Fluid mechanics of plastic debris clogging the hydraulic structures in Indonesia

2020 ◽  
Author(s):  
Vesna Bertoncelj ◽  
Wim Uijttewaal ◽  
Mohammad Farid ◽  
Jeremy Bricker
Keyword(s):  
Water Level ◽  
Monsoon Season ◽  
Optimal Solution ◽  
Field Measurements ◽  
Hydraulic Structures ◽  
Field Observations ◽  
River Systems ◽  
Plastic Debris ◽  
Experimental Modelling ◽  
Driving Mechanisms

<p>The frequent urban floods in Jakarta and Bandung, Indonesia affect the lives and livelihoods of millions of people. Floods cause damage and casualties, while climate change, unchecked development and land subsidence are worsening the problem. One factor contributing to these floods is floating debris clogging the city's drainage structures. A major proportion of floating debris consists of macro plastics which are extremely persistent in the environment. Trash racks that are clogged due to continuous accumulation of plastics in front of them can block the water flow in the river, leading to an increase in upstream water level and causing floods. </p><p>The understanding of transport and accumulation of the macro plastics in the river systems is limited as the field surveys are difficult to perform and the variety of properties of plastic debris is enormous. However, understanding of the origin, fate and pathway of plastic waste is required in order to come up with an optimal solution for plastic collection and prevention of harmful accumulation in front of the hydraulic structures. With this urge in mind field observations will be conducted on the selected river sections in Bandung and Jakarta during the monsoon season in 2020. Field observations will include the measurements of bathymetry, velocity profiles, concentrations and the characterization of floating debris, as well as identifying the accumulation hot spots of floating debris. Furthermore, experimental and numerical modelling will be performed based on the data collected during the field campaign in order to couple different debris classes to a range of riverine situations and understand the differences in their driving mechanisms.</p><p>Using a combination of field measurements, experimental modelling and empirical relations we aim to investigate the driving mechanisms of riverine plastic transport and changes in hydraulic properties due to local disturbances of the current. We will therefore link the type of hydraulic structures and the extend of obstructions due to accumulation of plastic debris to the changes in the upstream water level. This will lead to a better understanding of plastic transport in the river systems in Bandung and Jakarta, to formulate design criteria for structures in trash-laden streams and devise ways to pass trash during floods.</p>

Saturated Hydraulic Conductivity of Clayey Tills and the Role of Fractures

1990 ◽  
Vol 21 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Johnny Fredericia
Keyword(s):  
Hydraulic Conductivity ◽  
American Studies ◽  
Field Measurements ◽  
Present Knowledge ◽  
Saturated Hydraulic Conductivity ◽  
Field Observations ◽  
Laboratory Measurements ◽  
Vertical Hydraulic Conductivity ◽  
Data Field

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.

scholarly journals India’s Commitments to Increase Tree and Forest Cover: Consequences for Water Supply and Agriculture Production within the Central Indian Highlands

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 959
Author(s):  
Benjamin Clark ◽  
Ruth DeFries ◽  
Jagdish Krishnaswamy
Keyword(s):  
Groundwater Recharge ◽  
Forest Cover ◽  
Hydrological Modeling ◽  
Monsoon Season ◽  
Forest Policy ◽  
Central India ◽  
Field Measurements ◽  
Tree Cover ◽  
Policy Goals ◽  
The Impact

As part of its nationally determined contributions as well as national forest policy goals, India plans to boost tree cover to 33% of its land area. Land currently under other uses will require tree-plantations or reforestation to achieve this goal. This paper examines the effects of converting cropland to tree or forest cover in the Central India Highlands (CIH). The paper examines the impact of increased forest cover on groundwater infiltration and recharge, which are essential for sustainable Rabi (winter, non-monsoon) season irrigation and agricultural production. Field measurements of saturated hydraulic conductivity (Kfs) linked to hydrological modeling estimate increased forest cover impact on the CIH hydrology. Kfs tests in 118 sites demonstrate a significant land cover effect, with forest cover having a higher Kfs of 20.2 mm hr−1 than croplands (6.7mm hr−1). The spatial processes in hydrology (SPHY) model simulated forest cover from 2% to 75% and showed that each basin reacts differently, depending on the amount of agriculture under paddy. Paddy agriculture can compensate for low infiltration through increased depression storage, allowing for continuous infiltration and groundwater recharge. Expanding forest cover to 33% in the CIH would reduce groundwater recharge by 7.94 mm (−1%) when converting the average cropland and increase it by 15.38 mm (3%) if reforestation is conducted on non-paddy agriculture. Intermediate forest cover shows however shows potential for increase in net benefits.

3D modelling of the flow distribution in the delta of Lake Øyeren, Norway

2010 ◽  
Vol 41 (2) ◽  
pp. 92-103 ◽  
Author(s):  
Peggy Zinke ◽  
Nils Reidar Bøe Olsen ◽  
Jim Bogen ◽  
Nils Rüther
Keyword(s):  
Water Level ◽  
Cross Sections ◽  
Stokes Equations ◽  
Morphological Changes ◽  
Flow Distribution ◽  
Field Measurements ◽  
Navier Stokes ◽  
Error Sources ◽  
Navier Stokes Equations ◽  
Water Level Measurements

A 3D numerical model was used to compute the discharge distribution in the channel branches of Lake Øyeren's delta in Norway. The model solved the Navier–Stokes equations with the k–ɛ turbulence model on a 3D unstructured grid. The bathymetry dataset for the modelling had to be combined from different data sources. The results for three different flow situations in 1996 and 1997 showed a relative accuracy of the computed discharges within the range of 0 to±20% compared with field measurements taken by an ADCP at 13 cross sections of the distributary channels. The factors introducing the most error in the computed results are believed to be uncertainties concerning the bathymetry. A comparison between the computational results of the older morphology data from 1985–1990 and the model morphology from 1995–2004 indicated that morphological changes in this period had already had consequences for the flow distribution in some channels. Other important error sources were the inevitable use of averaged water level gradients because of unavailable water level measurements within the delta.

scholarly journals Feedback Mechanism in Bifurcating River Systems: the Effect on Water-Level Sensitivity

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1915
Author(s):  
Matthijs R.A. Gensen ◽  
Jord J. Warmink ◽  
Fredrik Huthoff ◽  
Suzanne J.M.H. Hulscher
Keyword(s):  
Water Level ◽  
Flood Risk ◽  
River System ◽  
Feedback Mechanism ◽  
Water Levels ◽  
River Systems ◽  
Water Level Variations ◽  
System Water ◽  
Discharge Distribution ◽  
Single Branch

Accurate and reliable estimates of water levels are essential to assess flood risk in river systems. In current practice, uncertainties involved and the sensitivity of water levels to these uncertainties are studied in single-branch rivers, while many rivers in deltas consist of multiple distributaries. In a bifurcating river, a feedback mechanism exists between the downstream water levels and the discharge distribution at the bifurcation. This paper aims to quantify the sensitivity of water levels to main channel roughness in a bifurcating river system. Water levels are modelled for various roughness scenarios under a wide range of discharge conditions using a one-dimensional hydraulic model. The results show that the feedback mechanism reduces the sensitivity of water levels to local changes of roughness in comparison to the single-branch river. However, in the smaller branches of the system, water-level variations induced by the changes in discharge distribution can exceed the water-level variations of the single-branch river. Therefore, water levels throughout the entire system are dominated by the conditions in the largest branch. As the feedback mechanism is important, the river system should be considered as one interconnected system in river maintenance of rivers, flood-risk analyses, and future planning of river engineering works.

scholarly journals A numerical geotechnical model for computing soil slides at banks of water reservoirs

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nils Reidar B. Olsen ◽  
Stefan Haun
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Stokes Equations ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Field Measurements ◽  
Navier Stokes ◽  
Adaptive Grids ◽  
Groundwater Levels ◽  
Before And After

AbstractSoil slides can occur when the water level in a lake or a reservoir is lowered. This may take place in situations when a reservoir is flushed to remove sediments. The current study describes a three-dimensional numerical model used for the simulation of reservoir flushing that includes the slide movements. The geotechnical failure algorithms start with modelling the groundwater levels at the banks of the reservoir. A limit equilibrium approach is further used to find the location of the slides. The actual movement of the sediments is computed by assuming the soil to be a viscous liquid and by solving the Navier–Stokes equations. The resulting bed elevation changes from the slides are computed in adaptive grids that change as a function of water level, bed erosion and slide movements. The numerical model is tested on the Bodendorf reservoir in Austria, where field measurements are available of the bank elevations before and after a flushing operation. The results from the numerical simulations are compared with these observations. A parameter test shows that the results are very sensitive to the cohesion and less sensitive to the E and G modules of the soil.

Variability of Peak Hour Factor at Intersections

2005 ◽  
Vol 1920 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Andrew P. Tarko ◽  
Rafael I. Perez-Cartagena
Keyword(s):  
Flow Rate ◽  
Field Measurements ◽  
Past Research ◽  
Time Of Day ◽  
Strong Impact ◽  
Field Observations ◽  
Average Value ◽  
The Common ◽  
Multiple Field ◽  
Over Time

A peak hour factor (PHF) is used to convert hourly traffic volume into the flow rate that represents the busiest 15 min of the rush hour. Past research indicated that PHF had a strong impact on traffic analysis results. The common practice is to use a default value recommended by national or local guidelines or to use limited field observations. This paper investigates the variability of PHF over time and across locations. The day-to-day variability of PHF was found to be as strong as the site-to-site variability. This finding prompts estimation of the PHF on the basis of multiple field measurements or, when it is not possible to obtain measurements, for the use of a model that returns the average value of PHF. This paper presents such a model, which links PHF with the hourly volume, population, and time of day. The paper demonstrates that a large portion of the variability in the sample of observations either can be explained with the model or can be attributed to the day-to-day fluctuation.

CFD Study on Free-Surface Influence on Tidal Turbines in Hydraulic Structures

2015 ◽  
Author(s):  
Aldo Tralli ◽  
Arnout C. Bijlsma ◽  
Wilbert te Velde ◽  
Pieter de Haas
Keyword(s):  
Free Surface ◽  
Storm Surge ◽  
Field Measurements ◽  
Hydraulic Structures ◽  
Generic Structure ◽  
Tidal Turbines ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Method Model ◽  
Blade Element

In order to estimate the impact on energy production and environment of tidal turbines placed in or near hydraulic structures like discharge sluices or storm surge barriers, a Computational Fluid Dynamics (CFD) study has been carried out on the relation between (head) loss induced by the turbines and their gross power production. CFD computations have been performed for Tocardo T2 turbines, using STAR-CCM+. Simulations of a single turbine in free flow conditions compare favorably with results of Blade Element Momentum (BEM) computations, in terms of torque and thrust. This BEM method model had been previously validated against both CFD data and field measurements. Then, a series of tests has been performed in a “virtual tow tank”, including the effect of the free surface and the blockage by side and bottom walls. These computations provide a base for a first estimate of the effect of turbines on the discharge capacity of a generic structure. This is considered to be the first step in a more general approach in which ultimately the effect of tidal turbines in the Eastern Scheldt Storm Surge Barrier will be assessed.

scholarly journals Flood Risk Pattern Recognition Using Chemometric Techniques Approach in Golok River, Kelantan

2018 ◽  
Vol 7 (3.14) ◽  
pp. 75
Author(s):  
Wan Nur Amyliyana Wan Faizurie Zaidee ◽  
Ahmad Shakir Mohd Saudi ◽  
Mohd Khairul Amri Kamarudin ◽  
Mohd Ekhwan Toriman ◽  
Hafizan Juahir ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Water Level ◽  
Flood Risk ◽  
Stream Flow ◽  
Monsoon Season ◽  
Factor Loading ◽  
Suspended Solid ◽  
P Value ◽  
Statistical Process ◽  
Risk Pattern

This study was implemented to evaluate the flood risk pattern recognition in Golok River, Kelantan. Based on Spearman correlation test, it showed that water level and suspended solid was very strong and significant (p < 0.0001). There was also a weak correlation of coefficient of stream flow and rainfall with the changes of water level as the p-value close to 1. Suspended solid has strong corresponded in changing the rate of water level, as it described the rate of surface run-off that flowed into the water body. However, the risk of flood in study area is irrelevant to the monsoon season. Principle Component Analysis (PCA), the most sensitive parameters that contribute to the flood occurrence were identified with variability R2 value of 0.812 and 0.764. Expansion and development by human activities contribute to the incline of stream flow and suspended solid in Golok River. Based on Statistical Process Control (SPC), water level of all parameters exceeded the Upper Control Limit (UCL), considered as high risk and vulnerable for flood and it is mostly due to man-made activities. It was not deniable that monsoon season played role in contributing flood occurrence as parameters of rainfall and water level have moderately positive factor loading.  

GRAVEL BED RIVER SCOURING ANALYSIS DOWNSTREAM OF BLOCK RAMP (EXAMPLE FROM THE PONICZANKA STREAM IN PONICE VILLAGE)

2017 ◽  
Vol 167 (47) ◽  
pp. 77-87
Author(s):  
Karol Plesiński
Keyword(s):  
Comparative Analysis ◽  
Hydraulic Structure ◽  
Field Research ◽  
Field Measurements ◽  
Field Observations ◽  
Empirical Relationships ◽  
Gravel Bed ◽  
Scouring Depth ◽  
Scouring Process ◽  
Block Ramp

The work describes the scouring process downstream of boulder block ramps on Poniczanka Stream in Ponice village. The depth of the downstream scouring rate was calculated using empirical formulae due to different authors. The results of the calculations were verified basing on the field measurements. Finally only those formulae which results were most consistent with field observations and those with were the worst consistent with field observations are presented along a paper. Thus the aim of the study was to verify the existing formulae of the scouring depth calculation downstream of block ramp hydraulic structure on the basis of the results of field research. It was found that the empirical relationships for calculating the scouring depth in observed case are not satisfied enough, however they can be used for comparative analysis for designers.

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