Editorial

5 pages, 183 KiB

Open AccessEditorial

Techniques and Applications in Water Science and Engineering

by Jian Guo Zhou, Haifei Liu, Alistair Borthwick and Carlo Gualtieri

Water 2020, 12(7), 2028; https://doi.org/10.3390/w12072028 - 16 Jul 2020

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This Special Issue of Water on “Techniques and Applications in Water Science and Engineering” publishes selected high-quality research papers presented at the Inaugural International Symposium on Water Modelling (iSymWater2019). The symposium was hosted by Beijing Normal University and Manchester Metropolitan University, and took [...] Read more.

This Special Issue of Water on “Techniques and Applications in Water Science and Engineering” publishes selected high-quality research papers presented at the Inaugural International Symposium on Water Modelling (iSymWater2019). The symposium was hosted by Beijing Normal University and Manchester Metropolitan University, and took place during 8–10 July 2019 in Beijing, China. A wide range of research topics were considered, including hydraulic modelling, hydro-environment modelling, hydro-ecology modelling, water management simulation, physical experiments, and software. The Issue reports eight papers by researchers from many institutions around the world, and focuses on solving sustainable water challenges through theoretical and physical modelling approaches. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

Research

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12 pages, 3475 KiB

Open AccessArticle

Effects of Dam Regulation on the Hydrological Alteration and Morphological Evolution of the Volta River Delta

by Mawusi Amenuvor, Weilun Gao, Dongxue Li and Dongdong Shao

Water 2020, 12(3), 646; https://doi.org/10.3390/w12030646 - 28 Feb 2020

Cited by 23 | Viewed by 3030

Abstract

The Volta River in West Africa is one of the most regulated rivers influenced by dams in the world, and the regulation has resulted in substantial impacts on the hydrological alteration and morphological evolution of the Volta River Delta. However, comprehensive analyses of [...] Read more.

The Volta River in West Africa is one of the most regulated rivers influenced by dams in the world, and the regulation has resulted in substantial impacts on the hydrological alteration and morphological evolution of the Volta River Delta. However, comprehensive analyses of the relevant effects are still lacking to date. In this study, inter-annual variations of river discharge and sediment load for pre- and post-Akosombo Dam periods (1936 to 2018) were analyzed through simple regression and Mann–Kendall (MK) trend analysis whereas the intra-annual variations were dictated by the non-uniformity and regulated coefficients. The shoreline changes were further evaluated using Landsat remote sensing images (1972 to 2018) to explore the effects of hydrological alteration on the morphological evolution of the Volta River Delta. Hydrological analyses show that the inter- and intra-annual variations are much higher in the pre-dam period, suggesting the substantial regulation of the Akosombo Dam on the Volta River. The dam regulation has more significant effects on the sediment load delivered to the delta than the river discharge, which decreased by 92.32% and 23.23%, respectively. Morphological analyses show that the progradation-erosion of the Volta River Delta constantly fluctuates within a relatively small range (maximum 0.5%) after the 1970s. The relationship between the variations of the delta area and sediment load implicates that a quasi-equilibrium state may have been established at the Volta River Delta, given the current sediment load. Our findings provide references for the future regulation and restoration of the Volta River Delta. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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28 pages, 18356 KiB

Open AccessArticle

CFD Investigations of Transient Cavitation Flows in Pipeline Based on Weakly-Compressible Model

by Xuelin Tang, Xiangyu Duan, Hui Gao, Xiaoqin Li and Xiaoyan Shi

Water 2020, 12(2), 448; https://doi.org/10.3390/w12020448 - 07 Feb 2020

Cited by 17 | Viewed by 3947

Abstract

In hydraulic systems, transient flow often occurs and may results in cavitation in pipelines. In this paper, the Computational Fluid Dynamics (CFD) method based on the Fluent software was used to investigate the cavitation flow in pipeline; the density-pressure model was incorporated into [...] Read more.

In hydraulic systems, transient flow often occurs and may results in cavitation in pipelines. In this paper, the Computational Fluid Dynamics (CFD) method based on the Fluent software was used to investigate the cavitation flow in pipeline; the density-pressure model was incorporated into the continuity equation by using further development of UDF (user defined function), which reflects the variable wave speed of the transient cavitation flow, and the related algorithms were established based on weakly compressible fluid Reynolds Average Navier-Stokes (RANS) techniques. Firstly, the numerical simulations of the transient non-cavitation and cavitation flows caused by the fast closing valve in the reservoir-pipe-valve system were carried out by using the grid slip technique. The simulation results can enrich the flow field information such as velocity, pressure and vapor volume fraction. Through the evolution process of the pressure field, the propagation characteristics of pressure waves can be analyzed qualitatively and quantitatively. Through the evolution process of the velocity field, it can be seen that the velocity distribution in the wall area changes rapidly and has a high gradient, which mainly depends on the viscosity. However, the change of the velocity distribution in the core region is related to the velocity distribution of the history of the past time, which mainly depends on the diffusion. The formation, development and collapse of the cavity can be successfully captured, and it can be clearly and visually observed that the uneven distribution of vapor cavity in the direction of pipe length and pipe diameter, and the vapor cavity move slowly along the top of the pipe wall. Rarefaction wave’s propagation into pressure decreasing region and pressure increasing region can lead to different results of cavitation flow. The accuracy and reliability of the weakly compressible fluid RANS method were verified by comparing the calculated results with the experimental data. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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17 pages, 2529 KiB

Open AccessArticle

Numerical Prediction of the Short-Term Trajectory of Microplastic Particles in Laizhou Bay

by Yu Ding, Haifei Liu and Wei Yang

Water 2019, 11(11), 2251; https://doi.org/10.3390/w11112251 - 27 Oct 2019

Cited by 9 | Viewed by 3425

Abstract

Microplastic particles are easily captured by microorganisms and enter the food chain, which poses a threat to ecological health. These particles are abundant in coastal areas because of the influence of anthropic activities and the interaction between the sea and land. Although much [...] Read more.

Microplastic particles are easily captured by microorganisms and enter the food chain, which poses a threat to ecological health. These particles are abundant in coastal areas because of the influence of anthropic activities and the interaction between the sea and land. Although much research on microplastics has been done, predicting the transportation of microplastic particles in coastal zones is still a challenge. In this paper, the trajectories of microplastic particles released from four river mouths around Laizhou Bay are investigated using the lattice Boltzmann method coupled with the Lagrangian particle-tracking method, involving inter-particle and particle-wall collisions. The trajectories of particles released from four river mouths are recorded within 30 days. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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14 pages, 3618 KiB

Open AccessArticle

A Landscape Connectivity Approach for Determining Minimum Ecological Lake Level: Implications for Lake Restoration

by Dan Liu, Xuan Wang, Yun-long Zhang, Sheng-jun Yan, Bao-shan Cui and Zhi-feng Yang

Water 2019, 11(11), 2237; https://doi.org/10.3390/w11112237 - 26 Oct 2019

Cited by 12 | Viewed by 3404

Abstract

We proposed a new approach to determine the minimum ecological lake level using a landscape connectivity approach. Using MIKE 21 and ArcGIS software, we simulated the water landscape and corresponding connectivity of Baiyangdian Lake on the North China Plain and analyzed the relationship [...] Read more.

We proposed a new approach to determine the minimum ecological lake level using a landscape connectivity approach. Using MIKE 21 and ArcGIS software, we simulated the water landscape and corresponding connectivity of Baiyangdian Lake on the North China Plain and analyzed the relationship between landscape connectivity and lake level. The minimum ecological lake level was defined as the breakpoint of the lake level-connectivity curve. Results suggested that the minimum ecological lake level of Baiyangdian Lake is 7.8–8.0 m, below which lake ecosystems become fragmented and potentially fragile. Alternatively, better connectivity at lower lake levels may be achieved by engineered modification of landscape patterns. Such approaches can mitigate the waste of water and economic resources due to excessive reliance on increasing water levels to meet minimum connectivity requirements. This approach provided a new perspective for lake ecosystem restoration of use in water-resource- and landscape management. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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13 pages, 3284 KiB

Open AccessArticle

Effects of Submerged Vegetation Density on Turbulent Flow Characteristics in an Open Channel

by Hanqing Zhao, Jing Yan, Saiyu Yuan, Jiefu Liu and Jinyu Zheng

Water 2019, 11(10), 2154; https://doi.org/10.3390/w11102154 - 16 Oct 2019

Cited by 20 | Viewed by 3217

Abstract

The vegetation density λ affects turbulent flow type in the submerged vegetated river. This laboratory study investigates different types of vegetated turbulent flow, especially the flow at 0.04 < λ < 0.1 and λ = 1.44 by setting the experimental λ within a [...] Read more.

The vegetation density λ affects turbulent flow type in the submerged vegetated river. This laboratory study investigates different types of vegetated turbulent flow, especially the flow at 0.04 < λ < 0.1 and λ = 1.44 by setting the experimental λ within a large range. Vertical distributions of turbulent statistics (velocity, shear stress and skewness coefficients), turbulence kinetic generation rate and turbulence spectra in different λ conditions have been presented and compared. Results indicate that for flow at 0.04 < λ < 0.1, the profiles of turbulent statistics manifest characteristics that are similar to those of both the bed-shear flow and the free-shear flow, and the turbulence spectral curves are characterized with some slight humps within the low-frequency range. For λ = 1.44, the turbulent statistics above the vegetation top demonstrate the characteristics of boundary-shear flow. The spectral curves fluctuate intensely within the low-frequency range, and the spectra of low-frequency eddies above vegetation top are significantly larger than the values below. The change of turbulent flow type induced by an increase of λ would increase the maximum value of turbulence kinetic generation rate G_S and change the point where G_S is vertically maximum upwards to the vegetation top. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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12 pages, 1694 KiB

Open AccessArticle

Simulation of Hydraulic Structures in 2D High-Resolution Urban Flood Modeling

by Yunsong Cui, Qiuhua Liang, Gang Wang, Jiaheng Zhao, Jinchun Hu, Yuehua Wang and Xilin Xia

Water 2019, 11(10), 2139; https://doi.org/10.3390/w11102139 - 15 Oct 2019

Cited by 11 | Viewed by 3997

Abstract

Urban flooding as a result of inadequate drainage capacity, failure of flood defenses, etc. is usually featured with highly transient hydrodynamics. Reliable and efficient prediction and forecasting of these urban flash floods is still a great technical challenge. Meanwhile, in urban environments, the [...] Read more.

Urban flooding as a result of inadequate drainage capacity, failure of flood defenses, etc. is usually featured with highly transient hydrodynamics. Reliable and efficient prediction and forecasting of these urban flash floods is still a great technical challenge. Meanwhile, in urban environments, the flooding hydrodynamics and process may be influenced by flow regulation and flood protection hydraulic infrastructure systems, such as sluice gates, which should be effectively taken into account in an urban flood model. However, direct simulation of hydraulic structures is not a current practice in 2D urban flood modeling. This work aims to develop a robust numerical approach to directly simulate the effects of gate structures in a 2D high-resolution urban flood model. A new modeling component is developed and fully coupled to a finite volume Godunov-type shock-capturing shallow water model, to directly simulate the highly transient flood waves through hydraulic structures. Different coupling approaches, i.e., flux term coupling and source term coupling, are implemented and compared. A numerical experiment conducted for an analytical dam-break test indicates that the flux term coupling approach may lead to more accurate results, with the calculated RMSE against water level 28%–38% less than that produced by the source term coupling approach. The flux term coupling approach is therefore adopted to improve the current urban flood model, and it is further tested by reproducing the laboratory experiments of flood routing in a flume with partially open sluice gates, conducted in the hydraulic laboratory at the Zhejiang Institute of Hydraulics and Estuary, China. The numerical results are compared favorably with experimental measurements, with a maximum RMSE of 0.0851 for all the individual tests. The satisfactory results demonstrate that the flood model implemented with the flux coupling approach is able to accurately simulate the flow through hydraulic structures, with enhanced predictive capability for urban flood modeling. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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17 pages, 2735 KiB

Open AccessArticle

Explicit Solution for Critical Depth in Closed Conduits Flowing Partly Full

by Haixin Shang, Song Xu, Kuandi Zhang and Luyou Zhao

Water 2019, 11(10), 2124; https://doi.org/10.3390/w11102124 - 13 Oct 2019

Cited by 9 | Viewed by 3051

Abstract

Critical depth is an essential parameter for the design, operation, and maintenance of conduits. Circular, arched, and egg-shaped sections are often used in non-pressure conduits in hydraulic engineering, irrigation, and sewerage works. However, equations governing the critical depth in various sections are complicated [...] Read more.

Critical depth is an essential parameter for the design, operation, and maintenance of conduits. Circular, arched, and egg-shaped sections are often used in non-pressure conduits in hydraulic engineering, irrigation, and sewerage works. However, equations governing the critical depth in various sections are complicated implicit transcendental equations. The function model is established for the geometric features of multiple sections using the mathematical transform method and while considering non-dimensional parameters. Then, revised PSO algorithms are implemented in MATLAB, and the right solution’s formula for the critical depths in various non-pressure conduit sections is established through optimization. The error analysis results show that the established formula has broad applicability. The maximum relative errors of the formula for critical depths are less than 0.182%, 0.0629%, and 0.170% in circular, arched, and egg-shaped sections, respectively, which are more accurate than those of existing formulas; the form of the formula proposed in this work is also more compact than that of the existing formulas. The results of this research may be useful in design, operation, and maintenance in conduit engineering. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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9 pages, 1409 KiB

Open AccessArticle

Numerical Study of Sulfonamide Occurrence and Transport at the Near-Shore Area of Laizhou Bay

by Liming Xing, Haifei Liu, Wenxian Guo, Yu Ding, Zhiming Ru, Gangqin Tu and Xuerong Wu

Water 2019, 11(10), 2065; https://doi.org/10.3390/w11102065 - 02 Oct 2019

Cited by 2 | Viewed by 2032

Abstract

Antibiotics are extensively applied in aquaculture for the treatment of microbial infections and to improve production. Among various antibiotics, sulfonamides (SA) are popular in fish farming, and SA residues in the aquatic environment have detrimental effects on both ecosystem and human health. Understanding [...] Read more.

Antibiotics are extensively applied in aquaculture for the treatment of microbial infections and to improve production. Among various antibiotics, sulfonamides (SA) are popular in fish farming, and SA residues in the aquatic environment have detrimental effects on both ecosystem and human health. Understanding the fate of SA in the aquatic environment is a basic necessity to provide an approach for solving the current problem. In this study, a two-dimensional lattice Boltzmann model was introduced to investigate the transport and occurrence of SA in Laizhou Bay, a prosperous aquaculture area in China. The model is based on the shallow-water equations and advection-diffusion equation with the Bhatnagaar–Gross–Krook scheme. Experimental data are used to verify the model after numerical simulations and the results illustrate the accuracy of the proposed model. This model provides a potential universal method for the simulation of the fate of antibiotics in the aquatic environment. Full article

(This article belongs to the Special Issue Techniques and Applications in Water Science and Engineering: Selected Papers from the Inaugural International Symposium on Water Modelling (iSymWater2019))

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