CNXs, providing a reference for better control and elimination of CNXs. A method for the detection of CNBr and CNI in solution was established using a liquid–liquid extraction/gas chromatography/electron capture detector. Specifically, the method was used to investigate the stability of CNBr and CNI in drinking water, especially in the presence of chlorine and sulfite, and it showed good reproducibility (relative standard deviation <3.05%), high sensitivity (method detection limit <100 ng/L), and good recovery (91.49–107.24%). Degradation kinetic studies of cyanogen halides were conducted, and their degradation rate constants were detected for their hydrolysis, chlorination, and sulfite reduction. For hydrolysis, upon increasing pH from 9.0 to 11.0, the rate constants of CNCl, CNBr, and CNI changed from 8 to 155 × 10⁻⁵ s⁻¹, 1.1 to 34.2 × 10⁻⁵ s⁻¹, and 1.5 to 6.2 × 10⁻⁵ s⁻¹, respectively. In the presence of 1.0 mg/L chlorine, upon increasing pH from 7.0 to 10.0, the rate constants of CNCl, CNBr, and CNI changed from 36 to 105 × 10⁻⁵ s⁻¹, 15.8 to 49.0 × 10⁻⁵ s⁻¹, and 1.2 to 24.2 × 10⁻⁵ s⁻¹, respectively. In the presence of 3 μmol/L sulfite, CNBr and CNI degraded in two phases. In the first phase, they degraded very quickly after the addition of sulfite, whereas, in the second phase, they degraded slowly with rate constants similar to those for hydrolysis. Owing to the electron-withdrawing ability of halogen atoms and the nucleophilic ability of reactive groups such as OH⁻ and ClO⁻, the rate constants of cyanogen halides increased with increasing pH, and they decreased in the order of CNCl > CNBr > CNI during hydrolysis and chlorination. The hydrolysis and chlorination results could be used to assess the stability of cyanogen halides in water storage and distribution systems. The sulfite reduction results indicate that quenching residual oxidants with excess sulfite could underestimate the levels of cyanogen halides, especially for CNBr and CNI. Full article

(This article belongs to the Special Issue Advanced Technologies in Drinking Water Treatment, Algae and Disinfection By-Products Control)

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19 pages, 5428 KiB

Open AccessArticle

Interaction between Strong Sound Waves and Aerosol Droplets: Numerical Simulation

by Fangfang Li, Han Cao, Yinghui Jia, Yu Guo and Jun Qiu

Water 2022, 14(10), 1661; https://doi.org/10.3390/w14101661 - 23 May 2022

Cited by 1 | Viewed by 2269

Abstract

In this study, we attempted to eliminate atmospheric fog and aerosol particles by strong sound waves. The action of sound waves created an air disturbance, and the oscillation of the local air caused the micron-sized aerosol droplet particles to move. To provide guidance [...] Read more.

In this study, we attempted to eliminate atmospheric fog and aerosol particles by strong sound waves. The action of sound waves created an air disturbance, and the oscillation of the local air caused the micron-sized aerosol droplet particles to move. To provide guidance of the characteristics of the effective sound waves, this study numerically simulated aerosol droplet agglomeration under the action of sound waves, which was solved by coupling computational fluid dynamics (CFD) and discrete element methods (DEMs) as a typical two-phase flow problem in this study. The movements of aerosol droplet particles were simulated, as well as their agglomeration. The evolution process of the average particle size and the number of multimers were obtained, and the influence of different sound frequencies, sound pressure level (SPL), and particle spacing on agglomeration were studied. It was found that the promotion effect of low-frequency sound waves on aerosol droplet agglomeration was significantly higher than that of high-frequency sound waves, and the sound wave promotion effect of high SPLs was better than that of low SPL. In addition, the concept of the average agglomeration time required to quantify the acoustic agglomeration speed was proposed, and it was found to be positively correlated with sound frequency and particle spacing, while being negatively correlated with SPL. Full article

(This article belongs to the Special Issue Atmospheric Water Resources Exploitation and Utilization)

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4 pages, 173 KiB

Open AccessEditorial

Coastal and Continental Shelf Dynamics in a Changing Climate

by Serafeim E. Poulos, Vasilios Kapsimalis and Ioannis P. Panagiotopoulos

Water 2022, 14(10), 1660; https://doi.org/10.3390/w14101660 - 23 May 2022

Viewed by 1425

Abstract

The coastal and associated shelf environments constitute the interface between the land and ocean regime [...] Full article

(This article belongs to the Special Issue Coastal and Continental Shelf Dynamics in a Changing Climate)

18 pages, 3551 KiB

Open AccessArticle

An Adaptive Surrogate-Assisted Simulation-Optimization Method for Identifying Release History of Groundwater Contaminant Sources

by Mengtian Wu, Jin Xu, Pengjie Hu, Qianyi Lu, Pengcheng Xu, Han Chen and Lingling Wang

Water 2022, 14(10), 1659; https://doi.org/10.3390/w14101659 - 23 May 2022

Cited by 1 | Viewed by 1787

Abstract

The simulation-optimization method, integrating the numerical model and the evolutionary algorithm, is increasingly popular for identifying the release history of groundwater contaminant sources. However, due to the usage of computationally intensive evolutionary algorithms, traditional simulation-optimization methods always require thousands of simulations to find [...] Read more.

The simulation-optimization method, integrating the numerical model and the evolutionary algorithm, is increasingly popular for identifying the release history of groundwater contaminant sources. However, due to the usage of computationally intensive evolutionary algorithms, traditional simulation-optimization methods always require thousands of simulations to find appropriate solutions. Such methods yield a prohibitive computational burden if the simulation involved is time-consuming. To reduce general computation, this study proposes a novel simulation-optimization method for solving the inverse contaminant source identification problems, which uses surrogate models to approximate the numerical model. Unlike many existing surrogate-assisted methods using the pre-determined surrogate model, this paper presents an adaptive surrogate technique to construct the most appropriate surrogate model for the current numerical model. Two representative cases about identifying the release history of contaminant sources are used to investigate the accuracy and robustness of the proposed method. The results indicate that the proposed adaptive surrogate-assisted method effectively identifies the release history of groundwater contaminant sources with a higher degree of accuracy and shorter computation time than traditional methods. Full article

(This article belongs to the Section Hydrogeology)

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5 pages, 188 KiB

Open AccessEditorial

Special Issue: Hydrological Extremes in a Warming Climate: Nonstationarity, Uncertainties and Impacts

by Rajesh R. Shrestha and Mohammad Reza Najafi

Water 2022, 14(10), 1658; https://doi.org/10.3390/w14101658 - 23 May 2022

Viewed by 2370

Abstract

The intensification of global water cycle, associated with anthropogenic climate change, is affecting the characteristics of hydrologic extreme events throughout the world [...] Full article

(This article belongs to the Special Issue Hydrological Extremes in a Warming Climate: Nonstationarity, Uncertainties and Impacts)

20 pages, 6051 KiB

Open AccessFeature PaperArticle

Time Series Features for Supporting Hydrometeorological Explorations and Predictions in Ungauged Locations Using Large Datasets

by Georgia Papacharalampous and Hristos Tyralis

Water 2022, 14(10), 1657; https://doi.org/10.3390/w14101657 - 23 May 2022

Cited by 10 | Viewed by 3251

Abstract

Regression-based frameworks for streamflow regionalization are built around catchment attributes that traditionally originate from catchment hydrology, flood frequency analysis and their interplay. In this work, we deviated from this traditional path by formulating and extensively investigating the first regression-based streamflow regionalization frameworks that [...] Read more.

Regression-based frameworks for streamflow regionalization are built around catchment attributes that traditionally originate from catchment hydrology, flood frequency analysis and their interplay. In this work, we deviated from this traditional path by formulating and extensively investigating the first regression-based streamflow regionalization frameworks that largely emerge from general-purpose time series features for data science and, more precisely, from a large variety of such features. We focused on 28 features that included (partial) autocorrelation, entropy, temporal variation, seasonality, trend, lumpiness, stability, nonlinearity, linearity, spikiness, curvature and others. We estimated these features for daily temperature, precipitation and streamflow time series from 511 catchments and then merged them within regionalization contexts with traditional topographic, land cover, soil and geologic attributes. Precipitation and temperature features (e.g., the spectral entropy, seasonality strength and lag-1 autocorrelation of the precipitation time series, and the stability and trend strength of the temperature time series) were found to be useful predictors of many streamflow features. The same applies to traditional attributes such as the catchment mean elevation. Relationships between predictor and dependent variables were also revealed, while the spectral entropy, the seasonality strength and several autocorrelation features of the streamflow time series were found to be more regionalizable than others. Full article

(This article belongs to the Special Issue Using Statistical and Machine Learning Algorithms for Big Data Applications in Hydrology)

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13 pages, 3722 KiB

Open AccessArticle

Remediation of PO₄³⁻ in Water Using Biodegradable Materials Embedded with Lanthanum Oxide Nanoparticles

by Kai Guo, Zirui Song and Chengchun Tang

Water 2022, 14(10), 1656; https://doi.org/10.3390/w14101656 - 23 May 2022

Cited by 2 | Viewed by 1991

Abstract

Eutrophication, a process in which algae grow inordinately, adversely affects aqueous fauna. Phosphorous at levels above 0.1 mg/L is adequate to cause eutrophication. In this study, we aimed to reduce the amount of PO₄³⁻ in water using biodegradable and ecofriendly sorbents. [...] Read more.

Eutrophication, a process in which algae grow inordinately, adversely affects aqueous fauna. Phosphorous at levels above 0.1 mg/L is adequate to cause eutrophication. In this study, we aimed to reduce the amount of PO₄³⁻ in water using biodegradable and ecofriendly sorbents. Lanthanum oxide nanoparticles were doped in agar and cellulose sponge to produce two new sorbents, agar–La and sponge–La, respectively. Both sorbents showed high efficacy in remediating up to 10 mg/L PO₄³⁻ in water. Sponge–La was found to be more proficient in terms of adsorption than agar–La because it required just 1 h to achieve 80% adsorption when the initial concentration of PO₄³⁻ was 10 mg/L. Sponge–La was effective at pH levels ranging from 4 to 8, with a removal rate of 80–100%. Although agar–La displayed a slow sorption process, it presented a high adsorption capacity (156 mg/g); moreover, the cake-shaped agar–La could be easily manufactured and separated from an aqueous matrix or any water-based solutions. These two sorbents could effectively remove high concentrations of PO₄³⁻, and their preparation requires a simple step. Agar–La was easier to manufacture, whereas the adsorption process using sponge–La was more rapid. In addition, both sorbents can be easily separated from the matrix after sorption. Full article

(This article belongs to the Special Issue Application of Biochar, Adsorbent and Nanomaterials in Wastewater Treatment)

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25 pages, 2413 KiB

Open AccessArticle

Study on the Relationship between Water Resources Utilization and Economic Growth in Tarim River basin from the Perspective of Water Footprint

by Quan Lu, Fengjiao Liu, Yanjun Li and Dezhen Wang

Water 2022, 14(10), 1655; https://doi.org/10.3390/w14101655 - 22 May 2022

Cited by 11 | Viewed by 2294

Abstract

Taking the Tarim River basin as the research object, the water footprint was calculated based on the water footprint theory based on the relevant data from 2008 to 2019, and the water resource evaluation system was constructed to analyze the water footprint and [...] Read more.

Taking the Tarim River basin as the research object, the water footprint was calculated based on the water footprint theory based on the relevant data from 2008 to 2019, and the water resource evaluation system was constructed to analyze the water footprint and water resource utilization of the Tarim River basin from three levels of structure, benefit, and ecology. Based on the water footprint theory, the annual water footprint and GDP of Tarim River basin were used to construct the Tapio decoupling model, and the decoupling type between water resources utilization and economic growth was obtained. The relationship between water resource utilization and economic growth in Tarim River was analyzed by combining the decoupling type evaluation and water footprint evaluation. The internal benefit is poor, and the external benefit is good; The degree of water resource shortage is on the rise, and the self-sufficiency rate of water resources is large. On the whole, the decoupling strength increases gradually. Decoupling strength has obvious industrial influence characteristics. Based on the above research conclusions, the sustainable economic and ecological development of the Tarim River basin can be realized from two aspects: reducing water footprint and strengthening decoupling intensity. Full article

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

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18 pages, 6201 KiB

Open AccessArticle

Temporal and Spatial Characteristics of River Water Quality and Its Influence Factors in the TAIHU Basin Plains, Lower Yangtze River, China

by Bin Gao, Youpeng Xu, Zhixin Lin, Miao Lu and Qiang Wang

Water 2022, 14(10), 1654; https://doi.org/10.3390/w14101654 - 22 May 2022

Cited by 8 | Viewed by 2350

Abstract

Water quality pollution has been a serious problem in the Taihu Basin plains, which is a highly urbanized area in China. This study aims to detect the interannual and seasonal changes and spatial patterns of water quality in this region. Based on cluster [...] Read more.

Water quality pollution has been a serious problem in the Taihu Basin plains, which is a highly urbanized area in China. This study aims to detect the interannual and seasonal changes and spatial patterns of water quality in this region. Based on cluster analysis, Moran’s I, and standard deviational ellipses, the site clusters, spatial heterogeneity of water quality characteristics and identified polluted regions were clarified. Results showed that (1) water quality improved since 2002, and nutrient concentrations were lower in summer and autumn than in winter and spring. (2) The monitoring sites were divided into six clusters according to the water quality during the period from 2010 to 2014. Water quality worsened from Cluster 1 to Cluster 4. Cluster 1 sites were mostly distributed beside the Yangtze River and Taihu Lake. Cluster 4 sites were mainly located along the southeast border near Shanghai, while the remaining sites were separately distributed in the main cities. (3) A polluted region of both total nitrogen (TN) and total phosphorus (TP) was present in the southeastern part of the study area near the border from 2010 to 2014. In addition, polluted regions were most likely to form near the junctions of main cities. (4) Anthropogenic factors had greater impacts on water quality than natural factors. More attention should be given to water quality protection around impervious surface areas due to the greatest considerable effect. Full article

(This article belongs to the Special Issue Ecohydrological Conditions and Modeling of Wetlands)

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22 pages, 7128 KiB

Open AccessArticle

Use of Heating Configuration to Control Marangoni Circulation during Droplet Evaporation

by Walid Foudhil, Costanza Aricò, Patrick Perré and Sadok Ben Jabrallah

Water 2022, 14(10), 1653; https://doi.org/10.3390/w14101653 - 22 May 2022

Cited by 4 | Viewed by 2507

Abstract

The present work presents a numerical study of the evaporation of a sessile liquid droplet deposited on a substrate and subjected to different heating configurations. The physical formulation accounts for evaporation, the Marangoni effect, conductive transfer in the support, radiative heating, and diffusion–convection [...] Read more.

The present work presents a numerical study of the evaporation of a sessile liquid droplet deposited on a substrate and subjected to different heating configurations. The physical formulation accounts for evaporation, the Marangoni effect, conductive transfer in the support, radiative heating, and diffusion–convection in the droplet itself. The moving interface is solved using the Arbitrary Lagrangian–Eulerian (ALE) method. Simulations were performed using COMSOL Multiphysics. Different configurations were performed to investigate the effect of the heating conditions on the shape and intensity of the Marangoni circulations. A droplet can be heated by the substrate (different natures and thicknesses were tested) and/or by a heat flux supplied at the top of the droplet. The results show that the Marangoni flow can be controlled by the heating configuration. An upward Marangoni flow was obtained for a heated substrate and a downward Marangoni flow for a flux imposed at the top of the droplet. Using both heat sources generated two vortices with an upward flow from the bottom and a downward flow from the top. The position of the stagnation zone depended on the respective intensities of the heating fluxes. Controlling the circulation in the droplet might have interesting applications, such as the control of the deposition of microparticles in suspension in the liquid, the deposition of the solved constituent, and the enhancement of the evaporation rate. Full article

(This article belongs to the Special Issue Hydraulic Dynamic Calculation and Simulation Ⅱ)

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17 pages, 8802 KiB

Open AccessArticle

Simulation of Internal Flow Characteristics of an Axial Flow Pump with Variable Tip Clearance

by Jiantao Shen, Fengyang Xu, Li Cheng, Weifeng Pan, Yi Ge, Jiaxu Li and Jiali Zhang

Water 2022, 14(10), 1652; https://doi.org/10.3390/w14101652 - 22 May 2022

Cited by 12 | Viewed by 1925

Abstract

This study investigated the influence of the change in blade tip clearance on the internal flow characteristics of a vertical axial flow pump. Taking the actual running vertical axial flow pump of a pumping station as the research object, based on the SST [...] Read more.

This study investigated the influence of the change in blade tip clearance on the internal flow characteristics of a vertical axial flow pump. Taking the actual running vertical axial flow pump of a pumping station as the research object, based on the SST k-ω turbulent flow model, the numerical simulation technology was used to study the effects of different tip clearances on the pressure, turbulent kinetic energy, Z–X section pressure and flow state of the impeller at the middle section. Furthermore, the impact of clearance layer tip leakage was also analyzed. Unsteady calculations of flow characteristics under the design conditions were performed. The research results showed that the variation trend of the pressure in the impeller was basically the same under different tip clearance values. With the increase in the clearance value, the pressure gradient along the water inlet direction of the blade decreased and the leakage vorticity increased. Observing the leakage vorticity distribution of the gap layer under the flow condition of

0.6 Q_{0}

, it was found that when the tip clearance was smaller than 1 mm, the leakage flow was small and easily assimilated by the mainstream, and the leakage flow and mainstream had a certain ability to compete, which caused adverse effects on the performance of the pump device. The pressure pulsation characteristics showed that the leakage flow caused by the tip clearance caused a high-frequency distribution, and the clearance obviously influenced the pressure pulsation characteristics. Full article

(This article belongs to the Special Issue Advancement in the Fluid Dynamics Research of Reversible Pump-Turbine)

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26 pages, 9326 KiB

Open AccessArticle

Three-Dimensional Hierarchical Hydrogeological Static Modeling for Groundwater Resource Assessment: A Case Study in the Eastern Henan Plain, China

by Baoyi Zhang, Fasha Zeng, Xiuzong Wei, Umair Khan and Yanhong Zou

Water 2022, 14(10), 1651; https://doi.org/10.3390/w14101651 - 22 May 2022

Cited by 4 | Viewed by 2253

Abstract

Groundwater is closely related to hydrogeological structure and hydro-lithology, which mainly refers to the spatial distributions and properties of the environment where groundwater occurs. To analyze the constraints of hydrogeological structure and hydro-lithology on regional groundwater resources in the Eastern Henan Plain, China, [...] Read more.

Groundwater is closely related to hydrogeological structure and hydro-lithology, which mainly refers to the spatial distributions and properties of the environment where groundwater occurs. To analyze the constraints of hydrogeological structure and hydro-lithology on regional groundwater resources in the Eastern Henan Plain, China, we reconstructed the three-dimensional (3D) hierarchical models at two scales, hydrogeological structural models and hydro-lithological models, using hydrogeological cross-sections. First, the hydrogeological structural models of four aquifer groups, corresponding to four formations of the Quaternary in the study area, were reconstructed. Second, the hierarchical hydro-lithological model was built using SIS and IK estimation under the constraint of each aquifer group model space, respectively. Compared to global model, the variograms of hierarchical model captured more spatial characteristics of lithology in each aquifer group. The IK hierarchical model presents more continuities, clear boundaries, and realistic geometric shapes of the three lithologies, excluding the banding characteristics of the IK global model. The hierarchical SIS models reproduced the lithology distribution of each aquifer group and captured small changes in the lithology, with the smallest absolute percentage errors (APEs). Third, coupling the SIS hierarchical models and the groundwater levels, the groundwater resource in the study area was estimated to have a total volume of 1.2339 × 10⁴ m³. The shallow groundwater in the study area is mainly concentrated in Hebi City and the Puyang basin of the Yellow River, and deep groundwater is mainly concentrated in the northern Anyang City and Hebi City. Finally, the possible quantities of shallow and deep groundwater recharges were estimated for future groundwater management decision in the study area. The hierarchical hydrogeological model, groundwater resource assessment, and possible groundwater recharge estimation can also provide a basis for groundwater vulnerability, groundwater extraction, and land subsidence assessment. Full article

(This article belongs to the Special Issue Advances in Hydrogeology and Groundwater Management Research)

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24 pages, 5797 KiB

Open AccessArticle

Spatio-Temporal Evaluation of GPM-IMERGV6.0 Final Run Precipitation Product in Capturing Extreme Precipitation Events across Iran

by Aydin Bakhtar, Akbar Rahmati, Afshin Shayeghi, Javad Teymoori, Navid Ghajarnia and Peyman Saemian

Water 2022, 14(10), 1650; https://doi.org/10.3390/w14101650 - 22 May 2022

Cited by 12 | Viewed by 2357

Abstract

Extreme precipitation events such as floods and droughts have occurred with higher frequency over the recent decades as a result of the climate change and anthropogenic activities. To understand and mitigate such events, it is crucial to investigate their spatio-temporal variations globally or [...] Read more.

Extreme precipitation events such as floods and droughts have occurred with higher frequency over the recent decades as a result of the climate change and anthropogenic activities. To understand and mitigate such events, it is crucial to investigate their spatio-temporal variations globally or regionally. Global precipitation products provide an alternative way to the in situ observations over such a region. In this study, we have evaluated the performance of the latest version of the Global Precipitation Measurement-Integrated Multi-satellitE Retrievals (GPM-IMERGV6.0 Final Run (GPM-IMERGF)). To this end, we have employed ten most common extreme precipitation indices, including maximum indices (Rx1day, Rx5day, CDD, and CWD), percentile indices (R95pTOT and R99pTOT), and absolute threshold indices (R10mm, R20mm, SDII, and PRCPTOT). Overall, the spatial distribution results for error metrics showed that the highest and lowest accuracy for GPM-IMERGF were reported for the absolute threshold indices and percentile indices, respectively. Considering the spatial distribution of the results, the highest accuracy of GPM-IMERGF in capturing extreme precipitations was observed over the western highlands, while the worst results were obtained along the Caspian Sea regions. Our analysis can significantly contribute to various hydro-metrological applications for the study region, including identifying drought and flood-prone areas and water resources planning. Full article

(This article belongs to the Section Hydrology)

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16 pages, 8039 KiB

Open AccessFeature PaperArticle

Low-Head Hydropower for Energy Recovery in Wastewater Systems

by Marco Sinagra, Calogero Picone, Paolo Picone, Costanza Aricò, Tullio Tucciarelli and Helena M. Ramos

Water 2022, 14(10), 1649; https://doi.org/10.3390/w14101649 - 21 May 2022

Cited by 8 | Viewed by 4031

Abstract

Hydraulic turbines for energy recovery in wastewater treatment plants, with relatively large discharges values and small head jumps, are usually screw Archimedes or Kaplan types. In the specific case of a small head jump (about 3 m) underlying a rectangular weir in the [...] Read more.

Hydraulic turbines for energy recovery in wastewater treatment plants, with relatively large discharges values and small head jumps, are usually screw Archimedes or Kaplan types. In the specific case of a small head jump (about 3 m) underlying a rectangular weir in the major Palermo (Italy) water treatment plant, a traditional Kaplan solution is compared with two other new proposals: a Hydrostatic Pressure Machine (HPM) located at the upstream channel and a cross-flow turbine (CFT) located in a specific underground room downstream of the same channel. The fluid mechanical formulations of the flow through these turbines are analyzed and the characteristic parameters are stated. Numerical analysis was carried out for the validation of the HPM design criteria. The efficiency at the design point of the CFT and HPM are estimated using the ANSYS CFX solver for resolution of 3D URANS analysis. The strong and weak points of the three devices are compared. Finally, a viability analysis is developed based on several economic indicators. This innovative study with a theoretical formulation of the most suitable turbomachine characterization, the potential energy estimation based on hydraulic energy recovery in a real case study of a wastewater treatment plant and the comparison of the three different low-head turbines, enhancing the main advantages, is of utmost importance towards the net-zero water sector decarbonization. Full article

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

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49 pages, 12959 KiB

Open AccessArticle

Dynamic Response and Failure Mechanism of Concrete Arch Dams under Extreme Loadings: A Solid Foundation for Real-World Actions to Reduce Dam Collapse Losses during Wartime or Terrorist Attacks

by Serges Mendomo Meye, Guowei Li, Zhenzhong Shen, Jingbin Zhang, Ghislain Franck Emani and Victor Edem Setordjie

Water 2022, 14(10), 1648; https://doi.org/10.3390/w14101648 - 21 May 2022

Cited by 5 | Viewed by 2485

Abstract

With massive energy demands, the majority of developing countries are at a critical juncture in their industrial development. Their energy structure, on the other hand, is relatively specific and heavily reliant on fossil fuels, resulting in significant environmental pollution. As a result, the [...] Read more.

With massive energy demands, the majority of developing countries are at a critical juncture in their industrial development. Their energy structure, on the other hand, is relatively specific and heavily reliant on fossil fuels, resulting in significant environmental pollution. As a result, the development of clean energy is on the horizon, which is related not only to whether developing countries can build a resource-saving and environmentally friendly society but also to whether they can achieve socially sustainable development. As a significant clean energy source, not only does hydropower play an important role in the development of an energy-efficient and environmentally friendly green economy, but it also has numerous benefits such as shipping, irrigation, flood control, and water supply. So, hydropower development is critical for developing countries to adjust their energy structures, achieve regional development balance, and ensure river defense safety. However, precision guidance technology is maturing around the world. If one side’s water-retaining dam is accurately blasted in the event of a full-scale war or local conflict, it may cause significant economic and human losses. Dam safety and protection from strong explosions deserve special attention given the obvious seriousness of the consequences. It is critical to improve the anti-explosion safety of major hydraulic structures by revealing the dynamic response behavior, damage mechanism, and dam characteristics under explosion impact loads, as well as evaluating the dam’s condition after extreme loads. In the critical work of disaster prevention and mitigation, this is crucial to our social and economic development. This study is not only a key technical problem and an important strategic task in hydraulic structure construction, but it may also serve as a guideline for governments to take effective measures to reduce the loss of dam break under special circumstances. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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13 pages, 2595 KiB

Open AccessFeature PaperArticle

Assessing the Forecasting Accuracy of a Modified Grey Self-Memory Precipitation Model Considering Scale Effects

by Fanxiang Meng, Zhimin Sun, Long Yang, Kui Yu and Zongliang Wang

Water 2022, 14(10), 1647; https://doi.org/10.3390/w14101647 - 21 May 2022

Cited by 4 | Viewed by 1789

Abstract

Precipitation is an important parameter in water resource management, urban flood warning systems, and hydrological analyses. Precipitation forecasting can provide a decision-making basis for relevant organizations, such as those in the agricultural sector and water conservancy departments. In this paper, a modified grey [...] Read more.

Precipitation is an important parameter in water resource management, urban flood warning systems, and hydrological analyses. Precipitation forecasting can provide a decision-making basis for relevant organizations, such as those in the agricultural sector and water conservancy departments. In this paper, a modified grey self-memory model (MGSM) was constructed by combining a self-memory function and grey theory. To verify the precision of the model in cases in which measured data are not available in the forecasting stage, a self-test method based on the scale effect in the precipitation forecasting stage was proposed. Ultimately, the model was verified based on three precipitation scales—the annual scale, the crop growth period, and the monthly scale—in the crop growth period from 1961 to 2018 in the Songnen Plain area, Heilongjiang Province. The results showed that the MGSM yielded higher fitting accuracy than the original GM(1,1) and grey self-memory models. Furthermore, the precipitation in the study area was predicted with the MSGM at the three different scales above from 2019 to 2023. The accuracy of forecasting meets the relevant requirements, and the model can be used to forecast precipitation trends at different time scales in the future. The results provide a reference for formulating scientific and rational agricultural water use strategies and guiding agricultural production practices. Full article

(This article belongs to the Special Issue Water and Soil Resources Management in Agricultural Areas)

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23 pages, 13743 KiB

Open AccessArticle

Numerical Investigation on a Flash Flood Disaster in Streams with Confluence and Bifurcation

by Qingyuan Yang, Xiekang Wang, Yi Sun, Wengang Duan and Shan Xie

Water 2022, 14(10), 1646; https://doi.org/10.3390/w14101646 - 21 May 2022

Cited by 4 | Viewed by 1836

Abstract

On 20 August 2019, a flash flood occurred in Sanjiang Town, Sichuan, China, and caused great damage to people living there. The town lies at the junction of five streams, with streams A, B, and C combining at the town and further dividing [...] Read more.

On 20 August 2019, a flash flood occurred in Sanjiang Town, Sichuan, China, and caused great damage to people living there. The town lies at the junction of five streams, with streams A, B, and C combining at the town and further dividing into streams D and E. The slope of streams A, B, and C is about 3~5%, while the slope of streams D and E is around 0.3%. The Sanjiang Town actually lies in the transition from supercritical slope to subcritical slope. During the flood, huge sediments were released to streams A, B, and C, and further transported to stream E. Due to the rapid change of velocity, only few sediments deposited at the supercritical slope parts of the stream, while plenty of them sedimented at the streams with subcritical slope. In order to simulate the flood with a hydrodynamic model, a field investigation was carried out to collect high DEM (digital elevation model) data, flood marks, sediment grading, etc., after the flood. The discharge curve of the flood was also obtained by the hydrometric station near Sanjiang Town. For the inlet sediment concentrations of streams A, B, and C, we made a series of assumptions and utilized the case which best fits the flood marks to set the inlet sediment concentration. Based on these data, we adopted a depth-averaged two-dimensional hydrodynamic model coupled with a sediment transport model to simulate the flash flood accident. The results revealed that the flash flood enlargement in confluence streams is mainly induced by the inflows, and the flash flood enlargement in bifurcation streams is largely affected by the sediment deposition. The bifurcation of flows can decrease the peak discharge of each branch, but may increase the flooded area near the streams. Flow in the supercritical slope runs at a very fast velocity, and seldom deposits sediment in the steep channel. Meanwhile, most sediment is transported to the streams with flat hydraulic slopes. Due to the functioning of the reservoir, the transition region from supercritical slope to subcritical slope has a much larger probability of being submerged during the flood. Full article

(This article belongs to the Special Issue Flash Floods: Forecasting, Monitoring and Mitigation Strategies)

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25 pages, 3456 KiB

Open AccessReview

Toward Water, Energy, and Food Security in Rural Indonesia: A Review

by Hunggul Yudono Setio Hadi Nugroho, Dewi Retna Indrawati, Nining Wahyuningrum, Rahardyan Nugroho Adi, Agung Budi Supangat, Yonky Indrajaya, Pamungkas Buana Putra, Sigit Andy Cahyono, Agung Wahyu Nugroho, Tyas Mutiara Basuki, Endang Savitri, Tri Wira Yuwati, Budi Hadi Narendra, Markus Kudeng Sallata, Merryana Kiding Allo, Achmad Rizal Bisjoe, Nurhaedah Muin, Wahyudi Isnan, Fajri Ansari, Aris Sudomo and Aditya Hani Show full author list Hide full author list

Water 2022, 14(10), 1645; https://doi.org/10.3390/w14101645 - 20 May 2022

Cited by 14 | Viewed by 6349

Abstract

Indonesia is an archipelago with significant variations in natural resources, infrastructure, socioeconomic, culture, human resource capacity, accessibility, and access to financial and technical assistance. In this situation, integrated and unique efforts are needed to manage natural resources and build synergy between their protection [...] Read more.

Indonesia is an archipelago with significant variations in natural resources, infrastructure, socioeconomic, culture, human resource capacity, accessibility, and access to financial and technical assistance. In this situation, integrated and unique efforts are needed to manage natural resources and build synergy between their protection and utilization to achieve water, energy, and food (WEF) security in accordance with the SDG targets. This paper analyzes the implementations of the WEF nexus in rural Indonesia by examining existing legal frameworks and other related policies, journals, textbooks, and publications. We explore factors influencing the success and failure of the implementation of the WEF nexus approaches from technical, socioeconomic, cultural, political, and institutional perspectives of the rural development framework. Full article

(This article belongs to the Special Issue The Food-Energy-Water Nexus: Governing Key Resources for Sustainable Development)

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27 pages, 7010 KiB

Open AccessArticle

Insight into ANN and RSM Models’ Predictive Performance for Mechanistic Aspects of Cr(VI) Uptake by Layered Double Hydroxide Nanocomposites from Water

by Nuhu Dalhat Mu’azu

Water 2022, 14(10), 1644; https://doi.org/10.3390/w14101644 - 20 May 2022

Cited by 4 | Viewed by 2197

Abstract

Mathematical predictive models are vital tools for understanding of pollutant uptake during adsorptive water and wastewater treatment processes. In this study, applications of CoAl-LDH and its bentonite-CoAl intercalated LDH (bentonite-CoAl-LDH) for uptake of Cr(VI) from water were modeled using response surface methodology (RSM) [...] Read more.

Mathematical predictive models are vital tools for understanding of pollutant uptake during adsorptive water and wastewater treatment processes. In this study, applications of CoAl-LDH and its bentonite-CoAl intercalated LDH (bentonite-CoAl-LDH) for uptake of Cr(VI) from water were modeled using response surface methodology (RSM) and artificial neural network (ANN), and their performance for predicting equilibrium, thermodynamics and kinetics of the Cr(VI) uptake were assessed and compared based on coefficient of determination (R2) and root mean square error (RMSE). The uptake of Cr(VI) fits well quartic RSM polynomial models and ANN models based on Levenberg–Marquardt algorithms (ANN-LMA). Both models predicted a better fit for the Langmuir model compared to the Freundlich model for the Cr(VI) uptake. The predicted non-linear Langmuir model contestant (K_L) values, for both the RSM and ANN-LMA models yielded better ΔG°, ΔH and ΔS predictions which supported the actual feasible, spontaneous and greater order of reaction as well as exothermic nature of Cr(VI) uptake onto the tested adsorbents. Employing the linear Langmuir model K_L values dwindles the thermodynamic parameter predictions, especially for the RSM models. The excellent kinetic parameter predictions for the ANN-LMA models further indicate a mainly pseudo-second-order process, thus confirming the predominant chemisorption mechanism as established by the Cr(VI) speciation and surface charges for the Cr(VI) uptake by both CoAl-LDH and bentonite-CoAl-LDH. The ANN-LMA models showed consistent and insignificant decline in their predictions under different mechanistic studies carried out compared to the RSM models. This study demonstrates the high potential reliability of ANN-LMA models in capturing Cr(VI) adsorption data for LDHs nanocomposite heavy metal uptake in water and wastewater treatment. Full article

(This article belongs to the Special Issue New Perspectives in Environmental Catalysis and Oxidation Processes for Removal of Pollutants from Water)

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30 pages, 9368 KiB

Open AccessArticle

Prediction of Total Nitrogen and Phosphorus in Surface Water by Deep Learning Methods Based on Multi-Scale Feature Extraction

by Miao He, Shaofei Wu, Binbin Huang, Chuanxiong Kang and Faliang Gui

Water 2022, 14(10), 1643; https://doi.org/10.3390/w14101643 - 20 May 2022

Cited by 16 | Viewed by 2957

Abstract

To improve the precision of water quality forecasting, the variational mode decomposition (VMD) method was used to denoise the total nitrogen (TN) and total phosphorus (TP) time series and obtained several high- and low-frequency components at four online surface water quality monitoring stations [...] Read more.

To improve the precision of water quality forecasting, the variational mode decomposition (VMD) method was used to denoise the total nitrogen (TN) and total phosphorus (TP) time series and obtained several high- and low-frequency components at four online surface water quality monitoring stations in Poyang Lake. For each of the aforementioned high-frequency components, a long short-term memory (LSTM) network was introduced to achieve excellent prediction results. Meanwhile, a novel metaheuristic optimization algorithm, called the chaos sparrow search algorithm (CSSA), was implemented to compute the optimal hyperparameters for the LSTM model. For each low-frequency component with periodic changes, the multiple linear regression model (MLR) was adopted for rapid and effective prediction. Finally, a novel combined water quality prediction model based on VMD-CSSA-LSTM-MLR (VCLM) was proposed and compared with nine prediction models. Results indicated that (1), for the three standalone models, LSTM performed best in terms of mean absolute error (MAE), mean absolute percentage error (MAPE), and the root mean square error (RMSE), as well as the Nash–Sutcliffe efficiency coefficient (NSE) and Kling–Gupta efficiency (KGE). (2) Compared with the standalone model, the decomposition and prediction of TN and TP into relatively stable sub-sequences can evidently improve the performance of the model. (3) Compared with CEEMDAN, VMD can extract the multiscale period and nonlinear information of the time series better. The experimental results proved that the averages of MAE, MAPE, RMSE, NSE, and KGE predicted by the VCLM model for TN are 0.1272, 8.09%, 0.1541, 0.9194, and 0.8862, respectively; those predicted by the VCLM model for TP are 0.0048, 10.83%, 0.0062, 0.9238, and 0.8914, respectively. The comprehensive performance of the model shows that the proposed hybrid VCLM model can be recommended as a promising model for online water quality prediction and comprehensive water environment management in lake systems. Full article

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

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19 pages, 3304 KiB

Open AccessArticle

Gas–Water Two-Phase Flow Characteristics and Flowback Evaluation for Shale Gas Wells

by Weiyang Xie, Jianfa Wu, Xuefeng Yang, Cheng Chang and Jian Zhang

Water 2022, 14(10), 1642; https://doi.org/10.3390/w14101642 - 20 May 2022

Cited by 3 | Viewed by 2012

Abstract

The dynamic characteristics of shale gas wells are complexly affected by the gas–water two-phase flow. Based on the special flow mechanism of gas–water two-phase flow in shale gas reservoir, this paper establishes a mathematical model for gas–water two-phase flow in shale gas multi-stage [...] Read more.

The dynamic characteristics of shale gas wells are complexly affected by the gas–water two-phase flow. Based on the special flow mechanism of gas–water two-phase flow in shale gas reservoir, this paper establishes a mathematical model for gas–water two-phase flow in shale gas multi-stage fractured horizontal wells, introduces the eigenvalue method and orthogonal transformation, and obtains the analytical solution of the two-phase flow model. The gas–water two-phase flow rules and main influence factors of shale gas wells were identified, further combined with the flowback test characteristics and data of the shale gas wells in southern Sichuan, the characteristic parameters for the evaluation of the gas well flowback effect were determined, and an index system was established for the evaluation of shale gas well flowback. The analysis result shows that the shale gas well flowback effect has a good relationship with its production capacity, which is mainly reflected in the flowback characteristic parameters such as gas breakthrough time, gas breakthrough flowback rate, 30 d flowback rate, and maximum production flowback rate. The shale gas wells with lower flowback factors have a better production capacity than those with higher flowback factors. The flowback evaluation index system can accurately forecast the shale gas well production capacity in its initial stage, and furthermore offer guidance to promptly ascertaining the block development potential and formulating the development schemes. Full article

(This article belongs to the Special Issue Flow and Transport in Fractured Porous Media)

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21 pages, 8401 KiB

Open AccessArticle

Development and Application of a Real-Time Flood Forecasting System (RTFlood System) in a Tropical Urban Area: A Case Study of Ramkhamhaeng Polder, Bangkok, Thailand

by Detchphol Chitwatkulsiri, Hitoshi Miyamoto, Kim Neil Irvine, Sitang Pilailar and Ho Huu Loc

Water 2022, 14(10), 1641; https://doi.org/10.3390/w14101641 - 20 May 2022

Cited by 18 | Viewed by 5193

Abstract

In urban areas of Thailand, and especially in Bangkok, recent flash floods have caused severe damage and prompted a renewed focus to manage their impacts. The development of a real-time warning system could provide timely information to initiate flood management protocols, thereby reducing [...] Read more.

In urban areas of Thailand, and especially in Bangkok, recent flash floods have caused severe damage and prompted a renewed focus to manage their impacts. The development of a real-time warning system could provide timely information to initiate flood management protocols, thereby reducing impacts. Therefore, we developed an innovative real-time flood forecasting system (RTFlood system) and applied it to the Ramkhamhaeng polder in Bangkok, which is particularly vulnerable to flash floods. The RTFlood system consists of three modules. The first module prepared rainfall input data for subsequent use by a hydraulic model. This module used radar rainfall data measured by the Bangkok Metropolitan Administration and developed forecasts using the TITAN (Thunderstorm Identification, Tracking, Analysis, and Nowcasting) rainfall model. The second module provided a real-time task management system that controlled all processes in the RTFlood system, i.e., input data preparation, hydraulic simulation timing, and post-processing of the output data for presentation. The third module provided a model simulation applying the input data from the first and second modules to simulate flash floods. It used a dynamic, conceptual model (PCSWMM, Personal Computer version of the Stormwater Management Model) to represent the drainage systems of the target urban area and predict the inundation areas. The RTFlood system was applied to the Ramkhamhaeng polder to evaluate the system’s accuracy for 116 recent flash floods. The result showed that 61.2% of the flash floods were successfully predicted with accuracy high enough for appropriate pre-warning. Moreover, it indicated that the RTFlood system alerted inundation potential 20 min earlier than separate flood modeling using radar and local rain stations individually. The earlier alert made it possible to decide on explicit flood controls, including pump and canal gate operations. Full article

(This article belongs to the Special Issue Advances in the Real-Time Monitoring and Control of Urban Water Networks)

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