scholarly journals COMPARISON OF SEDIMENT TRANSPORT MODELS WITH IN-SITU SAND FLUX MEASUREMENTS AND BEACH MORPHODYNAMIC EVOLUTION

2012 ◽  
Vol 1 (33) ◽  
pp. 19
Author(s):  
Adrien Cartier ◽  
Philippe Larroudé ◽  
Arnaud Héquette
Keyword(s):  
Sediment Transport ◽  
Mediterranean Coast ◽  
Sand Transport ◽  
Transport Models ◽  
In Situ Data ◽  
Flux Measurements ◽  
Coastal Sediment Transport ◽  
Set Up ◽  
Sand Flux

The aim of this study is to set up a procedure of linking of three codes to be able to simulate realistic coastal sediment transport and associated morphological change. In order to calibrate sediment transport formulae, comparisons of our simulations were carried out with in-situ data of sand transport measured on macrotidal beaches of northern France on the shore of the English Channel and Dover Strait. This technique of simulation was then used to compare and investigate the efficiency of several sediment transport models on the site of Sète (microtidal beach on the Mediterranean coast) during two storms events.

scholarly journals From Ripples to Large-Scale Sand Transport: The Effects of Bedform-Related Roughness on Hydrodynamics and Sediment Transport Patterns in Delft3D

2020 ◽  
Vol 8 (11) ◽  
pp. 892
Author(s):  
Laura Brakenhoff ◽  
Reinier Schrijvershof ◽  
Jebbe van der Werf ◽  
Bart Grasmeijer ◽  
Gerben Ruessink ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Water Movement ◽  
Small Scale ◽  
Sand Transport ◽  
Influence Model ◽  
The North ◽  
Ebb Tidal Delta ◽  
Transport Patterns ◽  
Set Up

Bedform-related roughness affects both water movement and sediment transport, so it is important that it is represented correctly in numerical morphodynamic models. The main objective of the present study is to quantify for the first time the importance of ripple- and megaripple-related roughness for modelled hydrodynamics and sediment transport on the wave- and tide-dominated Ameland ebb-tidal delta in the north of the Netherlands. To do so, a sensitivity analysis was performed, in which several types of bedform-related roughness predictors were evaluated using a Delft3D model. Also, modelled ripple roughness was compared to data of ripple heights observed in a six-week field campaign on the Ameland ebb-tidal delta. The present study improves our understanding of how choices in model set-up influence model results. By comparing the results of the model scenarios, it was found that the ripple and megaripple-related roughness affect the depth-averaged current velocity, mainly over the shallow areas of the delta. The small-scale ripples are also important for the suspended load sediment transport, both indirectly through the affected flow and directly. While the current magnitude changes by 10–20% through changes in bedform roughness, the sediment transport magnitude changes by more than 100%.

Modeling of channel processes in large rivers with the use of field data

2021 ◽  
Vol 9 (1) ◽  
pp. 87-102
Author(s):  
A.T. Zinoviev ◽  
◽  
A.V. Dyachenko ◽  
K.B. Koshelev ◽  
K.V. Marusin ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Anthropogenic Impacts ◽  
Three Dimensional ◽  
Large Rivers ◽  
Observation Data ◽  
Channel Processes ◽  
Channel Deformations ◽  
Study Section ◽  
In Situ Data

The paper deals with mathematical description of channel processes occurring in long sections of large rivers with a complex morphometry. To forecast negative manifestations of channel deformations, a computer model of river sediment transport in the study section is proposed. It is based on a three-dimensional (3D) / two-dimensional horizontal (2DH) flow model, a 2DH model of bed sediment transport and observation data. Comparative analysis of simulation results of channel processes in the Ob river section at the Barnaul water intakes and in situ data makes it possible to evaluate forecast capabilities of the designed model, in particular, for quantitative assessment of changes in channel topography of the study section caused by natural and anthropogenic impacts.

scholarly journals TOWARDS MODELLING COASTAL SEDIMENT TRANSPORT

1988 ◽  
Vol 1 (21) ◽  
pp. 144 ◽  
Author(s):  
Peter Nielsen
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Littoral Drift ◽  
Transport Models ◽  
Wave Flume ◽  
Oscillatory Velocity ◽  
Waves And Currents ◽  
Coastal Sediment Transport ◽  
Normal Transport ◽  
Insight Into

Sediment transport data from the field and laboratory tests are used to gain insight into two fundamental questions. Firstly: What is the relative importance of coexisting waves and currents for the resulting sediment transport? Secondly: Is the influence of grain size as strong as traditional models predict, or is it as weak as the empirical CERC-formula indicates? Wave tank data reveal that the oscillatory velocity will in most cases determine the direction as well as the magnitude of the shore normal sediment transport, and wave flume data on shore normal transport as well as field data on littoral drift show weaker grain size dependance than traditional sediment transport models predict. It is suggested that wave dominance as well as weak grain size dependence are manifestations of the fact that the dominant transport mechanisms are often more organised than the diffusion process on which many traditional models are based.

scholarly journals Validation of a Novel, Shear Reynolds Number Based Bed Load Transport Calculation Method for Mixed Sediments against Field Measurements

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2051 ◽  
Author(s):  
Gergely T. Török ◽  
János Józsa ◽  
Sándor Baranya
Keyword(s):  
Sediment Transport ◽  
Calculation Method ◽  
Field Measurements ◽  
Sand Transport ◽  
The Novel ◽  
Transport Models ◽  
Meaningful Improvement ◽  
Transport Calculation ◽  
Load Transport ◽  
Bed Material

In this study, the field measurement-based validation of a novel sediment transport calculation method is presented. River sections with complex bed topography and inhomogeneous bed material composition highlight the need for an improved sediment transport calculation method. The complexity of the morphodynamic features (spatially and temporally varied bed material) can result in the simultaneous appearance of the gravel and finer sand dominated sediment transport (e.g., parallel bed armoring and siltation) at different regions within a shorter river reach. For the improvement purpose of sediment transport calculation in such complex river beds, a novel sediment transport method was elaborated. The base concept of it was the combined use of two already existing empirical sediment transport models. The method was already validated against laboratory measurements. The major goal of this study was the verification of the novel method with a real river case study. The combining of the two sediment transport models was based on the implementation of a recently presented classification method of the locally dominant sediment transport nature (gravel or sand transport dominates). The results were compared with measured bed change maps. The verification clearly referred to the meaningful improvement in the sediment transport calculation by the novel manner in the case of spatially varying bed content.

Groundwater storage change in the Jinsha River basin from GRACE, hydrologic models, and in situ data

2020 ◽  
Author(s):  
Nengfang Chao
Keyword(s):  
Sediment Transport ◽  
River Basin ◽  
Human Activities ◽  
Water Storage ◽  
Hydrologic Models ◽  
Groundwater Storage ◽  
Jinsha River ◽  
In Situ Data ◽  
Storage Change

<p>Groundwater plays a major role in the hydrological processes driven by climate change and human activities, particularly in upper mountainous basins. The Jinsha River Basin (JRB) is the uppermost region of the Yangtze River and the largest hydropower production region in China. With the construction of artificial cascade reservoirs increasing in this region, the annual and seasonal flows are changing and affecting the water cycles. Here, we first infer the groundwater storage changes (GWSC), accounting for sediment transport in JRB, by combining the Gravity Recovery and Climate Experiment (GRACE) mission, hydrologic models and in situ data. The results indicate: (1) the average estimation of the GWSC trend, accounting for sediment transport in JRB, is 0.76±0.10 cm/year during the period 2003–2015, and the contribution of sediment transport accounts for 15%; (2) precipitation (P), evapotranspiration (ET), soil moisture change (SMC), GWSC and land water storage changes (LWSC) show clear seasonal cycles; the interannual trends of LWSC and GWSC increase, but P, runoff (R), surface water storage change (SWSC) and SMC decrease, and ET remains basically unchanged; (3) the main contributor to the increase in LWSC in JRB is GWSC, and the increased GWSC may be dominated by human activities, such as cascade damming, and climate variations (such as snow and glacier melt due to increased temperatures). This study can provide valuable information regarding JRB in China for understanding GWSC patterns and exploring their implications for regional water management.</p>

Tropical forest CH4: from termite mounds to tower  measurements

2021 ◽  
Author(s):  
Hella van Asperen ◽  
Thorsten Warneke ◽  
Alessandro C De Araújo ◽  
Bruce Forsberg ◽  
Leonardo Ramos de Oliveira ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Flux Chamber ◽  
Termite Mounds ◽  
Forest Region ◽  
Different Types ◽  
Emission Estimate ◽  
Flux Measurements ◽  
Set Up ◽  
Chamber Measurements

<div> <div> <div> <p>Methane (CH<sub>4</sub>) is one of the most important anthropogenic greenhouse gases.  Despite its importance, natural sources of methane, such as tropical wetlands and termites, are still not well understood and a large source of uncertainty in the tropical CH<sub>4</sub> budget. The Amazon rainforest is a key region for the (global) CH<sub>4</sub> budget but, due to its remote location, continous CH<sub>4</sub> concentration and flux measurements are still rare.</p> <p>The 50 m high K34 tower (field site ZF2) is located in a pristine ‘Terra Firme’ tropical forest region 60 km northwest of Manaus (Brazil), and is located next to a waterlogged valley, a possible location for anaerobic CH<sub>4</sub> production. In October 2018, in addition to the existing EC CO<sub>2</sub> system, an in-situ FTIR-analyzer (measuring CO<sub>2</sub>, CO, CH<sub>4</sub>, N<sub>2</sub>O and δ<sup>13</sup>CO<sub>2</sub>) was set up to measure tower profile concentrations, above and below the canopy, continuously. By analyses of vertical and temporal nighttime concentrations patterns, an emission estimate for all gases could be made, and an ecosystem emission of ~1 nmol CH<sub>4</sub> m<sup>-2</sup> s<sup>-1</sup>  was estimated. In addition, by use of different types of flux chambers, possible  CH<sub>4</sub> sinks and sources such as soils, trees, water and termite mounds were measured.</p> <p>By combining tower and flux chamber measurements, the role and magnitude of different ecosystem sources could be assessed. In this presentation, an overview of the measured CH<sub>4</sub> forest concentrations and fluxes will be given.</p> </div> </div> </div>

Validation and comparison of incoming solar radiation satellite databases on the Atlantic coast of Central Africa. 

2021 ◽  
Author(s):  
Amine Ouhechou ◽  
Nathalie Philippon ◽  
Béatrice Morel
Keyword(s):  
Solar Radiation ◽  
Atlantic Coast ◽  
Regional Scale ◽  
Central Africa ◽  
Data Sets ◽  
In Situ Data ◽  
Daily Data ◽  
Solar Radiation Incident ◽  
Set Up

<p>Solar radiation incident on the Earth's surface is important for the functioning of tropical forests, as it affects the availability of light and water. Due to the lack of in-situ data in tropical forest environments, satellite products and reanalyses are the only ways to estimate solar radiation on a regional scale. An intercomparison of five satellite databases including CERES-EBAF, CERES-SYN1deg, CMSAF-SARAH, CMSAF-CLARA, CAMS-JADE as well as the ERA5 reanalysis, is carried out for the Atlantic coast of Central Africa by evaluating them against two in-situ data sets: the monthly FAOCLIM2 database and original infra-daily data from meteorological stations set up within the framework of ecoclimatic projects. From this inter-comparison we show the differences between these six products and with in-situ data from monthly to daily scales. We also show that the Atlantic coast of Central Africa receives the least amount of solar radiation in all products compared to other regions of Central Africa.</p>

STORM ICE OIL WIND WAVE WATCH SYSTEM (SIOWS): WEB GIS APPLICATION FOR MONITORING THE ARCTIC

2017 ◽  
Author(s):  
Alexander Myasoedov ◽  
Alexander Myasoedov ◽  
Sergey Azarov ◽  
Sergey Azarov ◽  
Ekaterina Balashova ◽  
...  
Keyword(s):  
Satellite Data ◽  
Wind Wave ◽  
Arctic Region ◽  
Web Gis ◽  
The Arctic ◽  
Flexible Tool ◽  
In Situ Data ◽  
Current State ◽  
Watch System

Working with satellite data, has long been an issue for users which has often prevented from a wider use of these data because of Volume, Access, Format and Data Combination. The purpose of the Storm Ice Oil Wind Wave Watch System (SIOWS) developed at Satellite Oceanography Laboratory (SOLab) is to solve the main issues encountered with satellite data and to provide users with a fast and flexible tool to select and extract data within massive archives that match exactly its needs or interest improving the efficiency of the monitoring system of geophysical conditions in the Arctic. SIOWS - is a Web GIS, designed to display various satellite, model and in situ data, it uses developed at SOLab storing, processing and visualization technologies for operational and archived data. It allows synergistic analysis of both historical data and monitoring of the current state and dynamics of the "ocean-atmosphere-cryosphere" system in the Arctic region, as well as Arctic system forecasting based on thermodynamic models with satellite data assimilation.

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