Water

16 pages, 43317 KiB

Open AccessArticle

Possible Sources of Salinity in the Upper Dibdibba Aquifer, Basrah, Iraq

by Ahmed Abdulameer, Jassim Mohammed Thabit, Wael Kanoua, Oliver Wiche and Broder Merkel

Water 2021, 13(4), 578; https://doi.org/10.3390/w13040578 - 23 Feb 2021

Cited by 8 | Viewed by 3896

Salinity increase in groundwater was investigated in the area between Al-Zubair and Safwan, and close to the Khor Al-Zubair Channel of southern Iraq. Thirty-nine groundwater samples from the shallow aquifer and one sample from the Khor Al-Zubair Channel were analyzed. The mean total [...] Read more.

Salinity increase in groundwater was investigated in the area between Al-Zubair and Safwan, and close to the Khor Al-Zubair Channel of southern Iraq. Thirty-nine groundwater samples from the shallow aquifer and one sample from the Khor Al-Zubair Channel were analyzed. The mean total dissolved solids are 7556 mg/L. The δ²H and δ¹⁸O plot in two groups are below the global meteoric water line. Group A indicates the evaporation effect of irrigation return-flow, while group B is characterized by depleted δ¹⁸O values due to recharge under colder climate. Deuterium excess values plot within the region of modern precipitation and dilution of groundwater by precipitating water. The groundwater residence time is between 1000 and 2000 years and combining ¹⁴C -age with SO₄²⁻ shows a contrasting effect on groundwater on both sides of Khedr Almai Fault and the Zubair anticline, which indicates the role of these geological structures on the hydrochemical evolution in the western part. Jabal Sanam shows no clear effect in this regard. The ratio Cl⁻/Br⁻ and sulfate in groundwater showed that the measured salinity in groundwater is the result of a mixing process between groundwater, seawater intruding from Khor Al-Zubair Channel, and water from septic tanks in addition to dry and wet sea spray, and irrigation return-flow. Full article

(This article belongs to the Section Hydrology)

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23 pages, 5453 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Assessing Multi-Hazard Vulnerability and Dynamic Coastal Flood Risk in the Mississippi Delta: The Global Delta Risk Index as a Social-Ecological Systems Approach

by Carl C. Anderson, Fabrice G. Renaud, Michael Hagenlocher and John W. Day

Water 2021, 13(4), 577; https://doi.org/10.3390/w13040577 - 23 Feb 2021

Cited by 18 | Viewed by 7146

Abstract

The tight coupling of the social-ecological system (SES) of the Mississippi Delta calls for balanced natural hazard vulnerability and risk assessments. Most existing assessments have approached these components in isolation. To address this, we apply the Global Delta Risk Index (GDRI) in the [...] Read more.

The tight coupling of the social-ecological system (SES) of the Mississippi Delta calls for balanced natural hazard vulnerability and risk assessments. Most existing assessments have approached these components in isolation. To address this, we apply the Global Delta Risk Index (GDRI) in the Mississippi Delta at high-resolution census tract level. We assess SES spatial patterns of drought, hurricane-force wind, and coastal flood vulnerability and integrate hazard and exposure data for the assessment of coastal flood risk. Moreover, we compare current coastal flood risk to future risk in 2025 based on the modelled effects of flood depth, exposure, and changes in ecosystem area in the context of ongoing efforts under the 2017 Louisiana Coastal Master Plan. Results show that the Master Plan will lead to decreases in risk scores by 2025, but the tracts that are currently the most vulnerable benefit less from risk reduction efforts. Along with our index output, we discuss the need for further advancements in SES methodology and the potential for catastrophic hazard events beyond the model parameters, such as extreme rainfall events and very strong hurricanes. Assessing SES risk components can lead to more targeted policy recommendations, demonstrated by the need for Master Plan projects to consider their unequal spatial effects on vulnerability and risk reduction. Full article

(This article belongs to the Special Issue Sustainable Management, Conservation and Restoration in Deltaic Ecosystems with Special Emphasis on the Mississippi Delta)

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15 pages, 2371 KiB

Open AccessArticle

Understanding Public Acceptance of a Multifunctional Water Plaza: A Case Study

by Leon Netzel, Emily Drewing, Louis Netzel and Martin Denecke

Water 2021, 13(4), 576; https://doi.org/10.3390/w13040576 - 23 Feb 2021

Cited by 3 | Viewed by 3837

Abstract

Climate change enhances pluvial flood risk in many cities all over the world, especially in densely populated urban areas with high impervious surfaces that need to adapt to heavy precipitation. For this purpose, multifunctional stormwater infrastructures such as water plazas appear promising as [...] Read more.

Climate change enhances pluvial flood risk in many cities all over the world, especially in densely populated urban areas with high impervious surfaces that need to adapt to heavy precipitation. For this purpose, multifunctional stormwater infrastructures such as water plazas appear promising as there is a high competition for open space in most urban areas. Yet, to date only very few water plazas have been realized with at least one implementation hampered by a lack of public acceptance. In this study, semi-structured interviews are used to investigate how plans to build a water plaza in the city of Cologne are perceived by local residents. Factors crucial to public acceptance are identified. Experience with flooding, knowledge of the planned construction and awareness of benefits turned out to be important for acceptance, whereas social and personal norms were less relevant. The identified factors led to finding recommendations to promote public acceptance of innovative climate adaptation measures like water plazas. Full article

(This article belongs to the Section Urban Water Management)

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16 pages, 3191 KiB

Open AccessEditor’s ChoiceArticle

Deep Learning Framework with Time Series Analysis Methods for Runoff Prediction

by Zhenghe Li, Ling Kang, Liwei Zhou and Modi Zhu

Water 2021, 13(4), 575; https://doi.org/10.3390/w13040575 - 23 Feb 2021

Cited by 23 | Viewed by 5420

Abstract

Recent advances in deep learning, especially the long short-term memory (LSTM) networks, provide some useful insights on how to tackle time series prediction problems, not to mention the development of a time series model itself for prediction. Runoff forecasting is a time series [...] Read more.

Recent advances in deep learning, especially the long short-term memory (LSTM) networks, provide some useful insights on how to tackle time series prediction problems, not to mention the development of a time series model itself for prediction. Runoff forecasting is a time series prediction problem with a series of past runoff data (water level and discharge series data) as inputs and a fixed-length series of future runoff as output. Most previous work paid attention to the sufficiency of input data and the structural complexity of deep learning, while less effort has been put into the consideration of data quantity or the processing of original input data—such as time series decomposition, which can better capture the trend of runoff—or unleashing the effective potential of deep learning. Mutual information and seasonal trend decomposition are two useful time series methods in handling data quantity analysis and original data processing. Based on a former study, we proposed a deep learning model combined with time series analysis methods for daily runoff prediction in the middle Yangtze River and analyzed its feasibility and usability with frequently used counterpart models. Furthermore, this research also explored the data quality that affect the performance of the deep learning model. With the application of the time series method, we can effectively get some information about the data quality and data amount that we adopted in the deep learning model. The comparison experiment resulted in two different sites, implying that the proposed model improved the precision of runoff prediction and is much easier and more effective for practical application. In short, time series analysis methods can exert great potential of deep learning in daily runoff prediction and may unleash great potential of artificial intelligence in hydrology research. Full article

(This article belongs to the Special Issue Research of the Relationship between Climate Change and Runoff in Watershed)

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20 pages, 2814 KiB

Open AccessFeature PaperReview

Scientific Methods to Understand Fish Population Dynamics and Support Sustainable Fisheries Management

by Shewit Gebremedhin, Stijn Bruneel, Abebe Getahun, Wassie Anteneh and Peter Goethals

Water 2021, 13(4), 574; https://doi.org/10.3390/w13040574 - 23 Feb 2021

Cited by 33 | Viewed by 17406

Abstract

Fisheries play a significant role in the livelihoods of the world population, while the dependence on fisheries is acute in developing countries. Fisheries are consequently a critical element for meeting the sustainable development (SDG) and FAO goals to reduce poverty, hunger and improve [...] Read more.

Fisheries play a significant role in the livelihoods of the world population, while the dependence on fisheries is acute in developing countries. Fisheries are consequently a critical element for meeting the sustainable development (SDG) and FAO goals to reduce poverty, hunger and improve health and well-being. However, 90% of global marine fish stocks are fully or over-exploited. The amount of biologically unsustainable stocks increased from 10% in 1975 to 33% in 2015. Freshwater ecosystems are the most endangered ecosystems and freshwater fish stocks are worldwide in a state of crisis. The continuous fish stock decline indicates that the world is still far from achieving SDG 14 (Life Below Water), FAO’s Blue Growth Initiative goal and SDG 15 (Life on Land, including freshwater systems). Failure to effectively manage world fish stocks can have disastrous effects on biodiversity and the livelihoods and socio-economic conditions of millions of people. Therefore, management strategies that successfully conserve the stocks and provide optimal sustainable yields are urgently needed. However, successful management is only possible when the necessary data are obtained and decision-makers are well informed. The main problem for the management of fisheries, particularly in developing countries, is the lack of information on the past and current status of the fish stocks. Sound data collection and validation methods are, therefore, important. Stock assessment models, which support sustainable fisheries, require life history traits as input parameters. In order to provide accurate estimates of these life history traits, standardized methods for otolith preparation and validation of the rate of growth zone deposition are essential. This review aims to assist researchers and fisheries managers, working on marine and freshwater fish species, in understanding concepts and processes related to stock assessment and population dynamics. Although most examples and case studies originate from developing countries in the African continent, the review remains of great value to many other countries. Full article

(This article belongs to the Special Issue Ecology and Conservation of Freshwater Fishes Biodiversity)

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14 pages, 3479 KiB

Open AccessArticle

Optimal Sizing of Rooftop Rainwater Harvesting Tanks for Sustainable Domestic Water Use in the West Bank, Palestine

by Sameer Shadeed and Sandy Alawna

Water 2021, 13(4), 573; https://doi.org/10.3390/w13040573 - 23 Feb 2021

Cited by 16 | Viewed by 4583

Abstract

In highly water-poor areas, rooftop rainwater harvesting (RRWH) can be used for a self-sustaining and self-reliant domestic water supply. The designing of an optimal RRWH storage tank is a key parameter to implement a reliable RRWH system. In this study, the optimal size [...] Read more.

In highly water-poor areas, rooftop rainwater harvesting (RRWH) can be used for a self-sustaining and self-reliant domestic water supply. The designing of an optimal RRWH storage tank is a key parameter to implement a reliable RRWH system. In this study, the optimal size of RRWH storage tanks in the different West Bank governorates was estimated based on monthly (all governorates) and daily (i.e., Nablus) inflow (RRWH) and outflow (domestic water demand, DWD) data. In the estimation of RRWH, five rooftop areas varying between 100 m² and 300 m² were selected. Moreover, the reliability of the adopting RRWH system in the different West Bank governorates was tested. Two-time series scenarios were assumed: Scenario 1, S1 (12 months, annual) and scenario 2, S2 (8 months, rainy). As a result, reliable curves for preliminary estimation of optimal RRWH storage tanks for the different West Bank governorates were obtained. Results show that the required storage tank for S1 (annual) is more than that of the S2 (rainy) one. The required storage tank to fulfill DWD is based on the average rooftop area of 150 m², the average family members of 4.8, and the average DWD of 90 L per capita per day (L/c/d) varies between (75 m³ to 136 m³) and (24 m³ to 84 m³) for S2 for the different West Bank governorates. Further, it is found that the optimal RRWH tank size for the 150 m² rooftop ranges between 20 m³ (in Jericho) to 75 m³ (in Salfit and Nablus) and between 20 m³ (in Jericho) to 51 m³ (in Jerusalem) for S1 and S2 scenarios, respectively. Finally, results show that the implementation of an RRWH system for a rooftop area of 150 m² and family members of 4.8 is reliable for all of the West Bank governorates except Jericho. Whereas, the reliability doesn’t exceed 19% for the two scenarios. However, the reduction of DWDv is highly affecting the reliability of adopting RRWH systems in Jericho (the least rainfall governorate). For instance, a family DWDv of 3.2 m³/month (25% of the average family DWDv in the West Bank) will increase the reliability at a rooftop area of 150 m² to 51% and 76% for S1 and S2, respectively. Full article

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

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18 pages, 2026 KiB

Open AccessArticle

Assessment of Renewal Priority of Water Pipeline Network against Earthquake Risk

by Shogo Hamamoto, Lisa Ito and Akihiro Tokai

Water 2021, 13(4), 572; https://doi.org/10.3390/w13040572 - 23 Feb 2021

Cited by 4 | Viewed by 3031

Abstract

Long-term outage of drinking water supply after earthquakes has large adverse impacts on the lives of residents and cities’ water supply systems. Priority assessment is required to determine the effective order of preparing the measures against these hazards. Previous studies have insufficiently focused [...] Read more.

Long-term outage of drinking water supply after earthquakes has large adverse impacts on the lives of residents and cities’ water supply systems. Priority assessment is required to determine the effective order of preparing the measures against these hazards. Previous studies have insufficiently focused on the effects of seismic resistance of core pipelines, thereby affecting all the other branched pipelines that supply the water to each residential area. In our research, we aimed to propose the appropriate order of core pipelines derived from the center of the water treatment plants in Osaka, Japan against the Nankai Trough earthquake. Solutions that cause less damage have been needed because natural disaster prediction has had a lot of uncertainty. We proposed indices that can evaluate an appropriate renewal plan that considers the damage of core pipelines of water and the renewal cost for core pipeline networks based on the scenario analysis and the Monte Carlo simulation. The amount of water distribution of core pipelines in each area is the top priority when renewing them in terms of cost-effectiveness and expected rate of water outage under the disaster. Full article

(This article belongs to the Section Urban Water Management)

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3 pages, 167 KiB

Open AccessEditorial

New Trends in Environmental Catalytic Technologies for Water Remediation

by Zacharias Frontistis

Water 2021, 13(4), 571; https://doi.org/10.3390/w13040571 - 23 Feb 2021

Cited by 5 | Viewed by 2436

Abstract

Due to climate change, industrialization, and overpopulation, water resources management is becoming a crucial sector [...] Full article

(This article belongs to the Special Issue Wastewater Engineering and Environmental Catalysis)

25 pages, 7968 KiB

Open AccessArticle

Using Long Term Simulations to Understand Heat Transfer Processes during Steady Flow Conditions in Combined Sewers

by Mohamad Abdel-Aal, Simon Tait, Mostafa Mohamed and Alma Schellart

Water 2021, 13(4), 570; https://doi.org/10.3390/w13040570 - 23 Feb 2021

Cited by 11 | Viewed by 2700

Abstract

This paper describes a new heat transfer parameterisation between wastewater and in-sewer air based on understanding the physical phenomena observed in free surface wastewater and in-sewer air. Long-term wastewater and in-sewer air temperature data were collected and studied to indicate the importance of [...] Read more.

This paper describes a new heat transfer parameterisation between wastewater and in-sewer air based on understanding the physical phenomena observed in free surface wastewater and in-sewer air. Long-term wastewater and in-sewer air temperature data were collected and studied to indicate the importance of considering the heat exchange with in-sewer air and the relevant seasonal changes. The new parameterisation was based on the physical flow condition variations. Accurate modelling of wastewater temperature in linked combined sewers is needed to assess the feasibility of in-sewer heat recovery. Historically, the heat transfer coefficient between wastewater and in-sewer air has been estimated using simple empirical relationships. The newly developed parameterisation was implemented and validated using independent long-term flow and temperature datasets. Predictive accuracy of wastewater temperatures was investigated using a Taylor diagram, where absolute errors and correlations between modelled and observed values were plotted for different site sizes and seasons. The newly developed coefficient improved wastewater temperature modelling accuracy, compared with the older empirical approaches, which resulted in predicting more potential for heat recovery from large sewer networks. For individual locations, the RMSE between observed and predicted temperatures ranged between 0.15 and 0.5 °C with an overall average of 0.27 °C. Previous studies showed higher RMSE ranges, e.g., between 0.12 and 7.8 °C, with overall averages of 0.35, 0.42 and 2 °C. The new coefficient has also provided stable values at various seasons and minimised the number of required model inputs. Full article

(This article belongs to the Special Issue Industrial and Urban Wastewater Treatment and Reuse)

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14 pages, 23988 KiB

Open AccessArticle

Plant Nutrient Uptake in Full-Scale Floating Treatment Wetlands in a Florida Stormwater Pond: 2016–2020

by Sarah A. White

Water 2021, 13(4), 569; https://doi.org/10.3390/w13040569 - 23 Feb 2021

Cited by 19 | Viewed by 3729

Abstract

Nutrient enrichment of surface waters degrades water quality. Municipalities need effective and economical solutions to remove nutrients from surface waters. From July 2016 to May 2020, full-scale (900 m², 5% cover) floating treatment wetlands (FTWs) were deployed in Wickham Park pond, [...] Read more.

Nutrient enrichment of surface waters degrades water quality. Municipalities need effective and economical solutions to remove nutrients from surface waters. From July 2016 to May 2020, full-scale (900 m², 5% cover) floating treatment wetlands (FTWs) were deployed in Wickham Park pond, a eutrophic water body (0.13 mg/L total phosphorus (P), 0.96 mg/L total nitrogen (N)). The plants in FTWs in close proximity to a SB10000 mixer fixed N and P more efficiently. The rate of N (g/m²/year) fixed within tissues was highest for Juncus effusus (13.5), Agrostis alba (13.2), and Sagittaria lancifolia (12.1). The rate of P (g/m²/year) fixed within plant tissues was similar for all species (3.77, Agrostis alba, Canna spp., Iris hexagona, Juncus effusus, and Sagittaria lancifolia) save Pontederia cordata (2.52) volunteer species (1.41). The N and P removed with plant harvest were similar for non-mixed and mixed FTWs. Notably, the N:P ratio in plant tissues in 2017 (pre-mixer installation) was 11:1; after mixer installation (2018–2020), N:P ratios averaged 2.7:1, indicating increased P fixation within plant tissues. In 2017, 12,828 kg of plant tissues was harvested, removing 334 kg of N and 29.5 kg of P. In 2019, 32,958 kg of plant biomass was harvested from the pond, removing 425 kg of N and 138 kg of P. In 2020, 27,945 kg of biomass was harvested from FTWs, removing 267 kg of N and 95 kg of P. From 2016 to 2020, 73,000 kg of biomass was harvested, removing 1026 kg of N and 262 kg of P from Wickham Park pond. Knowing the total fresh biomass of tissues removed from FTWs at harvest is critical for accuracy in reporting nutrient removal aided by FTWs. Full article

(This article belongs to the Special Issue Constructed Wetlands for Water Pollution Control in Urban and Rural Areas)

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18 pages, 1851 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Monitoring Groundwater Use as a Domestic Water Source by Urban Households: Analysis of Data from Lagos State, Nigeria and Sub-Saharan Africa with Implications for Policy and Practice

by Kerstin Danert and Adrian Healy

Water 2021, 13(4), 568; https://doi.org/10.3390/w13040568 - 23 Feb 2021

Cited by 14 | Viewed by 6745

Abstract

The fundamental importance of groundwater for urban drinking water supplies in sub-Saharan Africa is increasingly recognised. However, little is known about the trends in urban groundwater development by individual households and its role in securing safely-managed drinking water supplies. Anecdotal evidence indicates a [...] Read more.

The fundamental importance of groundwater for urban drinking water supplies in sub-Saharan Africa is increasingly recognised. However, little is known about the trends in urban groundwater development by individual households and its role in securing safely-managed drinking water supplies. Anecdotal evidence indicates a thriving self-supply movement to exploit groundwater in some urban sub-Saharan African settings, but empirical evidence, or analysis of the benefits and drawbacks, remains sparse. Through a detailed analysis of official datasets for Lagos State, Nigeria we examine the crucial role played by groundwater and, specifically, by household self-supply for domestic water provision. We then set this in the context of Nigeria and of sub-Saharan Africa. One of the novelties of this multi-scalar approach is that it provides a granular understanding from large-scale datasets. Our analysis confirms the importance of non-piped water supplies in meeting current and future drinking water demand by households in parts of sub-Saharan Africa and the role played, through self-supply, by groundwater. Our results demonstrate inconsistencies between datasets, and we make recommendations for the future. We argue that a key actor in the provision of drinking water supplies, the individual household, is largely overlooked by officially reported data, with implications for both policy and practice. Full article

(This article belongs to the Special Issue Present and Future of Drinking Water Supplies in Low-Income Regions)

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21 pages, 1353 KiB

Open AccessArticle

Water Supply Portfolio Planning and Policy Evaluation under Climate Change: A Case Study of Central Taiwan

by Yen-Chen Huang, Chien-Ming Lee and Yue-Rong Hong

Water 2021, 13(4), 567; https://doi.org/10.3390/w13040567 - 23 Feb 2021

Viewed by 3339

Abstract

The present study examines the optimal water supply portfolio under the impact of climate change constructed by the authors previously. It incorporates feasibility planning for water supply projects, assesses a feasible water supply portfolio for central Taiwan, and uses the shadow price method [...] Read more.

The present study examines the optimal water supply portfolio under the impact of climate change constructed by the authors previously. It incorporates feasibility planning for water supply projects, assesses a feasible water supply portfolio for central Taiwan, and uses the shadow price method to assess the rationality of the compensation policy for transferring agricultural water to ensure water supply security for the industrial sector. The study finds that Changhua and Yunlin have the highest per-unit costs of raw water, and the Nantou region has the highest carbon emission coefficient (carbon footprint) per unit of water produced. The cumulative value (2021–2031) of the water resources policy to reallocate agricultural water to achieve water supply security is about TWD 15.904–31.13 billion. The shadow price of industrial water is about TWD 40.18/cubic meter. Therefore, a compensation price for agricultural water transfer of less than TWD 40.18/cubic meter represents a rational policy. Full article

(This article belongs to the Special Issue Smart Technologies and Water Supply Planning II)

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17 pages, 4559 KiB

Open AccessFeature PaperArticle

Terraced Landforms Onshore and Offshore the Cilento Promontory (South-Eastern Tyrrhenian Margin) and Their Significance as Quaternary Records of Sea Level Changes

by Alessandra Savini, Valentina Alice Bracchi, Antonella Cammarosano, Micla Pennetta and Filippo Russo

Water 2021, 13(4), 566; https://doi.org/10.3390/w13040566 - 23 Feb 2021

Cited by 10 | Viewed by 3617

Abstract

Climate change and tectonic uplift are the dominant forcing mechanisms responsible for the formation of long and narrow terraced landforms in a variety of geomorphic settings; and marine terraces are largely used to reconstruct the Quaternary glacial and interglacial climates. Along the Mediterranean [...] Read more.

Climate change and tectonic uplift are the dominant forcing mechanisms responsible for the formation of long and narrow terraced landforms in a variety of geomorphic settings; and marine terraces are largely used to reconstruct the Quaternary glacial and interglacial climates. Along the Mediterranean coast, a considerable number of popular scientific articles have acknowledged a range of marine terraces in the form of low-relief surfaces resulting from the combined effects of tectonic uplift and eustatic sea-level fluctuations, as relevant geomorphological indicators of past sea-level high-stands. With the exception of a few recent studies on the significance of submarine depositional terraces (SDT), submerged terraced landforms have been less investigated. By integrating different marine and terrestrial datasets, our work brings together and re-examines numerous terraced landforms that typify the Cilento Promontory and its offshore region. In this area, studies since the 1960s have allowed the recognition of well-defined Middle to Upper Pleistocene marine terraces on land, while only a few studies have investigated the occurrences of late Pleistocene SDT. Furthermore, to date, no studies have consistently integrated findings. For our work, we correlated major evidence of emerged and submarine terraced landforms in order to support an improved understanding of the tectono-geomorphological evolution of the Cilento Promontory and to further clarify the geomorphological significance of submerged terraces. Full article

(This article belongs to the Special Issue Landscapes and Landforms of Terrestrial and Marine Areas)

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13 pages, 14233 KiB

Open AccessFeature PaperArticle

Research about Organic Matter Removal and Biofilms Development of Pilot-Scale UV/H₂O₂-BAC Process

by Wuchang Song, Congcong Li, Zhenqi Du, Jiangang Yue, Wenjun Sun, Lian Hou, Jianguang Liu and Ruibao Jia

Water 2021, 13(4), 565; https://doi.org/10.3390/w13040565 - 23 Feb 2021

Cited by 6 | Viewed by 3090

Abstract

As a green advanced process for drinking water treatment, the UV/hydrogen peroxide (UV/H₂O₂) process has been gradually applied in China. To study the effect and mechanism of organic matter removal and the development of microbial communities in the UV/H [...] Read more.

As a green advanced process for drinking water treatment, the UV/hydrogen peroxide (UV/H₂O₂) process has been gradually applied in China. To study the effect and mechanism of organic matter removal and the development of microbial communities in the UV/H₂O₂-biological activated carbon (UV/H₂O₂-BAC) process, a pilot-scale UV/H₂O₂-BAC system was built and operated over one year. Low water temperature affects the UV/H₂O₂ process efficiency, the biofilms in the BAC system were mature and stable after 240 days, and the contribution rate of BAC adsorption to dissolved organic carbon (DOC) removal was approximately 14.2% after one year of operation. The liquid chromatography-organic carbon detection (LC-OCD) analysis shows that UV/H₂O₂ process can increase the amounts of Low Molecular Weight (LMW) neutrals, and the specific UV absorbance (SUVA₂₅₄) value is not suitable for predicting Trihalomethanes (THMs) precursor contents in water after UV/H₂O₂ treatment. High-throughput sequencing results prove that microbial species in the middle section are the most abundant compared to those in the influent and effluent sections, hydrogen peroxide has lower inhibition on the development of microbial community than ozone and the low concentration of hydrogen peroxide (<0.25 mg/L) promotes the development of the microbial communities, hydrogen peroxide can reduce Proteobacteria abundance by inhibiting the growth of anaerobes. Acidobacteria may have a certain contribution to the degradation of soil organic matter (SOM), and the effluent section of BAC with low DOC concentration cannot form the dominant species of Rhodobacter. Full article

(This article belongs to the Special Issue AOP Processes for Organics Removal in Water and Wastewater)

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19 pages, 11841 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Trend Analyses of Baseflow and BFI for Undisturbed Watersheds in Michigan—Constraints from Multi-Objective Optimization

by Benjamin Hagedorn and Christina Meadows

Water 2021, 13(4), 564; https://doi.org/10.3390/w13040564 - 23 Feb 2021

Cited by 6 | Viewed by 3915

Abstract

Documenting how ground- and surface water systems respond to climate change is crucial to understanding water resources, particularly in the U.S. Great Lakes region, where drastic temperature and precipitation changes are observed. This study presents baseflow and baseflow index (BFI) trend analyses for [...] Read more.

Documenting how ground- and surface water systems respond to climate change is crucial to understanding water resources, particularly in the U.S. Great Lakes region, where drastic temperature and precipitation changes are observed. This study presents baseflow and baseflow index (BFI) trend analyses for 10 undisturbed watersheds in Michigan using (1) multi-objective optimization (MOO) and (2) modified Mann–Kendall (MK) tests corrected for short-term autocorrelation (STA). Results indicate a variability in mean baseflow (0.09–8.70 m³/s) and BFI (67.9–89.7%) that complicates regional-scale extrapolations of groundwater recharge. Long-term (>60 years) MK trend tests indicate a significant control of total precipitation (P) and snow- to rainfall transitions on baseflow and BFI. In the Lower Peninsula Rifle River watershed, increasing P and a transition from snow- to rainfall has increased baseflow at a lower rate than streamflow; an overall pattern that may contribute to documented flood frequency increases. In the Upper Peninsula Ford River watershed, decreasing P and a transition from rain- to snowfall had no significant effects on baseflow and BFI. Our results highlight the value of an objectively constrained BFI parameter for shorter-term (<50 years) hydrologic trend analysis because of a lower STA susceptibility. Full article

(This article belongs to the Section Hydrology)

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20 pages, 18229 KiB

Open AccessFeature PaperArticle

Phosphorous Supply to a Eutrophic Artificial Lake: Sedimentary versus Groundwater Sources

by Wiebe Förster, Jan C. Scholten, Michael Schubert, Kay Knoeller, Nikolaus Classen, Michael Lechelt, Jan-Helge Richard, Udo Rohweder, Isabell Zunker and Susanne C. Wanner

Water 2021, 13(4), 563; https://doi.org/10.3390/w13040563 - 23 Feb 2021

Cited by 7 | Viewed by 2811

Abstract

The eutrophic Lake Eichbaumsee, a ~1 km long and 280 m wide (maximum water depth 16 m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e., aeration plants, removal of dissolved phosphorous by aluminum phosphorous [...] Read more.

The eutrophic Lake Eichbaumsee, a ~1 km long and 280 m wide (maximum water depth 16 m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e., aeration plants, removal of dissolved phosphorous by aluminum phosphorous precipitation, and by Bentophos^® (Phoslock Environmental Technologies, Sydney, Australia), adsorption) during the past ~15 years. Despite these treatments, no long-term improvement of the water quality has been observed and the lake water phosphorous content has continued to increase by e.g., ~670 kg phosphorous between autumn 2014 and autumn 2019. As no creeks or rivers drain into the lake and hydrological groundwater models do not suggest any major groundwater discharge into the lake, sources of phosphorous (and other nutrients) are unknown. We investigated the phosphorous fluxes from sediment pore water and from groundwater in the water body of the lake. Sediment pore water was extracted from sediment cores recovered by divers in August 2018 and February 2019. Diffusive phosphorous fluxes from pore water were calculated based on phosphorus gradients. Stable water isotopes (δ²H, δ¹⁸O) were measured in the lake water, in interstitial waters in the banks surrounding the lake, in the Elbe River, and in three groundwater wells close to the lake. Stable isotope (δ²H, δ¹⁸O) water mass balance models were used to compute water inflow/outflow to/from the lake. Our results revealed pore-water borne phosphorous fluxes between 0.2 mg/m²/d and 1.9 mg/m²/d. Assuming that the measured phosphorous fluxes are temporarily and spatially representative for the whole lake, about 11 kg/a to 110 kg/a of phosphorous is released from sediments. This amount is lower than the observed lake water phosphorous increase of ~344 kg between April 2018 and November 2018. Water stable isotope (δ²H, δ¹⁸O) compositions indicate a water exchange between an aquifer and the lake water. Based on stable isotope mass balances we estimated an inflow of phosphorous from the aquifer to the lake of between ~150 kg/a and ~390 kg/a. This result suggests that groundwater-borne phosphorous is a significant phosphorous source for the Eichbaumsee and highlights the importance of groundwater for lake water phosphorous balances. Full article

(This article belongs to the Special Issue Using Natural Radionuclides as Aquatic Tracers in the Terrestrial and the Coastal/Marine Environment)

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15 pages, 4159 KiB

Open AccessArticle

Late Holocene Peatland Evolution in Terelj and Tuul Rivers Drainage Basins in the Khentii Mountain Range of Northeastern Mongolia

by Alexander Orkhonselenge, Munkhjargal Uuganzaya, Tuyagerel Davaagatan and Ganbaatar Enkhbayar

Water 2021, 13(4), 562; https://doi.org/10.3390/w13040562 - 23 Feb 2021

Cited by 1 | Viewed by 3446

Abstract

This study reviews the late Holocene peatlands in Terelj River and Tuul River drainage basins in the Khentii (Khentii has been misspelled as Khentey (or Hentey) and Khentei (or Hentei) in many publications. The Khentii is the right English translation from Mongolian [...] Read more.

This study reviews the late Holocene peatlands in Terelj River and Tuul River drainage basins in the Khentii (Khentii has been misspelled as Khentey (or Hentey) and Khentei (or Hentei) in many publications. The Khentii is the right English translation from Mongolian Xэнmuй) Mountain Range of northeastern Mongolia. The peatlands were examined through their physical and chemical properties, diatom assemblages, and radiocarbon dating. In the Terelj River basin, the high contents of organic matter and biogenic silica and the dominant benthic diatom assemblages such as Eunotia praerupta, Pinnularia borealis, and Navicula mutica in the peat deposits indicate the warm and humid climates in the late Holocene. The high accretion rate of 0.97 mm/yr in the peatland records the intensive erosion in the surrounding landscape and deposition in the peatland due to increased precipitation and runoff in the humid climate since 0.5 cal. ka BP. In the Tuul River basin, the high content of mineral fractions and diatom assemblages dominated by benthic species Cymbella proxima, Encyonema silesiacum, and planktonic species Cyclotella ocellata in the peat deposits show a transition from humid to arid climates at 0.9 cal. ka BP. The accretion rate of 0.56 mm/yr in the peatland on the paleo-floodplain indicates strengthened erosion in the peatland over the past ~1000 years. This study in the southern Khentii Mountain Range provides new descriptive insights to extend the underestimated Mongolia’s peat studies, and it would be a useful proof-of-concept study for future detailed paleo-environmental analyses. Full article

(This article belongs to the Special Issue Ecology and Paleoecological Research on Lake and Peat Bog Ecosystems)

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32 pages, 17722 KiB

Open AccessFeature PaperArticle

Groundwater Monitoring Systems to Understand Sea Water Intrusion Dynamics in the Mediterranean: The Neretva Valley and the Southern Venice Coastal Aquifers Case Studies

by Ivan Lovrinović, Alessandro Bergamasco, Veljko Srzić, Chiara Cavallina, Danko Holjević, Sandra Donnici, Joško Erceg, Luca Zaggia and Luigi Tosi

Water 2021, 13(4), 561; https://doi.org/10.3390/w13040561 - 23 Feb 2021

Cited by 19 | Viewed by 4639

Abstract

Sea water intrusion (SWI) has been widely recognized as a global problem, significantly influencing coastal aquifers, mostly through reduced water quality and agricultural production indicators. In this paper, we present the outcomes of the implementation of two independent real-time monitoring systems, planned and [...] Read more.

Sea water intrusion (SWI) has been widely recognized as a global problem, significantly influencing coastal aquifers, mostly through reduced water quality and agricultural production indicators. In this paper, we present the outcomes of the implementation of two independent real-time monitoring systems, planned and installed to get insights on groundwater dynamics within the adjacent coastal aquifer systems, one located in the Neretva Valley, southeastern Croatia, the other located south of the Venice lagoon, northeastern Italy. Both systems are presented with technical details and the capacity to observe, store, and transmit (Neretva site) observed values in real-time. Analysis of time series reveals the significant influence of the sea level oscillations onto the observed groundwater electrical conductivity (EC) and piezometric head values, while precipitation rate is detected as a driving mechanism for groundwater parameters in shallow geological units. The installed monitoring systems are shown to be of great importance to provide qualitative and quantitative information on the processes influencing groundwater and surface water dynamics within two coastal systems. Full article

(This article belongs to the Special Issue Advances in Water Quality Monitoring and Assessment in Marine and Coastal Regions)

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5 pages, 196 KiB

Open AccessEditorial

Urban and Industrial Wastewater Disinfection and Decontamination by Advanced Oxidation Processes (AOPs): Current Issues and Future Trends

by Ana Rita Lado Ribeiro, Jorge Jesus Rodríguez-Chueca and Stefanos Giannakis

Water 2021, 13(4), 560; https://doi.org/10.3390/w13040560 - 23 Feb 2021

Cited by 5 | Viewed by 2491

Abstract

Without any doubt, the 21st century has kick-started a great evolution in all aspects of our everyday life [...] Full article

(This article belongs to the Special Issue Urban and Industrial Wastewater Disinfection and Decontamination by Advanced Oxidation Processes (AOPs): Current Issues and Future Trends)

18 pages, 8071 KiB

Open AccessArticle

Estimation of Soil Salt and Ion Contents Based on Hyperspectral Remote Sensing Data: A Case Study of Baidunzi Basin, China

by Libing Wang, Bo Zhang, Qian Shen, Yue Yao, Shengyin Zhang, Huaidong Wei, Rongpeng Yao and Yaowen Zhang

Water 2021, 13(4), 559; https://doi.org/10.3390/w13040559 - 22 Feb 2021

Cited by 18 | Viewed by 3224

Abstract

Soil salinity due to irrigation diversion affects regional agriculture, and the development of soil composition estimation models for the dynamic monitoring of regional salinity is important for salinity control. In this study, we evaluated the performance of hyperspectral data measured using an analytical [...] Read more.

Soil salinity due to irrigation diversion affects regional agriculture, and the development of soil composition estimation models for the dynamic monitoring of regional salinity is important for salinity control. In this study, we evaluated the performance of hyperspectral data measured using an analytical spectral device (ASD) field spec standard-res hand-held spectrometer and satellite sensor visible shortwave infrared advanced hyperspectral imager (AHSI) in estimating the soil salt content (SSC). First derivative analysis (FDA) and principal component analysis (PCA) were applied to the data using the raw spectra (RS) to select the best model input data. We tested the ability of these three groups of data as input data for partial least squares regression (PLSR), principal component regression (PCR), and multiple linear regression (MLR). Finally, an estimation model of the SSC, Na⁺, Cl⁻, and SO₄²⁻ contents was established using the best input data and modeling method, and a spatial distribution map of the soil composition content was drawn. The results show that the soil spectra obtained from the satellite hyperspectral data (AHSI) and laboratory spectral data (ASD) were consistent when the SSC was low, and as the SSC increased, the spectral curves of the ASD data showed little change in the curve characteristics, while the AHSI data showed more pronounced features, and this change was manifested in the AHSI images as darker pixels with a lower SSC and brighter pixels with a higher SSC. The AHSI data demonstrated a strong response to the change in SSC; therefore, the AHSI data had a greater advantage compared with the ASD data in estimating the soil salt content. In the modeling process, RS performed the best in estimating the SSC and Na⁺ content, with the R² reaching 0.79 and 0.58, respectively, and obtaining low root mean squared error (RMSE) values. FDA and PCA performed the best in estimating Cl⁻ and SO₄²⁻, while MLR outperformed PLSR and PCR in estimating the content of the soil components in the region. In addition, the hyperspectral camera data used in this study were very cost-effective and can potentially be used for the evaluation of soil salinization with a wide range and high accuracy, thus reducing the errors associated with the collection of individual samples using hand-held hyperspectral instruments. Full article

(This article belongs to the Special Issue Salinization of Water Resources: Ongoing and Future Trends)

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23 pages, 135602 KiB

Open AccessArticle

Evaluation of Groundwater Potential and Safe Yield of Heterogeneous Unconsolidated Aquifers in Chiang Mai Basin, Northern Thailand

by Sutthipong Taweelarp, Morrakot Khebchareon and Schradh Saenton

Water 2021, 13(4), 558; https://doi.org/10.3390/w13040558 - 22 Feb 2021

Cited by 4 | Viewed by 5625

Abstract

Chiang Mai basin has an escalating population growth resulting in high demand for water consumption. Lack of surface water supply in most parts of the basin gives rise to the increasing use of groundwater which leads to a continuous decline in groundwater level [...] Read more.

Chiang Mai basin has an escalating population growth resulting in high demand for water consumption. Lack of surface water supply in most parts of the basin gives rise to the increasing use of groundwater which leads to a continuous decline in groundwater level in the past decades. This study is the first long-term groundwater monitoring and modeling study that aims at developing a transient, regional groundwater flow model of heterogeneous unconsolidated aquifers based on the MODFLOW program. Long-term groundwater monitoring data from 49 piezometers were used in model calibration and validation. The pilot points technique was used to account for the spatial variability of hydrogeologic parameters of heterogeneous aquifers. The simulation results and statistics showed that most sensitive and significant model parameters were spatially variable hydraulic conductivities and recharge rates. The Chiang Mai basin’s unconsolidated aquifers do not have high potential. The water table and/or potentiometric surface in the southeast and southwest areas of Chiang Mai city were continuously decreasing with no sign of recovery indicating critical groundwater condition and careful management must be considered. Safe yield calculation, based on a 2-m average drawdown threshold, suggested that unconsolidated aquifers of the Chiang Mai basin can sustain overall abstraction rates up to 51.2 Mm³/y or approximately 214% of the current extraction rates. Full article

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23 pages, 3882 KiB

Open AccessArticle

Reliable Evapotranspiration Predictions with a Probabilistic Machine Learning Framework

by Hakan Başağaoğlu, Debaditya Chakraborty and James Winterle

Water 2021, 13(4), 557; https://doi.org/10.3390/w13040557 - 22 Feb 2021

Cited by 17 | Viewed by 7301

Abstract

Evapotranspiration is often expressed in terms of reference crop evapotranspiration (

E T_{o}

), actual evapotranspiration (

E T_{a}

), or surface water evaporation (

E_{s w}

), and their reliable predictions are critical for groundwater, irrigation, and aquatic ecosystem [...] Read more.

Evapotranspiration is often expressed in terms of reference crop evapotranspiration (

E T_{o}

), actual evapotranspiration (

E T_{a}

), or surface water evaporation (

E_{s w}

), and their reliable predictions are critical for groundwater, irrigation, and aquatic ecosystem management in semi-arid regions. We demonstrated that a newly developed probabilistic machine learning (ML) model, using a hybridized “boosting” framework, can simultaneously predict the daily

E T_{o}

,

E_{s w}

, &

E T_{a}

from local hydroclimate data with high accuracy. The probabilistic approach exhibited great potential to overcome data uncertainties, in which

100 %

of the

E T_{o}

,

89.9 %

of the

E_{s w}

, and

93 %

of the

E T_{a}

test data at three watersheds were within the models’

95 %

prediction intervals. The modeling results revealed that the hybrid boosting framework can be used as a reliable computational tool to predict

E T_{o}

while bypassing net solar radiation calculations, estimate

E_{s w}

while overcoming uncertainties associated with pan evaporation & pan coefficients, and predict

E T_{a}

while offsetting high capital & operational costs of EC towers. In addition, using the Shapley analysis built on a coalition game theory, we identified the order of importance and interactions between the hydroclimatic variables to enhance the models’ transparency and trustworthiness. Full article

(This article belongs to the Section Hydrology)

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20 pages, 2765 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Forecast-Skill-Based Dynamic Pre-Storm Level Control for Reservoir Flood-Control Operation

by Wenhua Wan, Xiaohui Lei, Jianshi Zhao, Mingna Wang, Soon-Thiam Khu and Chao Wang

Water 2021, 13(4), 556; https://doi.org/10.3390/w13040556 - 22 Feb 2021

Cited by 5 | Viewed by 3026

Abstract

The design and operation of reservoirs based on conventional flood-limited water levels (FLWL) implicitly adopts the assumption of hydrological stationarity. As such, historical-record-based FLWL may not be the best choice for flood-control operations due to the inherent non-stationarity of rainfall inputs. With maturing [...] Read more.

The design and operation of reservoirs based on conventional flood-limited water levels (FLWL) implicitly adopts the assumption of hydrological stationarity. As such, historical-record-based FLWL may not be the best choice for flood-control operations due to the inherent non-stationarity of rainfall inputs. With maturing flood forecasts, this study focuses on establishing linkage between FLWL and skill of forecast, thus developing a “dynamic pre-storm level” approach for reservoir flood-control operations. The approach utilizes forecast flood magnitude, forecast skill and exceedance probability of forecast error to determine the pre-storm reservoir storage for each flood event. The exceedance probability of forecast error for each incoming flood is used as the reservoir flood control standard instead of the probability of a static return interval flood. This approach is demonstrated in a hypothetical situation in the Three Gorges Reservoir in China. The results show that under zero-forecast-skill conditions, the proposed dynamic pre-storm level matches well with the Three Gorges Reservoir-designed FLWL; and, as the forecast accuracy/skill increase, the proposed approach can make better use of the increased forecast accuracy, thereby maximizing floodwater utilization and reservoir storage. In this way, coupling the new approach with FLWL allows for more efficient and economic day-to-day reservoir operations without adding any flood risk. This study validates the usefulness of dynamic water level control during flood season, considering the improvement of flood forecast accuracy. Full article

(This article belongs to the Special Issue Sustainable Development of Lakes and Reservoirs)

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16 pages, 4625 KiB

Open AccessArticle

Removal of Tetracycline Oxidation Products in the Nanofiltration Process

by Renata Żyłła, Stanisław Ledakowicz, Tomasz Boruta, Magdalena Olak-Kucharczyk, Magdalena Foszpańczyk, Zdzisława Mrozińska and Jacek Balcerzak

Water 2021, 13(4), 555; https://doi.org/10.3390/w13040555 - 22 Feb 2021

Cited by 15 | Viewed by 3788

Abstract

The possibility of removing tetracycline (TRC) from water in an integrated advanced oxidation and membrane filtration process was investigated. Ozonation and UV/H₂O₂ photooxidation were applied for the destruction of TRC. Six oxidation products (OPs) retaining the structural core of TRC [...] Read more.

The possibility of removing tetracycline (TRC) from water in an integrated advanced oxidation and membrane filtration process was investigated. Ozonation and UV/H₂O₂ photooxidation were applied for the destruction of TRC. Six oxidation products (OPs) retaining the structural core of TRC have been identified. One new TRC oxidation product, not reported so far in the literature, was identified—ethyl 4-ethoxybenzoate. All identified OPs were effectively retained on the membrane in the nanofiltration process. However, chemical oxygen demand (COD) measurements of the filtrates showed that in the case of UV/H₂O₂ oxidation, the OPs passed through the membrane into the filtrate. Various water matrices were used in the research, including the river water untreated and after ozone treatment. It has been shown that organic matter present in surface water can improve pharmaceutical retention, although it contributes to significant membrane fouling. Pre-ozonation of the river water reduced the membrane fouling. The XPS analysis was used to show ozone and H₂O₂ influence on the top polymer layer of the membrane. It was shown that the oxidants can damage the amide bond of the polyamide. Full article

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

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17 pages, 4749 KiB

Open AccessArticle

Stream Flow Generation for Simulating Yearly Bed Change at an Ungauged Stream in Monsoon Region

by Woong Hee Lee, Heung Sik Choi, Dongwoo Lee and Byungwoong Choi

Water 2021, 13(4), 554; https://doi.org/10.3390/w13040554 - 22 Feb 2021

Cited by 1 | Viewed by 2774

Abstract

The stream flow generation method is necessary for predicting yearly bed change at an ungauged stream in Monsoon region where there is no hydrologic and hydraulic information. This study developed the stream flow generation method of daily mean flow for each month over [...] Read more.

The stream flow generation method is necessary for predicting yearly bed change at an ungauged stream in Monsoon region where there is no hydrologic and hydraulic information. This study developed the stream flow generation method of daily mean flow for each month over a year for bed change simulation at an ungauged stream. The hydraulic geometries of cross-sections and the corresponding bankfull indicators of the Byeongseong river of 4 km reach were analyzed to estimate the bankfull discharge. The estimated bankfull discharge of the target reach was 77.50 m³/s, and the total annual discharge estimated 3720 m³/s through the correlation equation with the bankfull discharge. The measured total annual discharge of the Byeongseong river was 3887.30 m³/s, which is greater by 167.30 m³/s of 4.3% relative error. The volume and bed changes over a year by the Center for Computational Hydroscience and Engineering Two-Dimension (CCHE2D) model simulated using the measured discharge during 2013 and 2014 coincided with the surveyed in the same period. Estimated total annual discharge was used for the scenarios of stream flow generation. The generated stream flow using the flow apportioned to each month on the basis of the flow percentage in an adjacent stream simulated the river bed most appropriately. The generated stream flow using the flow based on the monthly rainfall percentage of the rainfall station in the target stream basin also simulated river bed well, which is confirmed as an alternative. Quantitatively, the root mean square error (RMSE), mean bias error (MBE), and mean absolute percentage error (MAPE) in-depth change of thalweg between the measured and the simulated were found to be 0.25 m, 0.04 m, and 0.44%, respectively. The result of the simulated cross-sectional river bed change for target reach coincided well with the surveyed. The proposed method is highly applicable to generate the stream flow for analyzing the yearly bed change at an ungauged stream in Monsoon region. Full article

(This article belongs to the Special Issue Shallow Water Modeling)

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15 pages, 4108 KiB

Open AccessFeature PaperArticle

Inherent Safety Analysis and Sustainability Evaluation of Chitosan Production from Shrimp Exoskeleton in Colombia

by Antonio Zuorro, Kariana Andrea Moreno-Sader and Ángel Darío González-Delgado

Water 2021, 13(4), 553; https://doi.org/10.3390/w13040553 - 21 Feb 2021

Cited by 9 | Viewed by 3864

Abstract

Waste valorization strategies are key to achieve more sustainable production within the shrimp industry. The crustacean exoskeletons can be potentially used to obtain value-added products such as chitosan. A comprehensive analysis including both safety and sustainability aspects of chitosan production from shrimp shells [...] Read more.

Waste valorization strategies are key to achieve more sustainable production within the shrimp industry. The crustacean exoskeletons can be potentially used to obtain value-added products such as chitosan. A comprehensive analysis including both safety and sustainability aspects of chitosan production from shrimp shells is presented in this study. The inherent safety analysis and sustainability evaluation was performed using the Inherent Safety Index (ISI) methodology and the Sustainable Weighted Return on Investment Metric (SWROIM), respectively. The process was designed for a processing capacity of 57,000 t/year. The return on investment (%ROI), potential environmental impact (PEI output), exergy efficiency, and the total inherent safety index (I_TI) were used as indicators to evaluate process sustainability. The total inherent safety index was estimated at 25 indicating that the process is inherently unsafe. The main process risks were given by handling of flammable substances, reactivity, and inventory subindices. The overall sustainability evaluation showed a SWROIM of 36.33% indicating that the case study showed higher weighted performance compared to the return on investment metric of 18.08%. Full article

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13 pages, 2092 KiB

Open AccessFeature PaperArticle

Nitrogen Loss in Vegetable Field under the Simulated Rainfall Experiments in Hebei, China

by Baoguo Ma, Ronghao Guan, Liang Liu, Zhixi Huang, Shuanwang Qi, Zengfu Xi, Ying Zhao, Shihao Song and Hong Yang

Water 2021, 13(4), 552; https://doi.org/10.3390/w13040552 - 21 Feb 2021

Cited by 13 | Viewed by 3320

Abstract

Agricultural non-point source pollution is one of the main factors contaminating the environment. However, the impact of rainfall on loss of non-point nitrogen is far from well understood. Based on the artificial rainfall simulation experiments to monitor the loss of dissolved nitrogen (DN) [...] Read more.

Agricultural non-point source pollution is one of the main factors contaminating the environment. However, the impact of rainfall on loss of non-point nitrogen is far from well understood. Based on the artificial rainfall simulation experiments to monitor the loss of dissolved nitrogen (DN) in surface runoff and interflow of vegetable field, this study analyzed the effects of rainfall intensity and fertilization scheme on nitrogen (N) loss. The results indicated that fertilizer usage is the main factor affecting the nitrogen loss in surface runoff, while runoff and rainfall intensity play important roles in interflow nitrogen loss. The proportion of DN lost through the surface runoff was more than 91%, and it decreased with increasing rainfall intensity. There was a clear linear trend (r² > 0.96) between the amount of DN loss and runoff. Over 95% of DN was lost as nitrate nitrogen (NN), which was the major component of nitrogen loss. Compared with the conventional fertilization treatment (CF), the amount of nitrogen fertilizer applied in the optimized fertilization treatment (OF) decreased by 38.9%, and the loss of DN decreased by 28.4%, but root length, plant height and yield of pak choi increased by 6.3%, 2.7% and 5.6%, respectively. Our findings suggest that properly reducing the amount of nitrogen fertilizer can improve the utilization rate of nitrogen fertilizer but will not reduce the yield of pak choi. Controlling fertilizer usage and reducing runoff generation are important methods to reduce the DN loss in vegetable fields. Full article

(This article belongs to the Special Issue The Impact of Climate Change and Human Activities on Aquatic Environments)

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12 pages, 2486 KiB

Open AccessArticle

Evaluation of Adsorption Mechanism of Chromium(VI) Ion Using Ni-Al Type and Ni-Al-Zr Type Hydroxides

by Fumihiko Ogata, Noriaki Nagai, Ayako Tabuchi, Megumu Toda, Masashi Otani, Chalermpong Saenjum, Takehiro Nakamura and Naohito Kawasaki

Water 2021, 13(4), 551; https://doi.org/10.3390/w13040551 - 21 Feb 2021

Cited by 7 | Viewed by 3132

Abstract

To evaluate the feasibility of nickel–aluminum (the Ni²⁺:Al³⁺ molar ratios of 1.0:1.0 and 1.0:2.0 are denoted as NA11 and NA12, respectively) and nickel–aluminum–zirconium type (the Ni²⁺:Al³⁺:Zr⁴⁺ molar ratios of 0.9:1.0:0.09 and 0.9:2.0:0.09 are denoted as [...] Read more.

To evaluate the feasibility of nickel–aluminum (the Ni²⁺:Al³⁺ molar ratios of 1.0:1.0 and 1.0:2.0 are denoted as NA11 and NA12, respectively) and nickel–aluminum–zirconium type (the Ni²⁺:Al³⁺:Zr⁴⁺ molar ratios of 0.9:1.0:0.09 and 0.9:2.0:0.09 are denoted as NAZ1 and NAZ2, respectively) hydroxides for Cr(VI) removal from aqueous media, the adsorption capability and adsorption mechanism of Cr(VI) using the above-mentioned adsorbents were investigated in this study. The quantity of Cr(VI) adsorbed onto NA11, NA12, NAZ1, and NAZ2 was 25.5, 25.6, 24.1, and 24.6 mg g⁻¹, respectively. However, the quantity of aluminum (base metal) released from NA11 (approximately 0.14 mg g⁻¹) was higher than that from NAZ1 (approximately 1.0 µg g⁻¹), indicating that NAZ1 was more suitable for Cr(VI) removal than NA11. In addition, the effects of pH, contact time, and temperature on the adsorption of Cr(VI) were evaluated. Moreover, to elucidate the adsorption mechanism of Cr(VI) using NA11 and NAZ1, the elemental distribution, X-ray photoelectron spectrometry spectra, and ion exchange capability were also determined. Cr(VI) adsorbed onto the NAZ1 surface was easily desorbed using a sodium hydroxide solution under our experimental conditions. The information regarding this study can be useful for removing Cr(VI) from aqueous media. Full article

(This article belongs to the Special Issue Sustainable Processes for the Removing of Heavy Metals from Aqueous Solutions)

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17 pages, 1511 KiB

Open AccessArticle

Stepwise Identification of Influencing Factors and Prediction of Typhoon Precipitation in Anhui Province Based on the Back Propagation Neural Network Model

by Yuliang Zhou, Yang Li, Juliang Jin, Ping Zhou, Dong Zhang, Shaowei Ning and Yi Cui

Water 2021, 13(4), 550; https://doi.org/10.3390/w13040550 - 21 Feb 2021

Cited by 5 | Viewed by 2821

Abstract

Typhoon is one of the most frequent meteorological phenomena that covers most of central-eastern China during the summer. Typhoon-induced precipitation is one of the most important water resources, but it often leads to severe flood disasters. Accurate typhoon precipitation prediction is crucial for [...] Read more.

Typhoon is one of the most frequent meteorological phenomena that covers most of central-eastern China during the summer. Typhoon-induced precipitation is one of the most important water resources, but it often leads to severe flood disasters. Accurate typhoon precipitation prediction is crucial for mitigating typhoon disasters and managing water resources. Anhui Province, located in East China, is a typhoon affected region. Typhoon-related disasters are its major natural disasters. This study aims at developing a new back propagation (BP) neural network model to predict both the typhoon precipitation event and the typhoon precipitation amount. The predictors in the model are identified through correlation analysis of the above two target variables and a large set of candidate variables. We further improve the predictor selection through an iterative approach, which proposes new predictors for the BP model in each iteration by analyzing the differences of candidate predictors between the years with large prediction errors and the normal years. The results show that the accuracy of the BP-based summer typhoon event prediction model in the simulation period from 1957 to 2006 is 100%, and its accuracy in the validation period from 2007 to 2016 is 90%. In addition, the absolute value of the mean relative error predicted by the typhoon precipitation amount model for the simulation period is 20.9%. A significant error can be found in 2000 as the mechanism of typhoon precipitation in this year is different from that of other normal years. The error in 2000 is probably caused by the impact of vertical shear anomalies over the western Pacific which hinders the development of typhoon embryos. Additionally, the absolute value of the mean relative error predicted by the typhoon precipitation amount model in the validation period is 14.2%. A significant error also can be found in 2009, probably due to the influence of the asymmetry in the typhoon cloud system. Full article

(This article belongs to the Special Issue Hydrological Modeling in Water Cycle Processes)

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17 pages, 3406 KiB

Open AccessArticle

Case Study for the Predictive Environmental Risk Assessment of Hexamethylenetetramine Release to the Yodo River during a Massive Tsunami Attack

by Shogo Hamamoto, Lisa Ito, Nozomu Yoneyama and Akihiro Tokai

Water 2021, 13(4), 549; https://doi.org/10.3390/w13040549 - 21 Feb 2021

Cited by 3 | Viewed by 3073

Abstract

Untreated hexamethylenetetramine (HMT) was discharged into the Tone River in the central area of Japan, and the risk management plan in the watershed area has been strengthened because HMT is the precursor of formaldehyde (FA) regulated by Japanese water supply law. The release [...] Read more.

Untreated hexamethylenetetramine (HMT) was discharged into the Tone River in the central area of Japan, and the risk management plan in the watershed area has been strengthened because HMT is the precursor of formaldehyde (FA) regulated by Japanese water supply law. The release of HMT could occur not only in steady but also in unsteady environmental conditions. In this context, no quantitative environmental risk assessments have dealt with the combined events of FA precursor outflow and natural disasters, such as a massive tsunami attack. In this study, we estimated the time course changes of HMT concentrations at the near water treatment plant (WTP) intakes due to tsunami run-up in the river after HMT discharge from facilities along the river during a massive tsunami attack, then potential ecological and health impacts were estimated. This method has a strong analytical ability to reveal the relationship between wave source and inland water run-up in consideration of 3D density flow. For ecological risk, the half maximal effective concentration (EC₅₀) was employed. We found that HMT concentration would not reach a level of concern even after the accident. For potential health risk in terms of the possible maximum inlet concentration of HMT at the WTP, the FA formation amount was 5.3 × 10⁻² mg/L, which was below the water quality standard. Full article

(This article belongs to the Section Urban Water Management)

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