Water

19 pages, 3823 KiB

Open AccessFeature PaperArticle

Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil

by Munique A. B. Moraes, Raphaella A. M. Rodrigues, Louise Schlüter, Raju Podduturi, Niels O. G. Jørgensen and Maria C. Calijuri

Water 2021, 13(12), 1716; https://doi.org/10.3390/w13121716 - 21 Jun 2021

Cited by 11 | Viewed by 3711

Abstract

Blooms of cyanobacteria are frequent in Brazilian water reservoirs used for drinking water. The warning for the presence of potential toxin-producing cyanobacteria is typically based on time-consuming microscopy, rather than specific molecular detection of toxic genes in cyanobacteria. In this study, we developed [...] Read more.

Blooms of cyanobacteria are frequent in Brazilian water reservoirs used for drinking water. The warning for the presence of potential toxin-producing cyanobacteria is typically based on time-consuming microscopy, rather than specific molecular detection of toxic genes in cyanobacteria. In this study, we developed a quantitative PCR assay for the detection of cyanobacteria producing the neurotoxin saxitoxin (STX). The assay targets the sxtA gene in the sxt gene cluster. Potential and dominant STX-producers in the Itupararanga reservoir were the genera Raphidiopsis, Aphanizomenon and Geitlerinema. Numbers of the sxtA gene varied from 6.76 × 10³ to 7.33 × 10⁵ cells mL⁻¹ and correlated positively with SXT concentrations in the water. Concentrations of STX and the sxtA gene also correlated positively with TN:TP ratio and pH, but correlated negatively with inorganic nutrients and turbidity, confirming that regulation of the SXT production was impacted by environmental variables. In contrast, the occurrence of another cyanotoxin, microcystin, did not correlate with any environmental variables. The developed qPCR assay was found to be a rapid and robust approach for the specific quantification of potential STX-producing cyanobacteria and should be considered in future investigations on toxic cyanobacteria to provide an early warning of potential toxin episodes. Full article

(This article belongs to the Special Issue Water Quality Changes of Lakes and Rivers)

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14 pages, 4228 KiB

Open AccessArticle

Potential Climate Change Impacts on Water Resources in Egypt

by Soha M. Mostafa, Osama Wahed, Walaa Y. El-Nashar, Samia M. El-Marsafawy, Martina Zeleňáková and Hany F. Abd-Elhamid

Water 2021, 13(12), 1715; https://doi.org/10.3390/w13121715 - 21 Jun 2021

Cited by 23 | Viewed by 8351

Abstract

This paper presents a comprehensive study to assess the impact of climate change on Egypt’s water resources, focusing on irrigation water for agricultural crops, considering that the agriculture sector is the largest consumer of water in Egypt. The study aims to estimate future [...] Read more.

This paper presents a comprehensive study to assess the impact of climate change on Egypt’s water resources, focusing on irrigation water for agricultural crops, considering that the agriculture sector is the largest consumer of water in Egypt. The study aims to estimate future climate conditions using general circulation models (GCMs), to assess the impact of climate change and temperature increase on water demands for irrigation using the CROPWAT 8 model, and to determine the suitable irrigation type to adapt with future climate change. A case study was selected in the Middle part of Egypt. The study area includes Giza, Bani-Sweif, Al-Fayoum, and Minya governorates. The irrigation water requirements for major crops under current weather conditions and future climatic changes were estimated. Under the conditions of the four selected models CCSM-30, GFDLCM20, GFDLCM21, and GISS-EH, as well as the chosen scenario of A1BAIM, climate model (MAGICC/ScenGen) was applied in 2050 and 2100 to estimate the potential rise in the annual mean temperature in Middle Egypt. The results of the MAGICC/SceGen model indicated that the potential rise in temperature in the study area will be 2.12 °C in 2050, and 3.96 °C in 2100. The percentage of increase in irrigation water demands for winter crops under study ranged from 6.1 to 7.3% in 2050, and from 11.7 to 13.2% in 2100. At the same time, the increase in irrigation water demands for summer crops ranged from 4.9 to 5.8% in 2050, and from 9.3 to 10.9% in 2100. For Nili crops, the increase ranged from 5.0 to 5.1% in 2050, and from 9.6 to 9.9% in 2100. The increase in water demands due to climate change will affect the water security in Egypt, as the available water resources are limited, and population growth is another challenge which requires a proper management of water resources. Full article

(This article belongs to the Special Issue Assessment and Management of Flood Risk in Urban Areas)

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14 pages, 5008 KiB

Open AccessArticle

A Study on the Friction Factor and Reynolds Number Relationship for Flow in Smooth and Rough Channels

by Yeon-Moon Choo, Jong-Gu Kim and Sang-Ho Park

Water 2021, 13(12), 1714; https://doi.org/10.3390/w13121714 - 21 Jun 2021

Cited by 2 | Viewed by 6349

Abstract

The shear velocity and friction coefficient for representing the resistance of flow are key factors to determine the flow characteristics of the open-channel flow. Various studies have been conducted in the open-channel flow, but many controversies remain over the form of equation and [...] Read more.

The shear velocity and friction coefficient for representing the resistance of flow are key factors to determine the flow characteristics of the open-channel flow. Various studies have been conducted in the open-channel flow, but many controversies remain over the form of equation and estimation methods. This is because the equations developed based on theory have not fully interpreted the friction characteristics in an open-channel flow. In this paper, a friction coefficient equation is proposed by using the entropy concept. The proposed equation is determined under the rectangular, the trapezoid, the parabolic round-bottomed triangle, and the parabolic-bottomed triangle open-channel flow conditions. To evaluate the proposed equation, the estimated results are compared with measured data in both the smooth and rough flow conditions. The evaluation results showed that R (correlation coefficient) is found to be above 0.96 in most cases, and the discrepancy ratio analysis results are very close to zero. The advantage of the developed equation is that the energy slope terms are not included, because the determination of the exact value is the most difficult in the open-channel flow. The developed equation uses only the mean velocity and entropy M to estimate the friction loss coefficient, which can be used for maximizing the design efficiency. Full article

(This article belongs to the Special Issue Flow Hydrodynamic in Open Channels: Interaction with Natural or Man-Made Structures)

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27 pages, 1570 KiB

Open AccessEditor’s ChoiceReview

Current Progress on Marine Microplastics Pollution Research: A Review on Pollution Occurrence, Detection, and Environmental Effects

by Fei-Fei Liu, Su-Chun Wang, Zhi-Lin Zhu and Guang-Zhou Liu

Water 2021, 13(12), 1713; https://doi.org/10.3390/w13121713 - 21 Jun 2021

Cited by 16 | Viewed by 8938

Abstract

Recently, microplastics pollution has attracted much attention in the environmental field, as researchers have found traces of microplastics in both marine and terrestrial ecological environments. Here, we reviewed and discussed the current progress on microplastics pollution in the marine environment from three main [...] Read more.

Recently, microplastics pollution has attracted much attention in the environmental field, as researchers have found traces of microplastics in both marine and terrestrial ecological environments. Here, we reviewed and discussed the current progress on microplastics pollution in the marine environment from three main aspects including their identification and qualification methods, source and distribution, and fate and toxicity in a marine ecosystem. Microplastics in the marine environment originate from a variety of sources and distribute broadly all around the world, but their quantitative information is still lacking. Up to now, there have been no adequate and standard methods to identify and quantify the various types of microplastics, which need to be developed and unified. The fate of microplastics in the environment is particularly important as they may be transferred or accumulated in the biological chain. Meanwhile, microplastics may have a high adsorption capacity to pollutants, which is the basic research to further study their fate and joint toxicity in the environment. Therefore, all the findings are expected to fill the knowledge gaps in microplastics pollution and promote the development of relative regulations. Full article

(This article belongs to the Special Issue Microplastics Pollution in Marine Environment)

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19 pages, 4330 KiB

Open AccessFeature PaperArticle

The River Influence Controls Water Quality and Spatio-Temporal Microalgal Distribution in Pacific Estuaries (Padre Ramos and Salinas Grandes) of Nicaragua

by Carmen Rojo, Dalia Lumbi, Ariel Aguilar, Karen Palacios, Katherine Osorio and Pilar Ruiz

Water 2021, 13(12), 1712; https://doi.org/10.3390/w13121712 - 21 Jun 2021

Cited by 2 | Viewed by 2626

Abstract

Estuaries are coastal wetlands that deserve special attention because they are vulnerable, biodiversity- and service-rich environments. However, estuaries of tropical areas have been scarcely studied regarding water quality and biodiversity in spite of strong developments of their agricultural and livestock sectors. Two estuaries [...] Read more.

Estuaries are coastal wetlands that deserve special attention because they are vulnerable, biodiversity- and service-rich environments. However, estuaries of tropical areas have been scarcely studied regarding water quality and biodiversity in spite of strong developments of their agricultural and livestock sectors. Two estuaries on the Pacific Nicaragua in which snapper cages had been set up were studied regarding water physicochemical properties, microalgae and cyanobacteria along with their dynamics over a hydrological year. Both environments showed excellent water quality (oligotrophy and absence of harmful organisms) arising from their fluvial features. During the rainy season, there was a decline in chemical compounds and microorganisms. In the dry period nutrients and salinity promoted different assemblages of microscopic primary producers that were never too dense. Nutrient inputs from shrimp farms, agricultural crops and snapper cages did not appear to increase eutrophication and cyanobacterial blooms did not occur. Furthermore, the strong fluvial character of these estuaries seems to prevent the entry of harmful dinoflagellates from marine areas. Full article

(This article belongs to the Special Issue Tropical Wetlands in a Changing World: Current Status and Future Perspectives)

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19 pages, 7778 KiB

Open AccessArticle

Estimation of the Average Retention Time of Precipitation at the Surface of a Catchment Area for Lake Biwa

by Maho Iwaki, Yosuke Yamashiki, Takashi Toda, Chunmeng Jiao and Michio Kumagai

Water 2021, 13(12), 1711; https://doi.org/10.3390/w13121711 - 21 Jun 2021

Cited by 3 | Viewed by 3987

Abstract

In a lake catchment system, we analyzed the lake water-level responses to precipitation. Moreover, we identified the average precipitation retention time—due to subsurface flows—from the delay time calculated using the response function with data of water level and catchment precipitation (both rainfall and [...] Read more.

In a lake catchment system, we analyzed the lake water-level responses to precipitation. Moreover, we identified the average precipitation retention time—due to subsurface flows—from the delay time calculated using the response function with data of water level and catchment precipitation (both rainfall and snowfall) collected over 30 years of continuous observations of Lake Biwa, Japan. We focused on the snow reserves and the water-level response delay due to the snowmelt of Lake Biwa catchment. We concluded that the average precipitation retention time of the catchment subsurface flow (i.e., above the impermeable layer) in Lake Biwa was approximately 45 days. Additionally, the precipitation retention time during snowmelt was shorter than that during the dry season. Overall, the shape of the response function reflects the lake system. This knowledge improves the understanding of lake systems and can be helpful for lake resource managers. Furthermore, finding the delay time from the response function may be useful for determining the contribution of rainfall to increasing the water levels of other lakes. Therefore, our results can contribute to the development of management strategies to address inland aquatic ecosystems and conservation. Full article

(This article belongs to the Special Issue Inland Aquatic Ecosystems and Conservation)

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29 pages, 2626 KiB

Open AccessArticle

Wastewater Treatment Plants in Mediterranean Spain: An Exploration of Relations between Water Treatments, Water Reuse, and Governance

by Paula Rodríguez-Villanueva and David Sauri

Water 2021, 13(12), 1710; https://doi.org/10.3390/w13121710 - 21 Jun 2021

Cited by 13 | Viewed by 8478

Abstract

Wastewater treatment plants (WWTPs) are fundamental to enable the transition towards the principles of a circular economy in water supply. In Mediterranean Spain, an area with recurrent episodes of water stress, treated wastewater may become a critical resource for the future. However, its [...] Read more.

Wastewater treatment plants (WWTPs) are fundamental to enable the transition towards the principles of a circular economy in water supply. In Mediterranean Spain, an area with recurrent episodes of water stress, treated wastewater may become a critical resource for the future. However, its incorporation into the array of potential water options opens up questions regarding the different qualities obtained with each treatment, the extent of existing water reuse practices, or the governance regime of plants. In this paper, the state of WWTPs in Mediterranean Spain is analyzed, with focus on plant sizes, treatment technologies, water use, and governance regimes. The latter shows a strong presence of private WWTPs and a lesser extent of public–private WWTPs, while the number of public plants is small. Regarding treatment technologies, the most sophisticated systems are found in public–private plants that are also the largest in size. Reclaimed water is very significant for agricultural and golf course irrigation in some areas (Valencia, Murcia, Andalusia), but still relatively incipient for other uses. Full article

(This article belongs to the Special Issue Social Learning on Desalinated and Reclaimed Water for Irrigation and Urban Tourism Demand)

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16 pages, 2246 KiB

Open AccessArticle

Improved Streamflow Calibration of a Land Surface Model by the Choice of Objective Functions—A Case Study of the Nakdong River Watershed in the Korean Peninsula

by Jong Seok Lee and Hyun Il Choi

Water 2021, 13(12), 1709; https://doi.org/10.3390/w13121709 - 21 Jun 2021

Cited by 7 | Viewed by 2595

Abstract

Long-term streamflow simulations of the Land Surface Models (LSMs) are necessary for the comprehensive evaluation of hydrological responses to climate change. The high complexity and uncertainty in the LSM modelling require the model calibration to improve the simulation performance and stability. Objective functions [...] Read more.

Long-term streamflow simulations of the Land Surface Models (LSMs) are necessary for the comprehensive evaluation of hydrological responses to climate change. The high complexity and uncertainty in the LSM modelling require the model calibration to improve the simulation performance and stability. Objective functions are commonly used in the calibration process, and the choice of objective functions plays a crucial role in model performance identification. The Kling and Gupta Efficiency (KGE) has been widely used in the hydrological model calibration by the measure of the three components (variability, bias, and correlation) decomposed from the Nash and Sutcliffe Efficiency (NSE). However, there is a clear tendency of systematic errors in the peak flow and/or water balance of streamflow time series optimized by the KGE calibration when the correlation between simulations and observations is relatively low. For a more balanced optimal solution of the KGE, this study has proposed the adjusted KGE (aKGE) by substituting the normalized correlation score in the KGE. The proposed aKGE was assessed by long-term daily streamflow simulation results from the Common Land Model (CoLM) for the calibration (2000–2009) and validation (2010–2019) periods in the Nakdong River Watershed, Korea. The case study demonstrated that the aKGE calibration can improve the simulation performance of high flow and annual average flow with a slightly inferior correlation of flows compared with the KGE and NSE criteria. Full article

(This article belongs to the Special Issue Watershed Hydrology and Water Quality: Emerging Environmental Issues and Novel Modeling Techniques)

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13 pages, 6157 KiB

Open AccessArticle

A Study on Urban Inundation Using SWMM in Busan, Korea, Using Existing Dams and Artificial Underground Waterways

by Yeon-Moon Choo, Sang-Bo Sim and Yeon-Woong Choe

Water 2021, 13(12), 1708; https://doi.org/10.3390/w13121708 - 20 Jun 2021

Cited by 11 | Viewed by 3466

Abstract

The annual average rainfall in Busan area is increasing, causing frequent flooding of Busan’s Suyeong and Oncheon rivers. Due to the increase in urbanized areas and climate change, it is difficult to reduce flood damage. Therefore, new methods are needed to reduce urban [...] Read more.

The annual average rainfall in Busan area is increasing, causing frequent flooding of Busan’s Suyeong and Oncheon rivers. Due to the increase in urbanized areas and climate change, it is difficult to reduce flood damage. Therefore, new methods are needed to reduce urban inundation. This study models the effects of three flood reduction methods involving Oncheon River, Suyeong River, and the Hoedong Dam, which is situated on the Suyeong. Using EPA-SWMM, a virtual model of the dam and the rivers was created, then modified with changes to the dam’s height, the installation of a floodgate on the dam, and the creation of an underground waterway to carry excess flow from the Oncheon to the Hoedong Dam. The results of this study show that increasing the height of the dam by 3 m, 4 m, or 6 m led to a 27%, 37%, and 48% reduction in flooding, respectively, on the Suyeong River. It was also found that installing a floodgate of 10 × 4 m, 15 × 4 m, or 20 × 4 min the dam would result in a flood reduction of 2.7% and 2.9%, respectively. Furthermore, the construction of the underground waterway could lead to an expected 25% flood reduction in the Oncheon River. Measures such as these offer the potential to protect the lives and property of citizens in densely populated urban areas and develop sustainable cities and communities. Therefore, the modifications to the dam and the underground waterway proposed in this study are considered to be useful. Full article

(This article belongs to the Special Issue Design, Planning, and Management of Urban Water Infrastructures in a Changing Climate)

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18 pages, 1819 KiB

Open AccessArticle

Hillslope Contribution to the Clark Instantaneous Unit Hydrograph: Application to the Seolmacheon Basin, Korea

by Chulsang Yoo, Huy Phuong Doan, Changhyun Jun and Wooyoung Na

Water 2021, 13(12), 1707; https://doi.org/10.3390/w13121707 - 20 Jun 2021

Cited by 1 | Viewed by 3028

Abstract

In this study, the time–area curve of an ellipse is analytically derived by considering flow velocities within both channel and hillslope. The Clark IUH is also derived analytically by solving the continuity equation with the input of the derived time–area curve to the [...] Read more.

In this study, the time–area curve of an ellipse is analytically derived by considering flow velocities within both channel and hillslope. The Clark IUH is also derived analytically by solving the continuity equation with the input of the derived time–area curve to the linear reservoir. The derived Clark IUH is then evaluated by application to the Seolmacheon basin, a small mountainous basin in Korea. The findings in this study are summarized as follows. (1) The time–area curve of a basin can more realistically be derived by considering both the channel and hillslope velocities. The role of the hillslope velocity can also be easily confirmed by analyzing the derived time–area curve. (2) The analytically derived Clark IUH shows the relative roles of the hillslope velocity and the storage coefficient. Under the condition that the channel velocity remains unchanged, the hillslope velocity controls the runoff peak flow and the concentration time. On the other hand, the effect of the storage coefficient can be found in the runoff peak flow and peak time, as well as in the falling limb of the runoff hydrograph. These findings are also confirmed in the analysis of rainfall–runoff events of the Seolmacheon basin. (3) The effect of the hillslope velocity varies considerably depending on the rainfall events, which is also found to be mostly dependent upon the maximum rainfall intensity. Full article

(This article belongs to the Special Issue Modelling Hydrologic Response of Non-homogeneous Catchments)

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17 pages, 3429 KiB

Open AccessFeature PaperArticle

Physiological Responses of the Submerged Macrophyte Stuckenia pectinata to High Salinity and Irradiance Stress to Assess Eutrophication Management and Climatic Effects: An Integrative Approach

by Lamprini Malea, Konstantinia Nakou, Apostolos Papadimitriou, Athanasios Exadactylos and Sotiris Orfanidis

Water 2021, 13(12), 1706; https://doi.org/10.3390/w13121706 - 20 Jun 2021

Cited by 3 | Viewed by 3239

Abstract

Stuckenia pectinata, a submerged macrophyte of eutrophic to hyper-eutrophic fresh to brackish waters, faces management and climatic-forced increment of salinity and irradiance in Vistonis Lake (Greece) that may endanger its existence and the ecosystem functioning. A pre-acclimated clone under low irradiance and [...] Read more.

Stuckenia pectinata, a submerged macrophyte of eutrophic to hyper-eutrophic fresh to brackish waters, faces management and climatic-forced increment of salinity and irradiance in Vistonis Lake (Greece) that may endanger its existence and the ecosystem functioning. A pre-acclimated clone under low irradiance and salinity conditions was treated to understand the effects of high salinity and irradiance on a suite of subcellular (chlorophyll a fluorescence kinetics and JIP-test, and chlorophyll content) to organismal (relative growth rate—RGR) physiological parameters. The responses to high irradiance indicated the plant’s great photo-acclimation potential to regulate the number and size of the reaction centers and the photosynthetic electron transport chain by dissipation of the excess energy to heat. A statistically significant interaction (p < 0.01) of salinity and irradiance on Chl a, b content indicated acclimation potential through adjusting the Chl a, b contents. However, no significant (p > 0.05) difference was observed on Chl a/b ratio and the RGR, indicating the species’ potential to become acclimatized by reallocating resources to compensate for growth. Thus, the regulation of photosynthetic pigment content and photosystem II performance consisted of the primary growth strategy to present and future high salinity and irradiance stressful conditions due to eutrophication management and the ongoing climatic changes. Full article

(This article belongs to the Special Issue Ecological Monitoring and Assessment of Freshwater Ecosystems: New Trends and Future Challenges)

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18 pages, 5964 KiB

Open AccessArticle

Assessing the Impact of Lining Polluted Streams on Groundwater Quality: A Case Study of the Eastern Nile Delta Aquifer, Egypt

by Ismail Abd-Elaty, Abdelrahman M. Said, Gamal M. Abdelaal, Martina Zeleňáková, Jan Jandora and Hany F. Abd-Elhamid

Water 2021, 13(12), 1705; https://doi.org/10.3390/w13121705 - 20 Jun 2021

Cited by 8 | Viewed by 3651

Abstract

Groundwater is considered to be an important water supply for domestics, industry, and irrigation in many areas of the world. Renewable groundwater is recharged by rainfall and seepage from canals and open drain networks. Agricultural and industrial drainage, as well as domestic drainage, [...] Read more.

Groundwater is considered to be an important water supply for domestics, industry, and irrigation in many areas of the world. Renewable groundwater is recharged by rainfall and seepage from canals and open drain networks. Agricultural and industrial drainage, as well as domestic drainage, represent the main discharges into open drains. Therefore, these drains are considered to be a source of recharge as well as a source of pollution. In this study, we aim to evaluate the impact of the Bahr El Baqar drain system on groundwater quality in the Eastern Nile Delta, Egypt. MODFLOW was used to create a numerical model to simulate groundwater flow in an aquifer and MT3DS was used to simulate solute transport from the open contaminated Bahr El Baqar drain to the groundwater. Two approaches were developed in the study area. The first approach was applied to investigate the impact of increasing the abstraction rates on the contaminant transport into the aquifer, the second approach was developed to identify the effect of lining the drain using different materials on contaminant extension in the aquifer to protect groundwater quality in the east Nile Delta Aquifer. The results showed that the TDS values increased by 18.23%, 23.29%, and 19.24% with increased abstraction rates of 15%, 34%, and 70%, resulting from population increases in 2010, 2025, and 2040, respectively; however, the TDS in the aquifer decreased from 0.6%, to 6.36%, 88.35%, and 90.47% by using lining materials. Full article

(This article belongs to the Special Issue Assessment and Management of Flood Risk in Urban Areas)

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20 pages, 3742 KiB

Open AccessArticle

Spatial–Temporal Variations of Total Nitrogen and Phosphorus in Poyang, Dongting and Taihu Lakes from Landsat-8 Data

by Wei Shang, Shuanggen Jin, Yang He, Yuanyuan Zhang and Jian Li

Water 2021, 13(12), 1704; https://doi.org/10.3390/w13121704 - 20 Jun 2021

Cited by 31 | Viewed by 4949

Abstract

Poyang Lake, Dongting Lake, and Taihu Lake are the largest freshwater lakes in the middle and lower reaches of the Yangtze River, China. In recent years, the eutrophication level of lakes has increased with the development of the social economy and caused many [...] Read more.

Poyang Lake, Dongting Lake, and Taihu Lake are the largest freshwater lakes in the middle and lower reaches of the Yangtze River, China. In recent years, the eutrophication level of lakes has increased with the development of the social economy and caused many environmental and social problems. The concentrations of total nitrogen (TN) and total phosphorus (TP) are the key indicators of the degree of eutrophication, but the traditional ground monitoring methods are not capable of capturing such parameters in whole lakes with high spatial-temporal resolution. In this paper, empirical models are established and evaluated between the TN and TP and remote sensing spectral factors in the three lakes using Landsat 8 Operational Land Imager (OLI) satellite data and in-situ data. The results show that the inversion accuracy is higher than 75%. The TN and TP concentrations in the three lakes are inversed based on the Google Earth Engine (GEE) platform from 2014 to 2020 and their spatial-temporal variations are analyzed. The results show that the concentrations of TN and TP in Poyang Lake were decreased by 5.99% and 7.13% over 7 years, respectively, and the TN in Dongting Lake was decreased by 5.25% while the TP remained stable. The temporal changes in TN and TP concentrations displayed seasonal variations. A low concentration was observed in summer and high concentrations were in spring and winter. The average concentrations of TN and TP in Taihu Lake were higher than that of the other two lakes. The TP concentration was increased by 17.3% over 7 years, while the TN concentration remained almost stable. The variation in TN in Taihu Lake was the same as the growth cycle of algae, with higher value in spring and winter and lower value in summer, while the concentration of TP was lower in spring and winter and higher in summer. The spatial distribution of TN and TP concentrations in the three major lakes was significantly affected by human activities, and the concentrations of TN and TP were higher in areas near cities and agricultural activities. Full article

(This article belongs to the Special Issue River Water Management and Water Quality)

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22 pages, 5109 KiB

Open AccessArticle

New Insights into the Seasonal Variation of DOM Quality of a Humic-Rich Drinking-Water Reservoir—Coupling 2D-Fluorescence and FTICR MS Measurements

by Christin Wilske, Peter Herzsprung, Oliver J. Lechtenfeld, Norbert Kamjunke, Jürgen W. Einax and Wolf von Tümpling

Water 2021, 13(12), 1703; https://doi.org/10.3390/w13121703 - 19 Jun 2021

Cited by 11 | Viewed by 3542

Abstract

Long-term changes in dissolved organic matter (DOM) quality, especially in humic-rich raw waters, may lead to intensive adaptions in drinking-water processing. However, seasonal DOM quality changes in standing waters are poorly understood. To fill this gap, the DOM quality of a German drinking [...] Read more.

Long-term changes in dissolved organic matter (DOM) quality, especially in humic-rich raw waters, may lead to intensive adaptions in drinking-water processing. However, seasonal DOM quality changes in standing waters are poorly understood. To fill this gap, the DOM quality of a German drinking water reservoir was investigated on a monthly basis by Fourier-transform ion cyclotron resonance mass spectrometry (FTICR MS) measurements and 2D fluorescence for 18 months. FTICR MS results showed seasonal changes of molecular formula (MF) intensities, indicating photochemical transformation of DOM as a significant process for DOM quality variation. For an assessment of the two humic-like components, identified by parallel factor analysis (PARAFAC) of excitation–emission matrices (EEM), their loadings were Spearman’s rank-correlated with the intensities of the FTICR MS-derived MF. One of the two PARAFAC components correlated to oxygen-rich and relatively unsaturated MF identified as easily photo-degradable, also known as coagulants in flocculation processes. The other PARAFAC component showed opposite seasonal fluctuations and correlated with more saturated MF identified as photo-products with some of them being potential precursors of disinfection byproducts. Our study indicated the importance of elucidating both the chemical background and seasonal behavior of DOM if raw water-quality control is implemented by bulk optical parameters. Full article

(This article belongs to the Special Issue Microbial Processing of Dissolved Organic Matter in Streams and Rivers)

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22 pages, 5755 KiB

Open AccessArticle

Projecting Relative Sea Level Rise under Climate Change at the Phrachula Chomklao Fort Tide Gauge in the Upper Gulf of Thailand

by Chirayu Jaroenongard, Mukand S. Babel, Sangam Shrestha, Sutat Weesakul, Vilas Nitivattananon and Dibesh Khadka

Water 2021, 13(12), 1702; https://doi.org/10.3390/w13121702 - 19 Jun 2021

Cited by 8 | Viewed by 3852

Abstract

This study aims to project future sea-level rise (SLR) at the Phrachula Chomklao Fort (PCF) tide gauge station in the Upper Gulf of Thailand (UGoT) using the outputs of 35 climate models under two greenhouse gas concentration scenarios: representative concentration pathway 4.5 (RCP4.5) [...] Read more.

This study aims to project future sea-level rise (SLR) at the Phrachula Chomklao Fort (PCF) tide gauge station in the Upper Gulf of Thailand (UGoT) using the outputs of 35 climate models under two greenhouse gas concentration scenarios: representative concentration pathway 4.5 (RCP4.5) and RCP8.5. The Linear Scaling method was found to be better than Variance Scaling and Quantile Mapping methods for removing biases in raw Global Circulation Models (GCMs) sea level data. Land subsidence, induced by excessive groundwater abstraction, was found to contribute significantly to SLR during the observed period the PCF gauging station; hence, the effects of land subsidence had to be removed from relative sea level before bias correction. The overall increase in SLR is projected to be 0.94–1.05 mm/year under RCP4.5 and 1.07–1.18 mm/year under RCP8.5 for the twenty-first century in the UGoT. The results suggest that future SLR due to climate change will not be as severe in the study region compared to average global projections. However, land subsidence can amplify future SLR. It is therefore important to regulate groundwater abstraction in the future so that SLR can be restricted. It is even more relevant in the UGoT as the raw water intake from the Chao Phraya River for municipal water supply to Bangkok is close to the estuary, and SLR in the future can pose additional challenges for the water utility. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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15 pages, 1104 KiB

Open AccessArticle

Copula-Based Infilling Methods for Daily Suspended Sediment Loads

by Jenq-Tzong Shiau and Yu-Cheng Lien

Water 2021, 13(12), 1701; https://doi.org/10.3390/w13121701 - 19 Jun 2021

Cited by 10 | Viewed by 2537

Abstract

Less-frequent and inadequate sampling of sediment data has negatively impacted the long and continuous records required for the design and operation of hydraulic facilities. This data-scarcity problem is often found in most river basins of Taiwan. This study aims to propose a parsimonious [...] Read more.

Less-frequent and inadequate sampling of sediment data has negatively impacted the long and continuous records required for the design and operation of hydraulic facilities. This data-scarcity problem is often found in most river basins of Taiwan. This study aims to propose a parsimonious probabilistic model based on copulas to infill daily suspended sediment loads using streamflow discharge. A copula-based bivariate distribution model of sediment and discharge of the paired recorded data is constructed first. The conditional distribution of sediment load given observed discharge is used to provide probabilistic estimation of sediment loads. In addition, four different methods based on the derived conditional distribution of sediment load are used to give single-value estimations. The obtained outcomes of these methods associated with the results of the traditional sediment rating curve are compared with recorded data and evaluated in terms of root mean square error (RMSE), mean absolute percentage error (MAPE), Nash-Sutcliffe efficiency (NSE), and modified Nash-Sutcliffe efficiency (MNSE). The proposed approach is applied to the Janshou station located in eastern Taiwan with recorded daily data for the period of 1960–2019. The results indicate that the infilled sediments by the sediment rating curve exhibit better performance in RMSE and NSE, while the copula-based methods outperform in MAPE and MNSE. Additionally, the infilled sediments by the copula-based methods preserve scattered characteristics of observed sediment-discharge relationships and exhibit similar frequency distributions to that of recorded sediment data. Full article

(This article belongs to the Section Hydrology)

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22 pages, 6336 KiB

Open AccessArticle

Deep Pools: Ecological Sanctuaries for Steindachneridion melanodermatum, a Large Endemic and Endangered Pimelodid of the Iguaçu River

by Lucileine de Assumpção, Maristela Cavicchioli Makrakis, Jhony Ferry Mendonça da Silva, Karane Allison Silvestre de Moraes, Suelen Fernanda Ranucci Pini, Patrícia Sarai da Silva, Elaine Antoniassi Luiz Kashiwaqui, Eduardo Gentil, Lenice Souza-Shibatta, Oscar Akio Shibatta and Sergio Makrakis

Water 2021, 13(12), 1700; https://doi.org/10.3390/w13121700 - 19 Jun 2021

Cited by 5 | Viewed by 3919

Abstract

Steindachneridion melanodermatum, an endemic and endangered species, is the largest catfish in the Lower Iguaçu River basin. Currently, the wild population of this species no longer exists in most of this basin, probably due to the loss of habitat by successive hydroelectric [...] Read more.

Steindachneridion melanodermatum, an endemic and endangered species, is the largest catfish in the Lower Iguaçu River basin. Currently, the wild population of this species no longer exists in most of this basin, probably due to the loss of habitat by successive hydroelectric dams. This study evaluated the spatial distribution and abundance of S. melanodermatum in the last free-flowing river stretch of approximately 190 km downstream from the Salto Caxias Dam, upstream of the Iguaçu Falls, as well as some tributaries. Hydroacoustic and fishing campaigns were performed between September 2010 to December 2016 to characterize the preferred habitat. A total of 180 specimens was sampled with higher abundances in a protected area near Iguaçu Falls in the Iguaçu National Park. Twenty-four deep pools were identified with maximum depths ranging from 5 to 25 m: 21 pools were along the main channel of the Iguaçu River, and three pools were in tributaries. Deep pools are preferential habitats for this species, especially the deep pool called Poço Preto (P23) and its surroundings. Conservation strategies are required to protect these habitats and prevent S. melanodermatum from becoming extinct, such as establishing deep pools as ecological sanctuaries, intensifying the inspection of illegal fishing, and maintaining dam-free tributaries. Full article

(This article belongs to the Special Issue Endangered Fish, Rivers at Risk: Spatial Aspects of Freshwater Biodiversity Conservation)

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21 pages, 2718 KiB

Open AccessEditor’s ChoiceArticle

Note on the Application of Transient Wave Packets for Wave–Ice Interaction Experiments

by Marco Klein, Moritz Hartmann and Franz von Bock und Polach

Water 2021, 13(12), 1699; https://doi.org/10.3390/w13121699 - 19 Jun 2021

Cited by 9 | Viewed by 2975

Abstract

This paper presents the transient wave packet (TWP) technique as an efficient method for wave–ice interaction experiments. TWPs are deterministic wave groups, where both the amplitude spectrum and the associated phases are tailor-made and manipulated, being well established for efficient wave–structure interaction experiments. [...] Read more.

This paper presents the transient wave packet (TWP) technique as an efficient method for wave–ice interaction experiments. TWPs are deterministic wave groups, where both the amplitude spectrum and the associated phases are tailor-made and manipulated, being well established for efficient wave–structure interaction experiments. One major benefit of TWPs is the possibility to determine the response amplitude operator (RAO) of a structure in a single test run compared to the classical approach by investigating regular waves of different wave lengths. Thus, applying TWPs for wave–ice interaction offers the determination of the RAO of the ice at specific locations. In this context, the determination of RAO means that the ice characteristics in terms of wave damping over a wide frequency range are obtained. Besides this, the wave dispersion of the underlying wave components of the TWP can be additionally investigated between the specific locations with the same single test run. For the purpose of this study, experiments in an ice tank, capable of generating tailored waves, were performed with a solid ice sheet. Besides the generation of one TWP, regular waves of different wave lengths were generated as a reference to validate the TWP results for specific wave periods. It is shown that the TWP technique is not only applicable for wave–ice interaction investigations, but is also an efficient alternative to investigations with regular waves. Full article

(This article belongs to the Special Issue The Occurrence, Physics and Impact of Wave–Ice Interaction)

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14 pages, 3788 KiB

Open AccessArticle

How Well Can Machine Learning Models Perform without Hydrologists? Application of Rational Feature Selection to Improve Hydrological Forecasting

by Vsevolod Moreido, Boris Gartsman, Dimitri P. Solomatine and Zoya Suchilina

Water 2021, 13(12), 1696; https://doi.org/10.3390/w13121696 - 19 Jun 2021

Cited by 18 | Viewed by 3164

Abstract

With more machine learning methods being involved in social and environmental research activities, we are addressing the role of available information for model training in model performance. We tested the abilities of several machine learning models for short-term hydrological forecasting by inferring linkages [...] Read more.

With more machine learning methods being involved in social and environmental research activities, we are addressing the role of available information for model training in model performance. We tested the abilities of several machine learning models for short-term hydrological forecasting by inferring linkages with all available predictors or only with those pre-selected by a hydrologist. The models used in this study were multivariate linear regression, the M5 model tree, multilayer perceptron (MLP) artificial neural network, and the long short-term memory (LSTM) model. We used two river catchments in contrasting runoff generation conditions to try to infer the ability of different model structures to automatically select the best predictor set from all those available in the dataset and compared models’ performance with that of a model operating on predictors prescribed by a hydrologist. Additionally, we tested how shuffling of the initial dataset improved model performance. We can conclude that in rainfall-driven catchments, the models performed generally better on a dataset prescribed by a hydrologist, while in mixed-snowmelt and baseflow-driven catchments, the automatic selection of predictors was preferable. Full article

(This article belongs to the Topic Recent Advances in Hydroinformatics: Focusing on Machine Learning and Remote Sensing in Hydrology)

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24 pages, 7803 KiB

Open AccessArticle

A Numerical Study on Impacts of Sediment Erosion/Deposition on Debris Flow Propagation

by Abiola Abraham Adebiyi and Peng Hu

Water 2021, 13(12), 1698; https://doi.org/10.3390/w13121698 - 18 Jun 2021

Cited by 5 | Viewed by 3276

Abstract

Debris flows tend to erode sediment from or deposit sediment on the bed, which changes their volume and, thus, in turn, affects their rheological properties. However, previous modeling studies on debris flows mostly ignore sediment erosion/deposition. Here, three models are presented: a debris [...] Read more.

Debris flows tend to erode sediment from or deposit sediment on the bed, which changes their volume and, thus, in turn, affects their rheological properties. However, previous modeling studies on debris flows mostly ignore sediment erosion/deposition. Here, three models are presented: a debris model without bed deformation, which is similar to traditional models in that it does not consider sediment erosion/deposition but uses the Herschel–Bulkley formulation to describe the non-Newtonian nature; a debris model with bed deformation, which is better improved than the traditional model in that it considers sediment erosion/deposition; and a turbidity current model, which is further simplified from the debris model with bed deformation by ignoring the non-Newtonian nature. These models, formulated in the same modeling framework, are solved by a shock-capturing finite volume method. These models were firstly validated against three laboratory experiments, which indicated that the debris models with and without bed deformation with reasonably well-specified parameters can give satisfactory agreements with the measurements, whereas the turbidity current model overestimated the experimental result due to its lack of yield stress and dynamic viscosity. Moreover, a hypothetical field application was used to explain the difference between a turbidity current and debris flows with and without bed deformation. It was shown that debris flows and turbidity currents are capable of impacting the bed significantly. However, turbidity currents have thinner tails, less shear stress, and form horizontal deposits on the bed, while debris flows have a thicker tail, high shear stress, and form vertical deposits on the bed. Finally, sensitivity analyses were carried out to study the impact of sediment size, bed slope, concentration, and porosity on the deformation of the bed after debris flow where they all showed a positive correlation. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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22 pages, 2658 KiB

Open AccessArticle

A Comparative Study of the Effects of the 1872 Storm and Coastal Flood Risk Management in Denmark, Germany, and Sweden

by Caroline Hallin, Jacobus L. A. Hofstede, Grit Martinez, Jürgen Jensen, Nina Baron, Thorsten Heimann, Aart Kroon, Arne Arns, Björn Almström, Per Sørensen and Magnus Larson

Water 2021, 13(12), 1697; https://doi.org/10.3390/w13121697 - 18 Jun 2021

Cited by 12 | Viewed by 5191

Abstract

From November 12th to 13th in 1872, an extreme coastal flood event occurred in the south Baltic Sea. An unusual combination of winds created a storm surge reaching up to 3.5 m above mean sea level, which is more than a meter higher [...] Read more.

From November 12th to 13th in 1872, an extreme coastal flood event occurred in the south Baltic Sea. An unusual combination of winds created a storm surge reaching up to 3.5 m above mean sea level, which is more than a meter higher than all other observations over the past 200 years. On the Danish, German, and Swedish coasts, about 300 people lost their lives. The consequences of the storm in Denmark and Germany were more severe than in Sweden, with significantly larger destruction and higher numbers of casualties. In Denmark and Germany, the 1872 storm has been more extensively documented and remembered and still influences local and regional risk awareness. A comparative study indicates that the collective memory of the 1872 storm is related to the background knowledge about floods, the damage extent, and the response to the storm. Flood marks and dikes help to remember the events. In general, coastal flood defence is to the largest degree implemented in the affected areas in Germany, followed by Denmark, and is almost absent in Sweden, corresponding to the extent of the collective memory of the 1872 storm. Within the affected countries, there is local variability of flood risk awareness associated with the collective memory of the storm. Also, the economic dependency on flood-prone areas and conflicting interests with the tourism industry have influence on flood protection decisions. The processes of climate change adaptation and implementation of the EU Floods Directive are slowly removing these differences in flood risk management approaches. Full article

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

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13 pages, 4591 KiB

Open AccessArticle

Long-Term Trend Analysis of Precipitation and Extreme Events over Kosi River Basin in India

by Prashant K. Srivastava, Rajani Kumar Pradhan, George P. Petropoulos, Varsha Pandey, Manika Gupta, Aradhana Yaduvanshi, Wan Zurina Wan Jaafar, Rajesh Kumar Mall and Atul Kumar Sahai

Water 2021, 13(12), 1695; https://doi.org/10.3390/w13121695 - 18 Jun 2021

Cited by 16 | Viewed by 5141

Abstract

Analysis of spatial and temporal changes of long-term precipitation and extreme precipitation distribution at a local scale is very important for the prevention and mitigation of water-related disasters. In the present study, we have analyzed the long-term trend of 116 years (1901–2016) of [...] Read more.

Analysis of spatial and temporal changes of long-term precipitation and extreme precipitation distribution at a local scale is very important for the prevention and mitigation of water-related disasters. In the present study, we have analyzed the long-term trend of 116 years (1901–2016) of precipitation and distribution of extreme precipitation index over the Kosi River Basin (KRB), which is one of the frequent flooding rivers of India, using the 0.25° × 0.25° resolution gridded precipitation datasets obtained from the Indian Meteorological Department (IMD), India. The non-parametric Mann–Kendall trend test together with Sen’s slope estimator was employed to determine the trend and the magnitude of the trend of the precipitation time series. The annual and monsoon seasons revealed decreasing trends with Sen’s slope values of −1.88 and −0.408, respectively. For the extreme indices viz. R10 and R20 days, a decreasing trend from the northeastern to the southwest part of the basin can be observed, whereas, in the case of highest one-day precipitation (RX1 day), no clear trend was found. The information provided through this study can be useful for policymakers and may play an important role in flood management, runoff, and understanding related to the hydrological process of the basin. This will contribute to a better understanding of the potential risk of changing rainfall patterns, especially the extreme rainfall events due to climatic variations. Full article

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16 pages, 1604 KiB

Open AccessArticle

The Decision of an Eco-Friendly Reservoir Operation Scheme Based on a Variable Set

by Hai-Tao Chen, A-Long Li, Wen-Chuan Wang and Zhao Zhao

Water 2021, 13(12), 1694; https://doi.org/10.3390/w13121694 - 18 Jun 2021

Cited by 1 | Viewed by 2034

Abstract

The river ecosystem has the characteristics of the coexistence of clarity and ambiguity. The starting point of eco-friendly reservoir operation is to fully consider the ecological water requirements of the lower reaches of the reservoir, so it also has the characteristics of clarity [...] Read more.

The river ecosystem has the characteristics of the coexistence of clarity and ambiguity. The starting point of eco-friendly reservoir operation is to fully consider the ecological water requirements of the lower reaches of the reservoir, so it also has the characteristics of clarity and vagueness. The fuzzy theory is an excellent tool to realize the quantification of fuzzy concepts. In this paper, the variable set theory (VS) is introduced into the decision-making field of eco-friendly reservoir scheduling scheme optimization. Taking Ertan Hydropower Station as an example, the scheduling scheme optimization is carried out. To verify the effectiveness of the evaluation method, this paper compares and analyzes the evaluation results of the fuzzy set evaluation method and the composite fuzzy matter-element method. The results show that the variable fuzzy set method has the advantages of rigorous theory, a concise model, and simple calculation, and the decision result is reasonable and reliable. This research can provide new ideas for the decision-making research of engineering. Full article

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51 pages, 4503 KiB

Open AccessEditor’s ChoiceArticle

An In-Depth Analysis of Physical Blue and Green Water Scarcity in Agriculture in Terms of Causes and Events and Perceived Amenability to Economic Interpretation

by Kalomoira Zisopoulou and Dionysia Panagoulia

Water 2021, 13(12), 1693; https://doi.org/10.3390/w13121693 - 18 Jun 2021

Cited by 21 | Viewed by 12013

Abstract

An analytical review of physical blue and green water scarcity in terms of agricultural use, and its amenability to economic interpretation, is presented, employing more than 600 references. The main definitions and classifications involved and information about reserves and resources are critically analyzed, [...] Read more.

An analytical review of physical blue and green water scarcity in terms of agricultural use, and its amenability to economic interpretation, is presented, employing more than 600 references. The main definitions and classifications involved and information about reserves and resources are critically analyzed, blue and green water scarcity are examined along with their interchange, while their causal connection with climate in general is analyzed along with the particular instances of Europe, Africa, Asia and the WANA region. The role of teleconnections and evaporation/moisture import-export is examined as forms of action at a distance. The human intervention scarcity driver is examined extensively in terms of land use land cover change (LULCC), as well as population increase. The discussion deals with following critical problems: green and blue water availability, inadequate accessibility, blue water loss, unevenly distributed precipitation, climate uncertainty and country level over global level precedence. The conclusion singles out, among others, problems emerging from the inter-relationship of physical variables and the difficulty to translate them into economic instrumental variables, as well as the lack of imbedding uncertainty in the underlying physical theory due to the fact that country level measurements are not methodically assumed to be the basic building block of regional and global water scarcity. Full article

(This article belongs to the Special Issue The Economic Role of Water under Scarcity and Sustainability Constraints)

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25 pages, 4047 KiB

Open AccessArticle

Variations in Benthic Macroinvertebrate Communities and Biological Quality in the Aguarico and Coca River Basins in the Ecuadorian Amazon

by Santiago Cabrera, Marie Anne Eurie Forio, Koen Lock, Marte Vandenbroucke, Tania Oña, Miguel Gualoto, Peter L. M. Goethals and Christine Van der heyden

Water 2021, 13(12), 1692; https://doi.org/10.3390/w13121692 - 18 Jun 2021

Cited by 14 | Viewed by 5067

Abstract

Adequate environmental management in tropical aquatic ecosystems is imperative. Given the lack of knowledge about functional diversity and bioassessment programs, management is missing the needed evidence on pollution and its effect on biodiversity and functional ecology. Therefore, we investigated the composition and distribution [...] Read more.

Adequate environmental management in tropical aquatic ecosystems is imperative. Given the lack of knowledge about functional diversity and bioassessment programs, management is missing the needed evidence on pollution and its effect on biodiversity and functional ecology. Therefore, we investigated the composition and distribution of the macroinvertebrate community along two rivers. Specifically, 15 locations were sampled in the Coca and Aguarico Rivers (Ecuadorian Amazon) and the macroinvertebrates were used to indicate water quality (WQ), expressed as the Biological Monitoring Working Party Colombia (BMWP-Col) classes. Results indicate that elevation, pH, temperature, width, and water depth played an important role in the taxa and functional feeding groups (FFG) composition. The results show that diversity of taxa and FFG were generally scarce but were more abundant in good quality sites. Collector-gathers (CG) were, in general, dominant and were particularly abundant at low WQ and downstream sites. Scrapers (SC) were the second most abundant group, dominating mostly at good WQ and upstream sites. Predators (PR) were homogeneously distributed among the sites, without clear dominance, and their abundance was slightly higher in sites with medium-low WQ and downstream sites. Lastly, both shredders (SH) and collector-filterers (CF) were almost absent and were more abundant in good quality sites. The findings of this research can be used as baseline information in the studied region since a dam was constructed two years after the sampling campaign, which has been operating since. Furthermore, the results can be used to fill the knowledge gaps related to the bioassessments of other similar systems, particularly for a tropical rainforest. Full article

(This article belongs to the Special Issue The Ecological Assessment of Rivers and Estuaries: Present and Future)

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22 pages, 43892 KiB

Open AccessFeature PaperArticle

A Weight of Evidence (WOE) Approach to Assess Environmental Hazard of Marine Sediments from Adriatic Offshore Platform Area

by Loredana Manfra, Chiara Maggi, Giuseppe d’Errico, Alice Rotini, Barbara Catalano, Silvia Maltese, Ginevra Moltedo, Giulia Romanelli, Giulio Sesta, Giuseppe Granato, Pasquale Lanera, Marina Amici, Giacomo Martuccio, Fulvio Onorati, Rossella Di Mento, Maria T. Berducci, Gianluca Chiaretti, Olga Faraponova, Francesco Regoli and Andrea Tornambè

Water 2021, 13(12), 1691; https://doi.org/10.3390/w13121691 - 18 Jun 2021

Cited by 7 | Viewed by 3414

Abstract

European legislative framework supports a multidisciplinary strategy of environmental monitoring because the environment is a complex system of abiotic and biotic interactions, and it should not be studied and protected by looking at one single aspect. The resulting heterogeneous data request to be [...] Read more.

European legislative framework supports a multidisciplinary strategy of environmental monitoring because the environment is a complex system of abiotic and biotic interactions, and it should not be studied and protected by looking at one single aspect. The resulting heterogeneous data request to be carefully processed, and the application of Weight of Evidence (WOE) approaches is, thereby, an integrated validated tool. In this perspective, the present study aims to: (i). apply a specific model (Sediqualsoft) based on the WOE approach for processing multidisciplinary data related to four Lines Of Scientific Evidence (LOEs: chemical analyses, ecotoxicological bioassays, bioaccumulation tests and biomarkers) regarding sediments from an area of the Adriatic Sea; (ii). evaluate the usefulness of this specific integrated approach to estimate the potential environmental hazard due to the presence of gas production platforms respect to the traditional approach of sediment chemical characterization. This latter recognized a more contaminated area within 100 m of the platforms in which the Sediqualsoft model showed the presence of a chemical hazard, ranging from moderate to severe, and identified the contaminants (e.g., some metals, benzo(a)pyrene and acenaphthene) most responsible for it. A significant hazard also appeared in some of the sampled stations by analyzing the LOEs dedicated to the biological responses. The choice of different reference values (regulatory limits, threshold values or concentrations measured in the control area) influenced only the chemical hazard but not the overall integration with other LOEs, showing a moderate hazard for the majority of stations. Here, the concentrations measured in a control area are firstly proposed as possible reference values in Sediqualsoft model applications; this could be of particular relevance when Sediment Quality Guidelines are not available for all the measured substances. Moreover, the limitations of a conventional pass-to-fail approach or worst-case scenario were overcoming interpreting whole chemical and ecotoxicological results. All data analyzed and discussed confirm Sediqualsoft as a suitable tool for processing environmental data, including those first processed here on a monitoring scenario of gas platforms that discharge Produced Water into the sea. Full article

(This article belongs to the Special Issue Aquatic Ecotoxicity Assessment)

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28 pages, 7238 KiB

Open AccessArticle

Uncertainty Estimation in Hydrogeological Forecasting with Neural Networks: Impact of Spatial Distribution of Rainfalls and Random Initialization of the Model

by Nicolas Akil, Guillaume Artigue, Michaël Savary, Anne Johannet and Marc Vinches

Water 2021, 13(12), 1690; https://doi.org/10.3390/w13121690 - 18 Jun 2021

Cited by 2 | Viewed by 2363

Abstract

Neural networks are used to forecast hydrogeological risks, such as droughts and floods. However, uncertainties generated by these models are difficult to assess, possibly leading to a low use of these solutions by water managers. These uncertainties are the result of three sources: [...] Read more.

Neural networks are used to forecast hydrogeological risks, such as droughts and floods. However, uncertainties generated by these models are difficult to assess, possibly leading to a low use of these solutions by water managers. These uncertainties are the result of three sources: input data, model architecture and parameters and their initialization. The aim of the study is, first, to calibrate a model to predict Champagne chalk groundwater level at Vailly (Grand-Est, France), and, second, to estimate related uncertainties, linked both to the spatial distribution of rainfalls and to the parameter initialization. The parameter uncertainties are assessed following a previous methodology, using nine mixed probability density functions (pdf), thus creating models of correctness. Spatial distribution of rainfall uncertainty is generated by swapping three rainfall inputs and then observing dispersion of 27 model outputs. This uncertainty is incorporated into models of correctness. We show that, in this case study, an ensemble model of 40 different initializations is sufficient to estimate parameter uncertainty while preserving quality. Logistic, Gumbel and Raised Cosine laws fit the distribution of increasing and decreasing groundwater levels well, which then allows the establishment of models of correctness. These models of correctness provide a confidence interval associated with the forecasts, with an arbitrary degree of confidence chosen by the user. These methodologies have proved to have significant advantages: the rigorous design of the neural network model has allowed the realisation of models able to generalize outside of the range of the data used for training. Furthermore, it is possible to flexibly choose the confidence index according to the hydrological configuration (e.g., recession or rising water table). Full article

(This article belongs to the Section Hydrology)

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3 pages, 159 KiB

Open AccessEditorial

Editorial—Modelling of Floods in Urban Areas

by Jorge Leandro and James Shucksmith

Water 2021, 13(12), 1689; https://doi.org/10.3390/w13121689 - 18 Jun 2021

Cited by 1 | Viewed by 2463

Abstract

Understanding the risk of flooding in urban areas is a societal priority [...] Full article

(This article belongs to the Special Issue Modelling of Floods in Urban Areas)

18 pages, 9544 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Story of a Steep River: Causes and Effects of the Flash Flood on 24 July 2017 in Western Norway

by Adina Moraru, Michal Pavlíček, Oddbjørn Bruland and Nils Rüther

Water 2021, 13(12), 1688; https://doi.org/10.3390/w13121688 - 18 Jun 2021

Cited by 6 | Viewed by 4687

Abstract

Flash floods can cause great geomorphological changes in ephemeral fluvial systems and result in particularly severe damages for the unprepared population exposed to it. The flash flood in the Storelva river in Utvik (western Norway) on 24 July 2017 was witnessed and documented. [...] Read more.

Flash floods can cause great geomorphological changes in ephemeral fluvial systems and result in particularly severe damages for the unprepared population exposed to it. The flash flood in the Storelva river in Utvik (western Norway) on 24 July 2017 was witnessed and documented. This study assessed the causes and effects of the 2017 flood and provides valuable information for the calibration and validation of future modelling studies. The flooded area at peak discharge, maximum wetted and dry areas during the entire event, critical points and main flow paths were reconstructed using on-site and post-event (i) visual documentation, such as photographs and videos, and (ii) aerial surveying, such as orthophotographs and laser scanning, of the lowermost reach. The steep longitudinal slope together with the loose material forming the valley and riverbed contributed to a large amount of sediment transport during this extreme event. Steep rivers such as the Storelva river have very short response times to extreme hydrologic conditions, which calls for exhaustive monitoring and data collection in case of future events, as well as modelling tools that can emulate the hydro-morphodynamics observed during events such as the 2017 flash flood. Full article

(This article belongs to the Special Issue Recent Advances in Flood Hazard and Risk Science)

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20 pages, 2613 KiB

Open AccessReview

Agricultural Conservation Practices and Aquatic Ecological Responses

by Richard E. Lizotte, Peter C. Smiley, Robert B. Gillespie and Scott S. Knight

Water 2021, 13(12), 1687; https://doi.org/10.3390/w13121687 - 18 Jun 2021

Cited by 5 | Viewed by 3334

Abstract

Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that [...] Read more.

Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function. Full article

(This article belongs to the Special Issue Water Quality and Ecological Aspects of Aquatic Ecosystems Influenced by Agricultural Activity)

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