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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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39 pages, 60539 KiB  
Article
Use of Modern Technologies for the Conservation of Historical Heritage in Water Management
by Adrian Șmuleac, Laura Șmuleac, Teodor Eugen Man, Cosmin Alin Popescu, Florin Imbrea, Isidora Radulov, Tabita Adamov and Raul Pașcalău
Water 2020, 12(10), 2895; https://doi.org/10.3390/w12102895 - 16 Oct 2020
Cited by 14 | Viewed by 5220
Abstract
Historical monuments represent a cultural heritage that humanity has a duty to preserve and conserve. Lately all over the world, scanning these heritage objectives has become a priority, in order to preserve in the smallest details the used architecture. The work aims to [...] Read more.
Historical monuments represent a cultural heritage that humanity has a duty to preserve and conserve. Lately all over the world, scanning these heritage objectives has become a priority, in order to preserve in the smallest details the used architecture. The work aims to complete the cultural heritage for Sânmihaiu Român hydro technical development built between 1912 and 1915, located on the Bega River in Western Romania, through modern mobile scanning technology, Leica Pegasus Backpack, necessary for the creation of a three-dimensional (3D) documentation, for the completion of the cultural heritage, and for the creation of a 3D database. The purpose of the scientific paper is restoring Sanmihaiu Roman Hidro technical Node, subject to degradation, in order to achieve the project “The navigable Bega”, waterway connection to Serbia. Collecting method of LiDAR data is Fused Slam, the acquisition of RINNEX data being made by placing a Leica GS08 Master Station. Visualization of quality graphics has been performed in Quality Control (QC) Tools. The scanning accuracy is between 2 and 3 cm and the 3D data processing was performed with the Cyclone Model version program, with SmartPick Point and Virtual Surveyor functions. The obtained point clouds will be of a great help in order to follow in time the construction which can be used whenever it will be needed by the designers and specialists in the field of hydrotechnics. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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22 pages, 3112 KiB  
Article
The Structure of Riparian Vegetation in Agricultural Landscapes Influences Spider Communities and Aquatic-Terrestrial Linkages
by Ellinor Ramberg, Francis J. Burdon, Jasmina Sargac, Benjamin Kupilas, Geta Rîşnoveanu, Danny C. P. Lau, Richard K. Johnson and Brendan G. McKie
Water 2020, 12(10), 2855; https://doi.org/10.3390/w12102855 - 14 Oct 2020
Cited by 20 | Viewed by 4522
Abstract
Riparian habitats are important ecotones connecting aquatic and terrestrial ecosystems, but are often highly degraded by human activities. Riparian buffers might help support impacted riparian communities, and improve trophic connectivity. We sampled spider communities from riparian habitats in an agricultural catchment, and analyzed [...] Read more.
Riparian habitats are important ecotones connecting aquatic and terrestrial ecosystems, but are often highly degraded by human activities. Riparian buffers might help support impacted riparian communities, and improve trophic connectivity. We sampled spider communities from riparian habitats in an agricultural catchment, and analyzed their polyunsaturated fatty acid (PUFA) content to quantify trophic connectivity. Specific PUFAs are exclusively produced by stream algae, and thus are used to track uptake of aquatic resources by terrestrial consumers. Riparian spiders were collected from 10 site pairs situated along agricultural streams, and from five forest sites (25 sites total). Each agricultural site pair comprised an unshaded site with predominantly herbaceous vegetation cover, and a second with a woody riparian buffer. Spider communities differed between site types, with web-building spiders dominating woody buffered sites and free-living spiders associated with more open habitats. PUFA concentrations were greatest overall in free-living spiders, but there was also evidence for increased PUFA uptake by some spider groups when a woody riparian buffer was present. Our results reveal the different roles of open and wooded riparian habitats in supporting terrestrial consumers and aquatic-terrestrial connectivity, and highlight the value of incorporating patches of woody vegetation within riparian networks in highly modified landscapes. Full article
(This article belongs to the Special Issue Ecosystem Functioning in Rivers and Riparian Zones)
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17 pages, 2928 KiB  
Article
The Use of Various Rainfall Simulators in the Determination of the Driving Forces of Changes in Sediment Concentration and Clay Enrichment
by Judit Alexandra Szabó, Csaba Centeri, Boglárka Keller, István Gábor Hatvani, Zoltán Szalai, Endre Dobos and Gergely Jakab
Water 2020, 12(10), 2856; https://doi.org/10.3390/w12102856 - 14 Oct 2020
Cited by 11 | Viewed by 3424
Abstract
Soil erosion is a complex, destructive process that endangers food security in many parts of the world; thus, its investigation is a key issue. While the measurement of interrill erosion is a necessity, the methods used to carry it out vary greatly, and [...] Read more.
Soil erosion is a complex, destructive process that endangers food security in many parts of the world; thus, its investigation is a key issue. While the measurement of interrill erosion is a necessity, the methods used to carry it out vary greatly, and the comparison of the results is often difficult. The present study aimed to examine the results of two rainfall simulators, testing their sensitivity to different environmental conditions. Plot-scale nozzle type rainfall simulation experiments were conducted on the same regosol under both field and laboratory conditions to compare the dominant driving factors of runoff and soil loss. In the course of the experiments, high-intensity rainfall, various slope gradients, and different soil surface states (moisture content, roughness, and crust state) were chosen as the response parameters, and their driving factors were sought. In terms of the overall erosion process, the runoff, and soil loss properties, we found an agreement between the simulators. However, in the field (a 6 m2 plot), the sediment concentration was related to the soil conditions and therefore its hydrological properties, whereas in the laboratory (a 0.5 m2 plot), slope steepness and rainfall intensity were the main driving factors. This, in turn, indicates that the design of a rainfall simulator may affect the results of the research it is intended for, even if the differences occasioned by various designs may be of a low order. Full article
(This article belongs to the Special Issue Soil Water Erosion)
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18 pages, 647 KiB  
Article
Cultivating Water Literacy in STEM Education: Undergraduates’ Socio-Scientific Reasoning about Socio-Hydrologic Issues
by David C. Owens, Destini N. Petitt, Diane Lally and Cory T. Forbes
Water 2020, 12(10), 2857; https://doi.org/10.3390/w12102857 - 14 Oct 2020
Cited by 19 | Viewed by 5126
Abstract
Water-literate individuals effectively reason about the hydrologic concepts that underlie socio-hydrological issues (SHI), but functional water literacy also requires concomitant reasoning about the societal, non-hydrological aspects of SHI. Therefore, this study explored the potential for the socio-scientific reasoning construct (SSR), which includes consideration [...] Read more.
Water-literate individuals effectively reason about the hydrologic concepts that underlie socio-hydrological issues (SHI), but functional water literacy also requires concomitant reasoning about the societal, non-hydrological aspects of SHI. Therefore, this study explored the potential for the socio-scientific reasoning construct (SSR), which includes consideration of the complexity of issues, the perspectives of stakeholders involved, the need for ongoing inquiry, skepticism about information sources, and the affordances of science toward the resolution of the issue, to aid undergraduates in acquiring such reasoning skills. In this fixed, embedded mixed methods study (N = 91), we found SHI to hold great potential as meaningful contexts for the development of water literacy, and that SSR is a viable and useful construct for better understanding undergraduates’ reasoning about the hydrological and non-hydrological aspects of SHI. The breadth of reasoning sources to which participants referred and the depth of the SSR they exhibited in justifying those sources varied within and between the dimensions of SSR. A number of participants’ SSR was highly limited. Implications for operationalizing, measuring, and describing undergraduate students’ SSR, as well as for supporting its development for use in research and the classroom, are discussed. Full article
(This article belongs to the Special Issue Water Literacy and Education)
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15 pages, 305 KiB  
Article
Pipe Fault Prediction for Water Transmission Mains
by Ariel Gorenstein, Meir Kalech, Daniela Fuchs Hanusch and Sharon Hassid
Water 2020, 12(10), 2861; https://doi.org/10.3390/w12102861 - 14 Oct 2020
Cited by 10 | Viewed by 2573
Abstract
Every network of supply waterlines experiences thousands of yearly bursts, breaks, leakages, and other failures. These failures waste a great amount of resources, as not only the waterlines need to be repaired, but also water is wasted and the distribution service is interrupted. [...] Read more.
Every network of supply waterlines experiences thousands of yearly bursts, breaks, leakages, and other failures. These failures waste a great amount of resources, as not only the waterlines need to be repaired, but also water is wasted and the distribution service is interrupted. For that reason, many water facilities employ proactive maintenance strategies in their networks, where they replace likely-to-fail pipes in advance to prevent the failures. In this paper, we aim to establish a reliable prediction model that can accurately predict faults in waterlines prior to their occurrence. We propose a specific segmentation method for long transmission mains, as well as three data-driven models and one rule-based prediction model. We evaluate a real world waterline network used in Israel, operated by Mekorot company, using three common metrics. The results show that the data-driven algorithms outperform the rule-based model by at least 5% in each of the metrics. Additionally, their prediction becomes more accurate as they are trained with more data, but enhancing these data with geographically related features does not improve the accuracy further. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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25 pages, 5861 KiB  
Article
Current and Future Ecological Status Assessment: A New Holistic Approach for Watershed Management
by André R. Fonseca, João A. Santos, Simone G.P. Varandas, Sandra M. Monteiro, José L. Martinho, Rui M.V. Cortes and Edna Cabecinha
Water 2020, 12(10), 2839; https://doi.org/10.3390/w12102839 - 13 Oct 2020
Cited by 6 | Viewed by 2900
Abstract
The Paiva River catchment, located in Portugal, integrates the Natura 2000 network of European Union nature protection areas. Resorting to topography, climate and land-use data, a semi-distributed hydrological model (Hydrological Simulation Program–FORTRAN) was run in order to simulate the hydrological cycle of the [...] Read more.
The Paiva River catchment, located in Portugal, integrates the Natura 2000 network of European Union nature protection areas. Resorting to topography, climate and land-use data, a semi-distributed hydrological model (Hydrological Simulation Program–FORTRAN) was run in order to simulate the hydrological cycle of the river and its tributaries. The model was calibrated over a 25-year period and validated within a 31-year period. Its performance was verified by comparing the recorded and simulated daily flows. The values of the Nash–Sutcliffe coefficient of efficiency of 0.95 and 0.76, and coefficient of determination of 0.95 and 0.82, were achieved for calibration and validation, respectively, thus showing a quite satisfactory model performance. Subsequently, the climate change impacts on temperature and precipitation, as well as their extremes, and on the flowrates were also assessed for a future period (2041–2070) under two anthropogenic forcing scenarios (representative concentration pathways 4.5 and 8.5). A procedure for selecting the most relevant metrics for assessing the ecological condition of the Paiva River was developed based upon a set of 52 invertebrate families sampled. Correspondence analyses were carried out for biological datasets (traits/metrics) with physicochemical and land use/land cover matrices separately. Out of all variables, water quality and flow and agriculture land use explained most of the variance observed. The integrated analysis undertaken in the present study is an important advance when compared to previous studies and it provides key information to stakeholders and decision-makers, particularly when planning suitable adaptation measures to cope with changing climates in the forthcoming decades. Full article
(This article belongs to the Special Issue Flowing Waters and Threatened Aquatic Life)
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34 pages, 2807 KiB  
Review
Interplay of the Factors Affecting Water Flux and Salt Rejection in Membrane Distillation: A State-of-the-Art Critical Review
by Lin Chen, Pei Xu and Huiyao Wang
Water 2020, 12(10), 2841; https://doi.org/10.3390/w12102841 - 13 Oct 2020
Cited by 62 | Viewed by 8342
Abstract
High water flux and elevated rejection of salts and contaminants are two primary goals for membrane distillation (MD). It is imperative to study the factors affecting water flux and solute transport in MD, the fundamental mechanisms, and practical applications to improve system performance. [...] Read more.
High water flux and elevated rejection of salts and contaminants are two primary goals for membrane distillation (MD). It is imperative to study the factors affecting water flux and solute transport in MD, the fundamental mechanisms, and practical applications to improve system performance. In this review, we analyzed in-depth the effects of membrane characteristics (e.g., membrane pore size and distribution, porosity, tortuosity, membrane thickness, hydrophobicity, and liquid entry pressure), feed solution composition (e.g., salts, non-volatile and volatile organics, surfactants such as non-ionic and ionic types, trace organic compounds, natural organic matter, and viscosity), and operating conditions (e.g., temperature, flow velocity, and membrane degradation during long-term operation). Intrinsic interactions between the feed solution and the membrane due to hydrophobic interaction and/or electro-interaction (electro-repulsion and adsorption on membrane surface) were also discussed. The interplay among the factors was developed to qualitatively predict water flux and salt rejection considering feed solution, membrane properties, and operating conditions. This review provides a structured understanding of the intrinsic mechanisms of the factors affecting mass transport, heat transfer, and salt rejection in MD and the intra-relationship between these factors from a systematic perspective. Full article
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15 pages, 1647 KiB  
Article
Reduction of Environmental Impacts Due to Using Permeable Pavements to Harvest Stormwater
by Lucas Niehuns Antunes, Calum Sydney, Enedir Ghisi, Vernon R. Phoenix, Liseane Padilha Thives, Christopher White and Emmanuelle Stefânia Holdefer Garcia
Water 2020, 12(10), 2840; https://doi.org/10.3390/w12102840 - 13 Oct 2020
Cited by 19 | Viewed by 4715
Abstract
While rainwater harvesting can provide additional water resources, this approach is largely undertaken using water from roofs. More recently, the potential for using stormwater harvested from permeable pavements was recognised as a potential additional water resource. The objective of this study was to [...] Read more.
While rainwater harvesting can provide additional water resources, this approach is largely undertaken using water from roofs. More recently, the potential for using stormwater harvested from permeable pavements was recognised as a potential additional water resource. The objective of this study was to estimate the reduction of environmental impacts caused by traditional drainage systems and centralised water utilities if permeable pavement systems were used to harvest stormwater for nonpotable purposes in buildings. The lifecycle environmental impacts and costs associated with the proposed pavements and hydraulic systems were assessed. The city of Glasgow was chosen as a case study. We used the Netuno computer programme to estimate the potential for potable water savings considering the use of stormwater for nonpotable purposes and the SimaPro software to perform a lifecycle assessment (LCA). With the implementation of permeable pavements and stormwater utilisation, great reductions in lifecycle emissions (i.e., CO2-, SO2-, and PM2.5-equivalent emissions) were observed. The proposed system also proved to be economically feasible, i.e., a payback period equal to 16.9 years. The results show the economic and environmental feasibility of permeable pavements when used on a large scale, proving to be an important strategy to reduce water and environmental stresses caused by centralised water utilities and traditional drainage systems. Full article
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19 pages, 2303 KiB  
Article
From Highs to Lows: Changes in Dissolved Organic Carbon in a Peatland Catchment and Lake Following Extreme Flow Events
by Eleanor Jennings, Elvira de Eyto, Tadhg Moore, Mary Dillane, Elizabeth Ryder, Norman Allott, Caitriona Nic Aonghusa, Martin Rouen, Russell Poole and Donald C. Pierson
Water 2020, 12(10), 2843; https://doi.org/10.3390/w12102843 - 13 Oct 2020
Cited by 10 | Viewed by 4493
Abstract
The concentration of dissolved organic carbon (DOC) in freshwater catchments has implications for carbon availability in downstream lakes and for water supplies. The links between catchment hydrology and stream and lake DOC concentrations are, however, still not fully understood. Much of the literature [...] Read more.
The concentration of dissolved organic carbon (DOC) in freshwater catchments has implications for carbon availability in downstream lakes and for water supplies. The links between catchment hydrology and stream and lake DOC concentrations are, however, still not fully understood. Much of the literature has been from catchments with organo-mineral soils, with fewer studies from upland peat sites. We used high-frequency fluorescence data, a proxy for DOC, to investigate 1. the relationship between stream discharge and concentration in a blanket peat catchment during extreme high flows and 2. the relationship between inflow and in-lake estimated DOC concentrations. We found that for approximately two thirds of extreme events, there was a decrease in stream DOC concentration (i.e., a dilution) on the rising limb rather than an increase (i.e., a flushing out of DOC from terrestrial stores). Flushing events dominated only in summer when concentrations in the stream were also increasing. In comparison to the stream, concentrations in the downstream lake were less variable, and peaks and troughs were damped and lagged. Replicating these patterns and processes in DOC models would be critical in order to provide appropriate simulations in response to shorter- and longer-term changes in climate, and thus inform future catchment and lake management. Full article
(This article belongs to the Special Issue Effect of Extreme Climate Events on Lake Ecosystems)
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15 pages, 1781 KiB  
Article
A Novel Method for Determination of the Natural Toxin Ptaquiloside in Ground and Drinking Water
by Natasa Skrbic, Ann-Katrin Pedersen, Sarah C. B. Christensen, Hans Christian Bruun Hansen and Lars Holm Rasmussen
Water 2020, 12(10), 2852; https://doi.org/10.3390/w12102852 - 13 Oct 2020
Cited by 11 | Viewed by 4620
Abstract
Ptaquiloside (PTA) is a carcinogenic compound naturally occurring in bracken ferns (Pteridium aquilinum). It is highly water soluble and prone to leaching from topsoil to surface and groundwaters. Due to possible human exposure via drinking water, PTA is considered as an [...] Read more.
Ptaquiloside (PTA) is a carcinogenic compound naturally occurring in bracken ferns (Pteridium aquilinum). It is highly water soluble and prone to leaching from topsoil to surface and groundwaters. Due to possible human exposure via drinking water, PTA is considered as an emerging contaminant. We present a sensitive and robust method for analysis of PTA and its degradation product pterosin B (PtB) in groundwater. The method comprises two steps: sample preservation at the field site followed by sample pre-concentration in the laboratory. The preservation step was developed by applying a Plackett–Burman experimental design testing the following variables: water type, pH, filtering, bottle type, storage temperature, transportation conditions and test time. The best sample preservation was obtained by using amber glass bottles, unfiltered solutions buffered at pH 6, transported without ice, stored at 4 °C and analysed within 48 h. The recovery was 94% to 100%. The sample purification step had a pre-concentration factor of 250, and the recovery percentages of the entire method were 85 ± 2 (PTA) and 91 ± 3 (PtB). The limits of detection (LOD) of the full method were 0.001 µg L−1 and 0.0001 µg L−1 for PTA and PtB, respectively. The method enables sensitive monitoring of PTA and PtB in groundwater. Carcinogenic PTA was detected in one groundwater well (0.35 µg L−1). Full article
(This article belongs to the Special Issue Emerging Contaminants (ECs) in Water)
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10 pages, 3240 KiB  
Article
Potential Effects of the COVID-19 Pandemic through Changes in Outbound Tourism on Water Demand: The Case of Liège (Belgium)
by Nguyen Bich-Ngoc and Jacques Teller
Water 2020, 12(10), 2820; https://doi.org/10.3390/w12102820 - 11 Oct 2020
Cited by 20 | Viewed by 4357
Abstract
The COVID-19 pandemic has led to many countries closing their borders, and numerous people spending their holidays at home instead of traveling abroad. This sudden reduction in travel activities, and other ‘new normals’, might have influenced people’s water usage. Hence, using Liège as [...] Read more.
The COVID-19 pandemic has led to many countries closing their borders, and numerous people spending their holidays at home instead of traveling abroad. This sudden reduction in travel activities, and other ‘new normals’, might have influenced people’s water usage. Hence, using Liège as a case study, this study aims to address the potential effect of outbound tourism on water consumption and how the current situation might affect the total water demand. Statistical models were developed and validated using the total daily volume of 23 municipalities in the Liège conurbation, the monthly total number of outbound trips, and other meteorological data. Results suggest significantly lower water demand in the months with high numbers of outbound travel activities. Though the projected risk of increased water needs due to fewer people traveling is moderate, the threat becomes much higher during long periods of dry and hot weather. Full article
(This article belongs to the Section Urban Water Management)
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17 pages, 1423 KiB  
Article
Monitoring Waterborne Pathogens in Surface and Drinking Waters. Are Water Treatment Plants (WTPs) Simultaneously Efficient in the Elimination of Enteric Viruses and Fecal Indicator Bacteria (FIB)?
by Daniel Salvador, Maria Filomena Caeiro, Fátima Serejo, Paulo Nogueira, Rui Neves Carneiro and Célia Neto
Water 2020, 12(10), 2824; https://doi.org/10.3390/w12102824 - 11 Oct 2020
Cited by 13 | Viewed by 5130
Abstract
Monitoring the quality of water is a requisite to prevent outbreaks related to waterborne diseases, predominantly caused by pathogens like enteric viruses, usually transmitted via the fecal-oral route. This study aimed to survey a group of enteric viruses (Enterovirus, Norovirus genogroups [...] Read more.
Monitoring the quality of water is a requisite to prevent outbreaks related to waterborne diseases, predominantly caused by pathogens like enteric viruses, usually transmitted via the fecal-oral route. This study aimed to survey a group of enteric viruses (Enterovirus, Norovirus genogroups I and II, and hepatitis A virus) in two surface water sources of drinking water, also intending to evaluate the extent of their elimination in the two water treatment plants (WTPs) involved in drinking water production. Correlations between these viruses and fecal indicator bacteria (FIB) were also evaluated. Positive samples for viral RNA were recurrently found by reverse transcription quantitative PCR (RT-qPCR) and quantified, in genomic copies per liter (gc/L) of sampled water. Viral RNAs were detected in 14 out of 27 samples of surface water, and 21 out of 36 samples of drinking water, NoV II having been the most frequently detected in both (0–78.6 gc/L and 0–12.5 gc/L, respectively). Both WTPs showed variable efficacies in the elimination of viral RNA. Only one correlation was found with FIB, between NoV II and intestinal enterococci. These results recommend the monitoring of enteric viruses over time and their inclusion in the mandatory analysis of water quality. Full article
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16 pages, 11491 KiB  
Article
Response of Agricultural Drought to Meteorological Drought: A Case Study of the Winter Wheat above the Bengbu Sluice in the Huaihe River Basin, China
by Chao Gao, Cai Chen, Yi He, Tian Ruan, Gang Luo and Yanwei Sun
Water 2020, 12(10), 2805; https://doi.org/10.3390/w12102805 - 10 Oct 2020
Cited by 11 | Viewed by 2533
Abstract
This study investigated the responses of winter wheat to drought for the above part of the Bengbu Sluice in the Huaihe River based on the daily scale dataset of 60 meteorological stations from 1961–2015. Crop water deficit index (CWDI) and relative [...] Read more.
This study investigated the responses of winter wheat to drought for the above part of the Bengbu Sluice in the Huaihe River based on the daily scale dataset of 60 meteorological stations from 1961–2015. Crop water deficit index (CWDI) and relative moisture index (M) were used to examine the winter wheat drought and meteorological drought, respectively. We then analyzed the spatial-temporal evolution characteristics of these two kinds of drought to calculate the time lag of winter wheat drought to meteorological drought, and finally discuss the relationship between the time lag of winter wheat drought to meteorological drought and the underlying surface geographical factors, and drew the following conclusions. (1) In terms of time scale, for CWDI, except for the filling and mature period, the CWDI at other growth periods showed a slight downward trend; for M, there was no significant change in the interannual trend of each growth period. In terms of spatial scale, the proportion of above moderate drought level in each station of CWDI and M presented a decreasing feature from north to south. (2) The time lag of winter wheat drought to meteorological drought was the shortest (3.21 days) in the greening and heading period and the longest in the over-wintering period (84.35 days). (3) The correlation between the geographical factors and the time lag of winter wheat drought in each growth period was better than 0.5. The high-value points of the relation between the underlying surface geographical factors and the time lag of winter wheat drought were mostly distributed in the mountainous areas with poor soil field capacity and at a greater depth of shallow groundwater, high elevation and steep slope in the areas with aspects to the east and northeast, and the northern areas with less precipitation and lower temperature. Full article
(This article belongs to the Section Water, Agriculture and Aquaculture)
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15 pages, 3529 KiB  
Article
Water Level Fluctuations and Air Temperatures Affect Common Reed Habitus and Productivity in an Intermittent Wetland Ecosystem
by Alenka Gaberščik, Mateja Grašič, Dragan Abram and Igor Zelnik
Water 2020, 12(10), 2806; https://doi.org/10.3390/w12102806 - 10 Oct 2020
Cited by 17 | Viewed by 3372
Abstract
Lake Cerknica is an intermittent wetland ecosystem with extreme water level fluctuations. It hosts extensive reed stands that have colonized different habitat types. Two different stands were compared: a lake stand not directly influenced by the intermittent River Stržen and a riparian stand [...] Read more.
Lake Cerknica is an intermittent wetland ecosystem with extreme water level fluctuations. It hosts extensive reed stands that have colonized different habitat types. Two different stands were compared: a lake stand not directly influenced by the intermittent River Stržen and a riparian stand near River Stržen. Reed productivity (growth and assimilate allocation) was monitored for these reed stand types over 13 years (2007–2019), and this measurement was compared to monthly water levels and air temperatures. Reeds from the lake reed stand were significantly shorter with a lower shoot density, overall biomass production, and ratio of flowering plants. A correlation analysis revealed stronger and more numerous significant correlations between environmental and reed productivity parameters for the lake reed stand compared to the riparian reed stand. The variabilities of the growth and assimilate allocation parameters in the lake reed stand were both mostly explained by the combined water levels for June and July, which explained 47% and 52% of the variability, respectively. The most influential temperatures were in May, which explained 29% and 19% of the variability of growth and assimilate allocation parameters, respectively. For the riparian reed stand, water levels and temperatures out of the vegetation season appeared more important. Therefore, habitats with permanent water are more suitable for reeds than those with fluctuating water. However, fluctuating water conditions are expected to become more common due to climate change. Full article
(This article belongs to the Special Issue Hydrology-Shaped Plant Communities: Diversity and Ecological Function)
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25 pages, 2906 KiB  
Article
Passive Detection of Phosphorus in Agricultural Tile Waters Using Reactive Hybrid Anion Exchange Resins
by Zhe Li, Maria Librada Chu, Lowell Gentry, Ying Li, Corey Mitchell and Yuji Arai
Water 2020, 12(10), 2808; https://doi.org/10.3390/w12102808 - 10 Oct 2020
Cited by 2 | Viewed by 1977
Abstract
Tile drainage waters carry considerable loads of phosphorus (P) from agricultural fields to rivers and streams in the Midwestern U.S. An innovative and economical approach to monitor dissolved reactive P (DRP) flux in tile waters is needed to understand the extent of P [...] Read more.
Tile drainage waters carry considerable loads of phosphorus (P) from agricultural fields to rivers and streams in the Midwestern U.S. An innovative and economical approach to monitor dissolved reactive P (DRP) flux in tile waters is needed to understand the extent of P loss in field-scale. In this study, a passive sampling technique was developed using iron oxide-coated polyacrylic/polystyrene anion exchange resins (hybrid resins) a P sink. Laboratory batch adsorption isotherm and kinetic experiments indicated that the hybrid resins had high P adsorption capacity (7.69–19.84 mg/g) and high kinetic performance. The passive sampling method with field-calibrated hybrid polyacrylic resin and hybrid polystyrene resins (sampling rate: 0.1351 and 0.0763 L/h, respectively) predicted the average DRP concentrations of 0.006–0.020 mg/L, which did not differ significantly (p > 0.05) from the auto-sampling data. A rapid increase in DRP concentration during storm events and subsequent flooding events was also predicted well. In conclusion, a passive detection method using iron oxide coated hybrid resins can be recommended for monitoring seasonally fluctuating DRP flux in agricultural waters as long as the hybrid resins are well-calibrated under specific field conditions (e.g., flow rate and concentration range). Full article
(This article belongs to the Section Water Quality and Contamination)
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22 pages, 7631 KiB  
Article
Phytoplankton–Macrophyte Interaction in the Lagoon of Venice (Northern Adriatic Sea, Italy)
by Fabrizio Bernardi Aubry, Francesco Acri, Gian Marco Scarpa and Federica Braga
Water 2020, 12(10), 2810; https://doi.org/10.3390/w12102810 - 10 Oct 2020
Cited by 9 | Viewed by 3638
Abstract
The coexistence of phytoplankton and macrophytes in the Lagoon of Venice (Northern Adriatic Sea, Italy) was investigated using in situ data collected monthly as part of International Long Term Ecosystem Research (LTER), together with satellite imagery for the period 1998–2017. The concentrations of [...] Read more.
The coexistence of phytoplankton and macrophytes in the Lagoon of Venice (Northern Adriatic Sea, Italy) was investigated using in situ data collected monthly as part of International Long Term Ecosystem Research (LTER), together with satellite imagery for the period 1998–2017. The concentrations of chlorophyll a and hydrochemical parameters were measured in three areas of the lagoon, where the expansion of well-developed stands of submerged vegetation was observed by remote sensing. Our results suggest interaction between phytoplankton and macrophytes (macroalgae and seagrasses) in the last few years of the time series, evidenced by decreasing chlorophyll a concentrations in the vicinity of the macrophyte stands. The integration of LTER and remotely sensed data made it possible to evaluate the interaction of macrophytes and phytoplankton at the ecosystem scale for the first time in the Lagoon of Venice. Full article
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28 pages, 1620 KiB  
Review
Big Data Analytics and Its Role to Support Groundwater Management in the Southern African Development Community
by Zaheed Gaffoor, Kevin Pietersen, Nebo Jovanovic, Antoine Bagula and Thokozani Kanyerere
Water 2020, 12(10), 2796; https://doi.org/10.3390/w12102796 - 9 Oct 2020
Cited by 25 | Viewed by 9033
Abstract
Big data analytics (BDA) is a novel concept focusing on leveraging large volumes of heterogeneous data through advanced analytics to drive information discovery. This paper aims to highlight the potential role BDA can play to improve groundwater management in the Southern African Development [...] Read more.
Big data analytics (BDA) is a novel concept focusing on leveraging large volumes of heterogeneous data through advanced analytics to drive information discovery. This paper aims to highlight the potential role BDA can play to improve groundwater management in the Southern African Development Community (SADC) region in Africa. Through a review of the literature, this paper defines the concepts of big data, big data sources in groundwater, big data analytics, big data platforms and framework and how they can be used to support groundwater management in the SADC region. BDA may support groundwater management in SADC region by filling in data gaps and transforming these data into useful information. In recent times, machine learning and artificial intelligence have stood out as a novel tool for data-driven modeling. Managing big data from collection to information delivery requires critical application of selected tools, techniques and methods. Hence, in this paper we present a conceptual framework that can be used to manage the implementation of BDA in a groundwater management context. Then, we highlight challenges limiting the application of BDA which included technological constraints and institutional barriers. In conclusion, the paper shows that sufficient big data exist in groundwater domain and that BDA exists to be used in groundwater sciences thereby providing the basis to further explore data-driven sciences in groundwater management. Full article
(This article belongs to the Special Issue The Application of Artificial Intelligence in Hydrology)
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21 pages, 2154 KiB  
Article
Benthic Diatom Communities in Urban Streams and the Role of Riparian Buffers
by Petra Thea Mutinova, Maria Kahlert, Benjamin Kupilas, Brendan G. McKie, Nikolai Friberg and Francis J. Burdon
Water 2020, 12(10), 2799; https://doi.org/10.3390/w12102799 - 9 Oct 2020
Cited by 22 | Viewed by 5039
Abstract
Urbanization impacts stream ecosystems globally through degraded water quality, altered hydrology, and landscape disturbances at the catchment and riparian scales, causing biodiversity losses and altered system functioning. Addressing the “urban stream syndrome” requires multiple mitigation tools, and rehabilitation of riparian vegetation may help [...] Read more.
Urbanization impacts stream ecosystems globally through degraded water quality, altered hydrology, and landscape disturbances at the catchment and riparian scales, causing biodiversity losses and altered system functioning. Addressing the “urban stream syndrome” requires multiple mitigation tools, and rehabilitation of riparian vegetation may help improve stream ecological status and provide key ecosystem services. However, the extent to which forested riparian buffers can help support stream biodiversity in the face of numerous environmental contingencies remains uncertain. We assessed how a key indicator of stream ecological status, benthic diatoms, respond to riparian habitat conditions using 10 urban site pairs (each comprising of one unbuffered and one buffered reach), and additional urban downstream and forest reference upstream sites in the Oslo Fjord basin. Diatom communities were structured by multiple drivers including spatial location, land use, water quality, and instream habitat. Among these, riparian habitat condition independently explained 16% of variation in community composition among site pairs. Changes in community structure and indicator taxa, along with a reduction in pollution-tolerant diatoms, suggested tangible benefits of forested riparian buffers for stream biodiversity in urban environments. Managing urban impacts requires multiple solutions, with forested riparian zones providing a potential tool to help improve biodiversity and ecosystem services. Full article
(This article belongs to the Special Issue Ecosystem Functioning in Rivers and Riparian Zones)
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28 pages, 959 KiB  
Review
What We Know about Water: A Water Literacy Review
by Meghan McCarroll and Hillary Hamann
Water 2020, 12(10), 2803; https://doi.org/10.3390/w12102803 - 9 Oct 2020
Cited by 44 | Viewed by 18066
Abstract
Water literacy, or the culmination of water-related knowledge, attitudes and behaviors, is a relatively new field of study with growing importance for sustainable water management and social water equity. However, its definition and use across existing literature are varied and often inconsistent. This [...] Read more.
Water literacy, or the culmination of water-related knowledge, attitudes and behaviors, is a relatively new field of study with growing importance for sustainable water management and social water equity. However, its definition and use across existing literature are varied and often inconsistent. This paper seeks to synthesize and streamline the conception of water literacy. We conducted a systematic review of literature that defines or describes in detail either “water literacy” or “watershed literacy”. From this, we suggest a new holistic framework for water literacy to guide a more inclusive, relevant use of the concept. We utilized the framework to examine existing surveys and studies of water knowledge, attitudes and behaviors in both student and adult populations, and summarized water literacy levels and knowledge gaps that exist around the world. To address knowledge gaps, we suggest using a suite of approaches drawn from the published literature, including enhanced visuals, place-based learning, interdisciplinary curricula, and reflective and iterative development of future water literacy initiatives. Full article
(This article belongs to the Special Issue Water Literacy and Education)
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24 pages, 1255 KiB  
Review
Addressing Challenges of Urban Water Management in Chinese Sponge Cities via Nature-Based Solutions
by Yunfei Qi, Faith Ka Shun Chan, Colin Thorne, Emily O’Donnell, Carlotta Quagliolo, Elena Comino, Alessandro Pezzoli, Lei Li, James Griffiths, Yanfang Sang and Meili Feng
Water 2020, 12(10), 2788; https://doi.org/10.3390/w12102788 - 8 Oct 2020
Cited by 107 | Viewed by 18723
Abstract
Urban flooding has become a serious issue in most Chinese cities due to rapid urbanization and extreme weather, as evidenced by severe events in Beijing (2012), Ningbo (2013), Guangzhou (2015), Wuhan (2016), Shenzhen (2019), and Chongqing (2020). The Chinese “Sponge City Program” (SCP), [...] Read more.
Urban flooding has become a serious issue in most Chinese cities due to rapid urbanization and extreme weather, as evidenced by severe events in Beijing (2012), Ningbo (2013), Guangzhou (2015), Wuhan (2016), Shenzhen (2019), and Chongqing (2020). The Chinese “Sponge City Program” (SCP), initiated in 2013 and adopted by 30 pilot cities, is developing solutions to manage urban flood risk, purify stormwater, and provide water storage opportunities for future usage. Emerging challenges to the continued implementation of Sponge Cities include (1) uncertainty regarding future hydrological conditions related to climate change projections, which complicates urban planning and designing infrastructure that will be fit for purpose over its intended operating life, and (2) the competing priorities of stakeholders and their reluctance to make trade-offs, which obstruct future investment in the SCP. Nature-Based Solutions (NBS) is an umbrella concept that emerged from Europe, which encourages the holistic idea of considering wider options that combine “Blue–Green” practices with traditional engineering to deliver “integrated systems of Blue–Green–Grey infrastructure”. NBS includes interventions making use of natural processes and ecosystem services for functional purposes, and this could help to improve current pilot SCP practices. This manuscript reviews the development of the SCP, focusing on its construction and design aspects, and discusses how approaches using NBS could be included in the SCP to tackle not only urban water challenges but also a wide range of social and environmental challenges, including human health, pollution (via nutrients, metals, sediments, plastics, etc.), flood risk, and biodiversity. Full article
(This article belongs to the Special Issue Integrated Approaches to Manage Floods in Urban Environments)
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20 pages, 3299 KiB  
Article
Estimating Human Impacts on Soil Erosion Considering Different Hillslope Inclinations and Land Uses in the Coastal Region of Syria
by Safwan Mohammed, Hazem G. Abdo, Szilard Szabo, Quoc Bao Pham, Imre J. Holb, Nguyen Thi Thuy Linh, Duong Tran Anh, Karam Alsafadi, Ali Mokhtar, Issa Kbibo, Jihad Ibrahim and Jesus Rodrigo-Comino
Water 2020, 12(10), 2786; https://doi.org/10.3390/w12102786 - 7 Oct 2020
Cited by 48 | Viewed by 6198
Abstract
Soils in the coastal region of Syria (CRoS) are one of the most fragile components of natural ecosystems. However, they are adversely affected by water erosion processes after extreme land cover modifications such as wildfires or intensive agricultural activities. The main goal of [...] Read more.
Soils in the coastal region of Syria (CRoS) are one of the most fragile components of natural ecosystems. However, they are adversely affected by water erosion processes after extreme land cover modifications such as wildfires or intensive agricultural activities. The main goal of this research was to clarify the dynamic interaction between erosion processes and different ecosystem components (inclination, land cover/land use, and rainy storms) along with the vulnerable territory of the CRoS. Experiments were carried out in five different locations using a total of 15 erosion plots. Soil loss and runoff were quantified in each experimental plot, considering different inclinations and land uses (agricultural land (AG), burnt forest (BF), forest/control plot (F)). Observed runoff and soil loss varied greatly according to both inclination and land cover after 750 mm of rainfall (26 events). In the cultivated areas, the average soil water erosion ranged between 0.14 ± 0.07 and 0.74 ± 0.33 kg/m2; in the BF plots, mean soil erosion ranged between 0.03 ± 0.01 and 0.24 ± 0.10 kg/m2. The lowest amount of erosion was recorded in the F plots where the erosion ranged between 0.1 ± 0.001 and 0.07 ± 0.03 kg/m2. Interestingly, the General Linear Model revealed that all factors (i.e., inclination, rainfall and land use) had a significant (p < 0.001) effect on the soil loss. We concluded that human activities greatly influenced soil erosion rates, being higher in the AG lands, followed by BF and F. Therefore, the current study could be very useful to policymakers and planners for proposing immediate conservation or restoration plans in a less studied area which has been shown to be vulnerable to soil erosion processes. Full article
(This article belongs to the Special Issue Soil–Water Conservation, Erosion, and Landslide)
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24 pages, 1697 KiB  
Review
Water and Land as Shared Resources for Agriculture and Aquaculture: Insights from Asia
by Steven G. Pueppke, Sabir Nurtazin and Weixin Ou
Water 2020, 12(10), 2787; https://doi.org/10.3390/w12102787 - 7 Oct 2020
Cited by 27 | Viewed by 12941
Abstract
Although agriculture and aquaculture depend on access to increasingly scarce, shared water resources to produce food for human consumption, they are most often considered in isolation. We argue that they should be treated as integrated components of a single complex system that is [...] Read more.
Although agriculture and aquaculture depend on access to increasingly scarce, shared water resources to produce food for human consumption, they are most often considered in isolation. We argue that they should be treated as integrated components of a single complex system that is prone to direct or indirect tradeoffs that should be avoided while also being amenable to synergies that should be sought. Direct tradeoffs such as competition for space or the pollution of shared water resources usually occur when the footprints of agriculture and aquaculture overlap or when the two practices coexist in close proximity to one another. Interactions can be modulated by factors such as hydropower infrastructure and short-term economic incentives, both of which are known to disrupt the balance between aquaculture and agriculture. Indirect tradeoffs, on the other hand, play out across distances, i.e., when agricultural food sources are diverted to feed animals in aquaculture. Synergies are associated with the culture of aquatic organisms in rice paddies and irrigation waters, seasonal rotations of crop cultivation with aquaculture, and various forms of integrated agriculture–aquaculture (IAA), including jitang, a highly developed variant of pond-dike IAA. Policy decisions, socioeconomic considerations, and technology warrant increased scrutiny as determinants of tradeoffs and synergies. Priority issues for the future include guiding the expansion of aquaculture from its traditional base in Asia, taking advantage of the heterogeneity that exists within both agricultural and aquaculture systems, the development of additional metrics of tradeoffs and synergies, and adapting to the effects of climate change. Full article
(This article belongs to the Special Issue Feature Papers of Water, Agriculture and Aquaculture)
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15 pages, 2966 KiB  
Article
Metal Distribution and Sediment Quality Variation across Sediment Depths of a Subtropical Ramsar Declared Wetland
by Tatenda Dalu, Rolindela Tshivhase, Ross N. Cuthbert, Florence M. Murungweni and Ryan J. Wasserman
Water 2020, 12(10), 2779; https://doi.org/10.3390/w12102779 - 6 Oct 2020
Cited by 23 | Viewed by 3692
Abstract
The study of wetlands is particularly important as these systems act as natural water purifiers and thus can act as sinks for contaminated particles. Wetland sediments are important as they provide an indication of potential contamination across temporal and spatial scales. The current [...] Read more.
The study of wetlands is particularly important as these systems act as natural water purifiers and thus can act as sinks for contaminated particles. Wetland sediments are important as they provide an indication of potential contamination across temporal and spatial scales. The current study aimed to investigate the distributions of selected metals and nutrients in different sites in relation to sediment depth, and identify relationships among sediment metals. Significant differences in nutrient (i.e., N, P) and metal (i.e., K, Mg, Na, Fe, Cu, B) concentrations were found across study sites, whereas nutrients (i.e., N, P) and metals (i.e., Ca, Mg, Fe, Cu, Zn) were significantly different with sediment depths. When compared against Canadian sediment standards, most of the assessed metals were within the “no effect” level across the different sites and depths. The K, Ca, and Mg concentration showed extreme contamination across all sites and depths. The enrichment factor values for K, Ca, and Mg showed extremely high enrichment levels for all sites and sediment depths. The Na, Mn, Fe, Cu, Zn, and B concentration showed mostly background enrichment levels. All sediments across the different sites and sediment depths indicated deterioration of sediment quality. Pearson correlations suggest that most metals might have originated in a similar source as that of Mn and B, owing to a lack of significant differences. These results provide baseline information for the general management of the Nylsvley Wetland in relation to sediment metal pollution. The specific sources of metal contaminants also require further elucidation to further inform management efforts. Full article
(This article belongs to the Special Issue Geochemistry of Water and Sediment)
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22 pages, 9722 KiB  
Article
Assessment of Surface Hydrological Connectivity in an Ungauged Multi-Lake System with a Combined Approach Using Geostatistics and Spaceborne SAR Observations
by Yueqing Chen, Lili Wu, Guangxin Zhang, Y. Jun Xu, Zhiqiang Tan and Sijia Qiao
Water 2020, 12(10), 2780; https://doi.org/10.3390/w12102780 - 6 Oct 2020
Cited by 3 | Viewed by 3299
Abstract
Connectivity metrics for surface water are important for predicting floods and droughts, and improving water management for human use and ecological integrity at the landscape scale. The integrated use of synthetic aperture radar (SAR) observations and geostatistics approach can be useful for developing [...] Read more.
Connectivity metrics for surface water are important for predicting floods and droughts, and improving water management for human use and ecological integrity at the landscape scale. The integrated use of synthetic aperture radar (SAR) observations and geostatistics approach can be useful for developing and quantifying these metrics and their changes, including geostatistical connectivity function (GCF), maximum distance of connection (MDC), surface water extent (SWE), and connection frequency. In this study, we conducted a geostatistical analysis based on 52 wet and dry binary state (i.e., water and non-water) rasters derived from Sentinel-1 A/B GRD products acquired from 2015 to 2019 for China’s Momoge National Nature Reserve to investigate applicability and dynamics of the hydrologic connectivity metrics in an ungauged (i.e., data such as flow and water level are scarce) multi-lake system. We found: (1) generally, the change of GCF in North–South and Northeast–Southwest directions was greater than that in the West–East and Northwest–Southeast directions; (2) MDC had a threshold effect, generally at most 25 km along the W–E, NW–SE and NE–SW directions, and at most 45 km along the N–S direction; (3) the flow paths between lakes are diverse, including channelized flow, diffusive overbank flow, over-road flow and “fill-and-merge”; (4) generally, the values of the three surface hydrological connectivity indicators (i.e., the MDC, the SWE, and the conneciton frequency) all increased from May to August, and decreased from August to October; (5) generally, the closer the distance between the lakes, the greater the connection frequency, but it is also affected by the dam and road barrier. The study demonstrates the usefulness of the geostatistical method combining Sentinel-1 SAR image analysis in quantifying surface hydrological connectivity in an ungagged area. This approach should be applicable for other geographical regions, in order help resource managers and policymakers identify changes in surface hydrological connectivity, as well as address potential impacts of these changes on water resources for human use and/or ecological integrity at the landscape level. Full article
(This article belongs to the Special Issue Wetland Ecohydrology and Water Resource Management)
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17 pages, 6318 KiB  
Review
Nutrient Retention in Ecologically Functional Floodplains: A Review
by Brad A. Gordon, Olivia Dorothy and Christian F. Lenhart
Water 2020, 12(10), 2762; https://doi.org/10.3390/w12102762 - 4 Oct 2020
Cited by 44 | Viewed by 13529
Abstract
Nutrient loads in fresh and coastal waters continue to lead to harmful algal blooms across the globe. Historically, floodplains—low-lying areas adjacent to streams and rivers that become inundated during high-flow events—would have been nutrient deposition and/or removal sites within riparian corridors, but many [...] Read more.
Nutrient loads in fresh and coastal waters continue to lead to harmful algal blooms across the globe. Historically, floodplains—low-lying areas adjacent to streams and rivers that become inundated during high-flow events—would have been nutrient deposition and/or removal sites within riparian corridors, but many floodplains have been developed and/or disconnected. This review synthesizes literature and data available from field studies quantifying nitrogen (N) and phosphorus (P) removal within floodplains across North America and Europe to determine how effective floodplain restoration is at removing nutrients. The mean removal of nitrate-N (NO3-N), the primary form of N in floodplain studies, was 200 (SD = 198) kg-N ha−1 year−1, and of total or particulate P was 21.0 (SD = 31.4) kg-P ha−1 year−1. Based on the literature, more effective designs of restored floodplains should include optimal hydraulic load, permanent wetlands, geomorphic diversity, and dense vegetation. Floodplain restorations along waterways with higher nutrient concentrations could lead to a more effective investment for nutrient removal. Overall, restoring and reconnecting floodplains throughout watersheds is a viable and effective means of removing nutrients while also restoring the many other benefits that floodplains provide. Full article
(This article belongs to the Special Issue River Floodplain Restoration)
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19 pages, 4351 KiB  
Article
Spatiotemporal Analysis of Water Quality Using Multivariate Statistical Techniques and the Water Quality Identification Index for the Qinhuai River Basin, East China
by Xiaoxue Ma, Lachun Wang, Hong Yang, Na Li and Chang Gong
Water 2020, 12(10), 2764; https://doi.org/10.3390/w12102764 - 4 Oct 2020
Cited by 48 | Viewed by 6455
Abstract
Monitoring water quality is indispensable for the identification of threats to water environment and later management of water resources. Accurate monitoring and assessment of water quality have been long-term challenges. In this study, multivariate statistical techniques (MST) and water quality identification index (WQII) [...] Read more.
Monitoring water quality is indispensable for the identification of threats to water environment and later management of water resources. Accurate monitoring and assessment of water quality have been long-term challenges. In this study, multivariate statistical techniques (MST) and water quality identification index (WQII) were applied to analyze spatiotemporal variation in water quality and determine the major pollution sources in the Qinhuai River, East China. A rotated principal component analysis (PCA) identified three potential pollution sources during the wet season (mixed pollution, physicochemical, and nonpoint sources of nutrients) and the dry season (nutrient, primary environmental, and organic sources) and they explained 81.14% of the total variances in the wet season and 78.42% of total variances in the dry season. The result of redundancy analysis (RDA) showed that population density, urbanization, and wastewater discharge are the main sources of organic pollution, while agricultural fertilizer consumption and industrial wastewater discharge are the main sources of nutrients such as nitrogen and phosphorus. The water quality of the Qinhuai River basin was determined to be mainly Class III (slightly polluted) and Class IV (moderately polluted) based on WQII. Temporally, the change trend of WQII showed that water quality gradually deteriorated between 1990 and 2005, improved between 2006 and 2010, and then deteriorated again. Spatially, the WQII distribution map showed that areas with more developed urbanization were relatively more polluted. Our results show that MST and WQII are useful tools to help the public and decision makers to evaluate the water quality of aquatic environment. Full article
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26 pages, 1925 KiB  
Article
Institutional Framework for Modeling Water Availability and Allocation
by Ralph A. Wurbs
Water 2020, 12(10), 2767; https://doi.org/10.3390/w12102767 - 4 Oct 2020
Cited by 11 | Viewed by 4323
Abstract
Effective water resources management requires assessments of water availability within a framework of complex institutions and infrastructure employed to manage extremely variable stream flow shared by numerous, often competing, water users and diverse types of use. The Water Rights Analysis Package (WRAP) modeling [...] Read more.
Effective water resources management requires assessments of water availability within a framework of complex institutions and infrastructure employed to manage extremely variable stream flow shared by numerous, often competing, water users and diverse types of use. The Water Rights Analysis Package (WRAP) modeling system is fundamental to water allocation and planning in the state of Texas in the United States. Integration of environmental flow standards into both the modeling system and comprehensive statewide water management is a high priority for continuing research and development. The public domain WRAP software and documentation are generalized for application any place in the world. Lessons learned in developing and implementing the modeling system in Texas are relevant worldwide. The modeling system combines: (1) detailed simulation of water right systems, interstate compacts, international treaties, federal/state/local agreements, and operations of storage and conveyance facilities, (2) simulation of river system hydrology, and (3) statistical frequency and reliability analyses. The continually evolving modeling system has been implemented in Texas by a water management community that includes the state legislature, planning and regulatory agencies, river authorities, water districts, cities, industries, engineering consulting firms, and university researchers. The shared modeling system contributes significantly to integration of water allocation, planning, system operations, and research. Full article
(This article belongs to the Special Issue Feature Papers of Water Resources Management, Policy and Governance)
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27 pages, 3881 KiB  
Review
Recent Advancements in the Removal of Cyanotoxins from Water Using Conventional and Modified Adsorbents—A Contemporary Review
by Tauqeer Abbas, George William Kajjumba, Meena Ejjada, Sayeda Ummeh Masrura, Erica J. Marti, Eakalak Khan and Tammy L. Jones-Lepp
Water 2020, 12(10), 2756; https://doi.org/10.3390/w12102756 - 3 Oct 2020
Cited by 48 | Viewed by 6182
Abstract
The prevalence of cyanobacteria is increasing in freshwaters due to climate change, eutrophication, and their ability to adapt and thrive in changing environmental conditions. In response to various environmental pressures, they produce toxins known as cyanotoxins, which impair water quality significantly. Prolonged human [...] Read more.
The prevalence of cyanobacteria is increasing in freshwaters due to climate change, eutrophication, and their ability to adapt and thrive in changing environmental conditions. In response to various environmental pressures, they produce toxins known as cyanotoxins, which impair water quality significantly. Prolonged human exposure to cyanotoxins, such as microcystins, cylindrospermopsin, saxitoxins, and anatoxin through drinking water can cause severe health effects. Conventional water treatment processes are not effective in removing these cyanotoxins in water and advanced water treatment processes are often used instead. Among the advanced water treatment methods, adsorption is advantageous compared to other methods because of its affordability and design simplicity for cyanotoxins removal. This article provides a current review of recent developments in cyanotoxin removal using both conventional and modified adsorbents. Given the different cyanotoxins removal capacities and cost of conventional and modified adsorbents, a future outlook, as well as suggestions are provided to achieve optimal cyanotoxin removal through adsorption. Full article
(This article belongs to the Special Issue Environmental Chemistry of Water Quality Monitoring)
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23 pages, 7848 KiB  
Article
A Modified HYDRUS Model for Simulating PFAS Transport in the Vadose Zone
by Jeff Allen Kai Silva, Jiří Šimůnek and John E. McCray
Water 2020, 12(10), 2758; https://doi.org/10.3390/w12102758 - 3 Oct 2020
Cited by 79 | Viewed by 9365
Abstract
The HYDRUS unsaturated flow and transport model was modified to simulate the effects of non-linear air-water interfacial (AWI) adsorption, solution surface tension-induced flow, and variable solution viscosity on the unsaturated transport of per- and polyfluoroalkyl substances (PFAS) within the vadose zone. These modifications [...] Read more.
The HYDRUS unsaturated flow and transport model was modified to simulate the effects of non-linear air-water interfacial (AWI) adsorption, solution surface tension-induced flow, and variable solution viscosity on the unsaturated transport of per- and polyfluoroalkyl substances (PFAS) within the vadose zone. These modifications were made and completed between March 2019 and May 2019, and were implemented into both the one-dimensional (1D) and two-dimensional (2D) versions of HYDRUS. Herein, the model modifications are described and validated against the available literature-derived PFAS transport data (i.e., 1D experimental column transport data). The results of both 1D and 2D example simulations are presented to highlight the function and utility of the model to capture the dynamic and transient nature of the temporally and spatially variable interfacial area of the AWI (Aaw) as it changes with soil moisture content (Θw) and how it affects PFAS unsaturated transport. Specifically, the simulated examples show that while AWI adsorption of PFAS can be a significant source of retention within the vadose zone, it is not always the dominant source of retention. The contribution of solid-phase sorption can be considerable in many PFAS-contaminated vadose zones. How the selection of an appropriate Aaw(Θw) function can impact PFAS transport and how both mechanisms contribute to PFAS mass flux to an underlying groundwater source is also demonstrated. Finally, the effects of soil textural heterogeneities on PFAS unsaturated transport are demonstrated in the results of both 1D and 2D example simulations. Full article
(This article belongs to the Special Issue Contaminant Transport and Fate)
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19 pages, 5115 KiB  
Article
Impacts of Extreme Weather Events on Bacterial Community Composition of a Temperate Humic Lake
by Alexa Hoke, Jason Woodhouse, Luca Zoccarato, Valerie McCarthy, Elvira de Eyto, Maria Calderó-Pascual, Ewan Geffroy, Mary Dillane, Hans-Peter Grossart and Eleanor Jennings
Water 2020, 12(10), 2757; https://doi.org/10.3390/w12102757 - 3 Oct 2020
Cited by 11 | Viewed by 4289
Abstract
Extreme weather events are projected to increase in frequency and intensity as climate change continues. Heterotrophic bacteria play a critical role in lake ecosystems, yet little research has been done to determine how they are affected by such extremes. The purpose of this [...] Read more.
Extreme weather events are projected to increase in frequency and intensity as climate change continues. Heterotrophic bacteria play a critical role in lake ecosystems, yet little research has been done to determine how they are affected by such extremes. The purpose of this study was to use high-throughput sequencing to explore the bacterial community composition of a humic oligotrophic lake on the North Atlantic Irish coast and to assess the impacts on composition dynamics related to extreme weather events. Samples for sequencing were collected from Lough Feeagh on a fortnightly basis from April to November 2018. Filtration was used to separate free-living and particle-associated bacterial communities and amplicon sequencing was performed for the 16S rRNA V4 region. Two named storms, six high discharge events, and one drought period occurred during the sampling period. These events had variable, context-dependent effects on bacterial communities in Lough Feeagh. The particle-associated community was found to be more likely to respond to physical changes, such as mixing, while the free-living population responded to changes in nutrient and carbon concentrations. Generally, however, the high stability of the bacterial community observed in Lough Feeagh suggests that the bacterial community is relatively resilient to extreme weather events. Full article
(This article belongs to the Special Issue Effect of Extreme Climate Events on Lake Ecosystems)
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19 pages, 2128 KiB  
Article
Heavy Metals in Wastewater and Sewage Sludge from Selected Municipal Treatment Plants in Eastern Cape Province, South Africa
by Mojeed A. Agoro, Abiodun O. Adeniji, Martins A. Adefisoye and Omobola O. Okoh
Water 2020, 12(10), 2746; https://doi.org/10.3390/w12102746 - 1 Oct 2020
Cited by 215 | Viewed by 24367
Abstract
This study assessed the distribution of five heavy metals (Cd, Pb, Cu, Zn, and Fe) across the various stages of treatment in three selected sewage treatment facilities and their receiving waterbodies in the Eastern Cape Province, South Africa. Aqueous and solid (sludge) samples [...] Read more.
This study assessed the distribution of five heavy metals (Cd, Pb, Cu, Zn, and Fe) across the various stages of treatment in three selected sewage treatment facilities and their receiving waterbodies in the Eastern Cape Province, South Africa. Aqueous and solid (sludge) samples were collected monthly from September 2015 to February 2016. Quantitation was achieved by atomic absorption spectrometry after necessary sample preparations. Concentrations of heavy metal cations in the sludge generally varied from <DL (below detection limit) to 1.17 mg kg−1, <DL to 0.14 mg kg−1, 27.588 to 69.789 mg kg−1, and <DL to 0.099 mg kg−1 for Cu, Cd, Fe and Pb; while Zn was below detection all through. Similarly, the levels of Cu, Cd, and Fe in the influents, effluents, upstream and downstream across the three plants ranged from <DL–6.588 mg L−1, <DL–0.636 mg L−1, <DL–0.878 mg L−1 and <DL–0.711 mg L−1, respectively; Zn and Pb were less than DL in all the matrices and study locations. All the contaminants were below hazardous levels in all the sludge and aqueous samples except Cd which was higher in effluents and surface waters across the board. Wastewater Treatment Plant (WWTP)-A exhibited better removal capacity for Fe (86.6%), compared to WWTP-B (34.7%) and WWTP-C (56.9%). However, the removal of Cu and Zn was very poor in all the treatment facilities studied. Carcinogenic and non-carcinogenic risks evaluated were sufficiently low. This suggests that the levels of contamination, even with respect to Cd, was minimal. Nevertheless, efforts should be made to keep the concentrations of these contaminants at levels safe for humans and aquatic organisms. Furthermore, the use of the effluents from these facilities for irrigation should be discouraged to prevent unnecessary build-up of metals in the soil and plants grown with such, as well as subsequent bioaccumulation and biomagnification in the food chain. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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27 pages, 8537 KiB  
Article
Simulating the Impact of Climate Change with Different Reservoir Operating Strategies on Sedimentation of the Mangla Reservoir, Northern Pakistan
by Muhammad Adnan Khan, Jürgen Stamm and Sajjad Haider
Water 2020, 12(10), 2736; https://doi.org/10.3390/w12102736 - 30 Sep 2020
Cited by 14 | Viewed by 5409
Abstract
Reservoir sedimentation reduces the gross storage capacity of dams and also negatively impacts turbine functioning, posing a danger to turbine inlets. When the sediment delta approaches the dam, further concerns arise regarding sediments passing through turbine intakes, blades abrasion due to increased silt/sand [...] Read more.
Reservoir sedimentation reduces the gross storage capacity of dams and also negatively impacts turbine functioning, posing a danger to turbine inlets. When the sediment delta approaches the dam, further concerns arise regarding sediments passing through turbine intakes, blades abrasion due to increased silt/sand concentration, choking of outlets, and dam safety. Thus, slowing down the delta advance rate is a worthy goal from a dam manager’s viewpoint. These problems can be solved through a flexible reservoir operation strategy that prioritize sediment deposition further away from the dam face. As a case study, the Mangla Reservoir in Pakistan is selected to elaborate the operational strategy. The methodology rests upon usage of a 1D sediment transport model to quantify the impact of different reservoir operating strategies on sedimentation. Further, in order to assess the long-term effect of a changing climate, a global climate model under representative concentration pathways scenarios 4.5 and 8.5 for the 21st century is used. The reduction of uncertainty in the suspended sediments concentration is achieved by employing an artificial neural networking technique. Moreover, a sensitivity analysis focused on estimating the impact of various parameters on sediment transport modelling was conducted. The results show that a gradual increase in the reservoir minimum operating level slows down the delta movement rate and the bed level close to the dam. However, it may compromise the downstream irrigation demand during periods of high water demand. The findings may help the reservoir managers to improve the reservoir operation rules and ultimately support the objective of a sustainable reservoir use for the societal benefit. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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22 pages, 5524 KiB  
Article
Investigating an Innovative Sea-Based Strategy to Mitigate Coastal City Flood Disasters and Its Feasibility Study for Brisbane, Australia
by Usman Khalil, Shu-Qing Yang, Muttucumaru Sivakumar, Keith Enever, Mariam Sajid and Muhammad Zain Bin Riaz
Water 2020, 12(10), 2744; https://doi.org/10.3390/w12102744 - 30 Sep 2020
Cited by 10 | Viewed by 4337
Abstract
This study examines an innovative Coastal Reservoir (CR) technique as a feasible solution for flood adaptation and mitigation in the Brisbane River Estuary (BRE), Australia, which is vulnerable to coastal flooding. The study analysed the operation of a CR by using the MIKE [...] Read more.
This study examines an innovative Coastal Reservoir (CR) technique as a feasible solution for flood adaptation and mitigation in the Brisbane River Estuary (BRE), Australia, which is vulnerable to coastal flooding. The study analysed the operation of a CR by using the MIKE 21 hydrodynamic modelling package. The 2D hydrodynamic model was calibrated and validated for the 2013 and 2011 flood events respectively, with a Nash-Sutcliffe coefficient (Ens) between 0.87 to 0.97 at all gauges. River right branch widening and dredging produced a 0.16 m reduction in water level at the Brisbane city gauge. The results show that by suitable gate operation of CR, the 2011 flood normal observed level of 4.46 m, with reference to the Australian Height Datum (AHD) at Brisbane city, could have been reduced to 3.88 m AHD, while under the improved management operation of the Wivenhoe Dam, the flood level could be lowered to 4 m AHD at Brisbane city, which could have been reduced with CR to 2.87 m AHD with an overall water level reduction below the maximum flood level. The results demonstrated that the innovative use of a CR could considerably decrease the overall flood peak and lessen flood severity in the coastal city of Brisbane. Full article
(This article belongs to the Special Issue Hydrodynamics in Estuaries and Coast: Analysis and Modeling)
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27 pages, 16227 KiB  
Article
Integrating C- and L-Band SAR Imagery for Detailed Flood Monitoring of Remote Vegetated Areas
by Alberto Refice, Marina Zingaro, Annarita D’Addabbo and Marco Chini
Water 2020, 12(10), 2745; https://doi.org/10.3390/w12102745 - 30 Sep 2020
Cited by 27 | Viewed by 6088
Abstract
Flood detection and monitoring is increasingly important, especially on remote areas such as African tropical river basins, where ground investigations are difficult. We present an experiment aimed at integrating multi-temporal and multi-source data from the Sentinel-1 and ALOS 2 synthetic aperture radar (SAR) [...] Read more.
Flood detection and monitoring is increasingly important, especially on remote areas such as African tropical river basins, where ground investigations are difficult. We present an experiment aimed at integrating multi-temporal and multi-source data from the Sentinel-1 and ALOS 2 synthetic aperture radar (SAR) sensors, operating in C band, VV polarization, and L band, HH and HV polarizations, respectively. Information from the globally available CORINE land cover dataset, derived over Africa from the Proba V satellite, and available publicly at the resolution of 100 m, is also exploited. Integrated multi-frequency, multi-temporal, and multi-polarizations analysis allows highlighting different drying dynamics for floodwater over various land cover classes, such as herbaceous vegetation, wetlands, and forests. They also enable detection of different scattering mechanisms, such as double bounce interaction of vegetation stems and trunks with underlying floodwater, giving precious information about the distribution of flooded areas among the different ground cover types present on the site. The approach is validated through visual analysis from Google EarthTM imagery. This kind of integrated analysis, exploiting multi-source remote sensing to partially make up for the unavailability of reliable ground truth, is expected to assume increasing importance as constellations of satellites, observing the Earth in different electromagnetic radiation bands, will be available. Full article
(This article belongs to the Special Issue Improving Flood Detection and Monitoring through Remote Sensing)
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17 pages, 5305 KiB  
Article
Infiltration Characteristics and Spatiotemporal Distribution of Soil Moisture in Layered Soil under Vertical Tube Irrigation
by Cheng Wang, Dan Bai, Yibo Li, Xinduan Wang, Zhen Pei and Zuochao Dong
Water 2020, 12(10), 2725; https://doi.org/10.3390/w12102725 - 29 Sep 2020
Cited by 5 | Viewed by 3070
Abstract
The limited quantity of irrigation water in Xinjiang has hindered agricultural development in the region and water-saving irrigation technologies are crucial to addressing this water shortage. Vertical tube irrigation, a type of subsurface irrigation, is a new water-efficient technology. In this study, field [...] Read more.
The limited quantity of irrigation water in Xinjiang has hindered agricultural development in the region and water-saving irrigation technologies are crucial to addressing this water shortage. Vertical tube irrigation, a type of subsurface irrigation, is a new water-efficient technology. In this study, field and laboratory experiments were conducted to analyze (1) the infiltration characteristics and spatiotemporal distribution of moisture in layered soil and (2) the water-saving mechanism of vertical tube irrigation. In the field experiments, we analyzed jujube yield, irrigation water productivity (IWP), and soil moisture in the jujube root zone. In the laboratory irrigation experiments, two soil types (silty and sandy loam) were selected to investigate homogeneous and layered soil, respectively. Cumulative infiltration, wetting body, and soil water moisture distribution were also analyzed. Relative to surface drip irrigation, vertical tube irrigation resulted in slightly lower jujube yields but higher savings in water use (47–68%) and improved IWP. The laboratory experiments demonstrated that layered soil had less cumulative infiltration, a larger ellipsoid wetted body, slower vertical wetting front migration (hindered by layer interface), and faster horizontal wetting front migration than homogenous soil had. The irrigation amount for vertical tube irrigation decreased in layered soil, and water content increased at the layer interface. Vertical tube irrigation in layered soil facilitates the retention of water in the root zone, prevents deep leakage, reduces irrigation amount, and improves the IWP of jujube trees. This study aids the popularization and application of vertical tube irrigation technology. Full article
(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture)
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15 pages, 1774 KiB  
Article
Influence of the Aggregate-Pouring Sequence on the Efficiency of Plugging Inundated Tunnels through Drilling Ground Boreholes
by Xiangming Jiang, Shuang Hui, Wanghua Sui, Zhiyuan Shi and Jiahao Wang
Water 2020, 12(10), 2698; https://doi.org/10.3390/w12102698 - 27 Sep 2020
Cited by 5 | Viewed by 2314
Abstract
This paper presents an experimental and field investigation on the efficiency of plugging by pouring aggregate in different sequences through multiple boreholes in a tunnel with flowing water. There have been controversies surrounding the selection of the pouring order for different particle sizes [...] Read more.
This paper presents an experimental and field investigation on the efficiency of plugging by pouring aggregate in different sequences through multiple boreholes in a tunnel with flowing water. There have been controversies surrounding the selection of the pouring order for different particle sizes of aggregates and the order in different boreholes. A visualized experimental setup is used to investigate the influence of the pouring orders on the efficiency of plugging through multiple boreholes under the flowing-water condition. A case study of the salvage of a flooded mine using ground directional boreholes was investigated and compared with the experimental results. The water-pressure difference at the aggregate-capping moment, when fine aggregate was poured first and coarse aggregate later, was relatively small, compared to that when fine aggregate was poured upstream and coarse aggregate, downstream. The result implies that the efficiency of plugging with the order of pouring fine aggregate first and coarse aggregate later in different boreholes is better than that with the order of pouring fine aggregate upstream and coarse aggregate downstream. When the poured aggregate is about to be capped, increasing the pouring intensity with the same or a larger particle size is more conducive to capping. The case study shows that pouring fine materials in the early stage reduced the cross-sectional area; in the later stage, the aggregate particle size was gradually increased, which can be helpful in forming an effective water-barrier section in the tunnel. The pouring of aggregate provided a base for cement grouting to form a water-plug section with a length of 106 m, resulting in a sealing efficiency of 100% for the case. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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23 pages, 3227 KiB  
Article
Technical Efficiency of China’s Agriculture and Output Elasticity of Factors Based on Water Resources Utilization
by Shiliang Yang, Huimin Wang, Jinping Tong, Jianfeng Ma, Fan Zhang and Shijuan Wu
Water 2020, 12(10), 2691; https://doi.org/10.3390/w12102691 - 26 Sep 2020
Cited by 22 | Viewed by 4424
Abstract
A stochastic frontier approach (SFA) model of translog production function was constructed to analyze the growth effect of agricultural production factors on grain production in China. Under the condition of unchanged cultivated land, the agricultural labor, capital, and water were regarded as input [...] Read more.
A stochastic frontier approach (SFA) model of translog production function was constructed to analyze the growth effect of agricultural production factors on grain production in China. Under the condition of unchanged cultivated land, the agricultural labor, capital, and water were regarded as input elements of the agricultural production function. The maximum likelihood estimation (MLE) method was used to analyze the technical efficiency, output elasticity, substitution elasticity, and relative variability of grain production in China from 2004 to 2018. The results showed that: (1) For the technical efficiency and output elasticity of the input factors of grain production, there were significant differences in different provinces. For example, the water resource was insufficient in Beijing and Shanghai, but the output elasticity of water was high. Heilongjiang was rich in water and had high technical efficiency. For Xinjiang, water was sufficient, but its output elasticity was deficient and the technical efficiency didn’t increase. (2) The overall technical efficiency level was relatively low and was still declining year by year; the output elasticity of water was much greater than that of capital. There was still great potential for grain growth. (3) Optimizing resource allocation and controlling the appropriate ratio of input factors to develop grain production could achieve the maximum benefits. Finally, according to the empirical results, this paper put forward some practical policy suggestions for optimizing the allocation of input factors, especially water and capital, which can ultimately improve agricultural productivity by improving technical efficiency. Full article
(This article belongs to the Special Issue The Water-Energy-Food Nexus: Sustainable Development)
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18 pages, 4121 KiB  
Article
Hybridised Artificial Neural Network Model with Slime Mould Algorithm: A Novel Methodology for Prediction of Urban Stochastic Water Demand
by Salah L. Zubaidi, Iqbal H. Abdulkareem, Khalid S. Hashim, Hussein Al-Bugharbee, Hussein Mohammed Ridha, Sadik Kamel Gharghan, Fuod F. Al-Qaim, Magomed Muradov, Patryk Kot and Rafid Al-Khaddar
Water 2020, 12(10), 2692; https://doi.org/10.3390/w12102692 - 26 Sep 2020
Cited by 123 | Viewed by 7420
Abstract
Urban water demand prediction based on climate change is always challenging for water utilities because of the uncertainty that results from a sudden rise in water demand due to stochastic patterns of climatic factors. For this purpose, a novel combined methodology including, firstly, [...] Read more.
Urban water demand prediction based on climate change is always challenging for water utilities because of the uncertainty that results from a sudden rise in water demand due to stochastic patterns of climatic factors. For this purpose, a novel combined methodology including, firstly, data pre-processing techniques were employed to decompose the time series of water and climatic factors by using empirical mode decomposition and identifying the best model input via tolerance to avoid multi-collinearity. Second, the artificial neural network (ANN) model was optimised by an up-to-date slime mould algorithm (SMA-ANN) to predict the medium term of the stochastic signal of monthly urban water demand. Ten climatic factors over 16 years were used to simulate the stochastic signal of water demand. The results reveal that SMA outperforms a multi-verse optimiser and backtracking search algorithm based on error scale. The performance of the hybrid model SMA-ANN is better than ANN (stand-alone) based on the range of statistical criteria. Generally, this methodology yields accurate results with a coefficient of determination of 0.9 and a mean absolute relative error of 0.001. This study can assist local water managers to efficiently manage the present water system and plan extensions to accommodate the increasing water demand. Full article
(This article belongs to the Special Issue Advanced Applications of Electrocoagulation in Water and Wastewater)
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18 pages, 3805 KiB  
Article
Spatiotemporal Variation in Phytoplankton Community Driven by Environmental Factors in the Northern East China Sea
by Yejin Kim, Seok-Hyun Youn, Hyun Ju Oh, Jae Joong Kang, Jae Hyung Lee, Dabin Lee, Kwanwoo Kim, Hyo Keun Jang, Junbeom Lee and Sang Heon Lee
Water 2020, 12(10), 2695; https://doi.org/10.3390/w12102695 - 26 Sep 2020
Cited by 18 | Viewed by 4632
Abstract
The East China Sea (ECS) is the largest marginal sea in the northern western Pacific Ocean. In comparison to various physical studies, little information on the seasonal patterns in community structure of phytoplankton is currently available. Based on high performance liquid chromatography (HPLC) [...] Read more.
The East China Sea (ECS) is the largest marginal sea in the northern western Pacific Ocean. In comparison to various physical studies, little information on the seasonal patterns in community structure of phytoplankton is currently available. Based on high performance liquid chromatography (HPLC) pigment analysis, spatiotemporal variations in phytoplankton community compositions were investigated in the northern ECS. Water temperature and salinity generally decreased toward the western part of the study area but warmer conditions in August led to strong vertical stratification of the water column. In general, major inorganic nutrient concentrations were considerably higher in the western part with a shallow water depth, and consistent with previous results, had no discernable vertical pattern during our observation period except in August. This study also revealed PO4-limited environmental conditions in May and August. The monthly averaged integral chlorophyll-a concentration varied seasonally, highest (35.2 ± 20.22 mg m−2) in May and lowest (5.2 ± 2.54 mg m−2) in February. No distinct vertical differences in phytoplankton community compositions were observed for all the sampling seasons except in August when cyanobacteria predominated in the nutrient-deficient surface layer and diatoms prevailed at deep layer. Canonical correlation analysis results revealed that nutrient distribution and the water temperature were the major drivers of the vertical distribution of phytoplankton communities in August. Spatially, a noticeable difference in phytoplankton community structure between the eastern and western parts was observed in November with diatom domination in the western part and cyanobacteria domination in the eastern part, which were significantly (p < 0.01) correlated with water temperature, salinity, light conditions, and nutrient concentrations. Overall, the two major phytoplankton groups were diatoms (32.0%) and cyanobacteria (20.6%) in the northern ECS and the two groups were negatively correlated, which holds a significant ecological meaning under expected warming ocean conditions. Full article
(This article belongs to the Special Issue Marine Nitrogen Fixation and Phytoplankton Ecology)
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12 pages, 1696 KiB  
Review
The Water Footprint of Global Food Production
by Mesfin M. Mekonnen and Winnie Gerbens-Leenes
Water 2020, 12(10), 2696; https://doi.org/10.3390/w12102696 - 26 Sep 2020
Cited by 162 | Viewed by 45169
Abstract
Agricultural production is the main consumer of water. Future population growth, income growth, and dietary shifts are expected to increase demand for water. The paper presents a brief review of the water footprint of crop production and the sustainability of the blue water [...] Read more.
Agricultural production is the main consumer of water. Future population growth, income growth, and dietary shifts are expected to increase demand for water. The paper presents a brief review of the water footprint of crop production and the sustainability of the blue water footprint. The estimated global consumptive (green plus blue) water footprint ranges from 5938 to 8508 km3/year. The water footprint is projected to increase by as much as 22% due to climate change and land use change by 2090. Approximately 57% of the global blue water footprint is shown to violate the environmental flow requirements. This calls for action to improve the sustainability of water and protect ecosystems that depend on it. Some of the measures include increasing water productivity, setting benchmarks, setting caps on the water footprint per river basin, shifting the diets to food items with low water requirements, and reducing food waste. Full article
(This article belongs to the Special Issue In Memory of Prof. Arjen Y. Hoekstra)
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17 pages, 3611 KiB  
Article
Risk Assessment of China’s Water-Saving Contract Projects
by Qian Li, Ziheng Shangguan, Mark Yaolin Wang, Dengcai Yan, Ruizhi Zhai and Chuanhao Wen
Water 2020, 12(10), 2689; https://doi.org/10.3390/w12102689 - 25 Sep 2020
Cited by 12 | Viewed by 4019
Abstract
In order to alleviate the problem of water shortage, the Ministry of Water Resources of China proposed a Water-Saving Contract (WSC) project management model in 2014, which is similar to the Energy Performance Contract (EPC). In this context, this research aims to explore [...] Read more.
In order to alleviate the problem of water shortage, the Ministry of Water Resources of China proposed a Water-Saving Contract (WSC) project management model in 2014, which is similar to the Energy Performance Contract (EPC). In this context, this research aims to explore the applicability of China’s WSC projects by risk assessment, and to help promote WSC projects in China. Different from traditional risk assessment, this paper takes into account the uncertainty of the EPC project’s risks, and adopts the multielement connection degree set pair analysis to evaluate both the level and trend of the risks. The results show: (1) the overall risk of China’s WSC projects is low, so WSC projects are very suitable for promotion in China. However, the overall risk shows a trend of decelerated ascent, which shows that there are some potential high-risk factors in China’s WSC projects; (2) among the many risks of the WSC projects, audit risk, financing risk, and payment risk are at a high-risk level; market competition risk is at a medium-risk level; the remaining risks are at a low-risk level; (3) among the medium and high risks, audit risk, financing risk, and market competition risk have a trend of accelerated ascent, while payment risk has a trend of decelerated decline; in low risks, inflation risk has a trend of decelerated ascent, while the remaining risks have a trend of accelerated decline. Full article
(This article belongs to the Special Issue Water Resources Management Models for Policy Assessment)
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21 pages, 1906 KiB  
Review
Environmental Flows in the Lower Ebro River and Delta: Current Status and Guidelines for a Holistic Approach
by Carles Ibáñez, Nuno Caiola and Oscar Belmar
Water 2020, 12(10), 2670; https://doi.org/10.3390/w12102670 - 24 Sep 2020
Cited by 22 | Viewed by 5133
Abstract
Deltas are a particular type of estuarine system in which the dependence on river flow (water, sediments and nutrients) is very strong, especially in river-dominated deltas such as the Mediterranean ones, but environmental flow (e-flow) proposals for deltaic systems are scarce. The Ebro [...] Read more.
Deltas are a particular type of estuarine system in which the dependence on river flow (water, sediments and nutrients) is very strong, especially in river-dominated deltas such as the Mediterranean ones, but environmental flow (e-flow) proposals for deltaic systems are scarce. The Ebro Delta is one of the largest wetland areas in the western Mediterranean and one of the most important estuarine systems in Europe. The aim of this paper is to review the state of the art regarding e-flows and to carry out a critical analysis of the proposals for the lower Ebro River and Delta, in order to highlight the possible environmental and socioeconomic impacts arising from the e-flow regime currently approved. Additionally, based on existing scientific information, methods to establish an e-flow regime that allows the maintenance of the main socio-ecological functions and values are discussed; including those functions and values for which not enough information is available. The study concludes that the currently approved e-flows are not suitable for maintaining most functions and values, as they would not prevent the proliferation of alien fish species and macrophytes in the river, the intrusion of the salt wedge in the estuary, the deficit of sediment/nutrient transport and the degradation of riparian habitats or the decline of coastal fisheries. Socioeconomic consequences on coastal fisheries, river navigation, salt water intrusion, sediment deficit, biodiversity, water quality, aquaculture and hydropower are also considered. Other e-flow proposals such as the proposed by the Catalan government would be more suitable to maintain the main socioecological functions and values of the lower Ebro River and Delta. Nevertheless, additional studies are needed to validate e-flows in some relevant aspects such as the capacity of the river to transport sediments to the delta to avoid coastal regression and mitigate the effects of sea level rise and subsidence, as well as the capacity of floods to control the spread of macrophytes. The lower Ebro River and delta is among the case studies where more quantitative and qualitative criteria to set e-flows with a holistic approach have been established. Full article
(This article belongs to the Special Issue Environmental Flows, Ecological Quality and Ecosystem Services)
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17 pages, 3201 KiB  
Review
Climate Change Impacts on Water and Agriculture Sectors in Southern Africa: Threats and Opportunities for Sustainable Development
by Charles Nhemachena, Luxon Nhamo, Greenwell Matchaya, Charity R. Nhemachena, Binganidzo Muchara, Selma T. Karuaihe and Sylvester Mpandeli
Water 2020, 12(10), 2673; https://doi.org/10.3390/w12102673 - 24 Sep 2020
Cited by 155 | Viewed by 24688
Abstract
Agriculture remains important in driving economic transformation, sustainable livelihoods, and development in developing countries. This paper provides a comprehensive analysis and discussion of climate change impacts on water and agriculture sectors and implications for the attainment of developmental outcomes such as food security, [...] Read more.
Agriculture remains important in driving economic transformation, sustainable livelihoods, and development in developing countries. This paper provides a comprehensive analysis and discussion of climate change impacts on water and agriculture sectors and implications for the attainment of developmental outcomes such as food security, poverty reduction, and sustainable development in Southern Africa. The review gives policy messages for coping, adapting, and building resilience of water and agricultural production systems in the face of projected changes in climate and variability. The aim is to guide the region towards the achievement of the Sustainable Development Goals. Future projections for Southern Africa indicate reduced rainfall, increased temperatures, and high variability for the greater part of the region with severe reductions on the drier and marginal western parts. These impacts have profound implications for agriculture performance and contribution to national and regional developmental goals. The region is projected to experience reductions of between 15% and 50% in agricultural productivity, a scenario that would exacerbate food insecurity in the region. The challenge is to increase productivity on current arable land through efficient and sustainable management of available water and energy, and at the same time reducing pressure on the environment. Affordability and accessibility of innovative adaptation measures on water resources remain critical and these strategies should be part of broader sustainable development efforts. Overall, efforts to enhance agricultural productivity need to emphasise investments in sustainable management and use of water and energy resources in agriculture to achieve sustainable economic growth and livelihoods. Full article
(This article belongs to the Section Water, Agriculture and Aquaculture)
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19 pages, 2784 KiB  
Article
Effect of Diverse Abiotic Conditions on the Structure and Biodiversity of Ichthyofauna in Small, Natural Water Bodies Located on Agricultural Lands
by Adam Brysiewicz, Przemysław Czerniejewski and Małgorzata Bonisławska
Water 2020, 12(10), 2674; https://doi.org/10.3390/w12102674 - 24 Sep 2020
Cited by 5 | Viewed by 3625
Abstract
Mid-field natural ponds promote regional biodiversity, providing alternative habitats for many valuable animal species. The study’s objective was to determine the most important abiotic factors, including hydrochemical and morphometric parameters, affecting fish occurrence in natural, small water bodies on agricultural lands. The studies [...] Read more.
Mid-field natural ponds promote regional biodiversity, providing alternative habitats for many valuable animal species. The study’s objective was to determine the most important abiotic factors, including hydrochemical and morphometric parameters, affecting fish occurrence in natural, small water bodies on agricultural lands. The studies were conducted in nine randomly selected water bodies located in Poland (the North European Plain). Eleven species of fish were recorded in the waterbodies, with the most abundant being cyprinids (mainly crucian carp). Canonical correspondence analysis (CCA) showed that an increase in oxygenation, temperature, amount of macrophytes, and K concentration and a decrease in the concentration of phosphates, electrical conductivity (EC), Mg, and Cl is associated with the most beneficial living conditions for the most frequently occurring species in the studied water bodies—crucian carp and tench. Aside from the hydrochemical parameters of water in the natural ponds, the number of fish correlates with the basin area and the pond area, maximum depth, area of the buffer zone surrounding the water bodies, and the number of macrophytes. This last factor also has a significant influence on the species’ abundance in the water bodies. Fish occurrences in mid-field ponds and common knowledge on their important role in the environment require taking steps to provide fish protection. Full article
(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)
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14 pages, 2214 KiB  
Article
The Role of Sewer Network Structure on the Occurrence and Magnitude of Combined Sewer Overflows (CSOs)
by Julian D. Reyes-Silva, Emmanuel Bangura, Björn Helm, Jakob Benisch and Peter Krebs
Water 2020, 12(10), 2675; https://doi.org/10.3390/w12102675 - 24 Sep 2020
Cited by 15 | Viewed by 4509
Abstract
Combined sewer overflows (CSOs) prevent surges in sewer networks by releasing untreated wastewater into nearby water bodies during intense storm events. CSOs can have acute and detrimental impacts on the environment and thus need to be managed. Although several gray, green and hybrid [...] Read more.
Combined sewer overflows (CSOs) prevent surges in sewer networks by releasing untreated wastewater into nearby water bodies during intense storm events. CSOs can have acute and detrimental impacts on the environment and thus need to be managed. Although several gray, green and hybrid CSO mitigation measures have been studied, the influence of network structure on CSO occurrence is not yet systematically evaluated. This study focuses on evaluating how the variation of urban drainage network structure affects the frequency and magnitude of CSO events. As a study case, a sewer subnetwork in Dresden, Germany, where 11 CSOs are present, was selected. Scenarios corresponding to the structures with the lowest and with the highest number of possible connected pipes, are developed and evaluated using long-term hydrodynamic simulation. Results indicate that more meshed structures are associated to a decrease on the occurrence and magnitude of CSO. Event frequency reductions vary between 0% and 68%, while reduction of annual mean volumes and annual mean loads ranged between 0% and 87% and 0% and 92%. These rates were mainly related to the additional sewer storage capacity provided in the more meshed scenarios, following a sigmoidal behavior. However, increasing network connections causes investment costs, therefore optimization strategies for selecting intervention areas are needed. Furthermore, the present approach of reducing CSO frequency may provide a new gray solution that can be integrated in the development of hybrid mitigation strategies for the CSO management. Full article
(This article belongs to the Section Urban Water Management)
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23 pages, 40132 KiB  
Article
A Stepwise Approach to Beach Restoration at Calabaia Beach
by Mario Maiolo, Riccardo Alvise Mel and Salvatore Sinopoli
Water 2020, 12(10), 2677; https://doi.org/10.3390/w12102677 - 24 Sep 2020
Cited by 23 | Viewed by 5347
Abstract
Sea hazards are increasingly threatening worldwide coastal areas, which are among the most strategic resources of the Earth in supporting human population, economy and the environment. These hazards enhance erosion processes and flooding events, producing severe socio-economic impacts and posing a challenge to [...] Read more.
Sea hazards are increasingly threatening worldwide coastal areas, which are among the most strategic resources of the Earth in supporting human population, economy and the environment. These hazards enhance erosion processes and flooding events, producing severe socio-economic impacts and posing a challenge to ocean engineers and stakeholders in finding the optimal strategy to protect both the coastal communities and the health of the environment. The impact of coastal hazards is actually worsened not only by an enhancing rate of relative sea level rise and storminess driven by climate changes, but also by increasing urban pressure related to the development of the sea economy. With regard to larger environmental awareness and climate change adaptation needs, the present study focuses on a stepwise approach that supports the actions for coastal protection at Calabaia Beach, which is located in the Marine Experimental Station of Capo Tirone (Cosenza, Italy). These actions first aim to protect humans and coastal assets, then to restore the environment and the local habitat, overcoming the need for the emergency interventions carried out in the last decades and pointing out that healthy ecosystems are more productive and support a sustainable marine economy (“Blue Growth”). Full article
(This article belongs to the Special Issue Nature-Based Solutions for Coastal Engineering and Management)
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15 pages, 1160 KiB  
Article
Cost Effectiveness of Ecosystem-Based Nutrient Targets—Findings from a Numerical Model for the Baltic Sea
by Ing-Marie Gren and Wondmagegn Tafesse Tirkaso
Water 2020, 12(10), 2679; https://doi.org/10.3390/w12102679 - 24 Sep 2020
Cited by 2 | Viewed by 2152
Abstract
An ecosystem-based management of a large sea can give heterogeneous nutrient load targets for different parts of the sea. Cost effective solutions to heterogeneous nutrient reductions targets based on ecological conditions are compared with the same overall nutrient reductions to the Baltic Sea. [...] Read more.
An ecosystem-based management of a large sea can give heterogeneous nutrient load targets for different parts of the sea. Cost effective solutions to heterogeneous nutrient reductions targets based on ecological conditions are compared with the same overall nutrient reductions to the Baltic Sea. To this end, a numerical programming model is used, which includes eight different nutrient abatement measures (fertilizer and livestock reduction, cultivation of catch crops, reduced airborne nitrogen emissions, improved cleaning at sewage treatment plants, construction of wetlands and buffer strips, and mussel farming) in 21 catchments of the Baltic Sea. The results indicate that the cost for the international agreement on maximum load targets to different marine basins amounts to 5.3 billion euro. This is more than twice as large as the cost for the same total nutrient load targets to the Baltic Sea without specific targets for the marine basins. However, the resulting nutrient loads to the different marine basins deviate from the basin targets where the loads are lower for some basins but can exceed that for one basin, Baltic Proper, by approximately 22 per cent. Whether or not the ecological costs and benefits from deviations in basin targets under the Baltic Sea targets exceed the excess abatement cost of 2.9 billion euro for achieving the marine basin targets remains to be verified. Full article
(This article belongs to the Section Oceans and Coastal Zones)
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14 pages, 2645 KiB  
Article
Machine Learning-Based Water Level Prediction in Lake Erie
by Qi Wang and Song Wang
Water 2020, 12(10), 2654; https://doi.org/10.3390/w12102654 - 23 Sep 2020
Cited by 42 | Viewed by 5787
Abstract
Predicting water levels of Lake Erie is important in water resource management as well as navigation since water level significantly impacts cargo transport options as well as personal choices of recreational activities. In this paper, machine learning (ML) algorithms including Gaussian process (GP), [...] Read more.
Predicting water levels of Lake Erie is important in water resource management as well as navigation since water level significantly impacts cargo transport options as well as personal choices of recreational activities. In this paper, machine learning (ML) algorithms including Gaussian process (GP), multiple linear regression (MLR), multilayer perceptron (MLP), M5P model tree, random forest (RF), and k-nearest neighbor (KNN) are applied to predict the water level in Lake Erie. From 2002 to 2014, meteorological data and one-day-ahead observed water level are the independent variables, and the daily water level is the dependent variable. The predictive results show that MLR and M5P have the highest accuracy regarding root mean square error (RMSE)  and mean absolute error (MAE). The performance of ML models has also been compared against the performance of the process-based advanced hydrologic prediction system (AHPS), and the results indicate that ML models are superior in predictive accuracy compared to AHPS. Together with their time-saving advantage, this study shows that ML models, especially MLR and M5P, can be used for forecasting Lake Erie water levels and informing future water resources management. Full article
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11 pages, 1924 KiB  
Article
Performance of Three Sorghum Cultivars under Excessive Rainfall and Waterlogged Conditions in the Sudano-Sahelian Zone of West Africa: A Case Study at the Climate-Smart Village of Cinzana in Mali
by Manuel Müller, Siaka Dembélé, Robert B. Zougmoré, Thomas Gaiser and Samuel T. Partey
Water 2020, 12(10), 2655; https://doi.org/10.3390/w12102655 - 23 Sep 2020
Cited by 8 | Viewed by 4448
Abstract
Recent climate analyses show trends for increasing precipitation variability with increasing precipitation sums in Mali. The increasing occurrence of temporary intra-seasonal droughts and waterlogging longer than a week demands climate-smart solutions. Research has focused on water deficits since the 1980s. However, besides droughts, [...] Read more.
Recent climate analyses show trends for increasing precipitation variability with increasing precipitation sums in Mali. The increasing occurrence of temporary intra-seasonal droughts and waterlogging longer than a week demands climate-smart solutions. Research has focused on water deficits since the 1980s. However, besides droughts, waterlogging can restrict productivity of sensitive cash and staple crops as cotton and corn. The year 2019 offered the historically unique opportunity to monitor waterlogging effects with 1088 mm precipitation in the rural commune Cinzanawith an isohyet of 681 mm. Impacts of two extreme downpours on three sorghum cultivars were monitored in a farmers-field experiment with three replications. All sorghum cultivars performed well in 2019 with significantly higher grain and above ground biomass yields than in the reference year 2007, with well distributed rainfall in Cinzana. “Jakumbè” (CSM63E) produced significantly higher grain yields than the hybrid cultivar “PR3009B” bred for high harvest index. The local cultivar “Gnofing” selected by local farmers produced significantly higher above ground biomass. All cultivars tolerated without severe stress symptoms 20 days waterlogging and 72 h inundation. Further waterlogging resilience research of other crops and other sorghum cultivars is needed to strengthen food security in Mali with expected increasing precipitation variation in the future. Full article
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17 pages, 1566 KiB  
Article
The Influence of Grain Size Distribution on the Hydraulic Gradient for Initiating Backward Erosion
by Willem-Jan Dirkx, Rens van Beek and Marc Bierkens
Water 2020, 12(9), 2644; https://doi.org/10.3390/w12092644 - 22 Sep 2020
Cited by 8 | Viewed by 3608
Abstract
Backward erosion by piping is one of the processes that threaten the stability of river embankments in the Netherlands. During high river stages, groundwater flow velocities underneath the embankment increase as a result of the steepened hydraulic gradient. If a single outflow point [...] Read more.
Backward erosion by piping is one of the processes that threaten the stability of river embankments in the Netherlands. During high river stages, groundwater flow velocities underneath the embankment increase as a result of the steepened hydraulic gradient. If a single outflow point exists or forms, the concentrated flow can entrain soil particles, leading to the formation of a subsurface pipe. The processes controlling this phenomenon are still relatively unknown due to their limited occurrence and because piping is a subsurface phenomenon. To study the initiation of piping, we performed laboratory experiments in which we induced water flow through a porous medium with a vertically orientated outflow point. In these experiments, we explicitly considered grain size variations, thus adding to the existing database of experiments. Our experiments showed that the vertical velocity needed for the initiation of particle transport can be described well by Stokes’ law using the median grain size. We combine this with a novel method to relate bulk hydraulic conductivity to the grain size distribution. This shows that knowledge of the grain size distribution and the location of the outflow point are sufficient to estimate the hydraulic gradient needed to initiate pipe formation in the experiment box. Full article
(This article belongs to the Special Issue Local Erosion of Hydraulic Structures and Flood Protection)
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