scholarly journals Sediment dynamics in shallow Lake Markermeer, The Netherlands: field/laboratory surveys and first results for a 3-D suspended solids model

2012 ◽  
Vol 66 (9) ◽  
pp. 1984-1990
Author(s):  
P. Kelderman ◽  
P. De Rozari ◽  
S. Mukhopadhyay ◽  
R. O. Ang'weya
Keyword(s):  
The Netherlands ◽  
Shallow Lake ◽  
Suspended Solids ◽  
Sediment Resuspension ◽  
Sediment Dynamics ◽  
Lake Area ◽  
Sediment Yields ◽  
Wind Speeds ◽  
First Results ◽  
Set Up

In 2007/08, a study was undertaken on sediment dynamics in shallow Lake Markermeer, The Netherlands. Firstly, the sediment characteristics median grain size, mud content and loss on ignition showed a spatial as well as water depth related pattern indicating wind-induced sediment transport. Sediment dynamics were investigated in a sediment trap field survey at two stations. Sediment yields, virtually all coming from sediment resuspension, were significantly correlated with wind speeds. Resuspension rates for Lake Markermeer were very high, viz. ca. 1,000 g/m2day as an annual average, leading to high suspended solids (SS) contents, due to the large lake area and its shallowness (high ‘Dynamic Ratio’). Sediment resuspension behaviour was further investigated in preliminary laboratory experiments using a ‘micro-flume’, applying increasing water currents onto five Lake Markermeer sediments. Resuspension showed a clear exponential behaviour. Finally, a 3-D model was set up for water quality and SS contents in Lake Markermeer; first results showed a good agreement between modelled and actual SS contents. Construction of artificial islands and dams will reduce wind fetches and may be expected to cause a substantial decrease in lake water turbidity.

scholarly journals Lampiran 1B Paper Sediment dynamics in shallow Lake Markermeer, The Netherlands: field/laboratory surveys and first results for a 3-D suspended solids model

2021 ◽  
Author(s):  
Philiphi de Rozari
Keyword(s):  
The Netherlands ◽  
Shallow Lake ◽  
Suspended Solids ◽  
Sediment Resuspension ◽  
Sediment Dynamics ◽  
Lake Area ◽  
Sediment Yields ◽  
Wind Speeds ◽  
First Results ◽  
Set Up

In 2007/08, a study was undertaken on sediment dynamics in shallow Lake Markermeer, The Netherlands. Firstly, the sediment characteristics median grain size, mud content and loss on ignition showed a spatial as well as water depth related pattern indicating wind-induced sediment transport. Sediment dynamics were investigated in a sediment trap field survey at two stations. Sediment yields, virtually all coming from sediment resuspension, were significantly correlated with wind speeds. Resuspension rates for Lake Markermeer were very high, viz. ca. 1,000 g/m2 day as an annual average, leading to high suspended solids (SS) contents, due to the large lake area and its shallowness (high ‘Dynamic Ratio’). Sediment resuspension behaviour was further investigated in preliminary laboratory experiments using a ‘micro-flume’, applying increasing water currents onto five Lake Markermeer sediments. Resuspension showed a clear exponential behaviour. Finally, a 3-D model was set up for water quality and SS contents in Lake Markermeer; first results showed a good agreement between modelled and actual SS contents. Construction of artificial islands and dams will reduce wind fetches and may be expected to cause a substantial decrease in lake water turbidity.

scholarly journals Lampiran 1A Paper Sediment Characteristics and Wind Induced Sediment Dynamics in Lake Markemeer, the Netherlands, Aquatic Sciences

2021 ◽  
Author(s):  
Philiphi de Rozari
Keyword(s):  
Sediment Resuspension ◽  
Sediment Dynamics ◽  
Sediment Characteristics ◽  
Wind Speeds ◽  
Sediment Bed ◽  
Trap Field ◽  
Average Wind ◽  
Waves And Currents ◽  
Aquatic Sciences ◽  
Extreme Winds

In 2007/08, a study was undertaken on thesediment dynamics in shallow Lake Markermeer (theNetherlands). Firstly, sediment characteristics were determined at 49 sites in the lake. Parameters such as median grain size and loss on ignition showed a spatial as well as water depth related pattern, indicating wind-induced sediment transport. Highly significant correlations were found between all sediment parameters. Lake Markermeer sediment dynamics were investigated in a sediment trap field survey at two permanent stations in the lake. Sedimentyields, virtually all coming from sediment resuspension, were significantly correlated with average wind speeds,though periods of extreme winds also played a role.Sediment resuspension rates for Lake Markermeer were high, viz. on average ca. 1,000 g m-2 day-1. The highlydynamic nature of Lake Markermeer sediments must bedue to the overall shallowness of the lake, together with itslarge surface area (dynamic ratio = [H(area)]/[averagedepth] = 7.5); wind-induced waves and currents willimpact most of the lake’s sediment bed. Indeed, near-bed currents can easily reach values 10 cm/s. Measurements of the thickness of the settled ‘‘mud’’ layer, as well as 137Csdating, showed that long-term deposition only takes placein the deeper SE area of the lake. Finally, lake sediment dynamics were investigated in preliminary laboratory experiments in a small ‘‘micro-flume’’, applying increasingwater currents onto five Lake Markermeer sediments.Sediment resuspension started off at 0.5–0.7 cm/s andshowed a strongly exponential behaviour with respect to these currents.

scholarly journals Sediment characteristics and wind-induced sediment dynamics in shallow Lake Markermeer, the Netherlands

2011 ◽  
Vol 74 (2) ◽  
pp. 301-313 ◽  
Author(s):  
P. Kelderman ◽  
R. O. Ang’weya ◽  
P. De Rozari ◽  
T. Vijverberg
Keyword(s):  
The Netherlands ◽  
Shallow Lake ◽  
Sediment Dynamics ◽  
Sediment Characteristics

Field Observation and Simulation of Sediment Resuspension in a Shallow Lake

1988 ◽  
Vol 20 (6-7) ◽  
pp. 263-270 ◽  
Author(s):  
K. Otsubo ◽  
K. Muraoka
Keyword(s):  
Numerical Simulation ◽  
Shallow Lake ◽  
Water Wave ◽  
Field Data ◽  
Sediment Resuspension ◽  
Field Research ◽  
Lake Kasumigaura ◽  
Bed Erosion ◽  
Current Water ◽  
Good Agreement

The dispersion and resuspension of sediments in Takahamairi Bay basin of Lake Kasumigaura were studied by means of field research and numerical simulation. The field data on wind direction and velocity, lake current, water wave, and turbidity were shown. Based on these results, we discuss how precipitated sediments were resuspended in this shallow lake. To predict the turbidity and the depth of bed erosion, a simulation model was established for this lake. The calculated turbidity showed good agreement with the field data. According to the simulated results, the turbidity reaches 200 ppm, and the bed is eroded several millimeters deep when the wind velocity exceeds 12 m/s in the lake.

Experiments on high rate effluent filtration in the Netherlands

1998 ◽  
Vol 38 (3) ◽  
pp. 127-134
Author(s):  
Jaap H. J. M. van der Graaf ◽  
Arjen F. van Nieuwenhuijzen
Keyword(s):  
Wastewater Treatment ◽  
The Netherlands ◽  
Suspended Solids ◽  
Practical Experience ◽  
High Rate ◽  
Treated Water ◽  
Low Concentrations ◽  
Wastewater Treatment Effluent

As yet, filtration of wastewater treatment effluent has not been practised in the Netherlands. The main objections were the expected high costs. In order to gain practical experience an investigation programme studied the applicability and optimization of effluent filtration. Especially multi-layer filtration with the addition of ironchloride seemed to be very effective. Very low concentrations of suspended solids and phosphorus were achieved, even at high filtration rates (up to 30 m/h). This leads to an impressive reduction of expected costs, down to Dfl. 0.02/m3 (treated water).

scholarly journals Endoscopic Pan/Tilt Camera for Thorax Interventions – Design and first results

2019 ◽  
Vol 5 (1) ◽  
pp. 517-519
Author(s):  
Alexander Mrokon ◽  
Peter P. Pott ◽  
Volker Steger
Keyword(s):  
Minimally Invasive ◽  
Inclination Angle ◽  
Magnetic Circuit ◽  
Mechanical Stability ◽  
Fem Simulation ◽  
Camera System ◽  
Design Changes ◽  
First Results ◽  
Set Up ◽  
Future Work

AbstractMinimally invasive surgery in some cases suffers from a limited view because certain areas are obscured by others. In this paper, a system is described, which can be used in minimally invasive procedures as an addition to a standard endoscope to improve the range of view. Through FEM simulation a magnetic circuit was designed to position the camera head. Subsequently, a camera positioning system was set up that includes an extracorporeal and an intracorporeal unit. The first controls the intracorporeal system. The latter has a camera inclination angle of up to 65° and an additional vertically downward viewing angle when aligned in parallel (inclination angle 0°). The panning angle is 360°. The camera system was evaluated in lab and cadaver trials. It has been found that the size of the intracorporeal system (16 × 10 × 150 mm) represents a major problem. Future work will focus of the reduction of the system’s size, the improvement of the camera image quality, and design changes considering mechanical stability.

Simulation Study on Dynamic Reactive Power Compensation of Grid-Connected Wind Farms

2013 ◽  
Vol 756-759 ◽  
pp. 4171-4174 ◽  
Author(s):  
Xiao Ming Wang ◽  
Xing Xing Mu
Keyword(s):  
Voltage Stability ◽  
Wind Farm ◽  
Reactive Power ◽  
Wind Farms ◽  
Reactive Power Compensation ◽  
Wind Speeds ◽  
Wind Generators ◽  
Reactive Compensation ◽  
Farm Model ◽  
Set Up

With the Asynchronous wind generators as research object, this paper analyzes the problems of the voltage stability and the generation mechanism of the reactive power compensation during the wind farms connected operation. For paralleling capacitor bank has shown obvious defects, therefore this paper employs dynamic reactive power compensation to improve reactive characteristics of grid-connected wind farms. With the influences of different wind disturbances and grid faults on wind farms, wind farm model is set up and dynamic reactive power compensation system and wind speeds are built in the Matlab/Simulink software, The simulation result shows that they can provide reactive power compensation to ensure the voltage stability of the wind farms. But STATCOM needs less reactive compensation capacity to make sure the voltage and active power approaching steady state before the faults more quickly, Therefore STATCOM is more suitable for wind farms connected dynamic reactive power compensation.

Operational storm surge forecasting in the Netherlands: developments in the last decade

2005 ◽  
Vol 363 (1831) ◽  
pp. 1441-1453 ◽  
Author(s):  
Martin Verlaan ◽  
Annette Zijderveld ◽  
Hans de Vries ◽  
Jan Kroos
Keyword(s):  
Quality Assurance ◽  
The Netherlands ◽  
Kalman Filtering ◽  
Model Calibration ◽  
Storm Surges ◽  
Operational Environment ◽  
Hydrodynamic Models ◽  
Future Developments ◽  
Set Up ◽  
Storm Surge Forecasting

The accurate forecasting of storm surges is an important issue in the Netherlands. With the emergence of the first numerical hydrodynamic models for surge forecasting at the beginning of the 1980s, new demands and possibilities were raised. This article describes the main phases of the development and the present operational set-up of the Dutch continental shelf model, which is the main hydrodynamic model for storm surges in the Netherlands. It includes a brief discussion of applied data-assimilation techniques, such as Kalman filtering, the model calibration process and some thoughts on quality assurance in an operational environment. After further describing some select recent investigations, the paper concludes with some remarks on future developments in a European context.

scholarly journals Application of the Conditional Nonlinear Optimal Perturbations Method in the Shallow Lake Ecological Degradation and Restoration

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Bo Wang ◽  
Qianqian Qi
Keyword(s):  
Shallow Lake ◽  
Sediment Resuspension ◽  
Finite Amplitude ◽  
Water Transparency ◽  
Lake Ecosystem ◽  
Lake Ecosystems ◽  
Ecological Degradation ◽  
Parameter Condition ◽  
Restoration Model ◽  
Simple Combination

In the shallow lake ecosystems, the recovery of the aquatic macrophytes and the increase in the water transparency have been the main contents of the ecological restoration. Using the shallow lake ecological degradation and restoration model, CNOP method is adopted to discuss the instability and sensitivity of the ecosystem to the finite-amplitude perturbations related to the initial condition and the parameter condition. Results show that the linearly stable clear (turbid) water states can be nonlinearly unstable with the finite-amplitude perturbations, which represent the nature factors and the human activities such as the excessive harvest of the macrophytes and the sediment resuspension caused by artificially dynamic actions on the ecosystems. The results also support the viewpoint of Scheffer et al., whose emphasis is that the facilitation interactions between the submerged macrophytes and the water transparency are the main trigger for an occasional shift from a turbid to a clear state. Also, by the comparison with CNOP-I, CNOP-P, CNOP, and (CNOP-I, CNOP-P), results demonstrate that CNOP, which is not a simple combination of CNOP-I and CNOP-P, could induce the shallow lake ecosystem larger departure from the same ground state rather than CNOP-I, CNOP-P, and (CNOP-I, CNOP-P).

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