Understanding the effects of dynamic sediment inputs on the prediction of coastal wetland evolution

2020 ◽  
Author(s):  
Angelo Breda ◽  
Patricia Saco ◽  
José Rodriguez ◽  
Steven Sandi-Rojas
Keyword(s):  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Sediment Concentration ◽  
Transport Processes ◽  
Water Levels ◽  
Time Varying ◽  
Modelling Framework ◽  
Dynamic Time ◽  
Wetland Evolution ◽  
Different Levels

<p>Over the last two decades, there have been important advances in eco-geomorphological modelling of coastal wetlands to predict their evolution. Different features have been incorporated into models, bust most applications still assume a constant or static sediment concentration as input representing average conditions. Such imposition is related to many constraints in obtaining a time series of total suspended matter (TSM). However, with the increasing availability of multispectral satellite products and the development of artificial intelligence algorithms, TSM data can be estimated through remote sensing. This work aims to assess the effect of using a dynamic time varying condition for the TSM input when simulating eco-geomorphological processes. We implemented a modelling framework adapted to conditions found in SE Australian estuaries, which includes hydrodynamic and sediment transport processes. Many scenarios where simulated encompassing different levels of average TSM and water levels. Our findings suggest that under low water levels and low sediment concentration, a static TSM input results in more accretion than a dynamic input. However, at higher levels and concentration, the dynamic input led to higher accretion. Predictions of vegetation distribution were not particularly sensitive to changes in TSM over time.</p>

A catchment to coast framework for the evolution of a coastal mangove wetland

2020 ◽  
Author(s):  
Jose Rodriguez ◽  
Eliana Jorquera ◽  
Patricia Saco ◽  
Angelo Breda
Keyword(s):  
Land Use ◽  
Coastal Wetlands ◽  
Land Use Changes ◽  
Storm Events ◽  
Sea Levels ◽  
Future Evolution ◽  
Modelling Framework ◽  
Sea Level Variations ◽  
Wetland Evolution ◽  
Catchment Model

<p>Coastal wetlands are at the interface between land and sea, receiving water, sediment and nutrients from upstream catchments and also being subject to tides, wave and changing sea levels. Analysis of their future evolution requires the analysis of the entire catchment to coast system, including the effects of climate variability and change and land use changes. We have developed a modelling framework that is able to include both catchment and coastal processes into the evolution of coastal wetlands by coupling an ecogeomorphological wetland evolution model with a hydrosedimentological catchment model to include both tidal and catchment runoff inputs. We drive the model with storm events and sea-level variations and analyse scenarios of future climate and land use for a catchment in Vanua Levu, Fiji that includes a mangrove wetland at the catchment outlet. We inform our model with field, remote sensing and historical data on land use, tides, sediment and nutrient transport and cyclone activity.</p>

Parameterization of Coastal Wetlands and Their Role in Back Bay Hydrodynamics

2020 ◽  
Author(s):  
Mary Cialone ◽  
Gregory Slusarczyk
Keyword(s):  
New Jersey ◽  
Flood Risk ◽  
Coastal Wetlands ◽  
Management Practices ◽  
Coastal Wetland ◽  
The United States ◽  
Hurricane Sandy ◽  
Water Levels ◽  
Depth Analysis

<p>This paper will provide an evaluation of the role of coastal wetlands in flood risk mediation by performing hydrodynamic modeling of storm surge in back bays that include various configurations of wetland features. Wetland parameters varied in the research study include the elevation, shape, volume, and vegetation type (represented by the Manning’s friction coefficient) to identify the role of wetlands in reducing back bay flooding.   This information can be used to determine best future management practices for dredged material placement that will serve to maintain and restore wetlands in light of environmental pressures such as climate change, subsidence, storm-induced erosion, boat wakes, and other factors influencing coastal wetland dynamics.</p><p>Following Hurricane Sandy in 2012, the United States (U.S.) Congress authorized the large scale North Atlantic Coast Comprehensive Study (NACCS) to address the present and future flood risk to this region. Part of that study was an in-depth numerical modeling and statistical analysis using the ADvanced CIRCulation (ADCIRC) and STeady-state spectral WAVE (STWAVE) models and the Joint Probability with Optimal Sampling (JPM-OS) statistical technique. Following the NACCS, the New Jersey back bays were identified as a high-risk area requiring further in-depth analysis of the effectiveness of surge barriers and coastal wetlands to reduce water levels in the back bays during storms. This paper will discuss the analysis of a set of coastal wetland configurations in the New Jersey back bay region simulated with a set of 10 synthetic storm suite selected from the NACCS study.   Analysis of maximum surge envelopes, water level time series, and characteristics of tropical storm forcing conditions were used to evaluate and compare the effectiveness of the wetland configurations.</p>

scholarly journals Accretion, retreat and transgression of coastal wetlands experiencing sea-level rise

2020 ◽  
Author(s):  
Angelo Breda ◽  
Patricia M. Saco ◽  
Steven G. Sandi ◽  
Neil Saintilan ◽  
Gerardo Riccardi ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Sediment Load ◽  
Tidal Range ◽  
Sediment Distribution ◽  
And Migration ◽  
Wetland Evolution ◽  
Inner Channel

Abstract. The vulnerability of coastal wetlands to future sea-level rise (SLR) has been extensively studied in recent years, and models of coastal wetland evolution have been developed to assess and quantify the expected impacts. Coastal wetlands respond to SLR by vertical accretion and landward migration. Wetlands accrete due to their capacity to trap sediments and to incorporate dead leaves, branches stems and roots into the soil, and they migrate driven by the preferred inundation conditions in terms of salinity and oxygen availability. Accretion and migration strongly interact and they both depend on water flow and sediment distribution within the wetland, so wetlands under the same external flow and sediment forcing but with different configurations will respond differently to SLR. Analyses of wetland response to SLR that do not incorporate realistic consideration of flow and sediment distribution, like the bathtub approach, are likely to result in poor estimates of wetland resilience. Here, we investigate how accretion and migration processes affect wetland response to SLR using a computational framework that includes all relevant hydrodynamic and sediment transport mechanisms that affect vegetation and landscape dynamics, and it is efficient enough computationally to allow the simulation of long time periods. Our framework incorporates two vegetation species, mangrove and saltmarsh, and accounts for the effects of natural and manmade features like inner channels, embankments and flow constrictions due to culverts. We apply our model to simplified domains that represent four different settings found in coastal wetlands, including a case of a tidal flat free from obstructions or drainage features and three other cases incorporating an inner channel, an embankment with a culvert, and a combination of inner channel, embankment and culvert. We use conditions typical of SE Australia in terms of vegetation, tidal range and sediment load, but we also analyse situations with three times the sediment load to assess the potential of biophysical feedbacks to produce increased accretion rates. We find that all wetland settings are unable to cope with SLR and disappear by the end of the century, even for the case of increased sediment load. Wetlands with good drainage that improves tidal flushing are more resilient than wetlands with obstacles that result in tidal attenuation, and can delay wetland submergence by 20 years. Results from a bathtub model reveals systematic overprediction of wetland resilience to SLR: by the end of the century, half of the wetland survives with a typical sediment load, while the entire wetland survives with increased sediment load.

scholarly journals A copula-based multivariate hidden Markov model for modelling momentum in football

2021 ◽  
Author(s):  
Marius Ötting ◽  
Roland Langrock ◽  
Antonello Maruotti
Keyword(s):  
Markov Model ◽  
Hidden Markov Models ◽  
Markov Models ◽  
Hidden Markov ◽  
State Dependence ◽  
Change Points ◽  
Sports Fans ◽  
Modelling Framework ◽  
State Dependent ◽  
Different Levels

AbstractWe investigate the potential occurrence of change points—commonly referred to as “momentum shifts”—in the dynamics of football matches. For that purpose, we model minute-by-minute in-game statistics of Bundesliga matches using hidden Markov models (HMMs). To allow for within-state dependence of the variables, we formulate multivariate state-dependent distributions using copulas. For the Bundesliga data considered, we find that the fitted HMMs comprise states which can be interpreted as a team showing different levels of control over a match. Our modelling framework enables inference related to causes of momentum shifts and team tactics, which is of much interest to managers, bookmakers, and sports fans.

scholarly journals Coastal wetlands in Lianyungang, Jiangsu Province, China: probably the most important site globally for the Asian Dowitcher (Limnodromus semipalmatus)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ziyou Yang ◽  
Jing Li ◽  
Yongxiang Han ◽  
Chris J. Hassell ◽  
Kar-Sin Katherine Leung ◽  
...  
Keyword(s):  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Migratory Bird ◽  
Jiangsu Province ◽  
Bohai Bay ◽  
High Concentration ◽  
Human Disturbances ◽  
Stopover Site ◽  
Stochastic Events ◽  
Global Population

Abstract Background Despite an increasing number of surveys and a growing interest in birdwatching, the population and distribution of Asian Dowitcher (Limnodromus semipalmatus), a species endemic to the East Asian–Australasian and Central Asian Flyways, remains poorly understood, and published information about the species is largely outdated. In boreal spring 2019, over 22,432 Asian Dowitchers were recorded in a coastal wetland at Lianyungang, Jiangsu Province, China, constituting 97.5% of its estimated global population. Methods In 2019 and 2020, we conducted field surveys at Lianyungang to determine the numbers of Asian Dowitchers using the area during both southward and northward migrations. We also assessed the distribution and abundance of Asian Dowitchers elsewhere along the China coast by searching literature and consulting expert opinion. Results The coastal wetlands of Lianyungang are the most important stopover site for Asian Dowitchers during both northward and southward migrations; they supported over 90% of the estimated global population during northward migration in two consecutive years (May 2019 and 2020). This area also supported at least 15.83% and 28.42% (or 30.74% and 53.51% using modelled estimates) of the global population during southward migration in 2019 and 2020 respectively. Coastal wetlands in the west and north of Bohai Bay also have been important stopover sites for the species since the 1990s. Although comprehensive, long-term monitoring data are lacking, available evidence suggests that the population of the species may have declined. Conclusions The high concentration of Asian Dowitchers at Lianyungang during migration means the species is highly susceptible to human disturbances and natural stochastic events. The coastal wetlands of Lianyungang should be protected and potentially qualify for inclusion in China’s forthcoming nomination for World Heritage listing of Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China (Phase II) in 2023. Additional research is needed to understand Asian Dowitchers’ distribution and ecology, as well as why such a high proportion of their population rely on the Lianyungang coast.

scholarly journals Influence of Vibration on Diffusion in Liquid Mixtures On-Board the International Space Station

2021 ◽  
Author(s):  
Aram Parsa
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Physical Properties ◽  
International Space Station ◽  
Diffusion Coefficients ◽  
Space Station ◽  
Flow Patterns ◽  
Transport Processes ◽  
International Space ◽  
Different Levels

Experiments on-board the International Space Station experience a convective flow due to the oscillatory g-jitters induced by several sources such as crew activities, mechanical systems, thrusters firing, spacecraft docking, etc. Although g-jitter seems to have a major impact on diffusion-related experiments in Space, very few experimental studies have addressed this topic. This study examined the effect of oscillatory g-jitters on transport processes (fluid flow, heat transfer and mass transfer). Cubic rigid cells filled with water and isopropanol at different concentrations were subjected to thermal gradients and forced vibrations. The cells were exposed to different levels of vibration in terms of frequency and amplitude, which were applied perpendicular to the temperature gradient. The full transient Navier Stokes equations coupled with the mass and heat transfer formulas were solved numerically using the control volume technique. The physical properties of the fluid mixture such as the density were determined using two different models. The effect of different levels of vibration on the flow was analysed and the results were compared in a benchmark study with other scientific groups. The effect of the diffusion coefficients variation and other physical properties on the temperature and concentration distribution was compared to those results obtained with constant diffusion coefficients. Results show that use of variable physical properties in the modelling produces different flow patterns and component concentration. By examining different flow patterns, it was found that the effect of using variable coefficients is much more significant in the cases with high Rayleigh vibration that result in strong flow when compared with numerical analysis using constant variables. The numerical analysis was also performed for the actual experiment on board the International Space Station. The same trend was seen for both the numerical and experimental results. However, the separation of components was higher in the experiment in comparison with the numerical analysis. This was discussed in detail for various scenarios in terms of the applied frequency and amplitude. Recommendations are made according to the findings from this study for the improvement of accuracy in the numerical and experimental analyses of future diffusion experiments in Space.

scholarly journals Influence of Vibration on Diffusion in Liquid Mixtures On-Board the International Space Station

2021 ◽  
Author(s):  
Aram Parsa
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Physical Properties ◽  
International Space Station ◽  
Diffusion Coefficients ◽  
Space Station ◽  
Flow Patterns ◽  
Transport Processes ◽  
International Space ◽  
Different Levels

Experiments on-board the International Space Station experience a convective flow due to the oscillatory g-jitters induced by several sources such as crew activities, mechanical systems, thrusters firing, spacecraft docking, etc. Although g-jitter seems to have a major impact on diffusion-related experiments in Space, very few experimental studies have addressed this topic. This study examined the effect of oscillatory g-jitters on transport processes (fluid flow, heat transfer and mass transfer). Cubic rigid cells filled with water and isopropanol at different concentrations were subjected to thermal gradients and forced vibrations. The cells were exposed to different levels of vibration in terms of frequency and amplitude, which were applied perpendicular to the temperature gradient. The full transient Navier Stokes equations coupled with the mass and heat transfer formulas were solved numerically using the control volume technique. The physical properties of the fluid mixture such as the density were determined using two different models. The effect of different levels of vibration on the flow was analysed and the results were compared in a benchmark study with other scientific groups. The effect of the diffusion coefficients variation and other physical properties on the temperature and concentration distribution was compared to those results obtained with constant diffusion coefficients. Results show that use of variable physical properties in the modelling produces different flow patterns and component concentration. By examining different flow patterns, it was found that the effect of using variable coefficients is much more significant in the cases with high Rayleigh vibration that result in strong flow when compared with numerical analysis using constant variables. The numerical analysis was also performed for the actual experiment on board the International Space Station. The same trend was seen for both the numerical and experimental results. However, the separation of components was higher in the experiment in comparison with the numerical analysis. This was discussed in detail for various scenarios in terms of the applied frequency and amplitude. Recommendations are made according to the findings from this study for the improvement of accuracy in the numerical and experimental analyses of future diffusion experiments in Space.

scholarly journals Prediction Potential of Remote Sensing-Related Variables in the Topsoil Organic Carbon Density of Liaohekou Coastal Wetlands, Northeast China

2021 ◽  
Vol 13 (20) ◽  
pp. 4106
Author(s):  
Shuai Wang ◽  
Mingyi Zhou ◽  
Qianlai Zhuang ◽  
Liping Guo
Keyword(s):  
Remote Sensing ◽  
Organic Carbon ◽  
Coastal Wetlands ◽  
Environmental Variables ◽  
Northeast China ◽  
Vegetation Index ◽  
Coastal Wetland ◽  
Wetland Ecosystems ◽  
Flat Terrain ◽  
Soc Density

Wetland ecosystems contain large amounts of soil organic carbon. Their natural environment is often both at the junction of land and water with good conditions for carbon sequestration. Therefore, the study of accurate prediction of soil organic carbon (SOC) density in coastal wetland ecosystems of flat terrain areas is the key to understanding their carbon cycling. This study used remote sensing data to study SOC density potentials of coastal wetland ecosystems in Northeast China. Eleven environmental variables including normalized difference vegetation index (NDVI), difference vegetation index (DVI), soil adjusted vegetation index (SAVI), renormalization difference vegetation index (RDVI), ratio vegetation index (RVI), topographic wetness index (TWI), elevation, slope aspect (SA), slope gradient (SG), mean annual temperature (MAT), and mean annual precipitation (MAP) were selected to predict SOC density. A total of 193 soil samples (0–30 cm) were divided into two parts, 70% of the sampling sites data were used to construct the boosted regression tree (BRT) model containing three different combinations of environmental variables, and the remaining 30% were used to test the predictive performance of the model. The results show that the full variable model is better than the other two models. Adding remote sensing-related variables significantly improved the model prediction. This study revealed that SAVI, NDVI and DVI were the main environmental factors affecting the spatial variation of topsoil SOC density of coastal wetlands in flat terrain areas. The mean (±SD) SOC density of full variable models was 18.78 (±1.95) kg m−2, which gradually decreased from northeast to southwest. We suggest that remote sensing-related environmental variables should be selected as the main environmental variables when predicting topsoil SOC density of coastal wetland ecosystems in flat terrain areas. Accurate prediction of topsoil SOC density distribution will help to formulate soil management policies and enhance soil carbon sequestration.

scholarly journals Comparison of Qinzhou bay wetland landscape information extraction by three methods

2014 ◽  
Vol XL-4 ◽  
pp. 21-28 ◽  
Author(s):  
X. Chang ◽  
Q. Zhang ◽  
M. Luo ◽  
C. Dong
Keyword(s):  
Coastal Wetlands ◽  
Supervised Classification ◽  
Coastal Wetland ◽  
Object Oriented ◽  
Visual Interpretation ◽  
Wetland Area ◽  
The Third ◽  
Tasseled Cap Transformation ◽  
Qinzhou Bay ◽  
Landscape Information

Wetland ecosystem plays an important role on the environment and sustainable socio-economic development. Based on the TM images in 2010 with a pretreament of Tasseled Cap transformation, three different methods are used to extract the Qinzhou Bay coastal wetlands using Supervised Classification (SC), Decision Trees (DT) and Object -oriented (OO) methods. Firstly coastal wetlands are picked out by artificial visual interpretation as discriminant standard. The result shows that when the same evaluation template used, the accuracy and Kappa coefficient of SC, DT and OO are 92.00 %, 0.8952; 89.00 %, 0.8582; 91.00 %, 0.8848 respectively. The total area of coastal wetland is 218.3 km<sup>2</sup> by artificial visual interpretation, and the extracted wetland area of SC, DT and OO is 219 km<sup>2</sup>, 193.70 km<sup>2</sup>, 217.40 km<sup>2</sup> respectively. The result indicates that SC is in the f irst place, followed by OO approach, and the third DT method when used to extract Qingzhou Bay coastal wetland.

Estimating rill erosion and sediment transport processes along a saturated purple soil slope

2021 ◽  
Author(s):  
Han Zhen ◽  
Xiaoyan Chen ◽  
Yanhai Li ◽  
Shiqi Chen ◽  
Xiaojie Gu ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Sediment Concentration ◽  
Transport Processes ◽  
Purple Soil ◽  
Rill Erosion ◽  
Soil Slope ◽  
Sediment Transportation ◽  
Erosion Models ◽  
Increasing Trend ◽  
Soil Slopes

A plough pan with reduced permeability always accumulates infiltrated water along slopes then saturates the cultivated layer under continuous rain. Topsoil saturation is a frequent phenomenon and an important process of the special soil slopes. A methodology and device system was used in this study to keep cultivated purple soil saturated. Strands of scouring tests were developed to quantify the rill erosion and sediment transport processes along a saturated purple soil slope at four experiment slopes (5°, 10°, 15°, and 20°) and three flow discharges (2, 4 and 8 L min−1). The experimental results indicated that the sediment transport capacity on a saturated purple soil slope ranged from 0.03 to 1.56 kg s−1 m−1 with the increasing trend along the slope gradient and flow discharge, and the increasing trend could be well matched by a nonlinear multivariable equation. The sediment concentration of the saturated purple soil slope exponentially increased with rill length and decreased with the increment rate and the maximum sediment concentrations observed in this study in different hydraulic events ranged from 108.13 to 1174.20 kg m-3. Saturated and non-saturated purple soil slopes erode differently with the maximum sediment concentration of saturated purple soil slope recorded at approximately 1.42-2.10 times the values for non-saturated purple soil slope. The findings of this research help illustrate the sediment transportation and erosion behaviors of a saturated purple soil slope, and serve as the basis for determining the parameters in the erosion models of the purple soil slope.

Sign in / Sign up

Export Citation Format

Share Document