Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Water, Volume 10, Issue 10 (October 2018)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-168
Export citation of selected articles as:
Open AccessArticle The Construction and Comparison of Regional Drought Severity-Duration-Frequency Curves in Two Colombian River Basins—Study of the Sumapaz and Lebrija Basins
Water 2018, 10(10), 1453; https://doi.org/10.3390/w10101453 (registering DOI)
Received: 27 August 2018 / Revised: 15 September 2018 / Accepted: 18 September 2018 / Published: 15 October 2018
PDF Full-text (6082 KB) | HTML Full-text | XML Full-text
Abstract
Accurate classification of drought-severity is one of the most challenging issues in designing regional monitoring and control plans, especially in developing countries, where resources are scarce and must be carefully optimized to maximize social benefit. Typically, drought assessment is performed using drought indices
[...] Read more.
Accurate classification of drought-severity is one of the most challenging issues in designing regional monitoring and control plans, especially in developing countries, where resources are scarce and must be carefully optimized to maximize social benefit. Typically, drought assessment is performed using drought indices which enable the interpretation of complex climatic information series for operational purposes. Frequency analyses are also useful for estimating future occurrence probabilities, even on regional scales. This study generated regional Severity-Duration-Frequency (SDF) curves for two Colombian catchments (Sumapaz and Lebrija River Basins), and 7 index-calculation procedures. First, the relationships between the two catchments were analyzed to obtain differences between drought indices. Second, the consistency among the indices that identified the same drought types for each region was evaluated. Finally, historical regional drought occurrences were selected, characterized, and located in local SDF curves to determine their gravity. It was concluded that (i) curves for the same indices displayed similar behavior, when comparing the two case studies; (ii) a certain degree of consistency existed in regional curves, which identify the same drought types (meteorological and agricultural droughts being the most coherent); (iii) meteorological drought regional events, identified through different drought-indices methodologies, were the most common for both case studies, followed by agricultural droughts and hydrological droughts; (iv) when analyzing occurrences with higher return periods, there is coherence when using different methodologies; and (v) identified historical events, which are located on larger return period zones of SDF curves (around 10, 25, and 50 years), had large impacts on regional socio-economic issues. Hence, it was possible to confirm that regional SDF curves could become potentially useful tools for the prioritization of drought-vulnerable zones. Full article
(This article belongs to the Section Hydrology)
Figures

Figure 1

Open AccessArticle Least Squares Support Vector Mechanics to Predict the Stability Number of Rubble-Mound Breakwaters
Water 2018, 10(10), 1452; https://doi.org/10.3390/w10101452 (registering DOI)
Received: 31 August 2018 / Revised: 11 October 2018 / Accepted: 11 October 2018 / Published: 15 October 2018
PDF Full-text (2277 KB) | HTML Full-text | XML Full-text
Abstract
In coastal engineering, empirical formulas grounded on experimental works regarding the stability of breakwaters have been developed. In recent years, soft computing tools such as artificial neural networks and fuzzy models have started to be employed to diminish the time and cost spent
[...] Read more.
In coastal engineering, empirical formulas grounded on experimental works regarding the stability of breakwaters have been developed. In recent years, soft computing tools such as artificial neural networks and fuzzy models have started to be employed to diminish the time and cost spent in these mentioned experimental works. To predict the stability number of rubble-mound breakwaters, the least squares version of support vector machines (LSSVM) method is used because it can be assessed as an alternative one to diverse soft computing techniques. The LSSVM models have been operated through the selected seven parameters, which are determined by Mallows’ Cp approach, that are, namely, breakwater permeability, damage level, wave number, slope angle, water depth, significant wave heights in front of the structure, and peak wave period. The performances of the LSSVM models have shown superior accuracy (correlation coefficients (CC) of 0.997) than that of artificial neural networks (ANN), fuzzy logic (FL), and genetic programming (GP), that are all implemented in the related literature. As a result, it is thought that this study will provide a practical way for readers to estimate the stability number of rubble-mound breakwaters with more accuracy. Full article
(This article belongs to the Special Issue Machine Learning Applied to Hydraulic and Hydrological Modelling)
Figures

Figure 1a

Open AccessArticle Variations of Water Runoff and Suspended Sediment Yield in the Kamchatsky Krai, Russia
Water 2018, 10(10), 1451; https://doi.org/10.3390/w10101451
Received: 13 September 2018 / Revised: 24 September 2018 / Accepted: 9 October 2018 / Published: 15 October 2018
PDF Full-text (3235 KB) | HTML Full-text | XML Full-text
Abstract
This study investigates the spatial and temporal variability of water runoff and suspended sediment yield in rivers in the Kamchatsky Krai territory (in the Far East of the Russian Federation). It is based on data from 269 monitoring stations for the period of
[...] Read more.
This study investigates the spatial and temporal variability of water runoff and suspended sediment yield in rivers in the Kamchatsky Krai territory (in the Far East of the Russian Federation). It is based on data from 269 monitoring stations for the period of hydrometeorological observations (1930–2015). The representativeness and the homogeneity of data on water runoff and suspended sediment yield was examined. Regions with prescribed limits of specific water discharge (L·s−1·km−2) and suspended sediment concentration (mg·L−1) variability were selected in the Kamchatsky Krai territory. Most rivers in this region are characterized by two relatively long trends in these characteristics that increased from the late 1970s to the early 1980s, followed by a subsequent decline (until 2015). Kamchatsky Krai includes 9 specific water discharge and 18 suspended sediment concentration regions. Hydrometeorological data of three zonal types of water runoff and corresponding suspended sediment concentration distribution were described, and five azonal types of water regime were characterized. One of these types was characterized by a nearly uniform distribution of water runoff within the year, due to the predominance of groundwater feeding source, while the rest of them had mixed feeding. The present study is the first study to describe the water regime of rivers on volcanic flanks in the Kamchatsky Krai. Full article
(This article belongs to the Section Hydrology)
Figures

Figure 1

Open AccessArticle Environmental Factors and the Microbial Quality of Urban Drinking Water in a Low-Income Country: The Case of Madagascar
Water 2018, 10(10), 1450; https://doi.org/10.3390/w10101450
Received: 25 July 2018 / Revised: 8 October 2018 / Accepted: 9 October 2018 / Published: 15 October 2018
PDF Full-text (5063 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Access to piped water is often limited to urban areas in low-income countries, and the microbiological quality of drinking water varies due to technical and environmental constraints. To analyse the parameters that modulate the contamination of these systems, this study examines 16 years
[...] Read more.
Access to piped water is often limited to urban areas in low-income countries, and the microbiological quality of drinking water varies due to technical and environmental constraints. To analyse the parameters that modulate the contamination of these systems, this study examines 16 years of microbial quality data for water supplied in 32 urban areas of Madagascar. A discriminant statistical approach and agglomerative hierarchical clusters were applied to environmental and climatic data. The microbial contamination varied between sites from 3.3 to 17.5%, and 78% of the supply systems showed large variations between years or months. Agglomerative hierarchical clusters (AHCs) revealed four supply system profiles that share a similar bacteriological evolution. Heavy rainfall and dry periods sustained increasing contamination, as reflected in levels of spores of sulphite-reducing clostridia (SSRC) and/or total coliforms (TC). SSRC were dominant in three profiles, with faecal indicator bacteria (FIB) dominant in the other. Principal component analysis demonstrated the main drivers of contamination: type of water source, implemented treatment, location of the site, population growth, lack of protection, agriculture, urbanization/sanitation, and flooding threats. Contamination increased over the 16-year period, reaching alarming levels. The protection of water sources should be a concern for public authorities. Full article
(This article belongs to the Special Issue Climate-Water-Ecosystem-Interaction)
Figures

Figure 1

Open AccessArticle Transdisciplinary Research and Development Cooperation: Insights from the First Phase of the Palestinian-Dutch Academic Cooperation Programme on Water
Water 2018, 10(10), 1449; https://doi.org/10.3390/w10101449
Received: 30 April 2018 / Revised: 22 September 2018 / Accepted: 27 September 2018 / Published: 15 October 2018
PDF Full-text (914 KB) | HTML Full-text | XML Full-text
Abstract
Transdisciplinary research offers a promising approach to development cooperation programs by integrating knowledge from academic and non-academic stakeholders, and from natural and social sciences. In the context of development research on water, there is little evidence on how stakeholder involvement takes place in
[...] Read more.
Transdisciplinary research offers a promising approach to development cooperation programs by integrating knowledge from academic and non-academic stakeholders, and from natural and social sciences. In the context of development research on water, there is little evidence on how stakeholder involvement takes place in the three stages of transdisciplinary research (problem definition, knowledge production, and knowledge application). This paper aims to create empirical evidence and insights on this question based on the Palestinian-Dutch Academic Cooperation Programme on Water (PADUCO). Six research projects, which have been implemented within the first phase of PADUCO, were examined using the data collected through a survey and document reviews. The results show that research problems were defined according to societal needs and contextual factors. Research teams were multidisciplinary and included non-academic members, whereas the institutional involvement of non-academic stakeholders was limited and unbalanced between the governmental and non-governmental actors. Although the application of the knowledge produced was mainly focused on academia, opportunities for broad dissemination were utilized, albeit to a limited extent. Finally, there was a lack of monitoring and evaluation of impacts, which is explained by the budget and time limitations of such small-scale projects and can be mitigated by programme-level measures. Full article
Figures

Figure 1

Open AccessArticle Application of Artificial Neural Networks to Rainfall Forecasting in the Geum River Basin, Korea
Water 2018, 10(10), 1448; https://doi.org/10.3390/w10101448
Received: 24 August 2018 / Revised: 2 October 2018 / Accepted: 12 October 2018 / Published: 14 October 2018
PDF Full-text (3327 KB) | HTML Full-text | XML Full-text
Abstract
This study develops a late spring-early summer rainfall forecasting model using an artificial neural network (ANN) for the Geum River Basin in South Korea. After identifying the lagged correlation between climate indices and the rainfall amount in May and June, 11 significant input
[...] Read more.
This study develops a late spring-early summer rainfall forecasting model using an artificial neural network (ANN) for the Geum River Basin in South Korea. After identifying the lagged correlation between climate indices and the rainfall amount in May and June, 11 significant input variables were selected for the preliminary ANN structure. From quantification of the relative importance of the input variables, the lagged climate indices of East Atlantic Pattern (EA), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), East Pacific/North Pacific Oscillation (EP/NP), and Tropical Northern Atlantic Index (TNA) were identified as significant predictors and were used to construct a much simpler ANN model. The final best ANN model, with five input variables, showed acceptable performance with relative root mean square errors of 25.84%, 32.72%, and 34.75% for training, validation, and testing data sets, respectively. The hit score, which is the number of hit years divided by the total number of years, was more than 60%, which indicates that the ANN model successfully predicts rainfall in the study area. The developed ANN model, incorporated with lagged global climate indices, could allow for more timely and flexible management of water resources and better preparation against potential droughts in the study region. Full article
(This article belongs to the Section Hydrology)
Figures

Figure 1

Open AccessCommunication Arsenic Removal Using Horizontal Subsurface Flow Constructed Wetlands: A Sustainable Alternative for Arsenic-Rich Acidic Waters
Water 2018, 10(10), 1447; https://doi.org/10.3390/w10101447
Received: 21 September 2018 / Revised: 11 October 2018 / Accepted: 12 October 2018 / Published: 14 October 2018
PDF Full-text (1841 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Constructed wetlands (CW) have been widely used to treat different types of water, including acid mine drainage (AMD). However, little is known about their performance in the removal of As from AMD. In this study, a laboratory-scale horizontal subsurface flow (HSSF) CW system
[...] Read more.
Constructed wetlands (CW) have been widely used to treat different types of water, including acid mine drainage (AMD). However, little is known about their performance in the removal of As from AMD. In this study, a laboratory-scale horizontal subsurface flow (HSSF) CW system was tested to evaluate its capacity to treat highly acidic, As-rich contaminated water resembling AMD. Vegetated and non-vegetated cells, having limestone or zeolite as the main supporting media, were built and operated to evaluate the effect of the media type and the presence of Phragmites australis on the removal of arsenic, iron (Fe), lead (Pb), and zinc (Zn), and on the neutralization capacity. The four types of cells were highly effective in the removal of As and Pb (removal > 99%), and Fe (removal > 98%), whereas Zn removal rates depended on the cell type. Limestone cells raised the pH from ~1.9 to ~7.5, while zeolite cells raised it to ~4. These results suggest that the media type has a key role in the neutralization capacity, and that the presence of vegetation affected mainly the removal of Zn. Knowledge from this study will contribute to guiding the implementation of HSSF CW for treating As-rich AMD. Full article
(This article belongs to the Section Water and Wastewater Treatment)
Figures

Figure 1a

Open AccessArticle New Patterns of Temporal and Spatial Variation in Water Quality of a Highly Artificialized Urban River-Course—a Case Study in the Tongzhou Section of the Beiyun River
Water 2018, 10(10), 1446; https://doi.org/10.3390/w10101446
Received: 17 July 2018 / Revised: 5 October 2018 / Accepted: 11 October 2018 / Published: 13 October 2018
PDF Full-text (1646 KB) | HTML Full-text | XML Full-text
Abstract
This paper aims to gain a better understanding of urban river pollution through evaluation of water quality. Data for 10 parameters at eight sites of the Tongzhou Section of the Beiyun River (TSBR) are analyzed. Hierarchical cluster analysis, fuzzy comprehensive assessment, discriminant analysis
[...] Read more.
This paper aims to gain a better understanding of urban river pollution through evaluation of water quality. Data for 10 parameters at eight sites of the Tongzhou Section of the Beiyun River (TSBR) are analyzed. Hierarchical cluster analysis, fuzzy comprehensive assessment, discriminant analysis and Spearman’s correlation analysis were used to estimate the water situation of each cluster and analyze its spatial-temporal variations. Principal component analysis/factor analysis were applied to extract and recognize the sources responsible for water-quality variations. The results showed that temporal variation is greater than spatial and sewage discharge is the dominant factor of the seasonal distribution. Moreover, during the rapid-flow period, water quality is polluted by a combination of organic matter, phosphorus, bio-chemical pollutants and nitrogen; during the gentle-flow period, water quality is influenced by domestic and industrial waste, the activities of algae, aquatic plants and phosphorus pollution. In regard to future improvement of water quality in TSBR, the control of reclaimed wastewater from adjacent factories should first be put in place, as well as other techniques, for example, an increase of the impervious area, low-impact development, and integrated management practices should also be proposed in managing storm water runoff. Full article
(This article belongs to the Section Water Quality and Ecosystems)
Figures

Figure 1

Open AccessArticle The Efficiency and Reliability of Pollutant Removal in a Hybrid Constructed Wetland with Common Reed, Manna Grass, and Virginia Mallow
Water 2018, 10(10), 1445; https://doi.org/10.3390/w10101445
Received: 10 July 2018 / Revised: 7 October 2018 / Accepted: 10 October 2018 / Published: 13 October 2018
PDF Full-text (2089 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the pollutant removal efficiency and the reliability of a vertical and horizontal flow hybrid constructed wetland (CW) planted with common reed, manna grass, and Virginia mallow were analyzed. The wastewater treatment plant, located in south-eastern Poland, treated domestic sewage at
[...] Read more.
In this paper, the pollutant removal efficiency and the reliability of a vertical and horizontal flow hybrid constructed wetland (CW) planted with common reed, manna grass, and Virginia mallow were analyzed. The wastewater treatment plant, located in south-eastern Poland, treated domestic sewage at an average flow rate of 2.5 m3/d. The tests were carried out during five years of its operation (2014–2018). The following parameters were measured: biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids, total nitrogen, and total phosphorus. The results showed that more than 95% of BOD5, COD, and total phosphorus was removed in the tested CW system. The average effectiveness of removal of total suspended solids and total nitrogen exceeded 86%. A reliability analysis performed using the Weibull probability model showed that the removal reliability in the tested CW was very high for BOD5, COD, total suspended solids, and total phosphorus (100%). The probability that the total nitrogen concentration in the treated effluents would reach the limit value (30 mg/L) established for effluents discharged from a treatment plant of less than 2000 PE (population equivalent) to standing waters was 94%. The values of all the pollution indicators in wastewater discharged to the receiver were significantly lower than the limit values required in Poland. The investigated hybrid CW system with common reed, manna grass, and Virginia mallow guaranteed stable low values of BOD5, COD, total suspended solids, and total phosphorus in the treated wastewater, which meant it was highly likely to be positively evaluated in case of an inspection. Full article
(This article belongs to the Section Water and Wastewater Treatment)
Figures

Figure 1

Open AccessArticle Evaluation of the Structure of Urban Stormwater Pipe Network Using Drainage Density
Water 2018, 10(10), 1444; https://doi.org/10.3390/w10101444
Received: 9 July 2018 / Revised: 8 September 2018 / Accepted: 10 October 2018 / Published: 13 October 2018
PDF Full-text (1950 KB) | HTML Full-text | XML Full-text
Abstract
In mega cities such as Seoul in South Korea, it is very important to protect the cities from surface flooding even for a short time period due to the enormous economic damage. That is why stormwater pipe networks are commonly applied to mega
[...] Read more.
In mega cities such as Seoul in South Korea, it is very important to protect the cities from surface flooding even for a short time period due to the enormous economic damage. That is why stormwater pipe networks are commonly applied to mega cities with large impervious areas to drain runoff from the city. Therefore, the stormwater pipe networks in urban catchments should be carefully designed for quick and efficient runoff removal. In this study, the structures of different stormwater pipe networks were evaluated based on the relationship between peak rainfall and runoff in the urban catchments in South Korea. More than 400 historical rainfall events from five urban catchments were used to develop respective linear regression models for estimating peak runoff for different pipe network structures. The developed regression models exhibited greater than 0.9 in determination coefficients and demonstrated overall the broader ranges in peak runoff with the greater rainfall amount, especially when the pipe networks were branched. This implies that the effect of pipe network structures on runoff is more profound in the branched networks whose runoff water flow is one-directional and thus tends to concentrate to the catchment outlet. In the case of the looped networks in which runoff paths are multiple, rainfall runoff can be routed to several alternative water paths depending on rainfall events resulting in the reduced peak runoff. The structures of pipe networks can be measured in drainage density which is defined as the ratio of total pipe length to catchment area. As a result, the range of the estimated runoff at the 95% confidence level increased as the drainage density increased, which implies increased uncertainty with the looped networks which commonly involve more pipe installation for unit area as compared to the branched. However, the looped networks with multiple water paths can reduce the time to drain rainfall from the catchments and thus the 95% confidence interval becomes narrow, which means greater reliability in peak runoff estimation. It would therefore be favorable to adopt looped stormwater pipe networks within an affordable budget and the complexity of pipe networks needs to be counted to reduce urban flood risk. Full article
(This article belongs to the Section Hydrology)
Figures

Figure 1

Open AccessArticle Prediction of Water Utility Performance: The Case of the Water Efficiency Rate
Water 2018, 10(10), 1443; https://doi.org/10.3390/w10101443
Received: 6 September 2018 / Revised: 8 October 2018 / Accepted: 10 October 2018 / Published: 13 October 2018
PDF Full-text (3232 KB) | HTML Full-text | XML Full-text
Abstract
This paper deals with the development of a decision-aiding model for predicting, in an ex-ante way, the effects of a mix of actions on an asset and on its operation. The objective is then to define a compromised policy between costs and performance
[...] Read more.
This paper deals with the development of a decision-aiding model for predicting, in an ex-ante way, the effects of a mix of actions on an asset and on its operation. The objective is then to define a compromised policy between costs and performance improvements. We investigate the use of multiple regression analysis (MRA) and an artificial neural network (ANN) to establish causal relationships between the network efficiency rate, and a set of explanatory variables on one hand, and potential water loss management actions such as leak detection, maintenance and asset renewal, on the other hand. The originality of our approach is in developing a two-step ex-ante model for predicting the efficiency rate involving low and high level explanatory variables in a context of unavailability of data at the scale of the water utility. The first step exploits a national French database «SISPEA» (Système d’Information d’information sur les Services Publics d’Eau et d’Assainissement) to calibrate a general prediction model that establishes a correlation between efficiency (output) and other performance indicators (inputs). The second step involves the utility manager to build a causal model between endogenous and exogenous variables of a specific water network (low level) and performance indicators considered as inputs for the previous step (high level). Uncertainty is taken into account by Monte Carlo simulations. An application of our decision model on a water utility in the southeast of France is provided as a case study. Full article
(This article belongs to the Section Urban Water Management)
Figures

Figure 1

Open AccessArticle Global Economic and Food Security Impacts of Demand-Driven Water Scarcity—Alternative Water Management Options for a Thirsty World
Water 2018, 10(10), 1442; https://doi.org/10.3390/w10101442
Received: 14 August 2018 / Revised: 21 September 2018 / Accepted: 9 October 2018 / Published: 13 October 2018
PDF Full-text (2911 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Global freshwater demand will likely continue its expansion under current expectations of economic and population growth. Withdrawals in regions which are already water-scarce will impose further pressure on the renewable water resource base threatening the long-term availability of freshwater across the many economic
[...] Read more.
Global freshwater demand will likely continue its expansion under current expectations of economic and population growth. Withdrawals in regions which are already water-scarce will impose further pressure on the renewable water resource base threatening the long-term availability of freshwater across the many economic activities dependent on this resource for various functions. This paper assesses the economy-wide implications of demand-driven water scarcity under a ‘middle-of-the-road’ socio-economic development pathway by considering the trade-offs between the macroeconomic and food security impacts. The study employs a global CGE model comprising an advanced level of detail regarding water uses across economic activities and which allows for a sector-specific endogenous adaptation to water scarcity. A sustainable withdrawal threshold is imposed in regions with extended river-basin overexploitation (India, South Asia, the Middle East, and Northern Africa) whilst different water management options are considered through four alternative allocation methods across users. The scale of macroeconomic effects is dependent on the relative size of sectors with low-water productivity, the amount of water uses in these sectors, and the flexibility of important water users to substitute away from water inputs in conditions of scarcity. The largest negative GDP deviations are obtained in scenarios with limited mobility to re-allocate water across users. A significant alleviation is obtained when demand patterns are shifted based on differences in water productivity, however, with a significant imposition on food security prospects. Full article
(This article belongs to the Special Issue Hydroeconomic Analysis for Sustainable Water Management)
Figures

Figure 1

Open AccessArticle Future Changes in Flood Hazards across Canada under a Changing Climate
Water 2018, 10(10), 1441; https://doi.org/10.3390/w10101441
Received: 4 September 2018 / Revised: 2 October 2018 / Accepted: 7 October 2018 / Published: 13 October 2018
PDF Full-text (5381 KB) | HTML Full-text | XML Full-text
Abstract
Climate change has induced considerable changes in the dynamics of key hydro-climatic variables across Canada, including floods. In this study, runoff projections made by 21 General Climate Models (GCMs) under four Representative Concentration Pathways (RCPs) are used to generate 25 km resolution streamflow
[...] Read more.
Climate change has induced considerable changes in the dynamics of key hydro-climatic variables across Canada, including floods. In this study, runoff projections made by 21 General Climate Models (GCMs) under four Representative Concentration Pathways (RCPs) are used to generate 25 km resolution streamflow estimates across Canada for historical (1961–2005) and future (2061–2100) time-periods. These estimates are used to calculate future projected changes in flood magnitudes and timings across Canada. Results obtained indicate that flood frequencies in the northernmost regions of Canada, and south-western Ontario can be expected to increase in the future. As an example, the historical 100-year return period events in these regions are expected to become 10–60 year return period events. On the other hand, northern prairies and north-central Ontario can be expected to experience decreases in flooding frequencies in future. The historical 100-year return period flood events in these regions are expected to become 160–200 year return period events in future. Furthermore, prairies, parts of Quebec, Ontario, Nunavut, and Yukon territories can be expected to experience earlier snowmelt-driven floods in the future. The results from this study will help decision-makers to effectively manage and design municipal and civil infrastructure in Canada under a changing climate. Full article
(This article belongs to the Special Issue Extreme Floods and Droughts under Future Climate Scenarios)
Figures

Figure 1

Open AccessArticle Reducing Computational Costs of Automatic Calibration of Rainfall-Runoff Models: Meta-Models or High-Performance Computers?
Water 2018, 10(10), 1440; https://doi.org/10.3390/w10101440
Received: 12 September 2018 / Revised: 28 September 2018 / Accepted: 3 October 2018 / Published: 12 October 2018
PDF Full-text (5617 KB) | HTML Full-text | XML Full-text
Abstract
Robust calibration of hydrologic models is critical for simulating water resource components; however, the time-consuming process of calibration sometimes impedes the accurate parameters’ estimation. The present study compares the performance of two approaches applied to overcome the computational costs of automatic calibration of
[...] Read more.
Robust calibration of hydrologic models is critical for simulating water resource components; however, the time-consuming process of calibration sometimes impedes the accurate parameters’ estimation. The present study compares the performance of two approaches applied to overcome the computational costs of automatic calibration of the HEC-HMS (Hydrologic Engineering Center-Hydrologic Modeling System) model constructed for the Tamar basin located in northern Iran. The model is calibrated using the Particle Swarm Optimization (PSO) algorithm. In the first approach, a machine learning algorithm, i.e., Artificial Neural Network (ANN) was trained to act as a surrogate for the original HMS (ANN-PSO), while in the latter, the computational tasks were distributed among different processors. Due to inefficacy of preliminary ANN-PSO, an efficient adaptive technique was employed to boost training and accelerate the convergence of optimization. We found that both approaches were helpful in improving computational efficiency. For jointly-events calibrations schemes, meta-models outperformed parallelization due to effective exploration of calibration space, where parallel processing was not practical owing to the time required for data sharing and collecting among many clients. Model approximation using meta-models becomes highly complex, particularly in the presence of combining more events, because larger numbers of samples and much longer training times are required. Full article
(This article belongs to the Section Hydrology)
Figures

Figure 1

Open AccessArticle Study of Cavitation Bubble Collapse near a Wall by the Modified Lattice Boltzmann Method
Water 2018, 10(10), 1439; https://doi.org/10.3390/w10101439
Received: 2 September 2018 / Revised: 21 September 2018 / Accepted: 3 October 2018 / Published: 12 October 2018
PDF Full-text (5446 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an improved lattice Boltzmann Shan‒Chen model coupled with Carnahan-Starling equation of state (C-S EOS) and the exact differential method (EDM) force scheme is used to simulate the cavitation bubble collapse in the near-wall region. First, the collapse of a single
[...] Read more.
In this paper, an improved lattice Boltzmann Shan‒Chen model coupled with Carnahan-Starling equation of state (C-S EOS) and the exact differential method (EDM) force scheme is used to simulate the cavitation bubble collapse in the near-wall region. First, the collapse of a single cavitation bubble in the near-wall region was simulated; the results were in good agreement with the physical experiment and the stability of the model was verified. Then the simulated model was used to simulate the collapse of two cavitation bubbles in the near-wall region. The main connection between the two cavitation bubble centre lines and the wall surface had a 45° angle and parallel and the evolution law of cavitation bubbles in the near-wall region is obtained. Finally, the effects of a single cavitation bubble and double cavitation bubble on the wall surface in the near-wall region are compared, which can be used to study the method to reduce the influence of cavitation on solid materials in practical engineering. The cavitation bubble collapse process under a two-dimensional pressure field is visualized, and the flow field is used to describe the morphological changes of cavitation bubble collapse in the near-wall region. The improved lattice Boltzmann Method (LBM) Shan‒Chen model has many advantages in simulating cavitation problems, and will provide a reference for further simulations. Full article
(This article belongs to the Special Issue Advances in Hydraulics and Hydroinformatics)
Figures

Figure 1

Open AccessArticle Potential Changes of Annual-Averaged Nutrient Export in the South Saskatchewan River Basin under Climate and Land-Use Change Scenarios
Water 2018, 10(10), 1438; https://doi.org/10.3390/w10101438
Received: 29 July 2018 / Revised: 24 September 2018 / Accepted: 29 September 2018 / Published: 12 October 2018
PDF Full-text (5887 KB) | HTML Full-text | XML Full-text
Abstract
Climate and land-use changes modify the physical functioning of river basins and, in particular, influence the transport of nutrients from land to water. In large-scale basins, where a variety of climates, topographies, soil types and land uses co-exist to form a highly heterogeneous
[...] Read more.
Climate and land-use changes modify the physical functioning of river basins and, in particular, influence the transport of nutrients from land to water. In large-scale basins, where a variety of climates, topographies, soil types and land uses co-exist to form a highly heterogeneous environment, a more complex nutrient dynamic is imposed by climate and land-use changes. This is the case of the South Saskatchewan River (SSR) that, along with the North Saskatchewan River, forms one of the largest river systems in western Canada. The SPAtially Referenced Regression On Watershed (SPARROW) model is therefore implemented to assess water quality in the basin, in order to describe spatial and temporal patterns and identify those factors and processes that affect water quality. Forty-five climate and land-use change scenarios comprehended by five General Circulation Models (GCMs) and three Representative Concentration Pathways (RCPs) were incorporated into the model to explain how total nitrogen (TN) and total phosphorus (TP) export could vary across the basin in 30, 60 and 90 years from now. According to model results, annual averages of TN and TP export in the SSR are going to increase in the range 0.9–1.28 kg km 2 year 1 and 0.12–0.17 kg km 2 year 1 , respectively, by the end of the century, due to climate and land-use changes. Higher increases of TP compared to TN are expected since TP and TN are going to increase ∼36% and ∼21%, respectively, by the end of the century. This research will support management plans in order to mitigate nutrient export under future changes of climate and land use. Full article
(This article belongs to the Special Issue Water Quality and Ecosystems in Times of Climate Change)
Figures

Figure 1

Open AccessArticle Efficiency of Flood Control Measures in a Sewer System Located in the Mediterranean Basin
Water 2018, 10(10), 1437; https://doi.org/10.3390/w10101437
Received: 17 September 2018 / Revised: 9 October 2018 / Accepted: 9 October 2018 / Published: 12 October 2018
PDF Full-text (2620 KB) | HTML Full-text | XML Full-text
Abstract
Pollution induced by surface runoff in urban areas constitutes a significant problem. The adoption of control measures aimed at improving the quality of recipient water bodies is a fundamental issue in the management of Mediterranean Basin sewer systems. Previous research in Mediterranean areas
[...] Read more.
Pollution induced by surface runoff in urban areas constitutes a significant problem. The adoption of control measures aimed at improving the quality of recipient water bodies is a fundamental issue in the management of Mediterranean Basin sewer systems. Previous research in Mediterranean areas using small virtual basins has shown that rainfall regimes have a limited impact on the pollutant load and discharge flowing into a receiving body. The aim of our research was to identify a sizing methodology for stormwater tanks located in the Mediterranean Basin. To achieve this, a numerical model of a sewer system, located in the Southern Iberian Peninsula, was developed. Different patterns related to peak periods of rainfall were considered. Furthermore, efficiency indices were used to evaluate and compare the effects of having a stormwater tank in the system. In our study (which considered a real area), significantly varied values were obtained for the pollution load removal rate (η) and the receiver overflow rate (θ). We nevertheless observed that, in our catchment, at a specific volume of V = 60 m3/ha, η and θ reached constant values without experiencing any significant improvement (η = 0.673 and θ = 0.133). Based on our model, this volume was proposed for the stormwater tank. The ATV (German Association for Water Pollution Control) A 128 standard was applied in order to validate the results, and the specific volume obtained (V = 60 m3/ha) matched with the one proposed. Thus, our proposed methodology is simple and different, and it is very easy to apply by obtaining the values of the efficiency indices η and θ through the development of a Storm Water Management Model (SWMM). Full article
(This article belongs to the Section Urban Water Management)
Figures

Figure 1

Open AccessArticle Observed Trends of Climate and River Discharge in Mongolia’s Selenga Sub-Basin of the Lake Baikal Basin
Water 2018, 10(10), 1436; https://doi.org/10.3390/w10101436
Received: 11 September 2018 / Revised: 1 October 2018 / Accepted: 9 October 2018 / Published: 12 October 2018
PDF Full-text (3632 KB) | HTML Full-text | XML Full-text
Abstract
Mongolia’s Selenga sub-basin of the Lake Baikal basin is spatially extensive, with pronounced environmental gradients driven primarily by precipitation and air temperature on broad scales. Therefore, it is an ideal region to examine the dynamics of the climate and the hydrological system. This
[...] Read more.
Mongolia’s Selenga sub-basin of the Lake Baikal basin is spatially extensive, with pronounced environmental gradients driven primarily by precipitation and air temperature on broad scales. Therefore, it is an ideal region to examine the dynamics of the climate and the hydrological system. This study investigated the annual precipitation, air temperature, and river discharge variability at five selected stations of the sub-basin by using Mann-Kendall (MK), Innovative trend analysis method (ITAM), and Sen’s slope estimator test. The result showed that the trend of annual precipitation was slightly increasing in Ulaanbaatar (Z = 0.71), Erdenet (Z = 0.13), and Tsetserleg (Z = 0.26) stations. Whereas Murun (Z = 2.45) and Sukhbaatar (Z = 1.06) stations showed a significant increasing trend. And also, the trend of annual air temperature in Ulaanbaatar (Z = 5.88), Erdenet (Z = 3.87), Tsetserleg (Z = 4.38), Murun (Z = 4.77), and Sukhbaatar (Z = 2.85) was sharply increased. The average air temperature has significantly increased by 1.4 °C in the past 38 years. This is very high in the semi-arid zone of central Asia. The river discharge showed a significantly decreasing trend during the study period years. It has been apparent since 1995. The findings of this paper could help researchers to understand the annual variability of precipitation, air temperature, and river discharge over the study region and, therefore, become a foundation for further studies. Full article
Figures

Figure 1

Open AccessFeature PaperArticle Experimental Optimization of Gate-Opening Modes to Minimize Near-Field Vibrations in Hydropower Stations
Water 2018, 10(10), 1435; https://doi.org/10.3390/w10101435
Received: 26 July 2018 / Revised: 3 October 2018 / Accepted: 10 October 2018 / Published: 12 October 2018
PDF Full-text (9375 KB) | HTML Full-text | XML Full-text
Abstract
Multi-Horizontal-Submerged Jets are successfully applied to dissipate energy within a large-scale hydropower station. However, notable near-field vibrations are generated when releasing high discharges through the gates, which is generally typical in a flooding case scenario. Under these conditions, the magnitude of the vibrations
[...] Read more.
Multi-Horizontal-Submerged Jets are successfully applied to dissipate energy within a large-scale hydropower station. However, notable near-field vibrations are generated when releasing high discharges through the gates, which is generally typical in a flooding case scenario. Under these conditions, the magnitude of the vibrations varies when applying different gate-opening modes. To investigate and find optimized gate-opening modes to reduce the near-field vibration, multiple combinations were tested by varying gate-opening modes and hydraulic conditions. For each of the tests conducted, fluctuating pressures acting on side-walls and bottoms of a stilling basin were measured. The collected datasets were used to determine the maximum and minimum fluctuating pressure values associated with the correspondent gate-opening mode and a detailed comparison between each of the gate-opening modes was completed. The paper presents the quantitative analysis of the discharge ratio’s effect on fluctuating pressures. It also investigates the influence of different gate-opening modes by including side to middle spillways and upper to lower spillways configurations. The flow pattern evolutions triggered by each different gate-opening mode are discussed and optimal configurations that minimize near-field vibrations at high discharges are recommended to support both the design of new systems and assessment of the performance of existing ones. Full article
(This article belongs to the Special Issue Advances in Hydraulics and Hydroinformatics)
Figures

Figure 1

Open AccessArticle Multiperiod Optimisation of Irrigated Crops under Different Conditions of Water Availability
Water 2018, 10(10), 1434; https://doi.org/10.3390/w10101434
Received: 10 August 2018 / Revised: 30 September 2018 / Accepted: 9 October 2018 / Published: 12 October 2018
PDF Full-text (762 KB) | HTML Full-text | XML Full-text
Abstract
We propose a nonlinear optimisation model which maximises profits by resource allocation on a monthly time scale, considering a monthly crop yield model. The proposed model was applied to six management scenarios (two seasonal and four monthly), nine conditions of water availability, and
[...] Read more.
We propose a nonlinear optimisation model which maximises profits by resource allocation on a monthly time scale, considering a monthly crop yield model. The proposed model was applied to six management scenarios (two seasonal and four monthly), nine conditions of water availability, and two situations of resource availability under Chilean conditions. These situations provided the same seasonal amount of resources, but different distributions over time. The model included improvements in water resource management such as water storage and water transactions, being the latter a monthly decision variable that can increase farmers’ profits. According to our results, monthly scenarios gave high profits, even better with appropriate resource distribution. When water costs are high, water transactions allow loss reduction of up to 50%. Regarding labour, the lack of availability is more critical than the wages. Full article
Figures

Figure 1

Open AccessArticle Computational Determination of Air Valves Capacity Using CFD Techniques
Water 2018, 10(10), 1433; https://doi.org/10.3390/w10101433
Received: 7 September 2018 / Revised: 4 October 2018 / Accepted: 8 October 2018 / Published: 12 October 2018
PDF Full-text (2199 KB) | HTML Full-text | XML Full-text
Abstract
The analysis of transient flow is necessary to design adequate protection systems that support the oscillations of pressure produced in the operation of motor elements and regulation. Air valves are generally used in pressurized water pipes to manage the air inside them. Under
[...] Read more.
The analysis of transient flow is necessary to design adequate protection systems that support the oscillations of pressure produced in the operation of motor elements and regulation. Air valves are generally used in pressurized water pipes to manage the air inside them. Under certain circumstances, they can be used as an indirect control mechanism of the hydraulic transient. Unfortunately, one of the major limitations is the reliability of information provided by manufacturers and vendors, which is why experimental trials are usually used to characterize such devices. The realization of these tests is not simple since they require an enormous volume of previously stored air to be used in such experiments. Additionally, the costs are expensive. Consequently, it is necessary to develop models that represent the behaviour of these devices. Although computational fluid dynamics (CFD) techniques cannot completely replace measurements, the amount of experimentation and the overall cost can be reduced significantly. This work approaches the characterization of air valves using CFD techniques, including some experimental tests to calibrate and validate the results. A mesh convergence analysis was made. The results show how the CFD models are an efficient alternative to represent the behavior of air valves during the entry and exit of air to the system, implying a better knowledge of the system to improve it. Full article
(This article belongs to the Special Issue New Challenges in Water Systems)
Figures

Graphical abstract

Open AccessArticle Regulatory Challenges for the Use of Reclaimed Water in Mexico: A Case Study in Baja California
Water 2018, 10(10), 1432; https://doi.org/10.3390/w10101432
Received: 18 September 2018 / Revised: 9 October 2018 / Accepted: 10 October 2018 / Published: 12 October 2018
PDF Full-text (9631 KB) | HTML Full-text | XML Full-text
Abstract
In Mexico, water planning is based on the National Water Law, the core of which is Integrated Water Resources Management (IWRM). The municipality provides wastewater treatment and reuse, and an integrated approach is mandatory for these processes. However, a traditional (non-integrated) management regime
[...] Read more.
In Mexico, water planning is based on the National Water Law, the core of which is Integrated Water Resources Management (IWRM). The municipality provides wastewater treatment and reuse, and an integrated approach is mandatory for these processes. However, a traditional (non-integrated) management regime has prevailed in water legislation, resulting in pollution and the inefficient use of water. The objectives of this research were to analyze the Mexican legal framework and international guidelines in the use of reclaimed water for agricultural irrigation and environmental discharges, and to evaluate challenges facing reclaimed water in the Maneadero Valley, Baja California, as a case study. Results show that wastewater reuse was implemented in the absence of integrative planning and assessment of the potential impacts on the environment and public health. In addition, gaps between decisions linked to the legal attributes of the relevant institutions were identified. Defined roles across the three levels of authority, transparent and congruent funding, coherent water-quality requirements and the strengthening of stakeholder participation are needed to adopt integrated water resource management for reclaimed water use. The alignment of common goals on public health, environmental protection and agricultural development between authorities and the different sectors is crucial to bridge these challenges. Full article
(This article belongs to the Section Water Resources Management and Governance)
Figures

Figure 1

Open AccessArticle Artificial Neural Networks for Predicting the Water Retention Curve of Sicilian Agricultural Soils
Water 2018, 10(10), 1431; https://doi.org/10.3390/w10101431
Received: 4 July 2018 / Revised: 2 October 2018 / Accepted: 8 October 2018 / Published: 12 October 2018
PDF Full-text (2311 KB) | HTML Full-text | XML Full-text
Abstract
Modeling soil-water regime and solute transport in the vadose zone is strategic for estimating agricultural productivity and optimizing irrigation water management. Direct measurements of soil hydraulic properties, i.e., the water retention curve and the hydraulic conductivity function, are often expensive and time-consuming, and
[...] Read more.
Modeling soil-water regime and solute transport in the vadose zone is strategic for estimating agricultural productivity and optimizing irrigation water management. Direct measurements of soil hydraulic properties, i.e., the water retention curve and the hydraulic conductivity function, are often expensive and time-consuming, and represent a major obstacle to the application of simulation models. As a result, there is a great interest in developing pedotransfer functions (PTFs) that predict the soil hydraulic properties from more easily measured and/or routinely surveyed soil data, such as particle size distribution, bulk density (ρb), and soil organic carbon content (OC). In this study, application of PTFs was carried out for 359 Sicilian soils by implementing five different artificial neural networks (ANNs) to estimate the parameter of the van Genuchten (vG) model for water retention curves. The raw data used to train the ANNs were soil texture, ρb, OC, and porosity. The ANNs were evaluated in their ability to predict both the vG parameters, on the basis of the normalized root-mean-square errors (NRMSE) and normalized mean absolute errors (NMAE), and the water retention data. The Akaike’s information criterion (AIC) test was also used to assess the most efficient network. Results confirmed the high predictive performance of ANNs with four input parameters (clay, sand, and silt fractions, and OC) in simulating soil water retention data, with a prediction accuracy characterized by MAE = 0.026 and RMSE = 0.069. The AIC efficiency criterion indicated that the most efficient ANN model was trained with a relatively low number of input nodes. Full article
(This article belongs to the Special Issue Soil Hydrology in Agriculture)
Figures

Figure 1

Open AccessArticle Three-Dimensional Aerators: Characteristics of the Air Bubbles
Water 2018, 10(10), 1430; https://doi.org/10.3390/w10101430
Received: 26 August 2018 / Revised: 29 September 2018 / Accepted: 29 September 2018 / Published: 12 October 2018
PDF Full-text (10581 KB) | HTML Full-text | XML Full-text
Abstract
Three-dimensional aerators are often used in hydraulic structures to prevent cavitation damage via enhanced air entrainment. However, the mechanisms of aeration and bubble dispersion along the developing shear flow region on such aerators remain unclear. A double-tip conductivity probe is employed in present
[...] Read more.
Three-dimensional aerators are often used in hydraulic structures to prevent cavitation damage via enhanced air entrainment. However, the mechanisms of aeration and bubble dispersion along the developing shear flow region on such aerators remain unclear. A double-tip conductivity probe is employed in present experimental study to investigate the air concentration, bubble count rate, and bubble size downstream of a three-dimensional aerator involving various approach-flow features and geometric parameters. The results show that the cross-sectional distribution of the air bubble frequency is in accordance with the Gaussian distribution, and the relationship between the air concentration and bubble frequency obeys a quasi-parabolic law. The air bubble frequency reaches an apex at an air concentration (C) of approximately 50% and decreases to zero as C = 0% and C = 100%. The relative location of the air-bubble frequency apex is 0.210, 0.326 and 0.283 times the thickness of the layers at the upper, lower and side nappes, respectively. The air bubble chord length decreases gradually from the air water interface to the core area. The air concentration increases exponentially with the bubble chord length. The air bubble frequency distributions can be fit well using a “modified” gamma distribution function. Full article
(This article belongs to the Special Issue Advances in Hydraulics and Hydroinformatics)
Figures

Figure 1

Open AccessArticle Risk-Based Decision-Making for Evacuation in Case of Imminent Threat of Flooding
Water 2018, 10(10), 1429; https://doi.org/10.3390/w10101429
Received: 26 July 2018 / Revised: 31 August 2018 / Accepted: 27 September 2018 / Published: 11 October 2018
PDF Full-text (1119 KB) | HTML Full-text | XML Full-text
Abstract
It is important for decision-makers in emergency response situations to determine the scope, scale, timing, path and resettlement area of an evacuation decision when there is an imminent threat of flooding. In this paper, a method called the “Evacuation Diagram” is described to
[...] Read more.
It is important for decision-makers in emergency response situations to determine the scope, scale, timing, path and resettlement area of an evacuation decision when there is an imminent threat of flooding. In this paper, a method called the “Evacuation Diagram” is described to support risk-based evacuation planning and decision-making. In case of an imminent threat of flooding, we refer to the conditional risk, which is the risk given the forecasted water levels and potential consequences during the next days of the event. Given the threat and potential costs and benefits, evacuation decisions have to mitigate this conditional risk. Since evacuation can be costly, decision-makers have to make a trade-off between costs and benefits. In this research we present a method using a cost–benefit analysis approach, in which we adopt the “Dutch flood risk approach” to define the required strength of levees based on flood risk considerations. The “Evacuation Diagram” method is derived from analytical derivations, based on differential weighing of costs and benefits, which have an impact on a binary choice (or a set of discrete choices) as to whether to instruct an area to evacuate or not. Basically, this is an analysis of behavioural decision-making under risk, investigating how a cost–benefit analysis can yield higher cost effectiveness in risk reduction for human lives lost during possible evacuation incidents. The method is applied to a Dutch case study and the results are compared to the outcomes of the largest evacuation exercise ever held in the Netherlands, called ‘Waterproef’. It is concluded that the risk-based evacuation method, as presented in this paper, provides useful insight into collective and authoritative evacuation order decisions. Full article
(This article belongs to the Section Water Resources Management and Governance)
Figures

Figure 1

Open AccessArticle Remote Sensing of Water Quality Parameters over Lake Balaton by Using Sentinel-3 OLCI
Water 2018, 10(10), 1428; https://doi.org/10.3390/w10101428
Received: 23 July 2018 / Revised: 24 September 2018 / Accepted: 4 October 2018 / Published: 11 October 2018
PDF Full-text (2254 KB) | HTML Full-text | XML Full-text
Abstract
The Ocean and Land Color Instrument (OLCI) onboard Sentinel 3A satellite was launched in February 2016. Level 2 (L2) products have been available for the public since July 2017. OLCI provides the possibility to monitor aquatic environments on 300 m spatial resolution on
[...] Read more.
The Ocean and Land Color Instrument (OLCI) onboard Sentinel 3A satellite was launched in February 2016. Level 2 (L2) products have been available for the public since July 2017. OLCI provides the possibility to monitor aquatic environments on 300 m spatial resolution on 9 spectral bands, which allows to retrieve detailed information about the water quality of various type of waters. It has only been a short time since L2 data became accessible, therefore validation of these products from different aquatic environments are required. In this work we study the possibility to use S3 OLCI L2 products to monitor an optically highly complex shallow lake. We test S3 OLCI-derived Chlorophyll-a (Chl-a), Colored Dissolved Organic Matter (CDOM) and Total Suspended Matter (TSM) for complex waters against in situ measurements over Lake Balaton in 2017. In addition, we tested the machine learning Gaussian process regression model, trained locally as a potential candidate to retrieve water quality parameters. We applied the automatic model selection algorithm to select the combination and number of spectral bands for the given water quality parameter to train the Gaussian Process Regression model. Lake Balaton represents different types of aquatic environments (eutrophic, mesotrophic and oligotrophic), hence being able to establish a model to monitor water quality by using S3 OLCI products might allow the generalization of the methodology. Full article
(This article belongs to the Special Issue Novel Lake Water Quality Monitoring Strategies)
Figures

Figure 1

Open AccessArticle FDOM Conversion in Karst Watersheds Expressed by Three-Dimensional Fluorescence Spectroscopy
Water 2018, 10(10), 1427; https://doi.org/10.3390/w10101427
Received: 31 May 2018 / Revised: 4 October 2018 / Accepted: 4 October 2018 / Published: 11 October 2018
PDF Full-text (2138 KB) | HTML Full-text | XML Full-text
Abstract
A karst system, formed by the dissolution of carbonate rocks, is usually susceptible to contamination. Little is known about the composition of natural dissolved organic matter (DOM) in groundwater systems, especially in karstic groundwater. To reveal the characteristics of DOM in a karst
[...] Read more.
A karst system, formed by the dissolution of carbonate rocks, is usually susceptible to contamination. Little is known about the composition of natural dissolved organic matter (DOM) in groundwater systems, especially in karstic groundwater. To reveal the characteristics of DOM in a karst aquifer, the Yufuhe River Basin, a typical karst watershed in northern China, was selected. DOM fluorescence (FDOM) was measured with the excitation-emission matrices (EEMs) spectroscopy technique. Parallel factor analysis (PARAFAC) was used to analyze the karst hydrogeological factors that affect FDOM biogeochemical behavior. Three fluorescent components, i.e., tyrosine-like, tryptophan-like, and ultraviolet fulvic acid were found. Their fluorescence properties were closely related to human activity and subterranean hydrology. Fluorescence properties suggested that FDOM in the Yufuhe River karst aquifer was predominant from anthropogenic activity. In addition, due to the effect of karstic heterogeneous hydrological conditions, FDOM showed obvious differentiation in the recharge, flow path, and discharge systems. The FDOM fluorescence intensity (FI) was weak in surface water and groundwater at the upper reaches (recharge area). In the middle of the flow path area, the percentage of tyrosine-like and tryptophan-like substances degraded and fulvic acid rose gradually. However, after infiltrating into the lower reaches (discharge area) of the deep karst aquifer system, the fulvic acid matter was consumed and protein-like matter accumulated. Full article
(This article belongs to the Special Issue Watershed Hydrology, Erosion and Sediment Transport Processes)
Figures

Graphical abstract

Open AccessArticle The Interrelations between a Multi-Layered Coastal Aquifer, a Surface Reservoir (Fish Ponds), and the Sea
Water 2018, 10(10), 1426; https://doi.org/10.3390/w10101426
Received: 1 September 2018 / Revised: 29 September 2018 / Accepted: 3 October 2018 / Published: 11 October 2018
PDF Full-text (6971 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This research examines the interrelations in a complex hydrogeological system, consisting of a multi-layered coastal aquifer, the sea, and a surface reservoir (fish ponds) and the importance of the specific connection between the aquifer and the sea. The paper combines offshore geophysical surveys
[...] Read more.
This research examines the interrelations in a complex hydrogeological system, consisting of a multi-layered coastal aquifer, the sea, and a surface reservoir (fish ponds) and the importance of the specific connection between the aquifer and the sea. The paper combines offshore geophysical surveys (CHIRP) and on land TDEM (Time Domain Electro Magnetic), together with hydrological measurements and numerical simulation. The Quaternary aquifer at the southern Carmel plain is sub-divided into three units, a sandy phreatic unit, and two calcareous sandstone (‘Kurkar’) confined units. The salinity in the different units is affected by their connection with the sea. We show that differences in the seaward extent of its clayey roof, as illustrated in the CHIRP survey, result in a varying extent of seawater intrusion due to pumping from the confined units. FEFLOW simulations indicate that the FSI (Fresh Saline water Interface) reached the coastline just a few years after pumping has begun, where the roof terminates ~100 m from shore, while no seawater intrusion occurred in an area where the roof is continuous farther offshore. This was found to be consistent with borehole observations and TDEM data from our study sites. The water level in the coastal aquifer was generally stable with surprisingly no indication for significant seawater intrusion although the aquifer is extensively pumped very close to shore. This is explained by contribution from the underlying Late Cretaceous aquifer, which increased with the pumping rate, as is also indicated by the numerical simulations. Full article
Figures

Graphical abstract

Open AccessArticle Two-Dimensional Numerical Simulation Study on Bed-Load Transport in the Fluctuating Backwater Area: A Case-Study Reservoir in China
Water 2018, 10(10), 1425; https://doi.org/10.3390/w10101425
Received: 22 August 2018 / Revised: 1 October 2018 / Accepted: 2 October 2018 / Published: 11 October 2018
PDF Full-text (4460 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Numerical modeling of sedimentation and erosion in reservoirs is an active field of reservoir research. However, simulation of the bed-load transport phenomena has rarely been applied to other water bodies, in particular, the fluctuating backwater area. This is because the complex morphological processes
[...] Read more.
Numerical modeling of sedimentation and erosion in reservoirs is an active field of reservoir research. However, simulation of the bed-load transport phenomena has rarely been applied to other water bodies, in particular, the fluctuating backwater area. This is because the complex morphological processes interacting between hydrodynamics and sediment transport are generally challenging to accurately predict. Most researchers assert that the shape of a river channel is mainly determined by the upstream water and sediment, and the physical boundary conditions of the river channel, rather than random events. In this study, the refinement and application of a two-dimensional shallow-water and bed-load transport model to the fluctuating backwater area is described. The model employs the finite volume method of the Godunov scheme and equilibrium sediment transport equations. The model was verified using experimental data produced by a scaled physical model, and the results indicated that the numerical model is believable. The numerical model was then applied to actual reservoir operations, including reservoir storage, reservoir drawdown, and the continuous flood process, to predict the morphology of reservoir sedimentation and sediment transport rates, and the changes in bed level in the fluctuating backwater area. It was found that the location and morphology of sedimentation affected by the downstream water level result in random evolution of the river bed, and bed-load sedimentation is moved from upstream to downstream as the slope of the longitudinal section of the river bed is reduced. Moreover, the research shows that the river channel sedimentation morphology is changed by the change water level of the downstream reach, causing the dislocation of the beach and channel and random events that will affect the river, which is of certain reference value for waterway regulation. Full article
(This article belongs to the Section Hydraulics)
Figures

Figure 1

Open AccessArticle Understanding Morphodynamic Changes of a Tidal River Confluence through Field Measurements and Numerical Modeling
Water 2018, 10(10), 1424; https://doi.org/10.3390/w10101424
Received: 20 August 2018 / Revised: 4 October 2018 / Accepted: 8 October 2018 / Published: 11 October 2018
PDF Full-text (10590 KB) | HTML Full-text | XML Full-text
Abstract
A confluence is a natural component in river and channel networks. This study deals, through field and numerical studies, with alluvial behaviors of a confluence affected by both river run-off and strong tides. Field measurements were conducted along the rivers including the confluence.
[...] Read more.
A confluence is a natural component in river and channel networks. This study deals, through field and numerical studies, with alluvial behaviors of a confluence affected by both river run-off and strong tides. Field measurements were conducted along the rivers including the confluence. Field data show that the changes in flow velocity and sediment concentration are not always in phase with each other. The concentration shows a general trend of decrease from the river mouth to the confluence. For a given location, the tides affect both the sediment concentration and transport. A two-dimensional hydrodynamic model of suspended load was set up to illustrate the combined effects of run-off and tidal flows. Modeled cases included the flood and ebb tides in a wet season. Typical features examined included tidal flow fields, bed shear stress, and scour evolution in the confluence. The confluence migration pattern of scour is dependent on the interaction between the river currents and tidal flows. The flood tides are attributable to the suspended load deposition in the confluence, while the ebb tides in combination with run-offs lead to erosion. The flood tides play a dominant role in the morphodynamic changes of the confluence. Full article
Figures

Figure 1

Back to Top