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20 pages, 4541 KiB

Open AccessArticle

Improving the Accuracy of Hydrodynamic Model Predictions Using Lagrangian Calibration

by Neda Mardani, Kabir Suara, Helen Fairweather, Richard Brown, Adrian McCallum and Roy C. Sidle

Water 2020, 12(2), 575; https://doi.org/10.3390/w12020575 - 20 Feb 2020

Cited by 20 | Viewed by 4298

Abstract

While significant studies have been conducted in Intermittently Closed and Open Lakes and Lagoons (ICOLLs), very few have employed Lagrangian drifters. With recent attention on the use of GPS-tracked Lagrangian drifters to study the hydrodynamics of estuaries, there is a need to assess [...] Read more.

While significant studies have been conducted in Intermittently Closed and Open Lakes and Lagoons (ICOLLs), very few have employed Lagrangian drifters. With recent attention on the use of GPS-tracked Lagrangian drifters to study the hydrodynamics of estuaries, there is a need to assess the potential for calibrating models using Lagrangian drifter data. Here, we calibrated and validated a hydrodynamic model in Currimundi Lake, Australia using both Eulerian and Lagrangian velocity field measurements in an open entrance condition. The results showed that there was a higher level of correlation (R² = 0.94) between model output and observed velocity data for the Eulerian calibration compared to that of Lagrangian calibration (R² = 0.56). This lack of correlation between model and Lagrangian data is a result of apparent difficulties in the use of Lagrangian data in Eulerian (fixed-mesh) hydrodynamic models. Furthermore, Eulerian and Lagrangian devices systematically observe different spatio-temporal scales in the flow with larger variability in the Lagrangian data. Despite these, the results show that Lagrangian calibration resulted in optimum Manning coefficients (n = 0.023) equivalent to those observed through Eulerian calibration. Therefore, Lagrangian data has the potential to be used in hydrodynamic model calibration in such aquatic systems. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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28 pages, 8944 KiB

Open AccessArticle

Bathymetry Time Series Using High Spatial Resolution Satellite Images

by Manuel Erena, José A. Domínguez, Joaquín F. Atenza, Sandra García-Galiano, Juan Soria and Ángel Pérez-Ruzafa

Water 2020, 12(2), 531; https://doi.org/10.3390/w12020531 - 14 Feb 2020

Cited by 16 | Viewed by 6492

Abstract

The use of the new generation of remote sensors, such as echo sounders and Global Navigation Satellite System (GNSS) receivers with differential correction installed in a drone, allows the acquisition of high-precision data in areas of shallow water, as in the case of [...] Read more.

The use of the new generation of remote sensors, such as echo sounders and Global Navigation Satellite System (GNSS) receivers with differential correction installed in a drone, allows the acquisition of high-precision data in areas of shallow water, as in the case of the channel of the Encañizadas in the Mar Menor lagoon. This high precision information is the first step to develop the methodology to monitor the bathymetry of the Mar Menor channels. The use of high spatial resolution satellite images is the solution for monitoring many hydrological changes and it is the basis of the three-dimensional (3D) numerical models used to study transport over time, environmental variability, and water ecosystem complexity. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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20 pages, 6847 KiB

Open AccessArticle

Wave Forecasting in Shallow Water: A New Set of Growth Curves Depending on Bed Roughness

by Sara Pascolo, Marco Petti and Silvia Bosa

Water 2019, 11(11), 2313; https://doi.org/10.3390/w11112313 - 5 Nov 2019

Cited by 9 | Viewed by 3367

Abstract

Forecasting relationships have been recognized as an important tool to be applied together, or not, with complete numerical modelling in order to reconstruct the wave field in coastal areas properly when the available wave data is limited. In recent years, the literature has [...] Read more.

Forecasting relationships have been recognized as an important tool to be applied together, or not, with complete numerical modelling in order to reconstruct the wave field in coastal areas properly when the available wave data is limited. In recent years, the literature has offered several comprehensive sets of field experiments investigating the form of the asymptotic, depth-limited wind waves. This has made it possible to reformulate the original deep water equations, taking into account the effects of water depth, if wind waves are locally generated in shallow and confined basins. The present paper is an initial attempt to further contribute to the shallow water forecasting curves which are currently available, also considering the role on the wave generation of a variable equivalent bottom roughness. This can offer the possibility of applying shallow growth curves to a broad variety of contexts, for which bed composition and forms can be different. Simple numerical tests have been conducted to reproduce the fully developed conditions of wave motion with variable roughness values. To validate the new set of equations, they have been applied to a real shallow lake for which both experimental and numerical wave data is available. The comparison of the obtained results is very encouraging in proceeding with this approach. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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24 pages, 5858 KiB

Open AccessArticle

Sediment Transport Mechanisms in a Lagoon with High River Discharge and Sediment Loading

by Jovita Mėžinė, Christian Ferrarin, Diana Vaičiūtė, Rasa Idzelytė, Petras Zemlys and Georg Umgiesser

Water 2019, 11(10), 1970; https://doi.org/10.3390/w11101970 - 21 Sep 2019

Cited by 20 | Viewed by 8058

Abstract

The aim of this study was to investigate the sediment dynamics in the largest lagoon in Europe (Curonian Lagoon, Lithuania) through the analysis of in situ data and the application of a sediment transport model. This approach allowed to identify the propagation pathway [...] Read more.

The aim of this study was to investigate the sediment dynamics in the largest lagoon in Europe (Curonian Lagoon, Lithuania) through the analysis of in situ data and the application of a sediment transport model. This approach allowed to identify the propagation pathway of the riverine suspended sediments, to map erosion-accumulation zones in the lagoon and calculate the sediment budget over a 13-year-long simulation. Sampled suspended sediment concentration data are important for understanding the characteristics of the riverine and lagoon sediments, and show that the suspended organic matter plays a crucial role on the sediment dynamics for this coastal system. The numerical experiments carried out to study sediment dynamics gave satisfactory results and the possibility to get a holistic view of the system. The applied sediment transport model with a new formula for settling velocity was used to estimate the patterns of the suspended sediments and the seasonal and spatial sediment distribution in the whole river–lagoon–sea system. The numerical model also allowed understanding the sensitivity of the system to strong wind events and the presence of ice. The results reveal that during extreme storm events, more than 11.4 × 10⁶ kg of sediments are washed out of the system. Scenarios without ice cover indicate that the lagoon would have much higher suspended sediment concentrations in the winter season comparing with the present situation with ice. The results of an analysis of a long-term (13 years) simulation demonstrate that on average, 62% of the riverine sediments are trapped inside the lagoon, with a marked spatially varying distribution of accumulation zones. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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18 pages, 4647 KiB

Open AccessArticle

North Sea Ecosystem-Scale Model-Based Quantification of Net Primary Productivity Changes by the Benthic Filter Feeder Mytilus edulis

by Carsten Lemmen

Water 2018, 10(11), 1527; https://doi.org/10.3390/w10111527 - 26 Oct 2018

Cited by 11 | Viewed by 4509

Abstract

Blue mussels are among the most abundant bivalves in shallow water along the German coasts. As filter feeders, a major ecosystem service they provide is water filtration and the vertical transfer of suspended organic and attached inorganic material to the sea floor. Laboratory [...] Read more.

Blue mussels are among the most abundant bivalves in shallow water along the German coasts. As filter feeders, a major ecosystem service they provide is water filtration and the vertical transfer of suspended organic and attached inorganic material to the sea floor. Laboratory and field studies previously demonstrated that blue mussels can remove large quantities of plankton from the surrounding water. I here perform numerical experiments that investigate the effect of filtration at the scale of an entire coastal sea—the southern North Sea. These experiments were performed with a state-of-the-art bentho-pelagic coupled hydrodynamic and ecosystem model and used a novel reconstruction of the benthic biomass distribution of blue mussels. The filtration effect was assessed as the simulated change in net primary productivity caused by blue mussels. In shallow water, filtration takes out up to half of the entire annual primary productivity; it is negligible in offshore waters. For the entire basin, the filtration effect is 10%. While many ecosystem models have a global parameterization for filter feeders, the coastal gradient in the filtration effect is usually not considered; our research demonstrates the importance of including spatially heterogeneous filtration in coupled bentho-pelagic ecosystem models if we want to better understand the spatial patterns in shallow water coastal systems. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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19 pages, 5861 KiB

Open AccessArticle

On the Wave Bottom Shear Stress in Shallow Depths: The Role of Wave Period and Bed Roughness

by Sara Pascolo, Marco Petti and Silvia Bosa

Water 2018, 10(10), 1348; https://doi.org/10.3390/w10101348 - 28 Sep 2018

Cited by 24 | Viewed by 4753

Abstract

Lagoons and coastal semi-enclosed basins morphologically evolve depending on local waves, currents, and tidal conditions. In very shallow water depths, typical of tidal flats and mudflats, the bed shear stress due to the wind waves is a key factor governing sediment resuspension. A [...] Read more.

Lagoons and coastal semi-enclosed basins morphologically evolve depending on local waves, currents, and tidal conditions. In very shallow water depths, typical of tidal flats and mudflats, the bed shear stress due to the wind waves is a key factor governing sediment resuspension. A current line of research focuses on the distribution of wave shear stress with depth, this being a very important aspect related to the dynamic equilibrium of transitional areas. In this work a relevant contribution to this study is provided, by means of the comparison between experimental growth curves which predict the finite depth wave characteristics and the numerical results obtained by means a spectral model. In particular, the dominant role of the bottom friction dissipation is underlined, especially in the presence of irregular and heterogeneous sea beds. The effects of this energy loss on the wave field is investigated, highlighting that both the variability of the wave period and the relative bottom roughness can change the bed shear stress trend substantially. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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33 pages, 11010 KiB

Open AccessFeature PaperArticle

Assessing the Hydrodynamic Response of the Mar Menor Lagoon to Dredging Inlets Interventions through Numerical Modelling

by Miriam García-Oliva, Ángel Pérez-Ruzafa, Georg Umgiesser, William McKiver, Michol Ghezzo, Francesca De Pascalis and Concepción Marcos

Water 2018, 10(7), 959; https://doi.org/10.3390/w10070959 - 20 Jul 2018

Cited by 43 | Viewed by 7187

Abstract

The Mar Menor lagoon has been subjected to high anthropogenic pressures. Among them, in the early 1970s, dredging and enlargement of one of the inlets to make a navigable channel has had strong consequences on the hydrology, ecology, and fisheries of the lagoon. [...] Read more.

The Mar Menor lagoon has been subjected to high anthropogenic pressures. Among them, in the early 1970s, dredging and enlargement of one of the inlets to make a navigable channel has had strong consequences on the hydrology, ecology, and fisheries of the lagoon. In recent years, changes in agricultural practices have induced an eutrophication process, leading to loss of water quality. As a solution, some management proposals have included dredging of the inlets in order to increase the water renewal. However, these proposals did not take into account the negative effects of previous experiences nor the consequences on environmental conditions of the lagoon and therefore on biological processes. The purpose of this work is to assess the effect that proposed mitigation measures, could have on the hydrodynamic conditions and discuss its possible ecological consequences. A three-dimensional (3D) numerical model has been used to simulate the lagoon under different dredging scenarios, covering different dredging depths and extensions. The simulated current fields and fluxes through the inlets, as well as water renewal times have been compared for the different scenarios. It is found that some of the considered scenarios take the system beyond the threshold of sustainability, where the modified current dynamics could affect sediment transport, beach dynamics and fishing capacities in a significant way. Water exchange with the Mediterranean is also strongly affected, with consequences for species connectivity, and a homogenization of the water renewal times that could lead to loss of ecosystem heterogeneity and structural complexity. The study demonstrates the utility of numerical models as effective tools for the management of coastal areas. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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29 pages, 17196 KiB

Open AccessArticle

A Novel Multislope MUSCL Scheme for Solving 2D Shallow Water Equations on Unstructured Grids

by Haiyong Xu, Xingnian Liu, Fujian Li, Sheng Huang and Chao Liu

Water 2018, 10(4), 524; https://doi.org/10.3390/w10040524 - 21 Apr 2018

Cited by 3 | Viewed by 5654

Abstract

Within the framework of the two-dimensional cell-centered Godunov-type finite volume (CCFV) method, this paper presents a novel multislope scheme on the basis of the monotone upstream scheme for conservation law (MUSCL) for numerically solving nonlinear shallow water equations on two-dimensional triangular grids. The [...] Read more.

Within the framework of the two-dimensional cell-centered Godunov-type finite volume (CCFV) method, this paper presents a novel multislope scheme on the basis of the monotone upstream scheme for conservation law (MUSCL) for numerically solving nonlinear shallow water equations on two-dimensional triangular grids. The Riemann states of the considered edge are calculated by an edge-based reconstructing procedure, where a limited scalar slope is employed to prevent potential numerical oscillations. The novel aspect of the new scheme is that it takes advantage of the geometrical characteristics of triangular grids in the reconstructing and limiting procedures, which effectively reduces the cost of computation and provides higher resolution and accuracy compared with classical MUSCL schemes. Seven tests are adopted to verify the scheme, and the results indicate that this scheme is efficient, accurate, robust, and high-resolution, and can be an ideal alternative for solving shallow water problems over uneven and frictional topography. Full article

(This article belongs to the Special Issue Study of Lagoons and Other Shallow Water Bodies Through the Application of Numerical Models)

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