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Special Issue "Water Resources and Environmental Fluid Mechanics: From the Glacier to the Lake/Ocean"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydraulics".

Deadline for manuscript submissions: closed (15 May 2018)

Special Issue Editors

Guest Editor
Prof. Koen Blanckaert

Research Center of Hydraulic Engineering, Vienna University of Technology, Vienna, Austria
Website | E-Mail
Interests: hydraulics; fluid mechanics; geomorphology; ecohydraulics; civil and environmental engineering
Guest Editor
Dr. Damien Bouffard

Department Surface Waters Research & Management, EAWAG, Seestrasse 79, 6047 Kastanienbaum, Switzerland
Website | E-Mail
Interests: environmental fluid mechanics; physical limnology; hydrodynamic and water quality modelling; turbulence and mixing in stratified flows

Special Issue Information

Dear Colleagues,

Water resources managers and engineers often need to balance conflicting objectives, such as hazard mitigation (floods, droughts), socio-economic use (hydropower, navigation, leisure), and environmental protection (conservation or restoration of ecosystem functions). They are faced with problems occurring all along the river axis, from the glacier upstream in the watershed, to the lake or ocean at its downstream end. Spatial scales in river systems are intrinsically related, i.e, local interventions, often have implications far upstream and/or downstream on the river and the final receiving water body, and large-scale changes to hydrology or morphology affect local processes. Water resources and environmental fluid mechanics become ever more multidisciplinary, and the development of tools for design or objective decision-making requires insight in processes occurring where water, sediment and biota meet. New measurement technologies and state-of-the-art experimental investigations in the field and in the laboratory are key to enhancing insight. The present Special Issue particularly welcomes contributions that: (i) focus on eco-hydro-morphological processes; (ii) focus on the relation between processes occurring at different locations along the river axis and in the downstream lake or ocean or at different spatial scales; and (iii) focus on experimental studies in the field and in the laboratory.

Prof. Koen Blanckaert
Dr. Damien Bouffard
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • environmental fluid mechanics

  • water resources

  • eco-hydro-morphological processes

  • instrumentation

  • field experiments

  • laboratory experiments

  • turbulent mixing and transport

  • downstream and upstream effects

Published Papers (10 papers)

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Research

Open AccessArticle Observation of the Dynamics and Horizontal Dispersion in a Shallow Intermittently Closed and Open Lake and Lagoon (ICOLL)
Water 2018, 10(6), 776; https://doi.org/10.3390/w10060776
Received: 28 March 2018 / Revised: 5 June 2018 / Accepted: 11 June 2018 / Published: 13 June 2018
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Abstract
Among the 135 or more estuaries on the southeast Australian coastline, 45% are intermittently open. A number of others, which would normally have an intermittently open entrance, are kept permanently open to improve the flushing and water quality that are functions of the
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Among the 135 or more estuaries on the southeast Australian coastline, 45% are intermittently open. A number of others, which would normally have an intermittently open entrance, are kept permanently open to improve the flushing and water quality that are functions of the horizontal dispersion of the estuarine system. Field studies that investigate the dynamics and horizontal dispersion processes of open and closed states of Intermittenly Closed and Open Lakes and Lagoons (ICOLL) are conducted. Clusters of Lagrangian drifters were used to characterise the surface flow. Horizontal dispersion coefficients (K) under study varied significantly for different tidal phases; the mean ebb tide K (~4.7 ± 3.8 m2 s−1) is an order of magnitude higher than that of the flood tide. During the closed state, K values were up to two orders of magnitude lower than those observed in the open state. These results highlight the contribution of tidal dispersion to transport and mixing processes within an ICOLL. The results showed that tidal pumping effects and tidal-induced horizontal velocity gradients are responsible for the horizontal surface transport and dispersion occurring during the open inlet state. The horizontal surface dispersion processes identified at different inlets and environmental conditions within this site are valuable for managing transport of particles, freshwater mixing, larvae transport, waste, and pest control. Full article
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Open AccessArticle An Unstructured-Grid Based Morphodynamic Model for Sandbar Simulation in the Modaomen Estuary, China
Water 2018, 10(5), 611; https://doi.org/10.3390/w10050611
Received: 23 March 2018 / Revised: 29 April 2018 / Accepted: 4 May 2018 / Published: 8 May 2018
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Abstract
The Modaomen Estuary is the most important passageway in discharging flood and sediment of the Pearl River Delta, which is one of the most complex estuarine systems in China. Due to the coupling effect among tidal currents, waves, and sediments, an immense sandbar
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The Modaomen Estuary is the most important passageway in discharging flood and sediment of the Pearl River Delta, which is one of the most complex estuarine systems in China. Due to the coupling effect among tidal currents, waves, and sediments, an immense sandbar area evolved in the outer subaqueous delta, impeding the flood releasing during wet season, as well as salinity intrusion during the dry season. In this work, an unstructured-grid based morphodynamic model was proposed to simulate the sandbar evolution process in the Modaomen Estuary. The proposed model was constructed by using the two-dimensional shallow water equations for tidal flow, the advection-diffusion equations for salinity and suspended sediment transport, and the non-equilibrium formulation of the Exner equation for bed evolution. To simulate the wave-induced longshore currents in the Modaomen Estuary, an adaptive time-stepping approach was proposed to couple the unstructured-grid based Simulating WAves Nearshore (SWAN) model and the shallow flow model. An integrated solver is proposed for computing flow, salinity, and sediment transport fluxes simultaneously, and then the shallow water equations and advection-diffusion equations are jointly solved by a high-resolution, unstructured-grid Godunov method. Application of the model to the Modaomen Estuary, using calibrated parameter values, gives results comparable to the measured data. The butterfly shape of the sandbar in the Modaomen Estuary is considerably well simulated by the proposed model, which matches well with the measured topography. Full article
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Open AccessFeature PaperArticle A Methodology for Measuring Microplastic Transport in Large or Medium Rivers
Water 2018, 10(4), 414; https://doi.org/10.3390/w10040414
Received: 30 January 2018 / Revised: 27 March 2018 / Accepted: 28 March 2018 / Published: 2 April 2018
Cited by 2 | PDF Full-text (33127 KB) | HTML Full-text | XML Full-text
Abstract
Plastic waste as a persistent contaminant of our environment is a matter of increasing concern due to the largely unknown long-term effects on biota. Although freshwater systems are known to be the transport paths of plastic debris to the ocean, most research has
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Plastic waste as a persistent contaminant of our environment is a matter of increasing concern due to the largely unknown long-term effects on biota. Although freshwater systems are known to be the transport paths of plastic debris to the ocean, most research has been focused on marine environments. In recent years, freshwater studies have advanced rapidly, but they rarely address the spatial distribution of plastic debris in the water column. A methodology for measuring microplastic transport at various depths that is applicable to medium and large rivers is needed. We present a new methodology offering the possibility of measuring microplastic transport at different depths of verticals that are distributed within a profile. The net-based device is robust and can be applied at high flow velocities and discharges. Nets with different sizes (41 µm, 250 µm, and 500 µm) are exposed in three different depths of the water column. The methodology was tested in the Austrian Danube River, showing a high heterogeneity of microplastic concentrations within one cross section. Due to turbulent mixing, the different densities of the polymers, aggregation, and the growth of biofilms, plastic transport cannot be limited to the surface layer of a river, and must be examined within the whole water column as for suspended sediments. These results imply that multipoint measurements are required for obtaining the spatial distribution of plastic concentration and are therefore a prerequisite for calculating the passing transport. The analysis of filtration efficiency and side-by-side measurements with different mesh sizes showed that 500 µm nets led to optimal results. Full article
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Open AccessArticle Influence of Meander Confinement on Hydro-Morphodynamics of a Cohesive Meandering Channel
Water 2018, 10(4), 354; https://doi.org/10.3390/w10040354
Received: 6 January 2018 / Revised: 18 March 2018 / Accepted: 19 March 2018 / Published: 22 March 2018
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Abstract
Despite several decades of intensive study of the morphological changes in meandering rivers, less attention has been paid to confined meanders. This paper studies the hydro-morphodynamics of two adjacent sub-reaches of a meandering creek, located in the City of Ottawa, Canada. Both of
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Despite several decades of intensive study of the morphological changes in meandering rivers, less attention has been paid to confined meanders. This paper studies the hydro-morphodynamics of two adjacent sub-reaches of a meandering creek, located in the City of Ottawa, Canada. Both of these sub-reaches are meandering channels with cohesive bed and banks, but one is confined by a railway embankment. Field reconnaissance revealed distinct differences in the morphological characteristics of the sub-reaches. To further study this, channel migration and morphological changes of the channel banks along each of these sub-reaches were analyzed by comparing the historical aerial photography (2004, 2014), light detection and ranging (LIDAR) data (2006), bathymetric data obtained from a total station survey (2014), and field examination. Moreover, two different spatially intensive acoustic Doppler current profiler (ADCP) surveys were conducted in the study area to find the linkage between the hydrodynamics and morphological changes in the two different sub-reaches. The unconfined sub-reach is shown to have a typical channel migration pattern with deposition on the inner bank and erosion on the outer bank of the meander bend. The confined sub-reach, on the other hand, experienced greater bank instabilities than the unconfined sub-reach. The average rate of bank retreat was 0.2 m/year in the confined sub-reach whereas it was lower (0.08 m/year) in the unconfined sampling reach. In the confined sub-reach, an irregular meandering pattern occurred by the evolution of a concave-bank bench, which was caused by reverse flow eddies. The sinuosity of the confined sub-reach decreased from 1.55 to 1.49 in the 10-year study period. The results of the present study demonstrate the physical mechanisms by which meander confinement can change the meandering pattern and morphological characteristics of a cohesive clay bed creek. Full article
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Open AccessArticle Experimental Assessment of a New Kinetic Turbine Performance for Artificial Channels
Water 2018, 10(3), 311; https://doi.org/10.3390/w10030311
Received: 22 December 2017 / Revised: 6 March 2018 / Accepted: 9 March 2018 / Published: 13 March 2018
Cited by 1 | PDF Full-text (6132 KB) | HTML Full-text | XML Full-text
Abstract
An experimental investigation to measure the performance of a first prototype of a kinetic turbine is presented. This turbine, developed using numerical simulation, recovers the kinetic energy of water in free surface canals. To assess the performance of the machine, a first prototype
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An experimental investigation to measure the performance of a first prototype of a kinetic turbine is presented. This turbine, developed using numerical simulation, recovers the kinetic energy of water in free surface canals. To assess the performance of the machine, a first prototype as well as an open-air platform were built, both installed in the tailrace canal of Lavey hydropower plant. This is the first time in Switzerland that on-site experiments have been carried out for kinetic turbines. An experimental procedure was set up using measurements in the laboratory and on site to assess the power coefficient of the turbine as a function of the tip speed ratio. The influence of the turbine depth and the tilt of the turbine axis were also explored. A maximal power coefficient of 0.93 was reached for the higher tilt and depth investigated. Full article
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Open AccessArticle Case Study: Effects of a Partial-Debris Dam on Riverbank Erosion in the Parlung Tsangpo River, China
Water 2018, 10(3), 250; https://doi.org/10.3390/w10030250
Received: 31 January 2018 / Revised: 23 February 2018 / Accepted: 26 February 2018 / Published: 28 February 2018
Cited by 1 | PDF Full-text (5746 KB) | HTML Full-text | XML Full-text
Abstract
This paper examines two successive debris flows that deposited a total of 1.4 million m3 of sediment into the Parlung Tsangpo River in China in 2010. As a result of these deposits, a partial-debris dam was formed in the river. This dam
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This paper examines two successive debris flows that deposited a total of 1.4 million m3 of sediment into the Parlung Tsangpo River in China in 2010. As a result of these deposits, a partial-debris dam was formed in the river. This dam rerouted the discharge in the river along one of the riverbanks, which supported a highway. The rerouted discharge eroded the riverbank and the highway eventually collapsed. To enhance our understanding of the threat posed by partial-debris dams, a field investigation was carried out to measure the discharge in the river and to collect soil samples of the collapsed riverbank. Findings from the field investigation were then used to back-analyze fluvial erosion along the riverbank using a combined erosion framework proposed in this study. This combined framework adopts a dam-breach erosion model which can capture the progressive nature of fluvial erosion by considering the particle size distribution of the soil being eroded. The results from the back-analysis were then evaluated against unique high-resolution images obtained from satellites. This case study not only highlights the consequences of the formation of partial-debris dams on nearby infrastructure, but it also proposes the use of a combined erosion framework to provide a first-order assessment of riverbank stability. Unique high-resolution satellite images are used to assess the proposed erosion framework and key challenges in assessing erosion are discussed. Full article
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Open AccessArticle Responses of Bed Morphology to Vegetation Growth and Flood Discharge at a Sharp River Bend
Water 2018, 10(2), 223; https://doi.org/10.3390/w10020223
Received: 14 November 2017 / Revised: 12 February 2018 / Accepted: 16 February 2018 / Published: 22 February 2018
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Abstract
In this study, we conducted simulations using a two-dimensional, depth-averaged river flow and river morphology model to investigate the effect of vegetation growth and degree of flow discharge on a shallow meandering channel. To consider the effects of these factors, it was assumed
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In this study, we conducted simulations using a two-dimensional, depth-averaged river flow and river morphology model to investigate the effect of vegetation growth and degree of flow discharge on a shallow meandering channel. To consider the effects of these factors, it was assumed that vegetation growth stage is changed by water flow and bed erosion. The non-uniformity of the vegetation growth was induced by the non-uniform and unsteady profile of the water depth due to the irregular shape of the bed elevation and the unsteady flow model reliant on hydrographs to evaluate three types of peak discharges: moderate flow, annual average maximum flow, and extreme flow. To compare the effects of non-uniform growing vegetation, the change in channel patterns was quantified using the Active Braiding Index (ABI), which indicates the average number of channels with flowing water at a cross section and the Bed Relief Index (BRI), which quantifies the degree of irregularity of the cross-sectional shape. Two types of erosion were identified: local erosion (due to increased flow velocity near a vegetation area) and global erosion (due to the discharge approaching peak and the large depth of the channel). This paper demonstrated that the growth of vegetation increases both the ABI and BRI when the peak discharge is lower than the annual average discharge, whereas the growth of vegetation reduces the BRI when the peak discharge is extreme. However, under extreme discharge, the ABI decreases because global erosion is dominant. The conclusions from this study help to deepen the understanding of the interactions between curved river channels and vegetation. Full article
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Open AccessArticle Cross-Scale Baroclinic Simulation of the Effect of Channel Dredging in an Estuarine Setting
Water 2018, 10(2), 163; https://doi.org/10.3390/w10020163
Received: 4 December 2017 / Revised: 20 January 2018 / Accepted: 31 January 2018 / Published: 7 February 2018
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Abstract
Holistic simulation approaches are often required to assess human impacts on a river-estuary-coastal system, due to the intrinsically linked processes of contrasting spatial scales. In this paper, a Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) is applied in quantifying the impact of a
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Holistic simulation approaches are often required to assess human impacts on a river-estuary-coastal system, due to the intrinsically linked processes of contrasting spatial scales. In this paper, a Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) is applied in quantifying the impact of a proposed hydraulic engineering project on the estuarine hydrodynamics. The project involves channel dredging and land expansion that traverse several spatial scales on an ocean-estuary-river-tributary axis. SCHISM is suitable for this undertaking due to its flexible horizontal and vertical grid design and, more importantly, its efficient high-order implicit schemes applied in both the momentum and transport calculations. These techniques and their advantages are briefly described along with the model setup. The model features a mixed horizontal grid with quadrangles following the shipping channels and triangles resolving complex geometries elsewhere. The grid resolution ranges from ~6.3 km in the coastal ocean to 15 m in the project area. Even with this kind of extreme scale contrast, the baroclinic model still runs stably and accurately at a time step of 2 min, courtesy of the implicit schemes. We highlight that the implicit transport solver alone reduces the total computational cost by 82%, as compared to its explicit counterpart. The base model is shown to be well calibrated, then it is applied in simulating the proposed project scenario. The project-induced modifications on salinity intrusion, gravitational circulation, and transient events are quantified and analyzed. Full article
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Open AccessArticle Near-Bed Monitoring of Suspended Sediment during a Major Flood Event Highlights Deficiencies in Existing Event-Loading Estimates
Water 2018, 10(2), 34; https://doi.org/10.3390/w10020034
Received: 15 November 2017 / Revised: 16 December 2017 / Accepted: 17 January 2018 / Published: 23 January 2018
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Abstract
Rates of fluvial sediment discharge are notoriously difficult to quantify, particularly during major flood events. Measurements are typically undertaken using event stations requiring large capital investment, and the high cost tends to reduce the spatial coverage of monitoring sites. This study aimed to
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Rates of fluvial sediment discharge are notoriously difficult to quantify, particularly during major flood events. Measurements are typically undertaken using event stations requiring large capital investment, and the high cost tends to reduce the spatial coverage of monitoring sites. This study aimed to characterise the near-bed suspended sediment dynamics during a major flood event using a low-cost approach. Monitoring nodes consisted of a total suspended sediment (TSS) logger, a single stage sampler, and a time-lapse camera for a total cost of less than US$420. Seven nodes were deployed across an elevation gradient on the stream bank of Laidley Creek, Queensland, Australia, and two of these nodes successfully characterised the near-bed suspended sediment dynamics across a major flood event. Near-bed TSS concentrations were closely related to stream flow, with the contribution of suspended bed material dominating the total suspended load during peak flows. Observed TSS concentrations were orders of magnitude higher than historical monitoring data for this site collected using the State government event station. This difference was attributed to the event station pump inlet screening the suspended bed material prior to sample collection. The ‘first flush’ phenomenon was detected and attributed to a local resuspension of muddy crusts immediately upstream of the study site. This low-cost approach will provide an important addition to the existing monitoring of fluvial sediment discharge during flood events. Full article
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Open AccessArticle A Semi-Analytical Model for the Hydraulic Resistance Due to Macro-Roughnesses of Varying Shapes and Densities
Water 2017, 9(9), 637; https://doi.org/10.3390/w9090637
Received: 21 June 2017 / Revised: 27 July 2017 / Accepted: 21 August 2017 / Published: 25 August 2017
Cited by 3 | PDF Full-text (1675 KB) | HTML Full-text | XML Full-text
Abstract
A friction model resulting from investigations into macro-roughness elements in fishways has been compared with a broad range of studies in the literature under very different bed configurations. In the context of flood modelling or aquatic habitats, the aim of the study is
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A friction model resulting from investigations into macro-roughness elements in fishways has been compared with a broad range of studies in the literature under very different bed configurations. In the context of flood modelling or aquatic habitats, the aim of the study is to show that the formulation is applicable to both emergent or submerged obstacles with either low or high obstacle concentrations. In the emergent case, the model takes into account free surface variations at large Froude numbers. In the submerged case, a vegetation model based on the double-averaging concept is used with a specific turbulence closure model. Calculation of the flow in the roughness elements gives the total hydraulic resistance uniquely as a function of the obstacles’ drag coefficient. The results show that the model is highly robust for all the rough beds tested. The averaged accuracy of the model is about 20% for the discharge calculation. In particular, we obtain the known values for the limiting cases of low confinement, as in the case of sandy beds. Full article
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