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Water, Volume 11, Issue 9 (September 2019)

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Open AccessArticle
Acetaminophen Removal from Water by Microalgae and Effluent Toxicity Assessment by the Zebrafish Embryo Bioassay
Water 2019, 11(9), 1929; https://doi.org/10.3390/w11091929 (registering DOI) - 15 Sep 2019
Abstract
In this work, zebrafish embryo bioassays were performed to assess the efficiency of microalgae in the removal of acetaminophen from water. Chlorella sorokiniana (CS), Chlorella vulgaris (CV) and Scenedesmus obliquus (SO) were the strains used for water treatment. Toxic effects on zebrafish embryo [...] Read more.
In this work, zebrafish embryo bioassays were performed to assess the efficiency of microalgae in the removal of acetaminophen from water. Chlorella sorokiniana (CS), Chlorella vulgaris (CV) and Scenedesmus obliquus (SO) were the strains used for water treatment. Toxic effects on zebrafish embryo caused by effluents from microalgae treatment were compared with those observed under exposure to experimental solutions with known concentrations of acetaminophen. The three microalgae strains allowed for the reduction of acetaminophen concentration and its toxic effects, but CS was the most efficient one. At the end of the batch culture, a 67% removal was provided by CS with a reduction of 62% in the total abnormalities on the exposed zebrafish embryo. On the other hand, toxic effects observed under exposure to effluents treated by microalgae were alike to those determined for acetaminophen experimental solutions with equivalent concentration. Thus, it may be inferred that microalgae biodegradation of acetaminophen did not involve an increased toxicity for zebrafish embryo. Full article
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Open AccessArticle
A Numerical Study of Fluid Flow in a Vertical Slot Fishway with the Smoothed Particle Hydrodynamics Method
Water 2019, 11(9), 1928; https://doi.org/10.3390/w11091928 (registering DOI) - 15 Sep 2019
Abstract
Fishways have a great ecological importance as they help mitigate the interruptions of fish migration routes. In the present work, the novel DualSPHysics v4.4 solver, based on the smoothed particle hydrodynamics method (SPH), has been applied to perform three-dimensional (3-D) simulations of water [...] Read more.
Fishways have a great ecological importance as they help mitigate the interruptions of fish migration routes. In the present work, the novel DualSPHysics v4.4 solver, based on the smoothed particle hydrodynamics method (SPH), has been applied to perform three-dimensional (3-D) simulations of water flow in a vertical slot fishway (VSF). The model has been successfully calibrated against published field data of flow velocities that were measured with acoustic Doppler velocity probes. A state-of-the-art algorithm for the treatment of open boundary conditions using buffer layers has been applied to accurately reproduce discharges, water elevations, and average velocity profiles (longitudinal and transverse velocities) within the observed pool of the VSF. Results herein indicate that DualSPHysics can be an accurate tool for modeling turbulent subcritical free surface flows similar to those that occur in VSF. A novel relation between the number of fluid particles and the artificial viscosity coefficient has been formulated with a simple logarithmic fit. Full article
(This article belongs to the Section Hydraulics)
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Open AccessArticle
Investigation of Karst Spring Flow Cessation Using Grey System Models
Water 2019, 11(9), 1927; https://doi.org/10.3390/w11091927 (registering DOI) - 15 Sep 2019
Abstract
Karst aquifers are prominent sources of water worldwide; they store large amounts of water and are known for their beautiful springs. However, extensive groundwater development and climate variation has resulted in a decline in the flow of most karst springs; some have even [...] Read more.
Karst aquifers are prominent sources of water worldwide; they store large amounts of water and are known for their beautiful springs. However, extensive groundwater development and climate variation has resulted in a decline in the flow of most karst springs; some have even dried up. In order to obtain a better understanding of the factors contributing to this development, this study introduced grey system models, which quantified spring flow, taking Jinci Springs (China), which dried up in May 1994, as an example. Based on the characteristics of Jinci Springs, spring flow was divided into two stages: first (1954–1960), when the spring flow was affected only by climate variation; and second (1961–1994), when the flow was impacted by both climate variation and anthropogenic activities. The results showed that Jinci Springs flow had a strong relationship with precipitation occurring one year and three years earlier in the first stage. Subsequently, a grey system GM (1,3) model with one-year and three-year lags was set up for the first stage. By using the GM (1,3) model, we simulated the spring flow in the second stage under effects of climate variation only. By subtracting the observed spring flow from the simulated flow, we obtained the contribution of anthropogenic activities to Jinci Springs’ cessation. The contribution of anthropogenic activities and climate variation to the decline was 1.46 m3/s and 0.62 m3/s, respectively. Finally, each human activity that caused the decline was estimated. The methods devised herein can be used to describe karst hydrological processes that are under the effects of anthropogenic activities and climate variation. Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle
Water Infrastructure Always In-The-Making: Distributing Water and Authority through the Water Supply Network in Moamba, Mozambique
Water 2019, 11(9), 1926; https://doi.org/10.3390/w11091926 (registering DOI) - 15 Sep 2019
Viewed by 58
Abstract
Using the concept of sociotechnical tinkering, this paper provides detailed empirical observations about the everyday practices of design, construction, operation, maintenance and use of a piped water supply network in a small town in Mozambique. We use these to show that the form, [...] Read more.
Using the concept of sociotechnical tinkering, this paper provides detailed empirical observations about the everyday practices of design, construction, operation, maintenance and use of a piped water supply network in a small town in Mozambique. We use these to show that the form, materiality, and functioning of this water infrastructure are constantly changing as result of interactions with its physical environment as well as in response to experimentation and improvisation by engineers, construction workers, operators and water users. Sociotechnical tinkering not just (re)distributes water, but also provides an avenue through which powers to control water flows can be wielded and exercised. In this sense, empirical attention to sociotechnical tinkering provides a useful entry-point for rethinking the distribution of control, authority and responsibility in water governance, or more broadly the relations between power and infrastructure. This, in turn, may yield new inspirations for identifying pragmatic possibilities for progressive water politics. Full article
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Open AccessFeature PaperArticle
A Continuous Drought Probability Monitoring System, CDPMS, Based on Copulas
Water 2019, 11(9), 1925; https://doi.org/10.3390/w11091925 (registering DOI) - 14 Sep 2019
Viewed by 192
Abstract
The standardized precipitation index (SPI), is one of the most used drought indices. However, it is difficult to use to monitor the ongoing drought characteristics because it cannot be expeditiously related to precipitation deficits. It also does not provide information regarding the drought [...] Read more.
The standardized precipitation index (SPI), is one of the most used drought indices. However, it is difficult to use to monitor the ongoing drought characteristics because it cannot be expeditiously related to precipitation deficits. It also does not provide information regarding the drought probability nor the temporal evolution of the droughts. By assigning the SPI to drought-triggering precipitation thresholds, a copula-based continuous drought probability monitoring system (CDPMS), was developed aiming to monitor the probability of having a drought as the rainy season advances. In fact, in climates with very pronounced rainy seasonality, the absence of precipitation during the rainy season is the fundamental cause of droughts. After presenting the CDPMS, we describe its application to Mainland Portugal and demonstrate that the system has an increased capability of anticipating drought probability by the end of the rainy season as new precipitation records are collected. The good performance of the system results from the ability of the copula to model complex dependence structures as those existing between precipitations at different time intervals. CDPMS is an innovative and user-friendly tool to monitor precipitation and, consequently, the drought probability, allowing the user to anticipate mitigation and adaptation measures, or even to issue alerts. Full article
(This article belongs to the Special Issue Management of Hydrological Extremes: Floods and Droughts)
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Open AccessArticle
The Effect of Hydrological Connectivity on the Zooplankton Structure in Floodplain Lakes of a Regulated Large River (the Lower Vistula, Poland)
Water 2019, 11(9), 1924; https://doi.org/10.3390/w11091924 (registering DOI) - 14 Sep 2019
Viewed by 136
Abstract
The zooplankton community structure and diversity were analysed against the gradient of floodplain lakes connectivity and water level under different flood-pulse dynamics in the Vistula River. The lakes differed in terms of hydrology, among others in the degree/type of their connection with the [...] Read more.
The zooplankton community structure and diversity were analysed against the gradient of floodplain lakes connectivity and water level under different flood-pulse dynamics in the Vistula River. The lakes differed in terms of hydrology, among others in the degree/type of their connection with the river (permanent, temporary and no connection). The study was conducted during the growing seasons in the years 2006–2013 and involved the lower Vistula River and three floodplain lakes: isolated, transitional and connected. Water samples were collected biweekly from April to September. Zooplankton was the most diverse and abundant in the transitional lake (the highest Shannon α-diversity index H’ and Pielou’s evenness index J’). The gentle washing of the lakes might have stimulated the development of zooplankton in accordance with the Intermediate Disturbance Hypothesis. The diversity and density of zooplankton were higher in the connected lake compared to the isolated one. We confirmed the hypothesis that zooplankton should be more abundant and diverse in floodplain lakes connected with the river (or transitional) than in isolated ones. Zooplankton analyses indicated that hydrological conditions (flood-pulse regime) contributed most substantially to zooplankton diversity and density in the floodplain lakes of the lower Vistula valley. Full article
(This article belongs to the Special Issue Water Quality of Freshwater Ecosystems in a Temperate Climate)
Open AccessArticle
Examination of Nutrient Sources and Transport in a Catchment with an Audubon Certified Golf Course
Water 2019, 11(9), 1923; https://doi.org/10.3390/w11091923 (registering DOI) - 14 Sep 2019
Viewed by 159
Abstract
Water bodies in the East Bay Regional Park District (EBRPD), California, United States, provide aesthetic value and critical ecosystem services, but are often adversely affected by the activities and infrastructure of the intensely urban environment that surrounds the parks. EBRPD leases a golf [...] Read more.
Water bodies in the East Bay Regional Park District (EBRPD), California, United States, provide aesthetic value and critical ecosystem services, but are often adversely affected by the activities and infrastructure of the intensely urban environment that surrounds the parks. EBRPD leases a golf course (Tilden Golf Course (TGC)) in Tilden Regional Park, one of its most popular parks located in the Berkeley Hills, which was certified as an Audubon Cooperative Sanctuary in 2013. Nonetheless, application of nutrients and pesticides (fungicides, plant growth regulators and herbicides) are commonly used to maintain turf systems and may be transported via surface runoff or through subsurface drainage to surface waters, leading to the concern that golf courses are a major contributor to water pollution. We studied the possible contribution of nutrients (NO3-N and PO4-P) and pesticides transported via storm-generated surface runoff and via groundwater from TGC to the primary drainage in the watershed, Wildcat Creek. Lake Anza, a popular open water swimming lake, is located downstream from TGC and experiences occasional nutrient-driven algal blooms that have caused swim beach closures. Measured NO3-N and PO4-P in the stream, at times, exceeded concentration limits of 1 mg/L (as N) and 0.05 mg/L (as P), respectively, considered protective of aquatic ecosystems by the United States Environmental Protection Agency (1986). We found that phosphorous likely has a dominant natural source, but nitrogen is primarily derived from a golf course fertilizer source and its concentration increases in the stream during runoff events, while other soluble species decrease. Analyses of pesticides in water reveal the presence of Azoxystrobin in stream water at the golf course, but with concentrations well below the regulatory limit. These results indicate that all other pesticides applied on TGC are not likely transported to the stream, suggesting future reactive transport research must treat contaminant species independently based on their specific transport behaviors. Full article
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Open AccessArticle
Pilot-Scale Evaluation of a Permeable Reactive Barrier with Compost and Brown Coal to Treat Groundwater Contaminated with Trichloroethylene
Water 2019, 11(9), 1922; https://doi.org/10.3390/w11091922 (registering DOI) - 14 Sep 2019
Viewed by 151
Abstract
This study evaluates, under field conditions, the efficiency of a permeable reactive barrier (PRB) with compost and brown coal to remove trichloroethylene (TCE) (109 µg/L) from contaminated groundwater. Three stainless steel boxes (1.2 × 0.5 × 0.5 m) with the brown coal-compost mixture [...] Read more.
This study evaluates, under field conditions, the efficiency of a permeable reactive barrier (PRB) with compost and brown coal to remove trichloroethylene (TCE) (109 µg/L) from contaminated groundwater. Three stainless steel boxes (1.2 × 0.5 × 0.5 m) with the brown coal-compost mixture at three different mixing ratios of 1:1, 1:3, and 1:5 (by volume) were installed to simulate the PRB. Groundwater from the TCE-contaminated aquifer was pumped into the system at a flow rate of 3.6 L/h. Residence times in the boxes were of: 25, 20, 10 h, respectively. Effluent samples were analyzed for TCE and its daughter products: dichloroethylene (DCE), vinyl chloride (VC) and ethane. During the 198-day experimental period TCE concentrations in groundwater decreased below ≤1.1 µg/L, i.e., much lower than groundwater and drinking water standards in Poland. After 16 days cis-1,2-DCE was monitored indicating possible reductive dechlorination of TCE. However, complete transformation of TCE into non-toxic byproducts was not evidenced during the time of experiments, indicating that reductive dechlorination slowed down or stopped at DCE, and that the designed residence times were not long enough to allow the complete dechlorination process. Full article
(This article belongs to the Special Issue Groundwater and Soil Remediation)
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Open AccessArticle
Potential of Water Hyacinth Infestation on Lake Tana, Ethiopia: A Prediction Using a GIS-Based Multi-Criteria Technique
Water 2019, 11(9), 1921; https://doi.org/10.3390/w11091921 (registering DOI) - 14 Sep 2019
Viewed by 135
Abstract
Water hyacinth is a well-known invasive weed in lakes across the world and harms the aquatic environment. Since 2011, the weed has invaded Lake Tana substantially posing a challenge to the ecosystem services of the lake. The major factors which affect the growth [...] Read more.
Water hyacinth is a well-known invasive weed in lakes across the world and harms the aquatic environment. Since 2011, the weed has invaded Lake Tana substantially posing a challenge to the ecosystem services of the lake. The major factors which affect the growth of the weed are phosphorus, nitrogen, temperature, pH, salinity, and lake depth. Understanding and investigating the hotspot areas is vital to predict the areas for proper planning of interventions. The main objective of this study is therefore to predict the hotspot areas of the water hyacinth over the surface of the lake using the geographical information system (GIS)-based multi-criteria evaluation (MCE) technique. The main parameters used in the multi-criteria analysis were total phosphorus (>0.08 mg L−1), total nitrogen (>1.1 mg L−1), temperature (<26.2 °C), pH (<8.6), salinity (<0.011%), and depth (<6 m). These parameters were collected from 143 sampling sites on the lake in August, December (2016), and March (2017). Fuzzy overlay spatial analysis was used to overlay the different parameters to obtain the final prediction map of water hyacinth infestation areas. The results indicated that 24,969 ha (8.1%), 21,568.7 ha (7.1%), and 24,036 ha (7.9%) of the lake are susceptible to invasion by the water hyacinth in August, December, and March, respectively. At the maximum historical lake level, 30,728.4 ha will be the potential susceptible area for water hyacinth growth and expansion at the end of the rainy season in August. According to the result of this study, the north and northeastern parts of the lake are highly susceptible for invasion. Hence, water hyacinth management and control plans shall mainly focus on the north and northeastern part of Lake Tana and upstream contributing watersheds. Full article
Open AccessFeature PaperArticle
Analysis of the Effects of High Precipitation in Texas on Rainfed Sorghum Yields
Water 2019, 11(9), 1920; https://doi.org/10.3390/w11091920 (registering DOI) - 14 Sep 2019
Viewed by 145
Abstract
Most of the recent studies on the consequences of extreme weather events on crop yields are focused on droughts and warming climate. The knowledge of the consequences of excess precipitation on the crop yield is lacking. We attempted to fill this gap by [...] Read more.
Most of the recent studies on the consequences of extreme weather events on crop yields are focused on droughts and warming climate. The knowledge of the consequences of excess precipitation on the crop yield is lacking. We attempted to fill this gap by estimating reductions in rainfed grain sorghum yields for excess precipitation. The historical grain sorghum yield and corresponding historical precipitation data are collected by county. These data are sorted based on length of the record and missing values and arranged for the period 1973–2003. Grain sorghum growing periods in the different parts of Texas is estimated based on the east-west precipitation gradient, north-south temperature gradient, and typical planting and harvesting dates in Texas. We estimated the growing season total precipitation and maximum 4-day total precipitation for each county growing rainfed grain sorghum. These two parameters were used as independent variables, and crop yields of sorghum was used as the dependent variable. We tried to find the relationships between excess precipitation and decreases in crop yields using both graphical and mathematical relationships. The result were analyzed in four different levels; 1. Storm by storm consequences on the crop yield; 2. Growing season total precipitation and crop yield; 3. Maximum 4-day precipitation and crop yield; and 4. Multiple linear regression of independent variables with and without a principal component analysis (to remove the correlations between independent variables) and the dependent variable. The graphical and mathematical results show decreases in rainfed sorghum yields in Texas for excess precipitation could be between 18% and 38%. Full article
(This article belongs to the Special Issue Water Management for Sustainable Food Production)
Open AccessArticle
Water Brokers: Exploring Urban Water Governance through the Practices of Tanker Water Supply in Accra
Water 2019, 11(9), 1919; https://doi.org/10.3390/w11091919 (registering DOI) - 14 Sep 2019
Viewed by 137
Abstract
Accra, the capital city of Ghana, is characterized by limited networked supply, heterogeneous water providers, and various forms of provision. In this paper, we explore how the people delivering water through water tankers shape the distribution of water across the city. Drawing on [...] Read more.
Accra, the capital city of Ghana, is characterized by limited networked supply, heterogeneous water providers, and various forms of provision. In this paper, we explore how the people delivering water through water tankers shape the distribution of water across the city. Drawing on empirical descriptions of water sourcing and distribution by truck drivers, we show that who gets what water at what price is shaped by the ability of tanker drivers to act as brokers, piecing together various social and material arrangements and resorting to different rationalities and expertise. We analyze how state actors deal with tanker supply seeking to reconcile their mandates with the realities of water supply. Analyzing urban water supply through the practices of water distribution, we show the messy and open-ended character of water governance processes. A practice-based approach makes the complex interrelations between different water providers across the city visible, and underscores the role of individual and collective identities, emotions, moral norms, and unequal interdependencies between actors in shaping urban water distributions. Full article
Open AccessArticle
Modeling Sugar Beet Responses to Irrigation with AquaCrop for Optimizing Water Allocation
Water 2019, 11(9), 1918; https://doi.org/10.3390/w11091918 (registering DOI) - 14 Sep 2019
Viewed by 139
Abstract
Process-based crop models such as AquaCrop are useful for a variety of applications but must be accurately calibrated and validated. Sugar beet is an important crop that is grown in regions under water scarcity. The discrepancies and uncertainty in past published calibrations, together [...] Read more.
Process-based crop models such as AquaCrop are useful for a variety of applications but must be accurately calibrated and validated. Sugar beet is an important crop that is grown in regions under water scarcity. The discrepancies and uncertainty in past published calibrations, together with important modifications in the program, deemed it necessary to conduct a study aimed at the calibration of AquaCrop (version 6.1) using the results of a single deficit irrigation experiment. The model was validated with additional data from eight farms differing in location, years, varieties, sowing dates, and irrigation. The overall performance of AquaCrop for simulating canopy cover, biomass, and final yield was accurate (RMSE = 11.39%, 2.10 t ha−1, and 0.85 t ha−1, respectively). Once the model was properly calibrated and validated, a scenario analysis was carried out to assess the crop response in terms of yield and water productivity to different irrigation water allocations in the two main production areas of sugar beet in Spain (spring and autumn sowing). The results highlighted the potential of the model by showing the important impact of irrigation water allocation and sowing time on sugar beet production and its irrigation water productivity. Full article
(This article belongs to the Special Issue Modelling and Management of Irrigation System)
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Open AccessFeature PaperArticle
Implementation of a Full Momentum Conservative Approach in Modelling Flow Through Tidal Structures
Water 2019, 11(9), 1917; https://doi.org/10.3390/w11091917 (registering DOI) - 14 Sep 2019
Viewed by 148
Abstract
Understanding the impact of various hydraulic structures, such as coastal reservoirs and tidal range impoundments, has been one of the key challenges of hydro–environmental engineering in recent years. Over the last half-century, several proposals for tidal range schemes in the UK have been [...] Read more.
Understanding the impact of various hydraulic structures, such as coastal reservoirs and tidal range impoundments, has been one of the key challenges of hydro–environmental engineering in recent years. Over the last half-century, several proposals for tidal range schemes in the UK have been scrutinised and then abandoned due to the uncertainty over the environmental footprint and/or the cost of electricity. Therefore, it is essential to understand the fundamental assumptions for reliable hydrodynamic analysis of these projects. This study examined the impact of the fully conserved momentum through tidal structures using a novel approach. The method was applied to 2D and 3D versions of the regional model of Swansea Bay tidal lagoon, examining two different types of velocity distribution at turbine exit. A simplified distribution significantly increased the velocity and length of the jet exiting the turbines during power generation. A realistic distribution gave more accurate results, with jet velocities more closely resembling the situation without including the momentum. The 3D model with realistic distribution has markedly improved the resulting vertical velocity profile. The value of the improved methodology for momentum conservation has proved to be particularly useful in local-scale studies. It can be applied to other similar hydraulic structures and used for the analysis of sediment transport, water quality, etc. Full article
(This article belongs to the Section Hydraulics)
Open AccessArticle
Temporal and Spatial Characteristics of Precipitation and Temperature in Punjab, Pakistan
Water 2019, 11(9), 1916; https://doi.org/10.3390/w11091916 (registering DOI) - 14 Sep 2019
Viewed by 116
Abstract
Identifying the changes in precipitation and temperature at a regional scale is of great importance for the quantification of climate change. This research investigates the changes in precipitation and surface air temperature indices in the seven irrigation zones of Punjab Province during the [...] Read more.
Identifying the changes in precipitation and temperature at a regional scale is of great importance for the quantification of climate change. This research investigates the changes in precipitation and surface air temperature indices in the seven irrigation zones of Punjab Province during the last 50 years; this province is a very important region in Pakistan in terms of agriculture and irrigated farming. The reliability of the data was examined using double mass curve and autocorrelation analysis. The magnitude and significance of the precipitation and temperature were visualized by various statistical methods. The stations’ trends were spatially distributed to better understand climatic variability across the elevation gradient of the study region. The results showed a significant warming trend in annual Tmin (minimum temperature) and Tmean (mean temperature) in different irrigation zones. However, Tmax (maximum temperature) had insignificant variations except in the high elevation Thal zone. Moreover, the rate of Tmin increased faster than that of Tmax, resulting in a reduction in the diurnal temperature range (DTR). On a seasonal scale, warming was more pronounced during spring, followed by that in winter and autumn. However, the summer season exhibited insignificant negative trends in most of the zones and gauges, except in the higher-altitude Thal zone. Overall, Bahawalpur and Faisalabad are the zones most vulnerable to warming annually and in the spring, respectively. Furthermore, the elevation-dependent trend (EDT) indicated larger increments in Tmax for higher-elevation (above 500 m a.s.l.) stations, compared to the lower-elevation ones, on both annual and seasonal scales. In contrast, the Tmin showed opposite trends at higher- and lower-elevation stations, while a moderate increase was witnessed in Tmean trends from lower to higher altitude over the study region. An increasing trend in DTR was observed at higher elevation, while a decreasing trend was noticed at the lower-elevation stations. The analysis of precipitation data indicated wide variability over the entire region during the study period. Most previous studies reported no change or a decreasing trend in precipitation in this region. Conversely, our findings indicated the cumulative increase in annual and autumn precipitation amounts at zonal and regional level. However, EDT analysis identified the decrease in precipitation amounts at higher elevation (above 1000 m a.s.l.) and increase at the lower-elevation stations. Overall, our findings revealed unprecedented evidence of regional climate change from the perspectives of seasonal warming and variations in precipitation and temperature extremes (Tmax and Tmin) particularly at higher-elevation sites, resulting in a variability of the DTR, which could have a significant influence on water resources and on the phenology of vegetation and crops at zonal and station level in Punjab. Full article
(This article belongs to the Section Hydrology)
Open AccessArticle
Physically Based Estimation of Rainfall Thresholds Triggering Shallow Landslides in Volcanic Slopes of Southern Italy
Water 2019, 11(9), 1915; https://doi.org/10.3390/w11091915 (registering DOI) - 14 Sep 2019
Viewed by 96
Abstract
On the 4th and 5th of March 2005, about 100 rainfall-induced landslides occurred along volcanic slopes of Camaldoli Hill in Naples, Italy. These started as soil slips in the upper substratum of incoherent and welded volcaniclastic deposits, then evolved downslope according to debris [...] Read more.
On the 4th and 5th of March 2005, about 100 rainfall-induced landslides occurred along volcanic slopes of Camaldoli Hill in Naples, Italy. These started as soil slips in the upper substratum of incoherent and welded volcaniclastic deposits, then evolved downslope according to debris avalanche and debris flow mechanisms. This specific case of slope instability on complex volcaniclastic deposits remains poorly characterized and understood, although similar shallow landsliding phenomena have largely been studied in other peri-volcanic areas of the Campania region underlain by carbonate bedrock. Considering the landslide hazard in this urbanized area, this study focused on quantitatively advancing the understanding of the predisposing factors and hydrological conditions contributing to the initial landslide triggering. Borehole drilling, trial pits, dynamic penetrometer tests, topographic surveys, and infiltration tests were conducted on a slope sector of Camaldoli Hill to develop a geological framework model. Undisturbed soil samples were collected for laboratory testing to further characterize hydraulic and geotechnical properties of the soil units identified. In situ soil pressure head monitoring probes were also installed. A numerical model of two-dimensional variably saturated subsurface water flow was parameterized for the monitored hillslope using field and laboratory data. Based on the observed soil pressure head dynamics, the model was calibrated by adjusting the evapotranspiration parameters. This physically based hydrologic model was combined with an infinite-slope stability analysis to reconstruct the critical unsaturated/saturated conditions leading to slope failure. This coupled hydromechanical numerical model was then used to determine intensity–duration (I-D) thresholds for landslide initiation over a range of plausible rainfall intensities and topographic slope angles for the region. The proposed approach can be conceived as a practicable method for defining a warning criterion in urbanized areas threatened by rainfall-induced shallow landslides, given the unavailability of a consistent inventory of past landslide events that prevents a rigorous empirical analysis. Full article
(This article belongs to the Special Issue The Role of Water in Shallow and Deep Landslides)
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Open AccessArticle
Characteristics and Drivers of Reference Evapotranspiration in Hilly Regions in Southern China
Water 2019, 11(9), 1914; https://doi.org/10.3390/w11091914 (registering DOI) - 14 Sep 2019
Viewed by 92
Abstract
This paper has adopted related meteorological data collected by 69 meteorological stations between 1951 and 2013 to analyze changes and drivers of reference evapotranspiration (ET0) in the hilly regions located in southern China. Results show that: (1) ET0 in southern [...] Read more.
This paper has adopted related meteorological data collected by 69 meteorological stations between 1951 and 2013 to analyze changes and drivers of reference evapotranspiration (ET0) in the hilly regions located in southern China. Results show that: (1) ET0 in southern China’s hilly regions reaches its maximum in summer and its minimum in winter, and that the annual ET0 shows an increasing trend. ET0 happened abrupt change due to the impact of abrupt meteorological variables changes, and the significant year of mutation were 1953, 1964 and 2008. Most abrupt changes of ET0 in meteorological stations occurred in the 1950s and 1960s. (2) The low value of ET0 was mainly captured in high-altitude areas. Spatially, the ET0 in the east was higher than that in the west. With the exception of a handful of stations, the trend coefficients of ET0 were all positive, exhibiting a gradual rise. Changes in ET0 in the east were much more sensitive than that in the west. Since ET0 was affected by the cyclical changes in relative humidity, short-period oscillations were observed in all these changes. (3) In general, the ET0 was negatively correlated with relative humidity, and positively correlated with temperature and sunshine percentage. ET0 is most sensitive to changes in average temperature, with a sensitivity coefficient of 1.136. ET0 showed positive sensitivity to average temperature and sunshine hours, which were notable in the northeastern, and uniform in the spatial. ET0 showed negatively sensitivity to relative humidity, and the absolute value of sensitivity coefficient in the northwestern is smaller. The highest contribution to ET0 is the average temperature (6.873%), and the total contribution of the four meteorological variables to the change of ET0 is 7.842%. The contribution of average temperature, relative humidity, and sunshine hours to ET0 is higher in the northern and eastern, northern, northern and eastern areas, respectively. Climate indexes (Western Pacific Index (WP), Southern Oscillation Index (SOI), Tropical Northern Atlantic Index (TNA), and El Niño-Southern Oscillation (ENSO)) were correlated with the ET0. In addition, the ET0 and altitude, as well as the latitude and longitude were also correlated with each other. Full article
(This article belongs to the Special Issue Assessment of Spatial and Temporal Variability of Water Resources)
Open AccessArticle
The Performance of Satellite-Based Actual Evapotranspiration Products and the Assessment of Irrigation Efficiency in Egypt
Water 2019, 11(9), 1913; https://doi.org/10.3390/w11091913 (registering DOI) - 14 Sep 2019
Viewed by 153
Abstract
Monitoring of crop water consumption, also known as actual evapotranspiration (ETa), is crucial for the prudent use of limited freshwater resources. Remote-sensing-based algorithms have become a popular approach for providing spatio-temporal information on ETa. Satellite-based ETa products are widely available. However, identifying an [...] Read more.
Monitoring of crop water consumption, also known as actual evapotranspiration (ETa), is crucial for the prudent use of limited freshwater resources. Remote-sensing-based algorithms have become a popular approach for providing spatio-temporal information on ETa. Satellite-based ETa products are widely available. However, identifying an adequate product remains a challenge due to validation data scarcity. This study developed an assessment process to identify superior ETa products in agricultural areas in Egypt. The land cover product (MCD12Q1) from Moderate Resolution Imaging Spectroradiometer (MODIS) was evaluated and used to detect agricultural areas. The performances of three ETa products, namely: Earth Engine Evapotranspiration Flux (EEFlux), USGS-FEWS NET SSEBop ETa monthly product, and MODIS ETa monthly product (MOD16A2), were evaluated. The ETa values of these products were compared to previous ETa observations and evaluated using the integrated Normalized Difference Vegetation Index (iNDVI) on a seasonal and annual basis. Finally, the irrigation efficiency throughout Egypt was calculated based on the annual Relative Water Supply (RWS) index. Results reveal that the SSEBop monthly product has the best performance in Egypt, followed by the MOD16A2. The EEFlux overestimated ETa values by 36%. RWS had a range of 0.96–1.47, indicating high irrigation efficiency. The findings reported herein can assist in improving irrigation water management in Egypt and the Nile Basin. Full article
(This article belongs to the Special Issue Evapotranspiration and Plant Irrigation Strategies)
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Open AccessArticle
Adsorptive Removal of Iron and Manganese from Groundwater Samples in Ghana by Zeolite Y Synthesized from Bauxite and Kaolin
Water 2019, 11(9), 1912; https://doi.org/10.3390/w11091912 (registering DOI) - 13 Sep 2019
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Abstract
Ground water samples from residential homes in three Regions of Ghana: Central, Greater Accra and Ashanti, were analyzed for iron and manganese contamination. The samples were exposed to characterized zeolite Y by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transformed-infrared [...] Read more.
Ground water samples from residential homes in three Regions of Ghana: Central, Greater Accra and Ashanti, were analyzed for iron and manganese contamination. The samples were exposed to characterized zeolite Y by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transformed-infrared spectroscopy and thermos gravimetric-differential thermal analysis. Zeolite Y is able to remove 98% of iron and 97% of manganese within an hour. The adsorption of both iron and manganese followed the Freundlich model, suggesting that the ions were transported onto the zeolite Y surface and subsequently diffused into the zeolite Y framework. The kinetic studies showed that pseudo-first order and intra particle and film diffusion models provided the best fit. The adsorption at 0.2 mg L−1 Fe ( Q 0.2 ) is calculated to be 0.023 mg g−1 for the Freundlich adsorption model, whilst that of manganese at 0.05 mg L−1 Mn ( Q 0.05 ) is evaluated to be 0.015 mg g−1. The zeolite retains its adsorption properties when retrieved from the first exposure water sample, washed copiously with distilled water and added to fresh water samples. The results suggest that zeolite Y can be used as a potential adsorbent for the removal of iron and manganese from groundwater. Full article
(This article belongs to the Special Issue Technologies Developing in Heavy Metals' Removal from Water)
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Open AccessArticle
Evaluation of MOD16 Algorithm over Irrigated Rice Paddy Using Flux Tower Measurements in Southern Brazil
Water 2019, 11(9), 1911; https://doi.org/10.3390/w11091911 (registering DOI) - 13 Sep 2019
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Abstract
Evapotranspiration (ET) is an important component of the hydrological cycle. Understanding the ET process has become of fundamental importance given the scenario of global change and increasing water use, especially in the agricultural sector. Determining ET over large agricultural areas is a limiting [...] Read more.
Evapotranspiration (ET) is an important component of the hydrological cycle. Understanding the ET process has become of fundamental importance given the scenario of global change and increasing water use, especially in the agricultural sector. Determining ET over large agricultural areas is a limiting factor due to observational data availability. In this regard, remote sensing data has been used to estimate ET. In this study, we evaluated the Moderate-Resolution Imaging Spectroradiometer (MODIS) land surface ET product estimates (hereafter MOD16 ET – MODIS Global Terrestrial Evapotranspiration Product) over two rice paddy areas in Southern Brazil, through the ET measured using the eddy covariance technique (hereafter EC). The energy balance components were evaluated during fallow and flooded seasons showing latent heat flux dominates in both seasons. The results showed that MOD16 ET underestimated EC measurements. Overall, the RMSE (root mean square error) ranged between 13.40 and 16.35 mm 8-day−1 and percent bias (PBIAS) ranged between −33.7% and −38.7%. We also assessed the ET (measured and estimated) main drivers, with EC yielding higher correlation against observed net radiation (Rn) and global radiation (Rg), followed by air temperature (Temp) and vapor pressure deficit (VPD), whilst MOD16 ET estimates yielded higher correlation against leaf area index (LAI) and fraction of photosynthetically active radiation (fPAR). The MOD16 algorithm was forced with meteorological measurements but the results did not improve as expected, suggesting a low sensitivity to meteorological inputs. Our results indicated when a water layer was present over the soil surface without vegetation (LAI around zero), the largest differences between EC measurements and MOD16 ET were found. In this period, the expected domain of soil evaporation was not observed in MOD16 ET physical processes partition, indicating the algorithm was not able to detect areas with high soil moisture. In general, the MOD16 ET product presented low accuracy when compared against experimental measurements over flooded rice paddy, suggesting more studies are necessary, in order to reduce uncertainties associated to the land cover conditions. Full article
(This article belongs to the Section Hydrology)
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Open AccessArticle
Wall Stresses in Cylinder of Stationary Piped Carriage Using COMSOL Multiphysics
Water 2019, 11(9), 1910; https://doi.org/10.3390/w11091910 (registering DOI) - 13 Sep 2019
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Abstract
Hydraulic transportation of the piped carriage is a new energy-saving and environmentally-friendly transportation mode. There are two main states in the conveying process, stationary and moving. In the process of hydraulic transportation of the piped carriage, the study of the stress of the [...] Read more.
Hydraulic transportation of the piped carriage is a new energy-saving and environmentally-friendly transportation mode. There are two main states in the conveying process, stationary and moving. In the process of hydraulic transportation of the piped carriage, the study of the stress of the water flow act on the cylinder wall of the piped carriage can help to improve the design of the piped carriage structure and even the selection of piped carriage materials. The distribution of flow velocity around the stationary piped carriage and the stress distribution on the cylinder wall of the stationary piped carriage were investigated by combining numerical simulations with model experiment verification. The commercial finite element software, Comsol Multiphysics, was utilized to solve this problem using the arbitrary Lagrangian–Eulerian (ALE) method. The results showed that the simulation results were in good agreement with the experimental results. It also showed that the ALE method can well be applied for fluid-structure problems in the process of hydraulic transportation of the piped carriage. The simulation results showed that the low velocity region near the inner wall of the pipe was smaller than that near the outer wall of the piped carriage, and both regions decreased with the increase of the discharge. The maximum stress on the cylinder wall of the piped carriage appeared between the two support feet in the middle and rear sections of the cylinder. The influence of the unit discharge on wall stress increased with the increase of the discharge, that is, k1 < k2 < k3. Moreover, the increase of the discharge had the greatest influence on the circumferential component of the principal stress of the cylinder, followed by the axis component, and the smallest influence on the wall shear stress of the cylinder, i.e., k ¯ σ c > k ¯ σ a > k ¯ σ r > k ¯ τ c . Full article
(This article belongs to the Special Issue Pipeline Fluid Mechanics)
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Open AccessArticle
Optimized Conditioning Factors Using Machine Learning Techniques for Groundwater Potential Mapping
Water 2019, 11(9), 1909; https://doi.org/10.3390/w11091909 (registering DOI) - 13 Sep 2019
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Abstract
Assessment of the most appropriate groundwater conditioning factors (GCFs) is essential when performing analyses for groundwater potential mapping. For this reason, in this work, we look at three statistical factor analysis methods—Variance Inflation Factor (VIF), Chi-Square Factor Optimization, and Gini Importance—to measure the [...] Read more.
Assessment of the most appropriate groundwater conditioning factors (GCFs) is essential when performing analyses for groundwater potential mapping. For this reason, in this work, we look at three statistical factor analysis methods—Variance Inflation Factor (VIF), Chi-Square Factor Optimization, and Gini Importance—to measure the significance of GCFs. From a total of 15 frequently used GCFs, 11 most effective ones (i.e., altitude, slope angle, plan curvature, profile curvature, topographic wetness index, distance from river, distance from fault, river density, fault density, land use, and lithology) were finally selected. In addition, 917 spring locations were identified and used to train and test three machine learning algorithms, namely Mixture Discriminant Analysis (MDA), Linear Discriminant Analysis (LDA) and Random Forest (RF). The resultant trained models were then applied for groundwater potential prediction and mapping in the Haraz basin of Mazandaran province, Iran. MDA has been successfully applied for soil erosion and landslide mapping, but has not yet been fully explored for groundwater potential mapping (GPM). Although other discriminant methods, such as LDA, exist, MDA is worth exploring due to its capability to model multivariate nonlinear relationships between variables; it also undertakes a mixture of unobserved subclasses with regularization of non-linear decision boundaries, which could potentially provide more accurate classification. For the validation, areas under Receiver Operating Characteristics (ROC) curves (AUC) were calculated for the three algorithms. RF performed better with AUC value of 84.4%, while MDA and LDA yielded 75.2% and 74.9%, respectively. Although MDA performance is lower than RF, the result is satisfactory, because it is within the acceptable standard of environmental modeling. The outcome of factor analysis and groundwater maps emphasizes on optimization of multicolinearity factors for faster spatial modeling and provides valuable information for government agencies and private sectors to effectively manage groundwater in the region. Full article
(This article belongs to the Section Water Resources Management and Governance)
Open AccessArticle
Development Trend and Frontier of Stormwater Management (1980–2019): A Bibliometric Overview Based on CiteSpace
Water 2019, 11(9), 1908; https://doi.org/10.3390/w11091908 - 12 Sep 2019
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Abstract
The threat of urban floods due to climate change and urbanization has enabled sustained attention to the stormwater management field. Numerous scholars and countries have successively proposed innovative concepts for stormwater management. To grasp the current research focus and status quo and determine [...] Read more.
The threat of urban floods due to climate change and urbanization has enabled sustained attention to the stormwater management field. Numerous scholars and countries have successively proposed innovative concepts for stormwater management. To grasp the current research focus and status quo and determine the development trend and dynamic direction, this work used CiteSpace, a scientific bibliometric analysis software, to analyze and identify 3080 articles based on the core database of Web of Science from 1980 to 2019. Results show a comprehensive overview of the stormwater management field, including the changes of annual articles with time; the most influential countries, institutions, authors, and articles; and the periodical keywords, highly cited papers, and burst time in the field. A knowledge table in the stormwater management field was obtained, the development context of the field and the research focus of each stage were understood, and the future development trend of the field is inferred. This study aims to provide reference for researchers and practitioners in the stormwater management field. Full article
(This article belongs to the Section Water Resources Management and Governance)
Open AccessArticle
System Dynamics Approach to Groundwater Storage Modeling for Basin-Scale Planning
Water 2019, 11(9), 1907; https://doi.org/10.3390/w11091907 - 12 Sep 2019
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Abstract
A system dynamics approach to groundwater modeling suitable for groundwater management planning is presented for a basin-scale system. System dynamics techniques were used to develop a general model for estimating changes in net annual groundwater storage. This model framework was applied to two [...] Read more.
A system dynamics approach to groundwater modeling suitable for groundwater management planning is presented for a basin-scale system. System dynamics techniques were used to develop a general model for estimating changes in net annual groundwater storage. This model framework was applied to two inland groundwater basins in California and tested against groundwater depletion data developed by the United States Geological Survey. Changes in net groundwater storage developed from these models were compared to values from numerical models provided by the United States Geological Survey. The basin-specific models were able to replicate changes in net annual groundwater storage volumes for 1-year and 5-year periods at a level suitable for planning, with R2 values ranging from 0.88 to 0.93. At the 10-year prediction period, R2 values ranged from 0.83 to 0.91. The results of this research illustrate that a system dynamics model using observed relationships between components may be capable of predicting behavior for the purposes of groundwater management planning. Full article
(This article belongs to the Section Water Resources Management and Governance)
Open AccessArticle
Functionalized Leather: a Novel and Effective Hazardous Solid Waste Adsorbent for the Removal of the Diazo Dye Congo Red from Aqueous Solution
Water 2019, 11(9), 1906; https://doi.org/10.3390/w11091906 - 12 Sep 2019
Viewed by 209
Abstract
The leather industry produces a high yield of solid hazardous wastes that generate a major impact on the environment. At the same time, the use of dyes by different manufacturing industries, including the footwear industry, creates large amounts of colored wastewater that is [...] Read more.
The leather industry produces a high yield of solid hazardous wastes that generate a major impact on the environment. At the same time, the use of dyes by different manufacturing industries, including the footwear industry, creates large amounts of colored wastewater that is hard to treat. In this paper, potential adsorbents based on the functionalization of solid waste from leather in the removal of anionic dye Congo Red were studied. Twelve different functionalized adsorbents were analyzed in terms of dye removal. From those, the best adsorbents were characterized and tested to determine their life cycle, pH dependency and the resulting phytotoxicity of the treated dye baths. Different kinetic models were evaluated to describe this adsorption process. It was found that functionalized leather adsorbents presented multi-linearity behavior when removing Congo Red. Life cycle analysis showed that the adsorbents presented a high yield of absorption until the third cycle of operation, while phytotoxicity tested showed reductions up to 50% in the toxicity of the treated dye baths. Full article
(This article belongs to the Section Water and Wastewater Treatment)
Open AccessArticle
The Role of Management of Stream–Riparian Zones on Subsurface–Surface Flow Components
Water 2019, 11(9), 1905; https://doi.org/10.3390/w11091905 - 12 Sep 2019
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Abstract
A managed riparian lowland in a glacial landscape (Holtum catchment, Denmark) was studied to quantify the relative importance of subsurface and surface flow to the recipient stream. The hydrogeological characterization combined geoelectrical methods, lithological logs, and piezometric heads with monthly flow measurements of [...] Read more.
A managed riparian lowland in a glacial landscape (Holtum catchment, Denmark) was studied to quantify the relative importance of subsurface and surface flow to the recipient stream. The hydrogeological characterization combined geoelectrical methods, lithological logs, and piezometric heads with monthly flow measurements of springs, a ditch, and a drain, to determine seasonality and thereby infer flow paths. In addition, groundwater discharge through the streambed was estimated using temperature and water-stable isotopes as tracers. The lowland received large groundwater inputs with minimal seasonal variations from adjacent upland aquifers. This resulted in significant amounts of groundwater-fed surface flow to the stream, via man-made preferential flow paths comprising ditches, drainage systems, and a pond, and via two natural springs. Roughly, two thirds of the stream gain was due to surface flow to the stream, mainly via anthropogenic alterations. In contrast, direct groundwater discharge through the streambed accounted for only 4% of the stream flow gain, although bank seepage (not measured) to the straightened and deepened stream potentially accounted for an additional 17%. Comparison to analogous natural flow systems in the catchment substantiate the impact of anthropogenic alterations of riparian lowlands for the subsurface and surface flow components to their streams. Full article
(This article belongs to the Special Issue Groundwater-Surface Water Interactions)
Open AccessArticle
Application of MODFLOW with Boundary Conditions Analyses Based on Limited Available Observations: A Case Study of Birjand Plain in East Iran
Water 2019, 11(9), 1904; https://doi.org/10.3390/w11091904 - 12 Sep 2019
Viewed by 121
Abstract
Increasing water demands, especially in arid and semi-arid regions, continuously exacerbate groundwater resources as the only reliable water resources in these regions. Groundwater numerical modeling can be considered as an effective tool for sustainable management of limited available groundwater. This study aims to [...] Read more.
Increasing water demands, especially in arid and semi-arid regions, continuously exacerbate groundwater resources as the only reliable water resources in these regions. Groundwater numerical modeling can be considered as an effective tool for sustainable management of limited available groundwater. This study aims to model the Birjand aquifer using GMS: MODFLOW groundwater flow modeling software to monitor the groundwater status in the Birjand region. Due to the lack of the reliable required data to run the model, the obtained data from the Regional Water Company of South Khorasan (RWCSK) are controlled using some published reports. To get practical results, the aquifer boundary conditions are improved in the established conceptual method by applying real/field conditions. To calibrate the model parameters, including the hydraulic conductivity, a semi-transient approach is applied by using the observed data of seven years. For model performance evaluation, mean error (ME), mean absolute error (MAE), and root mean square error (RMSE) are calculated. The results of the model are in good agreement with the observed data and therefore, the model can be used for studying the water level changes in the aquifer. In addition, the results can assist water authorities for more accurate and sustainable planning and management of groundwater resources in the Birjand region. Full article
(This article belongs to the Section Hydraulics)
Open AccessArticle
The Impact of the Quality of Tap Water and the Properties of Installation Materials on the Formation of Biofilms
Water 2019, 11(9), 1903; https://doi.org/10.3390/w11091903 - 12 Sep 2019
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Abstract
The article presents changes in the quality of tap water depending on time spent in installation and its impact on the creation of biofilms on various materials (polyethylene (PE), polyvinyl chloride (PVC), chrome-nickel steel and galvanized steel). For the first time, quantitative analyses [...] Read more.
The article presents changes in the quality of tap water depending on time spent in installation and its impact on the creation of biofilms on various materials (polyethylene (PE), polyvinyl chloride (PVC), chrome-nickel steel and galvanized steel). For the first time, quantitative analyses of biofilm were performed using methods such as: Adenosine 5’-triphosphate (ATP) measurement, flow cytometry, heterotrophic plate count and using fractographical parameters. In the water, after leaving the experimental installation, the increase of turbidity, content of organic compounds, nitrites and nitrates was found, as well as the decrease in the content of chlorine compounds, dissolved oxygen and phosphorus compounds. There was an increase in the number of mesophilic and psychrophilic bacteria. In addition, the presence of Escherichia coli was also found. The analysis of the quantitative determination of microorganisms in a biofilm indicates that galvanized steel is the most susceptible material for the adhesion of microorganisms. These results were also confirmed by the analysis of the biofilm morphology. The roughness profile, the thickness of the biofilm layer can be estimated at about 300 μm on galvanized steel. Full article
(This article belongs to the Special Issue Water Quality in Drinking Water Distribution Systems)
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Open AccessArticle
Development of a Safety-Inspection Method for River Bridges in Turkey
Water 2019, 11(9), 1902; https://doi.org/10.3390/w11091902 - 12 Sep 2019
Viewed by 147
Abstract
In this paper, findings of a research project about river bridges in Turkey are shared and details of the developed safety-inspection method based on hydrological and hydraulic factors are presented. In the project, the Western Black Sea Basin was chosen as the pilot [...] Read more.
In this paper, findings of a research project about river bridges in Turkey are shared and details of the developed safety-inspection method based on hydrological and hydraulic factors are presented. In the project, the Western Black Sea Basin was chosen as the pilot area, where the basin is mountainous with steep slopes and has a rainy climate with frequent flash floods. Many river bridges in the basin were inspected at different flow conditions throughout the project duration of three years. The developed safety-inspection method is composed of four main parts: evaluation of watershed hydrology and its flood potential, stream stability, bridge characteristics and a rapid scour assessment. A structural assessment is also included in the method. Five river bridges in the area were chosen for detailed inspection and application of the method. Results showed that the method was capable of identifying and ranking the bridges in regard to maintenance needs and forming a comprehensive inventory for bridge engineers. Full article
(This article belongs to the Special Issue Bridge Hydraulics: Current State of the Knowledge and Perspectives)
Open AccessArticle
Organic Contaminants in Zooplankton of Italian Subalpine Lakes: Patterns of Distribution and Seasonal Variations
Water 2019, 11(9), 1901; https://doi.org/10.3390/w11091901 - 12 Sep 2019
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Abstract
Zooplankton is a key node in many trophic webs, both for food that for persistent organic contaminants that can accumulate in biota. Zooplankton of different size was seasonally sampled for two years in three deep Italian subalpine lakes (Maggiore, Como, Iseo) with the [...] Read more.
Zooplankton is a key node in many trophic webs, both for food that for persistent organic contaminants that can accumulate in biota. Zooplankton of different size was seasonally sampled for two years in three deep Italian subalpine lakes (Maggiore, Como, Iseo) with the aim of determining the concentrations of perfluoroalkyl substances (PFAS), DDT, and PCB, and assessing the seasonality impacts on contaminants concentrations. In general, Lake Maggiore showed the highest concentrations for each group of contaminants, with mean values of 7.6 ng g−1 ww for PFAS, 65.0 ng g−1 dw for DDT, and 65.5 ng g−1 dw for PCB. When considering the composition pattern, perfluorooctane sulfonate (PFOS) was detected in 96% of the samples and it was the predominant PFAS compound in all of the lakes. pp’ DDE was the most detected congener among DDTs and their metabolites, while for PCBs, the prevalent group was hexa-CB that constituted 35.4% of the total PCB contamination. A seasonal trend was highlighted for all contaminant groups with concentrations in colder months greater than in spring and summer; it was evident that the contaminant concentrations were more dependent from seasonality than from size, trophic levels, and taxa composition of zooplankton. Principal component analysis showed that one of the main driver for the accumulation of most of the studied contaminants is their lipophilicity, except for perfluorooctanoic acid (PFOA) and octachlorobiphenyl. Full article
(This article belongs to the Special Issue Emerging Organic Contaminants in Water Ecosystems)
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Open AccessArticle
Turbulence Characteristics before and after Scour Upstream of a Scaled-Down Bridge Pier Model
Water 2019, 11(9), 1900; https://doi.org/10.3390/w11091900 - 12 Sep 2019
Viewed by 137
Abstract
Bridge pier scour is one of the main causes of bridge failure and a major factor that contributes to the total construction and maintenance costs of bridge. Recently, because of unexpected high water during extreme hydrologic events, the resilience and security of hydraulic [...] Read more.
Bridge pier scour is one of the main causes of bridge failure and a major factor that contributes to the total construction and maintenance costs of bridge. Recently, because of unexpected high water during extreme hydrologic events, the resilience and security of hydraulic infrastructure with respect to the scour protection measure along a river reach has become a more immediate topic for river engineering society. Although numerous studies have been conducted to suggest pier scour estimation formulas, understanding of turbulence characteristics which is dominant driver of sediment transport around a pier foundation is still questionable. Thus, to understand near bed turbulence characteristics and resulting sediment transport around a pier, hydraulic laboratory experiments were conducted in a prismatic rectangular flume using scale-down bridge pier models. Three-dimensional velocities and turbulent intensities before and after scour were measured with Acoustic Doppler Velocimeter (ADV), and the results were compared/analyzed using the best available tools and current knowledge gained from recent studies. The results show that the mean flow variable is not enough to explain complex turbulent flow field around the pier leading to the maximum scour because of unsteady flows. Furthermore, results of quadrant analysis of velocity measurements just upstream of the pier in the horseshoe vortex region show significant differences before and after scour. Full article
(This article belongs to the Special Issue Turbulence and Flow–Sediment Interactions in Open-Channel Flows)
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