Water

Research

17 pages, 5617 KiB

Open AccessArticle

Microplastic and Fibre Contamination in a Remote Mountain Lake in Switzerland

by Angel de Jesús Negrete Velasco, Lionel Rard, Wilfried Blois, David Lebrun, Franck Lebrun, Franck Pothe and Serge Stoll

Water 2020, 12(9), 2410; https://doi.org/10.3390/w12092410 - 27 Aug 2020

Cited by 65 | Viewed by 6521

Abstract

The contamination of aquatic environments by microplastics has been largely documented in the last years, especially in oceans, rivers, and lakes, but their occurrence in remote mountain lakes has been scarcely considered. This work aims to investigate the presence and abundance of microplastics [...] Read more.

The contamination of aquatic environments by microplastics has been largely documented in the last years, especially in oceans, rivers, and lakes, but their occurrence in remote mountain lakes has been scarcely considered. This work aims to investigate the presence and abundance of microplastics and fibres in a remote, alpine, and uninhabited lake in Switzerland (Sassolo). In this study, the water column as well as the sediments were analysed. The isolation of microplastics and fibres from the samples of the sediment was achieved with a digestion process using H₂O₂ and a density separation technique with NaI. Classification of microparticles (from 5 mm to 125 μm) was first developed with an optical microscope. Infrared spectroscopy was then used to identify and characterize the chemical nature of the microplastics and fibres. On average, 2.6 microplastics and 4.4 fibres per litre were identified in the water column. On the other hand, the results of the sediment samples revealed significant fibre concentrations compared to plastic microparticles (514 fibres and 33 microplastics per kilogram). The most abundant types of microplastic identified in the samples were composed of polyethylene (PE) and polypropylene (PP). Microplastic and fibre sources were not determined, but it is likely that the number of human activities in this area as well as aerial deposition are contributing to contaminate this remote environment with microplastics and fibres. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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15 pages, 4024 KiB

Open AccessArticle

Transient Evolution of Inland Freshwater Lenses: Comparison of Numerical and Physical Experiments

by Rachel Rotz, Adam Milewski and Todd C Rasmussen

Water 2020, 12(4), 1154; https://doi.org/10.3390/w12041154 - 17 Apr 2020

Cited by 5 | Viewed by 3015

Abstract

Brackish to saline groundwater in arid environments encourages the development and sustainability of inland freshwater lenses (IFLs). While these freshwater resources supply much-needed drinking water throughout the Arabian Peninsula and other drylands, little is understood about their sustainability. This study presents a numerical [...] Read more.

Brackish to saline groundwater in arid environments encourages the development and sustainability of inland freshwater lenses (IFLs). While these freshwater resources supply much-needed drinking water throughout the Arabian Peninsula and other drylands, little is understood about their sustainability. This study presents a numerical model using the SEAWAT programming code (i.e., MODFLOW and the Modular Three-Dimensional Multispecies Transport Model (MT3DMS)) to simulate IFL transient evolution. The numerical model is based on a physical laboratory model and calibrated using results from simulations conducted in a previous study of the Raudhatain IFL in northern Kuwait. Data from three previously conducted physical model simulations were evaluated against the corresponding numerical model simulations. The hydraulic conductivities in the horizontal and vertical directions were successfully optimized to minimize the objective function of the numerical model simulations. The numerical model matched observed IFL water levels at four locations through time, as well as IFL thicknesses and lengths (R² = 0.89, 0.94, 0.85). Predicted lens degradation times corresponded to the observed lenses, which demonstrated the utility of numerical models and physical models to assess IFL geometry and position. Improved understanding of IFL dynamics provides water-resource exploration and development opportunities in drylands throughout the Arabian Peninsula and elsewhere with similar environmental settings. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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14 pages, 5684 KiB

Open AccessArticle

Coupled Multifield Response to Coordinate Mining of Coal and Uranium: A Case Study

by Tong Zhang, Liang Yuan, Zhen Wei and Yang Liu

Water 2020, 12(1), 139; https://doi.org/10.3390/w12010139 - 1 Jan 2020

Cited by 5 | Viewed by 2701

Abstract

The coordinate mining of stack resources in the Ordos Basin, which involves the coupling effects of stress fracture, seepage, and reactive solute transport, plays an important role in resource exploration and environment protection. A coupled multiphysical–chemical model, involving a modified non-Darcy flow model, [...] Read more.

The coordinate mining of stack resources in the Ordos Basin, which involves the coupling effects of stress fracture, seepage, and reactive solute transport, plays an important role in resource exploration and environment protection. A coupled multiphysical–chemical model, involving a modified non-Darcy flow model, a leaching solution reaction, and a reactive solute transport model, was developed in this study. The Fast Lagrangian Analysis of Continua -Computational Fluid Dynamics (FLAC3D-CFD) simulator coupled with the developed models was used to investigate the evolution and morphology of mining-induced multifield coupling for the scenarios of concurrent mining and asynchronous mining of coal and uranium. As mining advanced to 160 m, the maximum principle stress characterized by a stress shell was observed. As mining progressed to 280 m, a rupture occurred, and a new stress shell was generated as a rear skewback was formed by the concentrated stress of the stope. An “arch-shaped” fracture field combined with a “saddle-shaped” seepage field was identified in the destressed zone of the stress shell. In the coordinated mining of uranium prior to coal, “funnel-shaped” and “asymmetric saddle-shaped” morphologies of the leaching solution were found during coal mining for ventilation in the stope and mining face. By contrast, “saddle-shaped”, “inclined funnel-shaped”, and “horizontal” morphologies of the leaching solution were observed for a short period for ventilation of the stope and mining face for coal mining prior to uranium mining, uranium mining prior to coal mining, and synchronized coal and uranium mining. A dynamic stress response was obtained in the coal seam, followed by the conglomerate aquifer and the uranium deposits. The diffusion depth of the solution was negatively correlated with the injection velocity and the pumping ratio and positively correlated with the diffusion coefficient. A dynamic increase in diffusion depth was observed as the diffusion coefficient increased to 1 × 10⁻⁴ m²/s. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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16 pages, 4458 KiB

Open AccessArticle

Numerical Rainfall Simulation of Different WRF Parameterization Schemes with Different Spatiotemporal Rainfall Evenness Levels in the Ili Region

by Zhenxia Mu, Yulin Zhou, Liang Peng and Ying He

Water 2019, 11(12), 2569; https://doi.org/10.3390/w11122569 - 5 Dec 2019

Cited by 6 | Viewed by 3161

Abstract

To obtain high-precision precipitation simulation results, different types of rainfall events in the Ili Region are simulated by using the Weather Research and Forecasting (WRF) model with different physical parameterization schemes. According to the spatiotemporal distribution of rainfall evenness, six rainfall events in [...] Read more.

To obtain high-precision precipitation simulation results, different types of rainfall events in the Ili Region are simulated by using the Weather Research and Forecasting (WRF) model with different physical parameterization schemes. According to the spatiotemporal distribution of rainfall evenness, six rainfall events in the Ili Region are divided into four types. Six microphysical parameterization (MP) schemes, five planetary boundary layer (PBL) schemes, and five cumulus (CU) schemes are combined into 14 parameterization members to simulate the rainfall events. It is worth noting that the simulation result sequence of the WRF model (from best to worst) is as follows: type I (events 3 and 5) > type II (events 1 and 6) > type III (event 2) > type IV (event 4). This finding would imply that the WRF model has the best performance for rainfall events with even spatiotemporal distributions, while it is hard to achieve good simulation results for rainfall events with highly uneven spatial and temporal distributions. The results suggest that no single combination of parameterization members provides the best performance for all rainfall events. According to the overall scheme rankings, d, n, and j are the optimal parameterization combination members that accurately describe the spatiotemporal characteristics of the six rainfall events. The study provides guidance for the selection of the physical parameters for the accurate simulation of different types of rainfall events in the arid region of northwestern China. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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17 pages, 4480 KiB

Open AccessArticle

Method for Identifying and Estimating Karst Groundwater Runoff Components Based on the Frequency Distributions of Conductivity and Discharge

by Zejun Wang, Qianlong Chen, Ziqi Yan, Mingming Luo, Hong Zhou and Wei Liu

Water 2019, 11(12), 2494; https://doi.org/10.3390/w11122494 - 26 Nov 2019

Cited by 9 | Viewed by 3263

Abstract

Identification and estimation of groundwater runoff components in karst groundwater systems to improve understanding of karst water circulation and water-rock interactions is essential for water resources assessment and development. A Gaussian mixture model is presented for identifying and estimating karst groundwater runoff components [...] Read more.

Identification and estimation of groundwater runoff components in karst groundwater systems to improve understanding of karst water circulation and water-rock interactions is essential for water resources assessment and development. A Gaussian mixture model is presented for identifying and estimating karst groundwater runoff components based on the frequency distributions of conductivity and discharge. Successful application of this method in the Heilongquan karst spring in South China showed that groundwater runoff components can be divided into 6–8 grades, corresponding to the grades of groundwater in karst fissures. The conductivity and discharge thresholds dividing fast and slow flow were determined to be approximately 300 μS cm⁻¹ and 0.3 m³ s⁻¹, respectively, with fast flow exhibiting lower conductivity and larger discharge. On an annual basis, fast flow occurred 9% of the time and accounted for 35% of total water volume. The results of the method compared favorably to that of hydrograph recession analysis. Estimation of groundwater runoff components based on frequency distributions of conductivity and discharge provides a novel alternative method for the quantitative evaluation of karst water resources. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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14 pages, 4795 KiB

Open AccessArticle

The Well Efficiency Criteria Revisited—Development of a General Well Efficiency Criteria (GWEC) Based on Rorabaugh’s Model

by Bedri Kurtulus, Tolga Necati Yaylım, Ozgur Avşar, Halit Fatih Kulac and Moumtaz Razack

Water 2019, 11(9), 1784; https://doi.org/10.3390/w11091784 - 27 Aug 2019

Cited by 7 | Viewed by 5971

Abstract

The Strategic Water Storage & Recovery (SWSR) Project in Liwa, Abu Dhabi is a leading and unique hydrogeology project in the world because of both its financial and scientific dimensions. The objective of the project is to store desalinized water in the local [...] Read more.

The Strategic Water Storage & Recovery (SWSR) Project in Liwa, Abu Dhabi is a leading and unique hydrogeology project in the world because of both its financial and scientific dimensions. The objective of the project is to store desalinized water in the local Liwa aquifer, to be able to supply water to Abu Dhabi in case of emergency. A total of 315 recovery wells have been drilled in pursuance of the scope of the SWSR project. Out of the total 315 wells, 25 wells met construction problems and were removed from the study. The remaining 290 wells have been analyzed using step drawdown tests (SDTs) and the model of Rorabaugh. This provided a large and unique database regarding the parameters of this model: linear aquifer-loss coefficient (B), non-linear well-loss coefficient (C) and the exponent p. Analysis of this exceptional data set revealed noteworthy and novel findings: (1) the range of the exponent p values is found to be very extensive, varying from 0.35 to 6.01. For comparison, the highest values of p given in the literature very seldom exceed 4; (2) p behaves like a lognormal variable; (3) parameters C and p are closely correlated. A semi-logarithmic diagram displays a linear relation of p vs. log C, with a determination coefficient R² = 0.83; (4) A graphical and tabulated procedure, termed General Well Efficiency Criteria, is proposed to assess well efficiency. Given the very wide range of p values implied in this procedure, it becomes possible thus to assess the efficiency of any well analyzed with an SDT. This study finally raises questions about Jacob’s model validity, which assumes that p is constant and equal to 2. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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18 pages, 12890 KiB

Open AccessArticle

Control Effects of Hydraulic Interception Wells on Groundwater Pollutant Transport in the Dawu Water Source Area

by Henghua Zhu, Jianwei Zhou, Chao Jia, Sheng Yang, Jing Wu, Lizhi Yang, Zhengrun Wei, Hongwei Liu and Zhizheng Liu

Water 2019, 11(8), 1663; https://doi.org/10.3390/w11081663 - 11 Aug 2019

Cited by 3 | Viewed by 3339

Abstract

Based on the comprehensive analysis of hydrogeological data of the Dawu water source in Zibo city, the Modflow module in Groundwater Modeling System is used to carry out three-dimensional geological modeling of the Dawu water source, and the flow field model and solute [...] Read more.

Based on the comprehensive analysis of hydrogeological data of the Dawu water source in Zibo city, the Modflow module in Groundwater Modeling System is used to carry out three-dimensional geological modeling of the Dawu water source, and the flow field model and solute transport model of the Dawu water source are established. Aiming at the problem of groundwater pollution in the key polluted area of the Hougao region—the Dawu water source—the pollutant transport model is established to explore the process of pollution transport. There are many types of groundwater pollutants in the Hougao area. Among them, ammonia nitrogen, chloride, petroleum, and benzene exceed the standard most seriously. In order to facilitate the research, we selected typical pollutants for in-depth study. The ammonia nitrogen is used as the control index of domestic and industrial waste water in the policy documents of pollution emission. It can show the specific situation of industrial waste water and domestic waste water pollution changing with time. Thus, the ammonia nitrogen with a higher exceeding standard is selected as the pollution factor in this simulation. Pollutant transport under the conditions of strong pumping and stop pumping is simulated. It is found that the pollutant is effectively controlled due to the pumping and discharging effects under the action of strong pumping, from 4 to 5 times exceeding the standard to slightly exceeding the standard. However, there is still a trend of migration to the eastern water supply area. After the pumping is stopped, the pollutant quickly migrates to the Xixia centralized water supply area, causing serious pollution to the water supply area. Finally, four other hydraulic interception wells are set up in the 500 m east of Hougao’s four wells to further control the pollutant transport. When hydraulic interception wells and strong pumping wells are used together, the scope of ammonia nitrogen pollution is basically controlled near the interception wells, and it does not continue to spread to the eastern water supply area. The maximum monitoring value of pollution is 0.11 mg/L, which is controlled within the standard limit of three types of groundwater, and the pollutant control effect is the best, providing certain reference for similar pollution control work. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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19 pages, 13065 KiB

Open AccessArticle

Hydrochemical Characteristics and Temporal Variations of Geothermal Water Quality in Tangtou, Shandong, China

by Zongjun Gao, Jiutan Liu, Fuquan Li, Min Wang, Jianguo Feng and Guangwei Wu

Water 2019, 11(8), 1643; https://doi.org/10.3390/w11081643 - 8 Aug 2019

Cited by 9 | Viewed by 3408

Abstract

Geothermal water resources are a kind of clean energy, which is a renewable resource to a certain extent and has a high value of development and utilization. To understand the hydrochemical characteristics, origins, and temporal variations of geothermal water quality in Tangtou, 13 [...] Read more.

Geothermal water resources are a kind of clean energy, which is a renewable resource to a certain extent and has a high value of development and utilization. To understand the hydrochemical characteristics, origins, and temporal variations of geothermal water quality in Tangtou, 13 geothermal water samples from 2007 to 2019 and geothermal geological conditions were collected. Cl⁻ and Na⁺ are the major ions, which make the geothermal water belong Cl-Na type. The total dissolved solids values of geothermal waters were 1560–2512 mg/L and pH were in the range of 6.7–8.8. The development of faulted structures provides conditions for the formation of geothermal water. In addition, geothermal water is recharged by shallow underground cold water. Water-rock interaction, as well as mixing processes, in the process of long runoff path and the slower deep-water cycle is the main factor controlling the chemical composition of geothermal water. Calculated saturation index values indicated that the geothermal water was saturated with respect to silicate and carbonate minerals. Cation and silica chemical geothermometers indicated that reservoir temperatures ranged from 94.63 to 196.10 °C and from 69.13 to 123.75 °C, respectively. Based on the grey relational analysis, the main physicochemical components of geothermal water are obviously correlated with the geothermal water exploitation and precipitation. Overall, affected by exploitation and precipitation, main physicochemical components (such as the total dissolved solids, total hardness, temperature, Na⁺, Ca²⁺, Cl⁻, K⁺, and Mg²⁺) showed a certain stage. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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19 pages, 4290 KiB

Open AccessArticle

Hydrogeochemical Characteristics and the Suitability of Groundwater in the Alluvial-Diluvial Plain of Southwest Shandong Province, China

by Zongjun Gao, Jiutan Liu, Jianguo Feng, Min Wang and Guangwei Wu

Water 2019, 11(8), 1577; https://doi.org/10.3390/w11081577 - 30 Jul 2019

Cited by 40 | Viewed by 4501

Abstract

The alluvial-diluvial plain of southwest Shandong Province is an important agricultural economic zone and energy base in Shandong Province. Groundwater plays an extremely significant role in the development of the regional social economy. In this study, 50 sets of water samples, collected from [...] Read more.

The alluvial-diluvial plain of southwest Shandong Province is an important agricultural economic zone and energy base in Shandong Province. Groundwater plays an extremely significant role in the development of the regional social economy. In this study, 50 sets of water samples, collected from 25 wells during October 2016 and June 2017, were utilized to determine the hydrogeochemistry and the suitability of groundwater in the alluvial-diluvial plain of southwest Shandong Province for different applications, such as drinking and irrigation. Most of the water samples could be classified as hard-fresh water or hard-brackish water, and the dominant water types were HCO₃-Na and mixed types. Water-rock interactions and evaporation were the dominant controlling factors in the formation of the hydrochemical components in the groundwater. Dissolutions of silicate, calcite, dolomite, and gypsum are the major reactions contributing and defining the groundwater chemistry in this plain. Moreover, cation exchange is a non-negligible hydrogeochemical process in this plain. Calculated saturation index (SI) values indicate that aragonite, calcite and dolomite are saturated, while the SI values for gypsum and halite are unsaturated. Based on fuzzy comprehensive evaluation, the groundwater quality ranges from excellent to very poor. More than 50% of all groundwater samples from 2016 are categorized as poor or very poor, suggesting that the water from these wells is not suitable for drinking. According to the sodium adsorption ratio and percentage sodium, most of the samples are suitable for agricultural irrigation. Overall, the quality of the groundwater in 2017 was found to be better than in 2016. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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15 pages, 6363 KiB

Open AccessArticle

Rooting Depth and Extreme Precipitation Regulate Groundwater Recharge in the Thick Unsaturated Zone: A Case Study

by Jin Shao, Bingcheng Si and Jiming Jin

Water 2019, 11(6), 1232; https://doi.org/10.3390/w11061232 - 13 Jun 2019

Cited by 8 | Viewed by 3658

Abstract

Many modeling efforts have been made for shallow soil, but little has been done in deep-rooted ecosystems, especially on the long-term impact of deep-rooted vegetation to understand the impact of vegetation type on hydrological processes. In this study, we used the Community Land [...] Read more.

Many modeling efforts have been made for shallow soil, but little has been done in deep-rooted ecosystems, especially on the long-term impact of deep-rooted vegetation to understand the impact of vegetation type on hydrological processes. In this study, we used the Community Land Model (CLM) version 4.0 to simulate the soil water dynamics and groundwater recharge with shallow-rooted and deep-rooted vegetation cover in the critical soil zone of 100 m thickness. We selected winter wheat and summer maize to represent shallow-rooted vegetation and apple trees as deep-rooted vegetation growing in the semi-humid Loess Plateau of China over the period of 1901–2015. Our results show that the rooting depth and precipitation dictate the occurrence of disconnected recharge. This occurred in soil depths that were below 75 m in wet years with annual precipitation of over 650, 730, and 1000 mm for the winter wheat field, summer maize field, and apple orchard, respectively. Connected recharge was the major component of groundwater recharge for all three crop fields. The transit time of precipitation ranged from several to hundreds of years via the disconnected recharge that is caused by extreme precipitation and the connected recharge that is generated by other precipitation. Therefore, both rooting depth and growth period of vegetation affect the groundwater recharge and transit time, as well as precipitation. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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23 pages, 5308 KiB

Open AccessArticle

Attribution Analysis of Dry Season Runoff in the Lhasa River Using an Extended Hydrological Sensitivity Method and a Hydrological Model

by Zhenhui Wu, Yadong Mei, Junhong Chen, Tiesong Hu and Weihua Xiao

Water 2019, 11(6), 1187; https://doi.org/10.3390/w11061187 - 7 Jun 2019

Cited by 13 | Viewed by 3465

Abstract

In this study, a coupled water–energy balance equation at an arbitrary time scale was proposed as an extension of the Budyko hypothesis. The second mixed partial derivative was selected to represent the magnitude of the interaction. The extended hydrological sensitivity method was used [...] Read more.

In this study, a coupled water–energy balance equation at an arbitrary time scale was proposed as an extension of the Budyko hypothesis. The second mixed partial derivative was selected to represent the magnitude of the interaction. The extended hydrological sensitivity method was used to quantitatively evaluate the impacts of climate change, anthropogenic activities, and their interaction on dry season runoff in the Lhasa River. In addition, an ABCD model, which is a monthly hydrological model included a snowmelt module, was used to calculate the change in soil water and groundwater storage. The Mann–Kendall test, Spearman’s test, dynamic linear model (DLM), and Yamamoto’s method were used to identify trends and change points in hydro-climatic variables from 1956–2016. The results found that dry season runoff increased non-significantly over the last 61 years. Climate change, which caused an increase in dry season runoff, was the dominant factor, followed by anthropogenic activities and their interaction, which led to varying degrees of decrease. This study concluded that the methods tested here performed well in quantifying the relative impacts of climate change, anthropogenic activities, and their interaction on dry season runoff change. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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19 pages, 4809 KiB

Open AccessArticle

A Numerical Study on Travel Time Based Hydraulic Tomography Using the SIRT Algorithm with Cimmino Iteration

by Pengxiang Qiu, Rui Hu, Linwei Hu, Quan Liu, Yixuan Xing, Huichen Yang, Junjie Qi and Thomas Ptak

Water 2019, 11(5), 909; https://doi.org/10.3390/w11050909 - 30 Apr 2019

Cited by 15 | Viewed by 3700

Abstract

Travel time based hydraulic tomography is a technique for reconstructing the spatial distribution of aquifer hydraulic properties (e.g., hydraulic diffusivity). Simultaneous Iterative Reconstruction Technique (SIRT) is a widely used algorithm for travel time related inversions. Due to the drawbacks of SIRT implementation in [...] Read more.

Travel time based hydraulic tomography is a technique for reconstructing the spatial distribution of aquifer hydraulic properties (e.g., hydraulic diffusivity). Simultaneous Iterative Reconstruction Technique (SIRT) is a widely used algorithm for travel time related inversions. Due to the drawbacks of SIRT implementation in practice, a modified SIRT with Cimmino iteration (SIRT-Cimmino) is proposed in this study. The incremental correction is adjusted, and an iteration-dependent relaxation parameter is introduced. These two modifications enable an appropriate speed of convergence, and the stability of the inversion process. Furthermore, a new result selection rule is suggested to determine the optimal iteration step and its corresponding result. SIRT-Cimmino and SIRT are implemented and verified by using two numerical aquifer models with different predefined (“true”) diffusivity distributions, where high diffusivity zones are embedded in a homogenous low diffusivity field. Visual comparison of the reconstructions shows that the reconstruction based on SIRT-Cimmino demonstrates the aquifer’s hydraulic features better than the conventional SIRT algorithm. Root mean square errors and correlation coefficients are also used to quantitatively evaluate the performance of the inversion. The reconstructions based on SIRT-Cimmino are found to preserve the connectivity of the high diffusivity zones and to provide a higher structural similarity to the “true” distribution. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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14 pages, 3007 KiB

Open AccessArticle

Behavior of TiO₂ and CeO₂ Nanoparticles and Polystyrene Nanoplastics in Bottled Mineral, Drinking and Lake Geneva Waters. Impact of Water Hardness and Natural Organic Matter on Nanoparticle Surface Properties and Aggregation

by Lina Ramirez, Stephan Ramseier Gentile, Stéphane Zimmermann and Serge Stoll

Water 2019, 11(4), 721; https://doi.org/10.3390/w11040721 - 6 Apr 2019

Cited by 63 | Viewed by 6285

Abstract

Intensive use of engineered nanoparticles (NPs) in daily products ineluctably results in their release into aquatic systems and consequently into drinking water resources. Therefore, understanding NPs behavior in various waters from naturel to mineral waters is crucial for risk assessment evaluation and the [...] Read more.

Intensive use of engineered nanoparticles (NPs) in daily products ineluctably results in their release into aquatic systems and consequently into drinking water resources. Therefore, understanding NPs behavior in various waters from naturel to mineral waters is crucial for risk assessment evaluation and the efficient removal of NPs during the drinking water treatment process. In this study, the impact of relevant physicochemical parameters, such as pH, water hardness, and presence of natural organic matter (NOM) on the surface charge properties and aggregation abilities of both NPs and nanoplastic particles is investigated. TiO₂, CeO₂, and Polystyrene (PS) nanoplastics are selected, owing to their large number applications and contrasting characteristics at environmental pH. Experiments are performed in different water samples, including, ultrapure water, three bottled mineral waters, Lake Geneva, and drinking water produced from Lake Geneva. Our findings demonstrate that both water hardness and negatively charged natural organic matter concentrations, which were measured via dissolved organic carbon determination, are playing important roles. At environmental pH, when negatively charged nanoparticles are considered, specific cation adsorption is promoting aggregation so long as NOM concentration is limited. On the other hand, NOM adsorption is expected to be a key process in NPs destabilization when positively charged PS nanoplastics are considered. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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25 pages, 5586 KiB

Open AccessArticle

Dominant Influencing Factors of Groundwater Recharge Spatial Patterns in Ergene River Catchment, Turkey

by Emmanuel Rukundo and Ahmet Doğan

Water 2019, 11(4), 653; https://doi.org/10.3390/w11040653 - 29 Mar 2019

Cited by 38 | Viewed by 5771

Abstract

Groundwater is of great significance in sustaining life on planet earth. The reliable estimation of groundwater recharge is the key understanding the groundwater reservoir and forecasting its potential accessibility. The main objective of this study was to assess the groundwater recharge and its [...] Read more.

Groundwater is of great significance in sustaining life on planet earth. The reliable estimation of groundwater recharge is the key understanding the groundwater reservoir and forecasting its potential accessibility. The main objective of this study was to assess the groundwater recharge and its controlling factors at the Ergene river catchment. A grid-based water balance model was adopted to determine the spatially distributed long-term groundwater recharge and other water budget components, relying upon the hydro-climatic variables, land-use, soil, geology, and relief of the investigated area. The model calculations were performed for the hydrological reference horizon of 20 years at a spatial resolution of 100 × 100 m. The base flow index (BFI) separation concept was applied to split up the simulated total runoff into groundwater recharge and direct runoff. Subsequently, the statistical methods of Pearson product–moment correlation and principal component analysis (PCA) were combined for identifying the dominant catchment and meteorological factors influencing the recharge. The average groundwater recharge over the investigated area amounts to 95 mm/year. The model validation and statistical analysis indicate that the difference between simulated and observed total runoff and recharge values is generally under 20% and no significant inconsistency was observed. PCA indicated that recharge is controlled, in order of significance, by land-use, soil, and climate variables. The findings of this research highlight the key role of spatial variables in recharge determination. In addition, the generated outputs may contribute to groundwater resource management in the Ergene river catchment. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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19 pages, 16701 KiB

Open AccessArticle

An Improved Method Constructing 3D River Channel for Flood Modeling

by Pengbo Hu, Jingming Hou, Zaixing Zhi, Bingyao Li and Kaihua Guo

Water 2019, 11(3), 403; https://doi.org/10.3390/w11030403 - 26 Feb 2019

Cited by 4 | Viewed by 3986

Abstract

The high-resolution topography is very crucial to investigate the hydrological and hydrodynamic process. To resolve the deficiency problem of high resolution terrain data in rivers, the Quartic Hermite Spline with Parameter (QHSP) method constructing the river channel terrain based on the limited cross-section [...] Read more.

The high-resolution topography is very crucial to investigate the hydrological and hydrodynamic process. To resolve the deficiency problem of high resolution terrain data in rivers, the Quartic Hermite Spline with Parameter (QHSP) method constructing the river channel terrain based on the limited cross-section data is presented. The proposed method is able to not only improve the reliability of the constructed river terrain, but also avoid the numerical oscillations caused by the existing constructing approach, e.g., the Cubic Hermite Spline (CHS) method. The performance of the proposed QHSP method is validated against two benchmark tests. Comparing the constructed river terrains, the QHSP method can improve the accuracy by at least 15%. For the simulated flood process, the QHSP method could reproduce more acceptable modeling results as well, e.g., in Wangmaogou catchment, the numerical model applying the Digital Elevation Model (DEM) produced by the QHSP method could increase the reliability by 18.5% higher than that of CHS method. It is indicated that the QHSP method is more reliable for river terrain model construction than the CHS and is a more reasonable tool investigating the hydrodynamic processes in river channels lacking of high resolution topography data. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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26 pages, 21145 KiB

Open AccessArticle

Application of Numerical Tools to Investigate a Leaky Aquitard beneath Urban Well Fields

by Farhad Jazaei, Brian Waldron, Scott Schoefernacker and Daniel Larsen

Water 2019, 11(1), 5; https://doi.org/10.3390/w11010005 - 20 Dec 2018

Cited by 13 | Viewed by 8333

Abstract

Memphis aquifer is the primary drinking water source in Shelby County (Tennessee, USA), and it supplies industrial, commercial, and residential water. Memphis aquifer is separated from the Shallow aquifer by a clayey layer known as the Upper Claiborne confining unit (UCCU). All of [...] Read more.

Memphis aquifer is the primary drinking water source in Shelby County (Tennessee, USA), and it supplies industrial, commercial, and residential water. Memphis aquifer is separated from the Shallow aquifer by a clayey layer known as the Upper Claiborne confining unit (UCCU). All of the production wells in the Memphis area are screened in the Memphis aquifer, or even deeper in the Fort Pillow aquifer. Traditionally, it was assumed that the UCCU could fully protect the Memphis aquifer from the contaminated Shallow aquifer groundwater. However, recent studies show that at some locations, the UCCU is thin or absent, which possibly leads to the contribution of Shallow aquifer to the Memphis aquifer. Accurately locating the breaches demands expensive and difficult geological or geochemical investigations, especially within an urban area. Hence, a pre-field investigation to identify the locations where the presence of breaches is likely can significantly reduce the cost of field investigations and improve their results. In this study, to identify the locations where the presence of breaches in the UCCU is likely, we develop a reliable MODFLOW-based numerical model, and use three different analyses: (1) pilot-point calibration (PPC), (2) velocity and flow budget (VFB), and (3) particle tracking (PT), to post-process the developed groundwater model results. These pre-field numerical investigations provide relevant and defensible explanations for groundwater flow anomalies in an aquifer system for informed decision-making and future field investigations. In this study, we identify five specific zones within the broad study area which are reasonable candidates for the future field investigations. Finally, we test the results of each analysis against other evidence for breaches, to demonstrate that the results of the numerical analyses are reliable and supported by previous studies. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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20 pages, 5065 KiB

Open AccessArticle

Groundwater Quality and Suitability for Different Uses in the Saloum Area of Senegal

by Seyni Ndoye, Claude Fontaine, Cheikh Becaye Gaye and Moumtaz Razack

Water 2018, 10(12), 1837; https://doi.org/10.3390/w10121837 - 12 Dec 2018

Cited by 30 | Viewed by 7180

Abstract

Hydrogeochemical analyses were conducted on groundwater sampled from the Saloum aquifer, in southern Senegal. The objective was to identify the chemical processes that control hydrochemistry and to assess the quality of groundwater for determining its suitability for drinking and agricultural purposes. Water samples [...] Read more.

Hydrogeochemical analyses were conducted on groundwater sampled from the Saloum aquifer, in southern Senegal. The objective was to identify the chemical processes that control hydrochemistry and to assess the quality of groundwater for determining its suitability for drinking and agricultural purposes. Water samples were collected from 79 wells during the dry season in May 2012, and were subjected to analysis for chemical characteristics (major ions), pH, electrical conductivity (EC) and total dissolved solid (TDS). The dominant hydrochemical facies observed for the groundwater samples are NaCl and CaHCO₃. Gibbs plot depicts predominance of rock water interaction and evaporation processes controlling the water chemistry. Percentage of Na⁺, Residual Sodium Carbonate (RSC), Total Hardness (TH) and Sodium Adsorption Ratio (SAR) values were calculated. The results were compared with the standard guideline values recommended by the World Health Organization and agricultural water standards. The TDS in groundwater is less than 1200 mg/L and SAR values are less than 10. RSC values overall are less than 1.25 meq/L. Results show that the groundwater in the area has generally a low hardness and is fresh (95%) to brackish. The majority of groundwater samples are appropriate for domestic uses. The indexes for water irrigation compared with standard limits revealed that most of the Saloum groundwater samples fall in the suitable range for irrigation. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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19 pages, 2715 KiB

Open AccessArticle

Modeling the Effects of Spatial Variability of Irrigation Parameters on Border Irrigation Performance at a Field Scale

by Qin’ge Dong, Shaohui Zhang, Meijian Bai, Di Xu and Hao Feng

Water 2018, 10(12), 1770; https://doi.org/10.3390/w10121770 - 1 Dec 2018

Cited by 3 | Viewed by 3454

Abstract

The interaction between surface and subsurface water flows plays an important role in surface irrigation systems. This interaction can effectively be simulated by the physical-based models, which have been developed on the basis of the numerical solutions to the Saint-Venant and Richards’ equations. [...] Read more.

The interaction between surface and subsurface water flows plays an important role in surface irrigation systems. This interaction can effectively be simulated by the physical-based models, which have been developed on the basis of the numerical solutions to the Saint-Venant and Richards’ equations. Meanwhile, the spatial variability of field physical properties (such as soil properties, surface micro-topography, and unit discharge) affects the interaction between surface and subsurface water flows and decreases the accuracy of simulating surface irrigation events at large scales. In this study, a new numerical methodology is developed based on the physical-based model of surface irrigation and the Monte Carlo simulation method to improve the modeling accuracy of surface irrigation performance at a field scale. In the proposed numerical methodology, soil properties, unit discharge, surface micro-topography, roughness, border length, and the cutoff time for the unit discharge are used as the stochastic parameters of the physical-based model, while field slope is assumed as the constant value because of the same field tillage and management conditions at a field scale. Monte Carlo simulation is used to obtain the stochastic parameter sample combinations of the physical-based model to represent the spatial variability of field physical properties. The updated stochastic simulation model of surface micro-topography, which is developed to model the spatial distribution of surface elevation differences (SED), is used to obtain the surface micro-topography samples at a field scale. Compared with the distributed-parameter modelling methodology and the field experimental data, the proposed numerical methodology presents the better simulation performance. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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14 pages, 3871 KiB

Open AccessArticle

Impact of Different Reanalysis Data and Parameterization Schemes on WRF Dynamic Downscaling in the Ili Region

by Yulin Zhou and Zhenxia Mu

Water 2018, 10(12), 1729; https://doi.org/10.3390/w10121729 - 26 Nov 2018

Cited by 7 | Viewed by 4232

Abstract

Different reanalysis data and physical parameterization schemes for the Weather Research and Forecasting (WRF) model are considered in this paper to evaluate their performance in meteorological simulations in the Ili Region. A 72-hour experiment was performed with two domains at the resolution of [...] Read more.

Different reanalysis data and physical parameterization schemes for the Weather Research and Forecasting (WRF) model are considered in this paper to evaluate their performance in meteorological simulations in the Ili Region. A 72-hour experiment was performed with two domains at the resolution of 27 km with one-way nesting of 9 km. (1) Final Analysis (FNL) and Global Forecast System (GFS) reanalysis data (hereafter, WRF-FNL experiment and WRF-GFS experiment, respectively) were used in the WRF model. For the simulation of accumulated precipitation, both the WRF-FNL (mean bias of 0.79 mm) and WRF-GFS (mean bias of 0.31 mm) simulations can display the main features of the general temporal pattern and geographical distribution of the observed precipitation. For the simulation of the 2-m temperature, the simulation of the WRF-GFS experiment (mean warm bias of 1.81 °C and correlation coefficient of 0.83) was generally better than that of the WRF-FNL experiment (mean cold bias of 1.79 °C and correlation coefficient of 0.27). (2) Thirty-six physical combination schemes were proposed, each with a unique set of physical parameters. Member 33 (with the smallest mean-metric of 0.53) performed best for the precipitation simulation, and member 29 (with the smallest mean-metric of 0.64) performed best for the 2-m temperature simulation. However, member 29 and 33 cannot be distinguished from the other members according to their parameterizations. For this domain, ensemble members that contain the Mellor–Yamada–Janjic (MYJ) boundary layer (PBL) scheme and the Grell–Devenyi (GD) cumulus (CU) scheme are recommended for the precipitation simulation. The Geophysical Fluid Dynamics Laboratory (GFDL) radiation (RA) scheme and the MYJ PBL scheme are recommended for the 2-m temperature simulation. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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16 pages, 2935 KiB

Open AccessArticle

A Stochastic Simulation Model for Monthly River Flow in Dry Season

by Wenzhuo Wang, Zengchuan Dong, Feilin Zhu, Qing Cao, Juan Chen and Xiao Yu

Water 2018, 10(11), 1654; https://doi.org/10.3390/w10111654 - 14 Nov 2018

Cited by 9 | Viewed by 3583

Abstract

Streamflow simulation gives the major information on water systems to water resources planning and management. The monthly river flows in dry season often exhibit high autocorrelation. The headwater catchment of the Yellow River basin monthly flow series in dry season exhibits this clearly. [...] Read more.

Streamflow simulation gives the major information on water systems to water resources planning and management. The monthly river flows in dry season often exhibit high autocorrelation. The headwater catchment of the Yellow River basin monthly flow series in dry season exhibits this clearly. However, existing models usually fail to capture the high-dimensional, nonlinear dependence. To address this issue, a stochastic model is developed using canonical vine copulas in combination with nonlinear correlation coefficients. Kendall’s tau values of different pairs of river flows are calculated to measure the mutual correlations so as to select correlated streamflows for every month. Canonical vine copula is used to capture the temporal dependence of every month with its correlated streamflows. Finally, monthly river flow by the conditional joint distribution functions conditioned upon the corresponding river flow records was generated. The model was applied to the simulation of monthly river flows in dry season at Tangnaihai station, which controls the streamflow of headwater catchment of Yellow River basin in the north of China. The results of the proposed method possess a smaller mean absolute error (MAE) than the widely-used seasonal autoregressive integrated moving average model. The performance test on seasonal distribution further verifies the great capacity of the stochastic-statistical method. Full article

(This article belongs to the Special Issue Advances in Hydrogeology: Trend, Model, Methodology and Concepts)

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