GRAVEL BEACH PROFILE EVOLUTION IN WAVE AND TIDAL ENVIRONMENTS

This paper reports progress made in modifying and applying the X-Beach code to predict and explain the observed behaviour of coarse grained beaches. In a previous study a comparison of beach profile evolution measured during large scale experiments under constant water level with numerical model simulations was made. This placed particular emphasis on the tendency for onshore transport and profile steepening during calm conditions (Jamal et al., 2010). The present paper extends that investigation to study the influence of the advection of surf processes induced by tidal water level variations effects, on gravel beach profile evolution. The parameter values and numerical model used in the simulation is similar to that presented previously. It is assumed that, to good approximation, the groundwater interface inside the beach follows the tidally modulated water level. The results obtained from the model shows that the model provides reasonable simulations of beach profile change in a tidal environment. In comparison with simulations under stationary water levels, a larger berm is produced in agreement with literature. Finally, good agreement is obtained between the model simulations and an example of field observations from a beach at Milford on Sea, UK. Further developments are outlined for future work.

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Analysis of Pore Water Pressure and Piping of Hydraulic Well

Water ◽

10.3390/w13040502 ◽

2021 ◽

Vol 13 (4) ◽

pp. 502

Author(s):

Jinman Kim ◽

Heuisoo Han ◽

Yoonhwa Jin

Keyword(s):

Numerical Analysis ◽

Water Level ◽

Pore Water ◽

Large Scale ◽

Pore Water Pressure ◽

Water Pressure ◽

Hydraulic Gradient ◽

Water Levels ◽

Seepage Velocity ◽

Seepage Analysis

This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.

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Development of One Dimensional Numerical Model on Large Water Diversion System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.744-746.1062 ◽

2015 ◽

Vol 744-746 ◽

pp. 1062-1065

Author(s):

Cheng Zhang ◽

Lin Zha

Keyword(s):

Numerical Model ◽

Boundary Conditions ◽

Water Level ◽

Large Scale ◽

Water Diversion ◽

One Dimensional ◽

Continuous Simulation ◽

North Water ◽

Flow Transitions ◽

Parallel Connections

A one-dimensional numerical model was developed for unsteady-flow in a large-scale conveyance channel with complex inner boundary conditions. Using Taylor expansion and finite difference method, this model incorporated three types of inner boundary conditions, including regulators, inverted siphons, and flumes with parallel connections. It can facilitate continuous simulation with large-amplitude variations in water level and flow discharge during the flow transitions. Transition flows were simulated by this model, which were caused by the operation of a single gate of the Middle Route of the South-to-North Water Diversion Project. The discharges of simulation were consistent with the discharges of formulas calculation, and the water level variations accords with hydraulic law. The results indicate its efficiency and applicability on simulating hydraulic response of large-scale conveyance channels with complex inner boundary conditions.

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An oceanic pathway for Madden–Julian Oscillation influence on Maritime Continent Tropical Cyclones

npj Climate and Atmospheric Science ◽

10.1038/s41612-021-00208-4 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Karthik Balaguru ◽

L. Ruby Leung ◽

Samson M. Hagos ◽

Sujith Krishnakumar

Keyword(s):

Numerical Model ◽

Tropical Cyclones ◽

Large Scale ◽

Sea Surface ◽

Madden Julian Oscillation ◽

Surface Cooling ◽

Maritime Continent ◽

Large Scale Circulation ◽

Model Simulations ◽

Sea Surface Cooling

AbstractWhile the Madden–Julian Oscillation (MJO) has been shown to affect tropical cyclones (TCs) worldwide through its modulation of large-scale circulation in the atmosphere, little or no role for the ocean has been identified to date in this influence of MJO on TCs. Using observations and numerical model simulations, we demonstrate that MJO events substantially impact TCs over the Maritime Continent (MC) region through an oceanic pathway. While propagating across the MC region, MJO events cause significant sea surface cooling with an area-averaged value of about 0.35 ± 0.12 °C. Hence, TCs over the MC region immediately following the passage of MJO events encounter considerably cooler sea surface temperatures. Consequently, the enthalpy fluxes under the storms are reduced and the intensification rates decrease by more than 50% on average. These results highlight an important role played by the ocean in facilitating MJO-induced sub-seasonal variability in TC activity over the MC region.

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Computational cognitive neuroscience: Model fitting should not replace model simulation

10.1101/079798 ◽

2016 ◽

Author(s):

Stefano Palminteri ◽

Valentin Wyart ◽

Etienne Koechlin

Keyword(s):

Decision Making ◽

Cognitive Neuroscience ◽

Large Scale ◽

Model Comparison ◽

Model Simulation ◽

Model Fitting ◽

Model Simulations ◽

Model Based ◽

Comparison Results ◽

Future Work

AbstractCognitive neuroscience, especially in the fields of learning and decision-making, is witnessing the blossoming of computational model-based analyses. Several methodological and review papers have indicated how and why candidate models should be compared by trading off their ability to predict the data as a function of their complexity. However, the importance of simulating candidate models has been so far largely overlooked, which entails several drawbacks and leads to invalid conclusions. Here we argue that the analysis of model simulations is often necessary to support the specific claims about behavioral function that most of model-based studies make. We defend this argument both informally by providing a large-scale (N>300) review of recent studies, and formally by showing how model simulations are necessary to interpret model comparison results. Finally, we propose guidelines for future work, which combine model comparison and simulation.

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NUMERICAL MODELLING OF THE MORPHODYNAMICS OF THE PLOČE GRAVEL BEACH IN RIJEKA

Elektronički časopis građevinskog fakulteta Osijek ◽

10.13167/2021.23.4 ◽

2021 ◽

Vol 12 (23) ◽

pp. 33-48

Author(s):

Goran Lončar ◽

◽

Filip Kalinić ◽

Dalibor Carević ◽

Damjan Bujak ◽

...

Keyword(s):

Sediment Transport ◽

Numerical Model ◽

Morphological Changes ◽

Wind Waves ◽

Surface Wind ◽

Point Clouds ◽

Beach Sediment ◽

Model Simulations ◽

Volume Method ◽

Gravel Beach

The morphodynamics of an artificial gravel beach in the Bay of Rijeka (Ploče Beach) was analyzed. The morphological changes of the beach face were monitored through an intense situation of gravitational surface wind waves from the incident SSW direction. A numerical modeling technique was applied, after initially establishing a numerical model for wave deformation. A model for sediment transport was established based on its results. Both models were based on the finite volume method. In addition, the partial contribution of the longshore component of sediment transport was analyzed based on empirical formulae. The modeling results were verified by comparing the positions and amounts of eroded/accumulated material along the beach with the processing of terrain images in the form of point clouds. The erosion and accumulation positions of the beach sediment material, obtained by numerical model simulations, corresponded to the surveyed positions. The total volume of eroded and accumulated material based on terrain image processing corresponded to the model values.

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Wave Climate Associated With Changing Water Level and Ice Cover in Lake Michigan

Frontiers in Marine Science ◽

10.3389/fmars.2021.746916 ◽

2021 ◽

Vol 8 ◽

Author(s):

Chenfu Huang ◽

Longhuan Zhu ◽

Gangfeng Ma ◽

Guy A. Meadows ◽

Pengfei Xue

Keyword(s):

Climate Change ◽

Water Level ◽

Lake Michigan ◽

Linear Trend ◽

Ice Cover ◽

Wave Climate ◽

Water Levels ◽

Regional Warming ◽

Model Simulations

Detailed knowledge of wave climate change is essential for understanding coastal geomorphological processes, ecosystem resilience, the design of offshore and coastal engineering structures and aquaculture systems. In Lake Michigan, the in-situ wave observations suitable for long-term analysis are limited to two offshore MetOcean buoys. Since this distribution is inadequate to fully represent spatial patterns of wave climate across the lake, a series of high-resolution SWAN model simulations were performed for the analysis of long-term wave climate change for the entirety of Lake Michigan from 1979 to 2020. Model results were validated against observations from two offshore buoys and 16 coastal buoys. Linear regression analysis of significant wave height (Hs) (mean, 90th percentile, and 99th percentile) across the entire lake using this 42-year simulation suggests that there is no simple linear trend of long-term changes of Hs for the majority (>90%) of the lake. To address the inadequacy of linear trend analysis used in previous studies, a 10-year trailing moving mean was applied to the Hs statistics to remove seasonal and annual variability, focusing on identifying long-term wave climate change. Model results reveal the regime shifts of Hs that correspond to long-term lake water level changes. Specifically, downward trends of Hs were found in the decade of 1990–2000; low Hs during 2000–2010 coincident with low lake levels; and upward trends of Hs were found during 2010–2020 along with rising water levels. The coherent pattern between the wave climate and the water level was hypothesized to result from changing storm frequency and intensity crossing the lake basin, which influences both waves (instantly through increased wind stress on the surface) and water levels (following, with a lag through precipitation and runoff). Hence, recent water level increases and wave growth were likely associated with increased storminess observed in the Great Lakes. With regional warming, the decrease in ice cover in Lake Michigan (particularly in the northernmost region of the lake) favored the wave growth in the winter due to increased surface wind stress, wind fetch, and wave transmission. Model simulations suggest that the basin-wide Hs can increase significantly during the winter season with projected regional warming and associated decreases in winter ice cover. The recent increases in wave height and water level, along with warming climate and ice reduction, may yield increasing coastal damages such as accelerating coastal erosion.

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Factors controlling longshore variations of beach changes induced by Tropical Storm Eta (2020) along Pinellas County beaches, west-central Florida

Shore & Beach ◽

10.34237/1008929 ◽

2021 ◽

pp. 75-85

Author(s):

Jun Cheng ◽

Francesca Toledo Cossu ◽

Ping Wang

Keyword(s):

Water Level ◽

Wave Height ◽

Tropical Storm ◽

Water Levels ◽

Dominant Factor ◽

Volume Loss ◽

Beach Profile ◽

Central Florida ◽

West Central ◽

Elevated Water

Tropical Storm Eta impacted the coast of west-central Florida from 11 November to 12 November 2020 and generated high waves over elevated water levels for over 20 hours. A total of 148 beach and nearshore profiles, spaced about 300 m (984 ft) apart, were surveyed one to two weeks before and one to eight days after the storm to examine the beach changes along four barrier islands, including Sand Key, Treasure Island, Long Key, and Mullet Key. The high storm waves superimposed on elevated water level reached the toe of dunes or seawalls and caused dune erosion and overwash at various places. Throughout most of the coast, the dune, dry beach, and nearshore area was eroded and most of the sediment was deposited on the seaward slope of the nearshore bar, resulting in a roughly conserved sand volume above closure depth. The longshore variation of beach-profile volume loss demonstrates an overall southward decreasing trend, mainly due to a southward decreasing nearshore wave height as controlled by offshore bathymetry and shoreline configurations. The Storm Erosion Index (SEI) developed by Miller and Livermont (2008) captured the longshore variation of beach-profile volume loss reasonably well. The longshore variation of breaking wave height is the dominant factor controlling the longshore changes of SEI and beach erosion. Temporal variation of water level also played a significant role, while beach berm elevation was a minor factor. Although wider beaches tended to experience more volume loss from TS Eta due to the availability of sediment, they were effective in protecting the back beach and dune area from erosion. On the other hand, smaller profile-volume loss from narrow beach did not necessarily relate to less dune/ structure damage. The opposite is often true. Accurate evaluation of a storm’s severity in terms of erosion potential would benefit beach management especially under the circumstance of increasing storm activities due to climate change.

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Smart Water Control with Internet of Things and Cloud Computing

Journal of Computational and Theoretical Nanoscience ◽

10.1166/jctn.2020.8427 ◽

2020 ◽

Vol 17 (4) ◽

pp. 1696-1702

Author(s):

A. Shiny ◽

Arpan Sarkar ◽

Sanchay Mishra ◽

Sarthak Pandita ◽

Aritra Paul

Keyword(s):

Water Level ◽

Large Scale ◽

Water Levels ◽

Sensor Data ◽

Water Control ◽

Smart Water ◽

Current Scenario ◽

Water Tanks ◽

And Control ◽

Level Monitoring

In this paper, we bring about the idea of water level monitoring and controlling with IOT and Mobile applications. The vast amount of water wasted in the current scenario, mostly due to overflowing tanks is not acceptable. Existing water tanks control systems can monitor and control the water level in tank, which leads to reduction in amount of wastage of ample water but the type of sensors which are used in such a system does not specify exact changes in water level leading to unstable control parameters. Other technologies had some drawbacks based on speed of detection and approximation of sensor data. The need of improvement of these short-comings and providing an accurate and ethinic solution has been the main aim of this project. The project has been further improvised by using electronic water level sensors which uses potentiometric techniques to measure water level in water tanks, along with ultrasonic sensors for better metrics and control. Further up, this project can be implemented on large scale to control and detect rising water levels in dams and reservoirs to avoid flash floods and excess pressure in dams. The proposed system will help to identify the smallest changes in water level in case of rainfall measurement as well.

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Assessment of riverside groundwater flood risk induced by high river water levels using a numerical model and monitoring data

Water Science & Technology Water Supply ◽

10.2166/ws.2015.144 ◽

2015 ◽

Vol 16 (2) ◽

pp. 388-401 ◽

Cited By ~ 1

Author(s):

Gyoo-Bum Kim ◽

Eun-Jee Cha

Keyword(s):

Numerical Model ◽

River Water ◽

Agricultural Land ◽

Control Measure ◽

Water Levels ◽

Coarse Grained ◽

Groundwater Levels ◽

Dry Seasons ◽

Greenhouse Cultivation ◽

Soil Wetting

Large barrages have been constructed on the main rivers in South Korea to store water and mitigate fluvial flooding damage. However, the increase in water levels behind the barrages can potentially lead to a rise in groundwater levels in the riversides. The purpose of this study was to describe the effect of a barrage on groundwater levels and to test the applicability of a numerical model to groundwater inundation in this context. The Shincheon–Baekcheon catchment is characterised mainly by agricultural land use and includes significant greenhouse cultivation. Its two zones, which are lower A and upper B basins, mainly yield fine- and coarse-grained deposits, respectively. Trend and distribution analyses of manual and automatic measurements of groundwater levels indicated that: (1) the groundwater levels generally increased as the river water levels rose after the river was dammed; (2) the significant correlation between groundwater and river water levels could lead to reductions in the groundwater levels if the barrage gates were opened as a control measure; and (3) the lowering of high groundwater levels during dry seasons is important for preventing soil wetting in the riversides.

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APPLICATION OF XBEACH TO MODEL STORM RESPONSE ON A MACROTIDAL GRAVEL BARRIER

Coastal Engineering Proceedings ◽

10.9753/icce.v32.sediment.39 ◽

2011 ◽

Vol 1 (32) ◽

pp. 39 ◽

Cited By ~ 4

Author(s):

Amaia Ruiz de Alegria-Arzaburu ◽

Jon J Williams ◽

Gerhard Masselink

Keyword(s):

Sediment Transport ◽

Hydraulic Conductivity ◽

Numerical Model ◽

Morphological Changes ◽

Coastal Engineering ◽

Beach Profile ◽

Morphological Response ◽

Total Drag ◽

Storm Response ◽

Gravel Beach

The process-based XBeach numerical model has been used to simulate storm-induced morphological response on a macrotidal gravel barrier located in southwest UK. Using well-established parameterisation to define all relevant hydrodynamic, groundwater and sediment processes, the model was applied in 1D mode to simulate observed storm-induced beach profile responses. Investigations showed that the morphological response of the beach was best modelled using a total drag coefficient, CD, of 0.007, and a hydraulic conductivity, K, of 0.05ms-1. Results obtained from simulations with and without beach groundwater highlighted the need to account for groundwater effects when modelling morphological changes on gravel beaches. The model has been found unable of reproducing the formation of a berm, thus, beach recovery conditions cannot be modelled. This is mainly attributed to the fact that XBeach models long waves rather than individual waves, and thus it cannot simulate individual swash events that contribute to onshore sediment transport and berm accretion. However, the model is shown to provide good estimates of post-storm gravel beach/barrier profiles, and to define the threshold for overwash occurrence. Both attributes have utility in a range of practical coastal engineering and management applications.

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