Water

24 pages, 5141 KiB

Open AccessArticle

Irrigation Salinity Risk Assessment and Mapping in Arid Oasis, Northwest China

by Jumeniyaz Seydehmet, Guang-Hui Lv, Abdugheni Abliz, Qing-Dong Shi, Abdulla Abliz and Abdusalam Turup

Water 2018, 10(7), 966; https://doi.org/10.3390/w10070966 - 23 Jul 2018

Cited by 13 | Viewed by 5122

Abstract

Irrigation salinity is a common environmental threat for sustainable development in the Keriya Oasis, arid Northwest China. It is mainly caused by unreasonable land management and excessive irrigation. The aim of this study was to assess and map the salinity risk distribution by [...] Read more.

Irrigation salinity is a common environmental threat for sustainable development in the Keriya Oasis, arid Northwest China. It is mainly caused by unreasonable land management and excessive irrigation. The aim of this study was to assess and map the salinity risk distribution by developing a composite risk index (CRI) for seventeen risk parameters from traditional and scientific fields, based on maximizing deviation method and analytic hierarchy process, the grey relational analysis and the Pressure-State-Response (PSR) sustainability framework. The results demonstrated that the northern part of the Shewol and Yeghebagh village has a very high salinity risk, which might be caused by flat and low terrain, high subsoil total soluble salt, high groundwater salinity and shallow groundwater depth. In contrast, the southern part of the Oasis has a low risk of salinity because of high elevation, proper drainage conditions and a suitable groundwater table. This achievement has shown that southern parts of the Oasis are suitable for irrigation agriculture; for the northern area, there is no economically feasible solution but other areas at higher risk can be restored by artificial measures. Therefore, this study provides policy makers with baseline data for restoring the soil salinity within the Oasis. Full article

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

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16 pages, 1065 KiB

Open AccessArticle

Financing Watershed Services in the Foothills of the Himalayas

by Rajesh Kumar Rai, Priya Shyamsundar, Mani Nepal and Laxmi Dutt Bhatta

Water 2018, 10(7), 965; https://doi.org/10.3390/w10070965 - 23 Jul 2018

Cited by 14 | Viewed by 6782

Abstract

Watershed management is critical for the sustainable supply of clean water to urban centers, particularly in areas of developing countries where large-scale infrastructure projects are costly to implement. In this paper, we discuss the potential for financing improvements in watershed services in the [...] Read more.

Watershed management is critical for the sustainable supply of clean water to urban centers, particularly in areas of developing countries where large-scale infrastructure projects are costly to implement. In this paper, we discuss the potential for financing improvements in watershed services in the foothills of the Himalayas through Payments for Ecosystem Services. Through the use of a choice experiment to disentangle household preferences, we show that downstream water users are interested in improvements in water quality through source water protection. Households in Dharan municipality are willing to finance watershed management to the extent of USD 118,000 per year. These payments can be used to incentivize upstream households to decrease domestic livestock grazing, change agricultural practices and reduce open defecation to improve the drinking water quality and quantity in downstream areas. The estimated cost of these activities is less than $50,000 per year. Through discussions with local stakeholders, we propose a tri-partite institutional structure to facilitate transactions between downstream and upstream communities and to improve watershed services. Full article

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

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15 pages, 2395 KiB

Open AccessArticle

Rainfall Prediction with AMSR–E Soil Moisture Products Using SM2RAIN and Nonlinear Autoregressive Networks with Exogenous Input (NARX) for Poorly Gauged Basins: Application to the Karkheh River Basin, Iran

by Majid Fereidoon and Manfred Koch

Water 2018, 10(7), 964; https://doi.org/10.3390/w10070964 - 23 Jul 2018

Cited by 15 | Viewed by 4735

Abstract

Accurate estimates of daily rainfall are essential for understanding and modeling the physical processes involved in the interaction between the land surface and the atmosphere. In this study, daily satellite soil moisture observations from the Advanced Microwave Scanning Radiometer–Earth Observing System (AMSR–E) generated [...] Read more.

Accurate estimates of daily rainfall are essential for understanding and modeling the physical processes involved in the interaction between the land surface and the atmosphere. In this study, daily satellite soil moisture observations from the Advanced Microwave Scanning Radiometer–Earth Observing System (AMSR–E) generated by implementing the standard National Aeronautics and Space Administration (NASA) algorithm are employed for estimating rainfall, firstly, through the use of recently developed approach, SM2RAIN and, secondly, the nonlinear autoregressive network with exogenous inputs (NARX) neural modelling at five climate stations in the Karkheh river basin (KRB), located in south-west Iran. In the SM2RAIN method, the period 1 January 2003 to 31 December 2005 is used for the calibration of algorithm and the remaining 9 months from 1 January 2006 to 30 September 2006 is used for the validation of the rainfall estimates. In the NARX model, the full study period is split into training (1 January 2003 to 31 September 2005) and testing (1 September 2005 to 30 September 2006) stages. For the prediction of the rainfall as the desired target (output), relative soil moisture changes from AMSR–E and measured air temperature time series are chosen as exogenous (external) inputs in NARX. The quality of the estimated rainfall data is evaluated by comparing it with observed rainfall data at the five rain gauges in terms of the coefficient of determination R², the RMSE and the statistical bias. For the SM2RAIN method, R² ranges between 0.32 and 0.79 for all stations, whereas for the NARX- model the values are generally slightly lower. Moreover, the values of the bias for each station indicate that although SM2RAIN is likely to underestimate large rainfall intensities, due to the known effect of soil moisture saturation, its biases are somewhat lower than those of NARX. Moreover, Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks–Climate Data Record (PERSIANN–CDR) is employed to evaluate its potential for predicting the ground-based observed station rainfall, but it is found to work poorly. In conclusion, the results of the present study show that with the use of AMSR–E soil moisture products in the physically based SM2RAIN algorithm as well as in the NARX neural network, rainfall for poorly gauged regions can be predicted satisfactorily. Full article

(This article belongs to the Section Hydrology)

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3 pages, 150 KiB

Open AccessEditorial

Turbulence in River and Maritime Hydraulics

by Michele Mossa, Donatella Termini and Peter Davies

Water 2018, 10(7), 963; https://doi.org/10.3390/w10070963 - 23 Jul 2018

Cited by 1 | Viewed by 3738

Abstract

Understanding of the role of turbulence in controlling transport processes is of paramount importance for the preservation and protection of aquatic ecosystems, the minimisation of deleterious consequences of anthropogenic activity, and the successful sustainable development of river and maritime areas. In this context, [...] Read more.

Understanding of the role of turbulence in controlling transport processes is of paramount importance for the preservation and protection of aquatic ecosystems, the minimisation of deleterious consequences of anthropogenic activity, and the successful sustainable development of river and maritime areas. In this context, the present Special Issue collects 15 papers which provide a representation of the present understanding of turbulent processes and their effects in river and maritime environments. The presented collection of papers is not exhaustive but it allows for highlighting key priority areas and knowledge gaps in this field of research. Full article

(This article belongs to the Special Issue Turbulence in River and Maritime Hydraulics)

17 pages, 4021 KiB

Open AccessArticle

A Flexible Framework HydroInformatic Modeling System—HIMS

by Lili Wang, Zhonggen Wang, Changming Liu, Peng Bai and Xiaocong Liu

Water 2018, 10(7), 962; https://doi.org/10.3390/w10070962 - 22 Jul 2018

Cited by 8 | Viewed by 4154

Abstract

It is important to simulate streamflow with hydrological models suitable for the particular study areas, as the hydrological characteristics of water cycling processes are distinctively different due to spatial heterogeneity at the watershed scale. However, most existing hydrological models cannot be customized to [...] Read more.

It is important to simulate streamflow with hydrological models suitable for the particular study areas, as the hydrological characteristics of water cycling processes are distinctively different due to spatial heterogeneity at the watershed scale. However, most existing hydrological models cannot be customized to simulate water cycling processes of different areas due to their fixed structures and modes. This study developed a HydroInformatic Modeling System (HIMS) model with a flexible structure which had multiple equations available to describe each of the key hydrological processes. The performance of the HIMS model was evaluated with the recommended structure for semi-arid areas by comparisons with two datasets of observed streamflow: the first one of 53 Australian watersheds, the second one of the Lhasa River basin in China. Based on the first dataset, the most appropriate watersheds were identified for the HIMS model utilization with areas of 400–600 km² and annual precipitation of 800–1200 mm. Based on the second dataset, the model performance was statistically satisfied with Nash-Sutcliffe Efficient (NSE) greater than 0.87 and Water Error (WE) within ±20% on the streamflow simulation at hourly, daily, and monthly time steps. In addition, the water balance was mostly closed with respect to precipitation, streamflow, actual evapotranspiration (ET), and soil moisture change at the annual time steps in both the periods of calibration and validation. Therefore, the HIMS model was reliable in estimating streamflow and simulating the water cycling processes for the structure of semi-arid areas. The simulated streamflow of HIMS was compared with those of the Variable Infiltration Capacity model (VIC) and Soil and Water Assessment Tool (SWAT) models and we found that the HIMS model performed better than the SWAT model, and had similar results to the VIC model with combined runoff generation mechanisms. Full article

(This article belongs to the Section Hydrology)

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20 pages, 7287 KiB

Open AccessArticle

Numerical Modelling of Cohesive Bank Migration

by Silvia Bosa, Marco Petti and Sara Pascolo

Water 2018, 10(7), 961; https://doi.org/10.3390/w10070961 - 21 Jul 2018

Cited by 20 | Viewed by 3738

Abstract

River morphological evolution is a challenging topic, involving hydrodynamic flow, sediment transport and bank stability. Lowland rivers are often characterized by the coexistence of granular and cohesive material, with significantly different behaviours. This paper presents a bidimensional morphological model to describe the evolution [...] Read more.

River morphological evolution is a challenging topic, involving hydrodynamic flow, sediment transport and bank stability. Lowland rivers are often characterized by the coexistence of granular and cohesive material, with significantly different behaviours. This paper presents a bidimensional morphological model to describe the evolution of the lower course of rivers, where there are both granular and cohesive sediments. The hydrodynamic equations are coupled with two advection–diffusion equations, which consider the transport of granular and cohesive suspended sediment concentration separately. The change of bed height is evaluated as the sum of the contributions of granular and sediment material. A bank failure criterion is developed and incorporated into the numerical simulation of the hydrodynamic flood wave and channel evolution, to describe both bed deformation and bank recession. To this aim, two particular mechanisms are considered: the former being a lateral erosion due to the current flow and consequent cantilever collapse and the latter a geostatic failure due to the submergence. The equation system is integrated by means of a finite volume scheme. The resulting model is applied to the Tagliamento River, in northern Italy, where the meander migration is documented through a sequence of aerial images. The channel evolution is simulated, imposing an equivalent hydrograph consisting of a sequence of flood waves, which represents a medium year, with reference to their effect on sediment transport. The results show that the model adequately describes the general morphological evolution of the meander. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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18 pages, 3995 KiB

Open AccessArticle

Effect of Green Roof Configuration and Hydrological Variables on Runoff Water Quantity and Quality

by Pascual Ferrans, Carlos Vicente Rey, Gabriel Pérez, Juan Pablo Rodríguez and Mario Díaz-Granados

Water 2018, 10(7), 960; https://doi.org/10.3390/w10070960 - 20 Jul 2018

Cited by 36 | Viewed by 6477

Abstract

Green roofs (GRs) are a feasible solution for mitigating increased runoff volumes in urban areas. Though many studies have focused their analysis on the quantity and quality of GR runoff, with respect to the relevance of specific site conditions in GR performance, the [...] Read more.

Green roofs (GRs) are a feasible solution for mitigating increased runoff volumes in urban areas. Though many studies have focused their analysis on the quantity and quality of GR runoff, with respect to the relevance of specific site conditions in GR performance, the information gathered for the tropical Andes is not sufficient. This study assessed the hydrological performance and runoff water quality of 12 green roof modular systems located at the Universidad de los Andes campus (Bogotá, Colombia). Based on 223 rainfall events spanning a 3-year period, average rainfall retention was 85% (coefficient of variation = 29%). t-tests, the Welch Test, multiple linear regressions, and correlation analysis were performed in order to assess the potential effect of air temperature, substrate type, vegetation cover, relative humidity, antecedent dry weather period (ADWP), rainfall duration, and rainfall maximum intensity. In some cases, GR design variables (i.e., substrate type and vegetation cover) were found to be significant for describing rainfall retention efficiencies and, depending on the GR type, some hydrological variables were also correlated with rainfall retention. Rainfall and GR runoff from 12 rainfall events were also monitored for total Kjeldahl nitrogen (TKN), nitrates, nitrites, ammonia, total phosphorus (TP), phosphates, pH, total dissolved solids (TDS), total suspended solids (TSS), color, turbidity, biological oxygen demand (BOD), chemical oxygen demand (COD), total coliforms, metals (i.e., zinc, copper, nickel, lead, selenium, aluminum, barium, boron, calcium, strontium, iron, lithium, magnesium, manganese, potassium, sodium), and polyaromatic hydrocarbons (PAHs). The results obtained confirmed that GR systems have the ability to neutralize pH, but are a source of the rest of the aforementioned parameters, excluding PAHs (with concentrations below detection limits), ammonia, TSS, selenium and lithium, where differences with control cases (rainfall and plastic panel runoff) were not statistically significant. Substrate type, event size, and rainfall regime are relevant variables for explaining runoff water quality. Full article

(This article belongs to the Special Issue Hydrological Performance of Green Roofs)

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33 pages, 11010 KiB

Open AccessFeature PaperArticle

Assessing the Hydrodynamic Response of the Mar Menor Lagoon to Dredging Inlets Interventions through Numerical Modelling

by Miriam García-Oliva, Ángel Pérez-Ruzafa, Georg Umgiesser, William McKiver, Michol Ghezzo, Francesca De Pascalis and Concepción Marcos

Water 2018, 10(7), 959; https://doi.org/10.3390/w10070959 - 20 Jul 2018

Cited by 43 | Viewed by 7187

Abstract

The Mar Menor lagoon has been subjected to high anthropogenic pressures. Among them, in the early 1970s, dredging and enlargement of one of the inlets to make a navigable channel has had strong consequences on the hydrology, ecology, and fisheries of the lagoon. [...] Read more.

The Mar Menor lagoon has been subjected to high anthropogenic pressures. Among them, in the early 1970s, dredging and enlargement of one of the inlets to make a navigable channel has had strong consequences on the hydrology, ecology, and fisheries of the lagoon. In recent years, changes in agricultural practices have induced an eutrophication process, leading to loss of water quality. As a solution, some management proposals have included dredging of the inlets in order to increase the water renewal. However, these proposals did not take into account the negative effects of previous experiences nor the consequences on environmental conditions of the lagoon and therefore on biological processes. The purpose of this work is to assess the effect that proposed mitigation measures, could have on the hydrodynamic conditions and discuss its possible ecological consequences. A three-dimensional (3D) numerical model has been used to simulate the lagoon under different dredging scenarios, covering different dredging depths and extensions. The simulated current fields and fluxes through the inlets, as well as water renewal times have been compared for the different scenarios. It is found that some of the considered scenarios take the system beyond the threshold of sustainability, where the modified current dynamics could affect sediment transport, beach dynamics and fishing capacities in a significant way. Water exchange with the Mediterranean is also strongly affected, with consequences for species connectivity, and a homogenization of the water renewal times that could lead to loss of ecosystem heterogeneity and structural complexity. The study demonstrates the utility of numerical models as effective tools for the management of coastal areas. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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18 pages, 1272 KiB

Open AccessArticle

Improving Public Participation Processes for the Floods Directive and Flood Awareness: Evidence from Cyprus

by Katerina Charalambous, Adriana Bruggeman, Elias Giannakis and Christos Zoumides

Water 2018, 10(7), 958; https://doi.org/10.3390/w10070958 - 20 Jul 2018

Cited by 12 | Viewed by 5530

Abstract

Public participation is integrated in the European Floods Directive to ensure engagement of societal actors in selecting and accepting measures. This study assesses the Directive’s public participation process and provides recommendations for its improvement by using Cyprus as a case study. Interviews with [...] Read more.

Public participation is integrated in the European Floods Directive to ensure engagement of societal actors in selecting and accepting measures. This study assesses the Directive’s public participation process and provides recommendations for its improvement by using Cyprus as a case study. Interviews with the organizers and attendees of the public consultations were carried out to evaluate the process while a citizen survey examined people’s flood awareness and opinions of three household-level flood protection measures (permeable pavements, rainwater harvesting systems, and green roofs). Public consultation organizers were generally satisfied with the process while participants suggested better structured information and a more participatory approach. The majority (77%) of the survey respondents did not know if they lived in a designated flood risk area while 93% were unaware of the public consultations carried out for the Floods Directive. Their perception about the effectiveness of the three flood protection measures was positively associated with their willingness to implement them. The results indicated the need for more participatory methods in the public participation process and better strategies to increase awareness and the engagement of people in flood management. Establishing procedures for evaluating the effectiveness of public participation could contribute to the recognition and improvement of the process. Full article

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

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15 pages, 1151 KiB

Open AccessFeature PaperArticle

Performance Evaluation of Small Sized Powdered Ferric Hydroxide as Arsenic Adsorbent

by Muhammad Usman, Ioannis Katsoyiannis, Manassis Mitrakas, Anastasios Zouboulis and Mathias Ernst

Water 2018, 10(7), 957; https://doi.org/10.3390/w10070957 - 20 Jul 2018

Cited by 45 | Viewed by 6760 | Correction

Abstract

The small sized powdered ferric oxy-hydroxide, termed Dust Ferric Hydroxide (DFH), was applied in batch adsorption experiments to remove arsenic species from water. The DFH was characterized in terms of zero point charge, zeta potential, surface charge density, particle size and moisture content. [...] Read more.

The small sized powdered ferric oxy-hydroxide, termed Dust Ferric Hydroxide (DFH), was applied in batch adsorption experiments to remove arsenic species from water. The DFH was characterized in terms of zero point charge, zeta potential, surface charge density, particle size and moisture content. Batch adsorption isotherm experiments indicated that the Freundlich model described the isothermal adsorption behavior of arsenic species notably well. The results indicated that the adsorption capacity of DFH in deionized ultrapure water, applying a residual equilibrium concentration of 10 µg/L at the equilibrium pH value of 7.9 ± 0.1, with a contact time of 96 h (i.e., Q₁₀), was 6.9 and 3.5 µg/mg for As(V) and As(III), respectively, whereas the measured adsorption capacity of the conventionally used Granular Ferric Hydroxide (GFH), under similar conditions, was found to be 2.1 and 1.4 µg/mg for As(V) and As(III), respectively. Furthermore, the adsorption of arsenic species onto DFH in a Hamburg tap water matrix, as well as in an NSF challenge water matrix, was found to be significantly lower. The lowest recorded adsorption capacity at the same equilibrium concentration was 3.2 µg As(V)/mg and 1.1 µg As(III)/mg for the NSF water. Batch adsorption kinetics experiments were also conducted to study the impact of a water matrix on the behavior of removal kinetics for As(V) and As(III) species by DFH, and the respective data were best fitted to the second order kinetic model. The outcomes of this study confirm that the small sized iron oxide-based material, being a by-product of the production process of GFH adsorbent, has significant potential to be used for the adsorptive removal of arsenic species from water, especially when this material can be combined with the subsequent application of low-pressure membrane filtration/separation in a hybrid water treatment process. Full article

(This article belongs to the Special Issue Recent Advances in Water and Wastewater Treatment with Emphasis in Membrane Treatment Operations)

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16 pages, 5087 KiB

Open AccessArticle

Evaluating the Erosion Process from a Single-Stripe Laser-Scanned Topography: A Laboratory Case Study

by Yung-Chieh Wang and Chun-Chen Lai

Water 2018, 10(7), 956; https://doi.org/10.3390/w10070956 - 19 Jul 2018

Cited by 11 | Viewed by 4306

Abstract

Topographies during the erosion process obtained from the single-stripe laser-scanning method may provide an accurate, but affordable, soil loss estimation based on high-precision digital elevation model (DEM) data. In this study, we used laboratory erosion experiments with a sloping flume, a rainfall simulator, [...] Read more.

Topographies during the erosion process obtained from the single-stripe laser-scanning method may provide an accurate, but affordable, soil loss estimation based on high-precision digital elevation model (DEM) data. In this study, we used laboratory erosion experiments with a sloping flume, a rainfall simulator, and a stripe laser apparatus to evaluate topographic changes of soil surface and the erosion process. In the experiments, six slope gradients of the flume (5° to 30° with an increment of 5°) were used and the rainfall simulator generated a 30-min rainfall with the kinetic energy equivalent to 80 mm/h on average. The laser-scanned topography and sediment yield were collected every 5 min in each test. The difference between the DEMs from laser scans of different time steps was used to obtain the eroded soil volumes and the corresponding estimates of soil loss in mass. The results suggest that the collected sediment yield and eroded soil volume increased with rainfall duration and slope, and quantified equations are proposed for soil loss prediction using rainfall duration and slope. This study shows the applicability of the stripe laser-scanning method in soil loss prediction and erosion evaluation in a laboratory case study. Full article

(This article belongs to the Special Issue Modeling and Practice of Erosion and Sediment Transport under Change)

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18 pages, 5564 KiB

Open AccessArticle

Decomposition of Contaminants of Emerging Concern in Advanced Oxidation Processes

by Edyta Kudlek

Water 2018, 10(7), 955; https://doi.org/10.3390/w10070955 - 19 Jul 2018

Cited by 54 | Viewed by 6343

Abstract

This paper compares the removal degrees of selected contaminants of emerging concern in water solutions during advanced oxidation processes (AOPs), such as H₂O₂, O₃, UV, UV/TiO₂, UV/H₂O₂, and UV/O₃. [...] Read more.

This paper compares the removal degrees of selected contaminants of emerging concern in water solutions during advanced oxidation processes (AOPs), such as H₂O₂, O₃, UV, UV/TiO₂, UV/H₂O₂, and UV/O₃. The tested micropollutants belong to the following groups: pharmaceuticals, dyes, UV filters, hormones, pesticides, and food additives. The highest removal rate of pharmaceutical compounds was observed during the UV/TiO₂ process. The decomposition of hormones in this process exceeded 96% and the concentration of the UV filter dioxybenzone was reduced by 75%. The pesticide triallat and the food additive butylated hydroxytoluene were most effectively oxidized by the UV process and their removal degrees exceeded 90%. The lowest removal degree in all examined processes was observed in the case of caffeine. Toxicological analysis conducted in post-processed water samples indicated the generation of several oxidation by-products with a high toxic potential. The presence of those compounds was confirmed by the GC-MS analysis. The performance of the UV/O₃ process leads to the increase of the toxicity of post-processed water solutions, especially solutions containing degradation by-products of carbamazepine, diclofenac sodium salt, acridine, trialatte, triclosan, and β-estradiol were characterized by high toxicity. Full article

(This article belongs to the Special Issue Selected Papers from the 2nd International Electronic Conference on Water Science)

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18 pages, 18639 KiB

Open AccessArticle

Projected Changes in Soil Temperature and Surface Energy Budget Components over the Alps and Northern Italy

by Claudio Cassardo, Seon Ki Park, Sungmin O and Marco Galli

Water 2018, 10(7), 954; https://doi.org/10.3390/w10070954 - 19 Jul 2018

Cited by 8 | Viewed by 4023

Abstract

This study investigates the potential changes in surface energy budget components under certain future climate conditions over the Alps and Northern Italy. The regional climate scenarios are obtained though the Regional Climate Model version 3 (RegCM3) runs, based on a reference climate (1961–1990) [...] Read more.

This study investigates the potential changes in surface energy budget components under certain future climate conditions over the Alps and Northern Italy. The regional climate scenarios are obtained though the Regional Climate Model version 3 (RegCM3) runs, based on a reference climate (1961–1990) and the future climate (2071–2100) via the A2 and B2 scenarios. The energy budget components are calculated by employing the University of Torino model of land Processes Interaction with Atmosphere (UTOPIA), and using the RegCM3 outputs as input data. Our results depict a significant change in the energy budget components during springtime over high-mountain areas, whereas the most relevant difference over the plain areas is the increase in latent heat flux and hence, evapotranspiration during summertime. The precedence of snow-melting season over the Alps is evidenced by the earlier increase in sensible heat flux. The annual mean number of warm and cold days is evaluated by analyzing the top-layer soil temperature and shows a large increment (slight reduction) of warm (cold) days. These changes at the end of this century could influence the regional radiative properties and energy cycles and thus, exert significant impacts on human life and general infrastructures. Full article

(This article belongs to the Section Hydrology)

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16 pages, 8600 KiB

Open AccessArticle

Model-Based Analysis of Macrophytes Role in the Flow Distribution in the Anastomosing River System

by Paweł Marcinkowski, Adam Kiczko and Tomasz Okruszko

Water 2018, 10(7), 953; https://doi.org/10.3390/w10070953 - 18 Jul 2018

Cited by 12 | Viewed by 4837

Abstract

The impact of vegetation on the hydrology and geomorphology of aquatic ecosystems has been studied intensively in recent years. Numerous hydraulic models developed to date help to understand and quantitatively assess the influence of in-stream macrophytes on a channel’s hydraulic conditions. However, special [...] Read more.

The impact of vegetation on the hydrology and geomorphology of aquatic ecosystems has been studied intensively in recent years. Numerous hydraulic models developed to date help to understand and quantitatively assess the influence of in-stream macrophytes on a channel’s hydraulic conditions. However, special focus is placed on single-thread rivers, leaving anastomosing rivers practically uninvestigated. To fill this gap, the objective of this study was to investigate the impact of vegetation on flow distribution in a complex anastomosing river system situated in northeastern Poland. The newly designed, one-dimensional, steady-flow model, dedicated for anastomosing rivers used in this study indicated high influence of vegetation on water flow distribution during the whole year in general, but—as expected—significantly higher in the summer season. Simulations of in-stream vegetation removal in selected channels reflected in Manning’s coefficient alterations caused relatively high discharge transitions during the growing season. This proved the significance of feedback between process of plants growth and distribution of flow in anabranches. The results are unique and relevant and could be successfully considered for the protection of semi-natural anabranching rivers. Full article

(This article belongs to the Special Issue Riparian Vegetation in River Functioning)

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6 pages, 203 KiB

Open AccessEditorial

Soil Water Conservation: Dynamics and Impact

by Simone Di Prima, Mirko Castellini, Mario Pirastru and Saskia Keesstra

Water 2018, 10(7), 952; https://doi.org/10.3390/w10070952 - 18 Jul 2018

Cited by 6 | Viewed by 5421

Abstract

Human needs like food and clean water are directly related to good maintenance of healthy and productive soils. A good understanding of human impact on the natural environment is therefore necessary to preserve and manage soil and water resources. This knowledge is particularly [...] Read more.

Human needs like food and clean water are directly related to good maintenance of healthy and productive soils. A good understanding of human impact on the natural environment is therefore necessary to preserve and manage soil and water resources. This knowledge is particularly important in semi-arid and arid regions, where the increasing demands on limited water supplies require urgent efforts to improve water quality and water use efficiency. It is important to keep in mind that both soil and water are limited resources. Thus, wise use of these natural resources is a fundamental prerequisite for the sustainability of human societies. This Special Issue collects 15 original contributions addressing the state of the art of soil and water conservation research. Contributions cover a wide range of topics, including (1) recovery of soil hydraulic properties; (2) erosion risk; (3) novel modeling, monitoring and experimental approaches for soil hydraulic characterization; (4) improvement of crop yields; (5) water availability; and (6) soil salinity. The collection of manuscripts presented in this Special Issue provides more insights into conservation strategies for effective and sustainable soil and water management. Full article

(This article belongs to the Special Issue Soil Water Conservation: Dynamics and Impact)

24 pages, 35904 KiB

Open AccessFeature PaperArticle

Heating Impact of a Tropical Reservoir on Downstream Water Temperature: A Case Study of the Jinghong Dam on the Lancang River

by Bo Jiang, Fushan Wang and Guangheng Ni

Water 2018, 10(7), 951; https://doi.org/10.3390/w10070951 - 17 Jul 2018

Cited by 20 | Viewed by 6432

Abstract

Reservoirs change downstream thermal regimes by releasing water of different temperatures to that under natural conditions, which may then alter downstream biodiversity and ecological processes. The hydropower exploitation in the mainstream Lancang-Mekong River has triggered concern for its potential effects on downstream countries, [...] Read more.

Reservoirs change downstream thermal regimes by releasing water of different temperatures to that under natural conditions, which may then alter downstream biodiversity and ecological processes. The hydropower exploitation in the mainstream Lancang-Mekong River has triggered concern for its potential effects on downstream countries, especially the impact of the released cold water on local fishery production. However, it was observed recently that the annual water temperature downstream of the Jinghong Reservoir (near the Chinese border) has increased by 3.0 °C compared to its historical average (1997–2004). In this study, a three-dimensional (3D) model of the Jinghong Reservoir was established to simulate its hydro- and thermodynamics. Results show that: (1) the impoundment of the Jinghong Reservoir contributed about 1.3 °C to the increment of the water temperature; (2) the solar radiation played a much more important role in comparison with atmosphere-water heat exchange in changing water temperatures; and (3) the outflow rate also imposed a significant influence on the water temperature by regulating the residence time. After impoundment, the residence time increased from 3 days to 11 days, which means that the duration that the water body can absorb solar radiation has been prolonged. The results explain the heating mechanism of the Jinghong Reservoir brought to downstream water temperatures. Full article

(This article belongs to the Special Issue Adaptive Catchment Management and Reservoir Operation)

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22 pages, 4696 KiB

Open AccessArticle

The Development of a 1-D Integrated Hydro-Mechanical Model Based on Flume Tests to Unravel Different Hydrological Triggering Processes of Debris Flows

by Theo W. J. Van Asch, Bin Yu and Wei Hu

Water 2018, 10(7), 950; https://doi.org/10.3390/w10070950 - 17 Jul 2018

Cited by 17 | Viewed by 4908

Abstract

Many studies which try to analyze conditions for debris flow development ignore the type of initiation. Therefore, this paper deals with the following questions: What type of hydro-mechanical triggering mechanisms for debris flows can we distinguish in upstream channels of debris flow prone [...] Read more.

Many studies which try to analyze conditions for debris flow development ignore the type of initiation. Therefore, this paper deals with the following questions: What type of hydro-mechanical triggering mechanisms for debris flows can we distinguish in upstream channels of debris flow prone gullies? Which are the main parameters controlling the type and temporal sequence of these triggering processes, and what is their influence on the meteorological thresholds for debris flow initiation? A series of laboratory experiments were carried out in a flume 8 m long and with a width of 0.3 m to detect the conditions for different types of triggering mechanisms. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. On the basis of these experiments, an integrated hydro-mechanical model was developed, which describes Hortonian and saturation overland flow, maximum sediment transport, through flow and failure of bed material. The model was calibrated and validated using process indicator values measured during the experiments in the flume. Virtual model simulations carried out in a schematic hypothetical source area of a catchment show that slope angle and hydraulic conductivity of the bed material determine the type and sequence of these triggering processes. It was also clearly demonstrated that the type of hydrological triggering process and the influencing geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves for the start of debris flows. Full article

(This article belongs to the Special Issue Landslide Hydrology)

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19 pages, 6287 KiB

Open AccessArticle

Characterization of Karst Conduit Network Using Long-Distance Tracer Test in Lijiang, Southwestern China

by Jihong Qi, Mo Xu, Xinyu Cen, Lu Wang and Qiang Zhang

Water 2018, 10(7), 949; https://doi.org/10.3390/w10070949 - 16 Jul 2018

Cited by 13 | Viewed by 3913

Abstract

The Ancient City in Lijiang of southwestern China was endowed as World Cultural Heritage by UNESCO, and the karst springs located in Black Dragon Pool are its main water source. However, the springs have dried up several times in recent years, which caused [...] Read more.

The Ancient City in Lijiang of southwestern China was endowed as World Cultural Heritage by UNESCO, and the karst springs located in Black Dragon Pool are its main water source. However, the springs have dried up several times in recent years, which caused serious damages to the landscape as well as the city water supply. Triggered by the dried-up event in Black Dragon Pool, a long-distance artificial tracer test up to 17 km was employed to investigate the karst conduit network distributing in the study area. Based on the tracer concentration breakthrough curves (BTCs), the hydraulic connection from the same injection point (located in a giant depression named the Jiuzi Sea) to the springs on both sides of the topography watershed was proven, and the conduit structure was discussed. According to the characteristics of BTCs and considering the low tracer concentration and tracer recovery, a conceptual structure of leaky reservoir with threshold effect above a certain groundwater level was established to interpret why the springs in Black Dragon Pool dried up several times in history, but those in the Ancient City never did. Furthermore, a method of injecting surface water into the Jiuzi Sea to raise the groundwater level up to the height of Black Dragon Pool was proposed to restore the springs. Our study provides insights into the long-distance artificial tracer test, and opens a new avenue for groundwater resource recovery of this Ancient City. Full article

(This article belongs to the Special Issue Water Resources Investigation: Geologic Controls on Groundwater Flow)

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17 pages, 8268 KiB

Open AccessArticle

Interaction between Perched Epikarst Aquifer and Unsaturated Soil Cover in the Initiation of Shallow Landslides in Pyroclastic Soils

by Roberto Greco, Pasquale Marino, Giovanni Francesco Santonastaso and Emilia Damiano

Water 2018, 10(7), 948; https://doi.org/10.3390/w10070948 - 16 Jul 2018

Cited by 15 | Viewed by 4079

Abstract

A physically based mathematical model of the slope of Cervinara (southern Italy), which is characterized by a shallow pyroclastic soil cover laying upon a limestone fractured bedrock, has been developed. Previous and current ongoing monitoring suggested that leakage through the soil–bedrock interface occurred, [...] Read more.

A physically based mathematical model of the slope of Cervinara (southern Italy), which is characterized by a shallow pyroclastic soil cover laying upon a limestone fractured bedrock, has been developed. Previous and current ongoing monitoring suggested that leakage through the soil–bedrock interface occurred, with leaking water temporarily stored in a perched aquifer located in the upper part of the fractured limestone (epikarst). This aquifer supplied several springs, and recharge to the deeper groundwater circulation occurred. Hence, in the proposed model, the unsaturated water flow taking place within the soil cover is coupled with the saturated water flow in the perched aquifer. The application of the model to the simulation of the slope hydrologic behavior over a period of 11 years, between 2006–2017, provides realistic results in terms of soil storage, epikarst storage, spring discharge, and groundwater recharge. The different response times of soil and epikarst aquifer to precipitation input allow distinguishing the hydrological predisposing causes of potential landsliding (i.e., a few months of persistent rainfall that is capable of filling the epikarst aquifer) from the triggers, which are represented by single intense rainfall events. The application of the model offers a key of interpretation of the hydrological processes leading to the landslide that occurred on 16 December 1999. Full article

(This article belongs to the Special Issue Landslide Hydrology)

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16 pages, 4160 KiB

Open AccessFeature PaperArticle

An Experimental and Theoretical Study on Separations by Vacuum Membrane Distillation Employing Hollow-Fiber Modules

by Anthoula Karanasiou, Margaritis Kostoglou and Anastasios Karabelas

Water 2018, 10(7), 947; https://doi.org/10.3390/w10070947 - 16 Jul 2018

Cited by 22 | Viewed by 5564

Abstract

Vacuum membrane distillation (VMD) is an attractive variant of the novel membrane distillation process, which is promising for various separations, including water desalination and bioethanol recovery through fermentation of agro-industrial by-products. This publication is part of an effort to develop a capillary membrane [...] Read more.

Vacuum membrane distillation (VMD) is an attractive variant of the novel membrane distillation process, which is promising for various separations, including water desalination and bioethanol recovery through fermentation of agro-industrial by-products. This publication is part of an effort to develop a capillary membrane module for various applications, as well as a model that would facilitate VMD process design. Experiments were conducted in a laboratory pilot VMD unit, comprising polypropylene capillary-membrane modules. Performance data, collected at modest temperatures (37 °C to 65 °C) with deionized and brackish water, confirmed the improved system productivity with increasing feed-water temperature; excellent salt rejection was obtained. The recovery of ethanol from ethanol-water mixtures and from fermented winery by-products was also studied, in continuous, semi-continuous, and batch operating modes. At low-feed-solution temperature (27–47 °C), ethanol-solution was concentrated 4 to 6.5 times in continuous operation and 2 to 3 times in the semi-continuous mode. Taking advantage of the small property variation in the module axial-flow direction, a simple VMD process model was developed, satisfactorily describing the experimental data. This VMD model appears to be promising for practical applications, and warrants further R&D work. Full article

(This article belongs to the Special Issue Recent Advances in Water and Wastewater Treatment with Emphasis in Membrane Treatment Operations)

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17 pages, 6945 KiB

Open AccessArticle

A Multidisciplinary Approach for Clarifying the Recharge Processes and Origin of Saline Water in the Semi-Arid Punata Alluvial fan in Bolivia

by Andres Gonzales Amaya, Gerhard Barmen and Galo Muñoz

Water 2018, 10(7), 946; https://doi.org/10.3390/w10070946 - 16 Jul 2018

Cited by 8 | Viewed by 4030

Abstract

The analysis of stable isotopes assisted in identifying that groundwater in the Punata alluvial fan is mainly recharged by heavy flash floods, and the recharge from rainfall is of less importance. In addition, the hydrochemical analysis identified the Pucara River as the main [...] Read more.

The analysis of stable isotopes assisted in identifying that groundwater in the Punata alluvial fan is mainly recharged by heavy flash floods, and the recharge from rainfall is of less importance. In addition, the hydrochemical analysis identified the Pucara River as the main source of recharge. Other streams in the north and northwest of the fan do not seem to contribute to the recharge. The hydrochemistry also shows that there is an increase of the Na⁺ and Cl⁻ concentrations in the middle and distal part of the fan. The salinization of groundwater is most likely a result of the mixing of fresh water with residual saline pore water in the lacustrine deposits and/or ion exchange within these layers. Geophysical surveys assisted in describing the aquifer system layering, and indicated a fine-grained bottom layer where ion exchange might occur. This study demonstrates that the integration of several methods (e.g., hydrochemistry, hydrogeophysics, and stable isotopes) is valuable for clarifying ambiguities during the interpretation process and for characterizing hydrogeological processes in alluvial fans in general. Full article

(This article belongs to the Section Hydrology)

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15 pages, 2456 KiB

Open AccessArticle

Optimal Surface Aeration Control in Full-Scale Oxidation Ditches through Energy Consumption Analysis

by Yong Qiu, Chi Zhang, Bing Li, Ji Li, Xiaoyuan Zhang, Yanchen Liu, Peng Liang and Xia Huang

Water 2018, 10(7), 945; https://doi.org/10.3390/w10070945 - 16 Jul 2018

Cited by 14 | Viewed by 6399

Abstract

Oxidation ditches are popularly used in rural areas and decentralized treatment facilities where energy deficiency is of concern. Aeration control technologies are well established for diffusion systems in order to improve energy efficiency, but there are still challenges in their application in oxidation [...] Read more.

Oxidation ditches are popularly used in rural areas and decentralized treatment facilities where energy deficiency is of concern. Aeration control technologies are well established for diffusion systems in order to improve energy efficiency, but there are still challenges in their application in oxidation ditches because surface aerators have unique characteristics with respect to oxygen transfer and energy consumption. In this paper, an integral energy model was proposed to include the energy, aeration, and fluidic effects of surface aerators, by which the energy for aeration of each aerator can be estimated using online data. Two types of rotating disks with different diameters (1800 mm and 1400 mm) were monitored in situ to estimate the model parameters. Furthermore, a feedforward–feedback loop control strategy was proposed using the concept of energy analysis and optimization. The simplified control system was implemented in a full-scale Orbal oxidation ditch, achieving an approximately 10% saving in full-process energy consumption. The cost–benefit analysis and carbon emission assessment confirmed the economic feasibility and environmental contribution of the control system. The energy model can help process designers and operators to better understand and optimally control the aeration process in oxidation ditches. Full article

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

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15 pages, 1944 KiB

Open AccessArticle

Seven-Year Running Effect Evaluation and Fate Analysis of Rain Gardens in Xi’an, Northwest China

by Chao Guo, Jiake Li, Huaien Li, Bei Zhang, Menghua Ma and Fan Li

Water 2018, 10(7), 944; https://doi.org/10.3390/w10070944 - 16 Jul 2018

Cited by 17 | Viewed by 4345

Abstract

Rain gardens have recently been studied as important low-impact development (LID) facilities that play a critical role in runoff volume reduction and pollutant purification. Approximately 16–40 rainfall events were monitored from March 2011 to October 2017 in order to determine the running effect [...] Read more.

Rain gardens have recently been studied as important low-impact development (LID) facilities that play a critical role in runoff volume reduction and pollutant purification. Approximately 16–40 rainfall events were monitored from March 2011 to October 2017 in order to determine the running effect of three rain gardens with respect to runoff volume reduction and pollutant purification. In particular, running fate analysis of rain gardens is the key focus in this study. Combined analyses revealed three key points. Firstly, performance assessment demonstrated that rain gardens effectively cut inflow volumes through the filter media; when the confluence area ratio was 6:1–20:1 (confluence ratio = roof area or road/garden area) and the rainfall was approximately 2.8–39.9 mm, the runoff volume reduction rate ranged from 9.8% to 100.0%. However, the average annual runoff reduction rate presented an initially increasing and then gradually decreasing trend with monitoring time. Secondly, according to water quality data in 54 rainfall events, the annual average concentration removal rate of NH₄⁺-N was relatively good, but generally decreased with monitoring time. The concentration removal rate of NO₃⁻-N and total phosphorus (TP) is unstable; however, the removal rate of total suspended solids (TSS) is better than that of total nitrogen (TN). Combined with runoff reduction, the pollutant load reduction by rain gardens is greater than 50%, although this decreases with increasing monitoring time. Thirdly, through the study of 7-year running effect on runoff reduction and pollutant purification, the “three-stage purification (TSP) concept” (periods of purification growth, stability, and attenuation) with respect to pollutant load reduction processes was finally proposed, and a curve chart was drawn for pollutant load reduction and rain garden operating fate (the “P–F” curve chart). Full article

(This article belongs to the Section Urban Water Management)

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15 pages, 1300 KiB

Open AccessArticle

Assessing Aquatic Ecological Health for Lake Poyang, China: Part I Index Development

by Lingyan Qi, Jiacong Huang, Qi Huang, Junfeng Gao, Shigang Wang and Yuyin Guo

Water 2018, 10(7), 943; https://doi.org/10.3390/w10070943 - 16 Jul 2018

Cited by 20 | Viewed by 5188

Abstract

The development of an ecosystem health index to assess health status in freshwater lakes is urgently needed in China, especially in polluted lakes. This study developed a specific Ecosystem Health Index (LP-EHI) for Lake Poyang in China. LP-EHI quantified lake health from the [...] Read more.

The development of an ecosystem health index to assess health status in freshwater lakes is urgently needed in China, especially in polluted lakes. This study developed a specific Ecosystem Health Index (LP-EHI) for Lake Poyang in China. LP-EHI quantified lake health from the perspectives of physical, chemical, biological integrity and social service. Physical integrity indices included hydrological conditions (water level and runoff), basic morphometric characteristics (lake area and shoreline), and tributary connectivity. Chemical integrity indices used water quality, nutrition, and toxicity to quantify chemical impairment. Biological integrity indicators covered six major components of the aquatic food chain, namely, phytoplankton, zooplankton, benthic macroinvertebrates, wetland plants, fish, and wintering birds. Social service indices included drinking water, pathogenic potential, flood storage capacity, sand mining, and dish-shaped sub-lake areas under management to measure whether the lake fulfilled the needs of human society. Reference and impaired conditions for each metric were defined by “historical” conditions, “least disturbed” conditions, national standards and expert opinions. The value of LP-EHI ranging from 0 to 1 was divided into five health conditions: excellent (≥0.8), good (0.6–0.8), fair (0.4–0.6), poor (0.2–0.4) and bad (<0.2). The metrics’ reliability was further validated using a box-and-whisker plot test. The developed index (LP-EHI) is so far the most comprehensive index to evaluate ecosystem health for Lake Poyang, and is well reflected in the unique characteristics of Lake Poyang. It can enhance our understanding of lake health conditions and thus guide lake management to achieve better health conditions. Full article

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

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17 pages, 7029 KiB

Open AccessArticle

Dominant Fish and Macroinvertebrate Response to Flow Changes of the Geum River in Korea

by Hyeongsik Kang and Byungwoong Choi

Water 2018, 10(7), 942; https://doi.org/10.3390/w10070942 - 15 Jul 2018

Cited by 11 | Viewed by 3738

Abstract

This study presents the impact of natural flow patterns on downstream aquatic species habitats in a reach of the Geum River, Korea. The study reach is a 13.4 km long, located downstream of the Yongdam Dam. To assess such an impact, this study [...] Read more.

This study presents the impact of natural flow patterns on downstream aquatic species habitats in a reach of the Geum River, Korea. The study reach is a 13.4 km long, located downstream of the Yongdam Dam. To assess such an impact, this study performed physical habitat simulations. The River2D model was used for the computation of the flow field and morphology, and the Habitat Suitability Index (HSI) model for the habitat simulation. Three habitat variables—flow depth, velocity, and substrate were used. The Zacco platypus and Baetis fuscatus were selected as the target fish and benthic macro-invertebrate, respectively. Using the building block approach (BBA), the scenarios for modifying dam operations were constructed in the study reach. Scenario 1, scenario 2, and scenario 3 were proposed by using the magnitude–duration concept, base flow allocation concept, and seasonally adjusted minimum flow allocation concept, respectively. Simulation results indicated that the scenarios’ effects significantly increased by about 14.3% for the weighted usable area (WUA). In addition, the morphology change with the restoration of flood events was investigated. It was revealed that the morphology change in the physical habitat simulations further increased by about 13% for the WUA. The change of dam operations through natural flow patterns is more advantageous to aquatic species. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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10 pages, 2991 KiB

Open AccessArticle

Temporal Variations in the Quantity of Groundwater Flow in Nam Co Lake

by Yan Du, Zhide Huang, Mowen Xie, Asim Farooq and Chen Chen

Water 2018, 10(7), 941; https://doi.org/10.3390/w10070941 - 14 Jul 2018

Cited by 6 | Viewed by 4436

Abstract

This paper aims to calculate and analyze the spatial and temporal variations in the groundwater flow quantity in Nam Co Lake based on the water balance principle. The results show that a large amount of groundwater was gradually lost and that, groundwater loss [...] Read more.

This paper aims to calculate and analyze the spatial and temporal variations in the groundwater flow quantity in Nam Co Lake based on the water balance principle. The results show that a large amount of groundwater was gradually lost and that, groundwater loss decreased from 1.9 billion m³ to 1.5 billion m³ from the period of 1980–1984 to 1995–2009. The comparative analysis in the current study indicates that the decrease in the groundwater index has a strong linear relationship with the temperature of the ground surface on the Tibetan Plateau, with a correlation coefficient as high as 0.92. Moreover, environmental variations such as large-scale engineering construction projects and increases in water storage may have played dominant roles in the sudden changes in the water quantities of plateau lakes (e.g., Nam Co Lake) during the periods of 1990–1995 and 2000–2009. The increased water levels resulted in reduced groundwater losses, which may lead to the substantial expansion or gradual shrinkage of the Qinghai–Tibet Plateau lakes over short periods of time. The results of this study provide an important reference for studying the mechanisms of lake water level changes on the Qinghai–Tibet Plateau. Full article

(This article belongs to the Special Issue Thermo-Hydro-Mechanical-Chemical Processes of Deep Underground Reservoirs)

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9 pages, 1185 KiB

Open AccessCommunication

Constructed Wetland-Microbial Fuel Cells for Sustainable Greywater Treatment

by Ignacio Araneda, Natalia F. Tapia, Katherine Lizama Allende and Ignacio T. Vargas

Water 2018, 10(7), 940; https://doi.org/10.3390/w10070940 - 14 Jul 2018

Cited by 61 | Viewed by 8783

Abstract

Greywater reuse through decentralized and low-cost treatment systems emerges as an opportunity to tackle the existing demand for water. In recent years, constructed wetlands (CW) systems and microbial fuel cells (MFCs) have emerged as attractive technologies for sustainable wastewater treatment. In this study, [...] Read more.

Greywater reuse through decentralized and low-cost treatment systems emerges as an opportunity to tackle the existing demand for water. In recent years, constructed wetlands (CW) systems and microbial fuel cells (MFCs) have emerged as attractive technologies for sustainable wastewater treatment. In this study, constructed wetland microbial fuel cells (CW-MFCs) planted with Phragmites australis were tested to evaluate the potential of combining these two systems for synthetic greywater treatment and energy recovery. Open (CW) and closed circuit (CW-MFCs) reactors were operated for 152 days to evaluate the effect of energy recovery on the removal of soluble chemical oxygen demand (sCOD), nutrients and total suspended solids (TSS). Results indicate no significant differences for sCOD and phosphate removal efficiencies. CW-MFCs and CW reactors presented sCOD removal efficiency of 91.7 ± 5.1% and 90 ± 10% and phosphate removal efficiencies of 56.3 ± 4.4% and 61.5 ± 3.5%, respectively. Nitrate removal efficiencies were higher in CW: 99.5 ± 1% versus 86.5 ± 7.1% in CW-MFCs, respectively. Energy generation reached a maximum power density of 33.52 ± 7.87 mW m⁻³ and 719.57 ± 67.67 mW m⁻³ at a poised anode potential of −150 mV vs. Ag/AgCl. Thus, our results suggest that the incorporation of MFC systems into constructed wetlands does allow energy recovery while providing effective greywater treatment. Full article

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

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13 pages, 277 KiB

Open AccessArticle

Developing a Statistical Model to Improve Drinking Water Quality for Water Distribution System by Minimizing Heavy Metal Releases

by Wei Peng and Rene V. Mayorga

Water 2018, 10(7), 939; https://doi.org/10.3390/w10070939 - 14 Jul 2018

Cited by 2 | Viewed by 3233

Abstract

This paper proposes a novel statistical approach for blending source waters in a public water distribution system to improve water quality (WQ) by minimizing the release of heavy metals (HMR). Normally, introducing a new source changes the original balanced environment and causes adverse [...] Read more.

This paper proposes a novel statistical approach for blending source waters in a public water distribution system to improve water quality (WQ) by minimizing the release of heavy metals (HMR). Normally, introducing a new source changes the original balanced environment and causes adverse effects on the WQ in a water distribution system. One harmful consequence of blending source water is the release of heavy metals, including lead, copper and iron. Most HMR studies focus on the forecasting of unfavorable effects using precise and complicated nonlinear equations. This paper uses a statistical multiple objectives optimization, namely Multiple Source Waters Blending Optimization (MSWBO), to find optimal blending ratios of source waters for minimizing three HMRs in a water supply system. In this paper, three response surface equations are applied to describe the reaction kinetics of HMR, and three dual response surface equations are used to track the standard deviations of the three response surface equations. A weighted sum method is performed for the multi-objective optimization problem to minimize three HMRs simultaneously. Finally, the experimental data of a pilot distribution system is used in the proposed statistical approach to demonstrate the model’s applicability, computational efficiency, and robustness. Full article

(This article belongs to the Special Issue Advances in Water Distribution Networks)

20 pages, 4604 KiB

Open AccessArticle

Time Variability Patterns of Eutrophication Indicators in the Bay of Algeciras (South Spain)

by Jesús M. Mercado, Pablo León, Soluna Salles, Dolores Cortés, Lidia Yebra, Francisco Gómez-Jakobsen, Inma Herrera, Aitor Alonso, Antonio Sánchez, Nerea Valcárcel-Pérez and Sébastien Putzeys

Water 2018, 10(7), 938; https://doi.org/10.3390/w10070938 - 14 Jul 2018

Cited by 6 | Viewed by 4478

Abstract

In the Bay of Algeciras (BA), intensive urban and industrial activityis underway, which is potentially responsible for the release of significant quantities of nutrients. However, the assessment of the impact of these discharges is complex. Nutrient concentration in the surface layer is per [...] Read more.

In the Bay of Algeciras (BA), intensive urban and industrial activityis underway, which is potentially responsible for the release of significant quantities of nutrients. However, the assessment of the impact of these discharges is complex. Nutrient concentration in the surface layer is per se strongly variable due to the variability associated with the upwelling of nutrient-enriched deep Mediterranean water (MW), which in turn is regulated by atmospheric forcing. The aim of this study is to determine the effects of changes in the upwelling intensity on the load of nitrate and phosphate in the BA and to appraise their impact on chlorophyll a variability. Based on this analysis, the possible influence of the nutrients released from land-based sources is indirectly inferred. Data and samples collected during nine research cruises carried out in different seasonal cycle periods between 2010 and 2015 in the BA were analysed. The vertical variation of temperature and salinity indicates that the MW upwelling was favoured in spring, as occurred in other coastal areas of the northern Alboran Sea. However, principal component analysis conducted on physical and chemical data reveals that shifts in nutrients and chlorophyll a in the euphotic layer are poorly explained by changes in the upwelling intensity. Furthermore, during some of these research surveys (particularly in summer), chlorophyll a concentrations were higher in the BA as compared to a nearby coastal area also affected by MW upwelling. Scarce information about land-based pollution sources precludes quantitative analysis of the impact of nutrient loads on water quality; however, the available data suggest that the main source of allochthanous inorganic nitrogen over the period 2010–2015 in the BA was nitrate. Therefore, it is reasonable to hypothesize that the high concentrations of nitrate and chlorophyll a in BA in summer are a consequence of those discharges. Our study highlights the need of more exhaustive inventories of sewage and river discharges to adequately rate their impact in the BA. Full article

(This article belongs to the Special Issue Eutrophication Management: Monitoring and Control)

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11 pages, 2084 KiB

Open AccessArticle

Effective Evaluation of Infiltration and Storage Measures in Sponge City Construction: A Case Study of Fenghuang City

by Jinjun Zhou, Jiahong Liu, Weiwei Shao, Yingdong Yu, Kun Zhang, Ying Wang and Chao Mei

Water 2018, 10(7), 937; https://doi.org/10.3390/w10070937 - 14 Jul 2018

Cited by 23 | Viewed by 5209

Abstract

In recent years, urban waterlogging problems have become more and more serious, which has led to flood disasters in some cities. The Chinese government launched the sponge city pilot construction in 2015 to mitigate the risk of urban flooding and control the runoff [...] Read more.

In recent years, urban waterlogging problems have become more and more serious, which has led to flood disasters in some cities. The Chinese government launched the sponge city pilot construction in 2015 to mitigate the risk of urban flooding and control the runoff in source areas. Rain-runoff control is one of the main indices of a sponge city, thus, evaluating its control effect is essential for sponge city construction. This paper chose Fenghuang city, located in the west of Hunan province, as a case study area to assess the rainwater control effect by using the MIKE FLOOD model. The results showed that: (1) the total annual runoff control rate (TARCR) of sponge city design was a reasonable indicator for daily rainwater control; (2) the goal of Fenghuang Sponge City was close to the 1-year rainfall event; and (3) infiltration and storage measures could reduce but not eliminate urban waterlogging. The capacity of the drainage system should be fundamentally improved to enhance the prevention standards of urban waterlogging. Full article

(This article belongs to the Section Urban Water Management)

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