Pollutant Transport Model Research Articles

Physical fundamental of layered structure stability of river-sea region (on the example of the Kola Bay)

Introduction. The process of transfer of dissolved salts in the mixing zone of river-sea in the early stages of mixing. Using the equation of convection-diffusion of impurity transport using variable coefficients of diffusion processes for the analysis of neighborhoods interfaces solutions. The analytical description and modeling of the processes and to assess their impact on the various components of the ecosystem.
 The experimental data. We used materials of field observations in the areas of water mixing Kola Bay total length of over 60 km. and the period of renovation of water in the mixing zone, depending on the season at 3-10 days. The results of measurements of the hydrophysical parameters in Kola Bay are presented according to the 25 stations separately for spring and autumn seasons, with a total of more than 5600 field observations.
 Results. On the basis of the analytical solution of the problem set that microcurrents gradient across the axis of elongation of form bi-layer hydrodynamic barrier layer, with the effect of blocking the diffusion of ion transport, which contributes to the conservation and sustainability of the layered structures. The results of field measurements for the Kola Bay, confirming the theoretical conclusions. Lamellar structure is formed in the areas of initial contact treatment of various origins, comes from a steady beam isohaline 10-33 ‰, which spreads along the fiber with isohaline 24,7 ‰, extending the strong deceleration at a steady angle of inclination of the border section area of river-sea.
 Conclusions. The theoretical conclusions about the formation of a special layer at the boundaries of the mixing zone, the physical effect of blocking ion transport and accelerates the heat transfer through the boundary between fresh and marine waters. Modeling of pollutant transport model for lamellar. Various models of formation of the layered structure in contact marine and fresh waters with different ionic composition.

A Markov Chain Monte Carlo technique for parameter estimation and inference in pesticide fate and transport modeling

A Bayesian method involving Markov Chain Monte Carlo (MCMC) technique was implemented into a pesticide fate and transport model to estimate the best input parameter ranges while considering uncertainties included in both the observed pesticide concentrations and in the model.The methodology used for integrating the MCMC technique into a pollutant fate and transport models was detailed. The uncertainties encompassed in the dissolution rate and in the adsorption coefficient of the herbicide mefenacet were greatly reduced by the MCMC simulations. In addition, an optimal set of input parameters extracted from the MCMC simulations accurately reproduced mefenacet concentrations in paddy water and paddy soil as compared to the original published dataset. Consequently, by simultaneously optimizing multiple parameters of environmental models and conducting uncertainty analysis, MCMC technique exhibits powerful capability for improving the reliability and accuracy of computer models.The main strengths of the MCMC methodology are: (1) the consideration of uncertainties from both input parameters and observations and (2) the prior distributions of the input parameters which can be reformulate when additional knowledge is available.

On the Existence of Global Weak Solutions to 1D Pollutant Transport Model

We consider a one-dimensionnal bilayer model coupling shallow water and Reynolds lubrication equations with a molecular interactions between molecules. These molecular interactions give rise to intermolecular forces, namely the long-range van der Waals forces and short-range Born intermolecular forces. In this paper, an expression will be used to take into account all these intermolecular forces. Our model is a similar model studied in (Roamba, Zabsonré & Zongo, 2017). The model considered is represented by the two superposed immiscible fluids. A similar model was studied in (Zabsonré Lucas & Fernandez-Nieto, 2009) but the authors do not take into account the intermolecular forces. Without hypothesis about the unknowns as in (Roamba, Zabsonré & Zongo, 2017), we show the existence of global weak solution in time in a periodic domain.

A Study on Mathematical Short-term Modelling of Environmental Pollutant Transport by Sea Currents: The Lagrangian Approach

This paper deals with short-term modelling of pollutant transport on the sea surface after environmental accidents. Using the Lagrangian approach, a two-dimensional model of pollutant flow is devel ...

Ocean outfalls as an alternative to minimizing risks to human and environmental health.

Submarine outfalls are proposed as an efficient alternative for the final destination of wastewater in densely populated coastal areas, due to the high dispersal capacity and the clearance of organic matter in the marine environment, and because they require small areas for implementation. This paper evaluates the probability of unsuitable bathing conditions in coastal areas nearby to the Ipanema, Barra da Tijuca and Icaraí outfalls based on a computational methodology gathering hydrodynamic, pollutant transport, and bacterial decay modelling. The results show a strong influence of solar radiation and all factors that mitigate its levels in the marine environment on coliform concentration. The aforementioned outfalls do not pollute the coastal areas, and unsuitable bathing conditions are restricted to nearby effluent launching points. The pollution observed at the beaches indicates that the contamination occurs due to the polluted estuarine systems, rivers and canals that flow to the coast.

A pollution fate and transport model application in a semi-arid region: Is some number better than no number?

Fate and transport models are powerful tools that aid authorities in making unbiased decisions for developing sustainable management strategies. Application of pollution fate and transport models in semi-arid regions has been challenging because of unique hydrological characteristics and limited data availability. Significant temporal and spatial variability in rainfall events, complex interactions between soil, vegetation and topography, and limited water quality and hydrological data due to insufficient monitoring network make it a difficult task to develop reliable models in semi-arid regions. The performances of these models govern the final use of the outcomes such as policy implementation, screening, economical analysis, etc. In this study, a deterministic distributed fate and transport model, SWAT, is applied in Lake Mogan Watershed, a semi-arid region dominated by dry agricultural practices, to estimate nutrient loads and to develop the water budget of the watershed. To minimize the discrepancy due to limited availability of historical water quality data extensive efforts were placed in collecting site-specific data for model inputs such as soil properties, agricultural practice information and land use. Moreover, calibration parameter ranges suggested in the literature are utilized during calibration in order to obtain more realistic representation of Lake Mogan Watershed in the model. Model performance is evaluated using comparisons of the measured data with 95%CI for the simulated data and comparison of unit pollution load estimations with those provided in the literature for similar catchments, in addition to commonly used evaluation criteria such as Nash-Sutcliffe simulation efficiency, coefficient of determination and percent bias. These evaluations demonstrated that even though the model prediction power is not high according to the commonly used model performance criteria, the calibrated model may provide useful information in the comparison of the effects of different management practices on diffuse pollution and water quality in Lake Mogan Watershed.

Methodology of determining effective porosity and longitudinal dispersivity of aquifer and the application to field tracer injection test in Southern Hanoi, Vietnam

Groundwater field pumping out and tracer injection test had been carried out at Nghiem Xuyen commune, Thuong Tin district, Hanoi where salinized and fresh groundwater boundary exist in the Pleistocene aquifer. The test was executed with pumping out rate of 9l/sec and tracer injection rate of 0.7l/sec of water with the salt concentration of 5g/l. The interpretation and analysis of the groundwater solute transport parameters by the field pumping out and tracer injection test is a rather complicated and delicate task due to the variability of the temporal boundary conditions. The test results have shown that although the tracer injection time is rather long (up to 60 hours), the tracer breakthrough curve of the tracer concentration of the pumped out water has its very specific characteristic shape, however with some variation due to the test invisible variability of conditions. The results of the parameter identification based on the method of least squares have given effective porosity of 0.32 and longitudinal dispersivity of 2.5m (which give the hydrodynamic dispersion of from D=250m2/day right outside the pumping well screen to D=18m2/day right outside the injection well screen). The minimal sum of squares of the differences between the observed and model normalized tracer concentration is 0.00119, which is corresponding to the average absolute difference between observed and model normalized concentrations of 0.0355 (while 1 is the worse and 0 is the best). The results have also shown that the maximal tracer concentration right outside the pumping out well screen is 6.1 times greater than the tracer concentration of the pumped out water. The distortion flow coefficient αW (the ratio between the flow rate through the injection well section without its presence) and the groundwater flow into the tracer injection well is from 18.66 (at the early testing time) to 10.76 (at the later testing time).References Bear J. and Verruijt A., 1987. Modeling groundwater flow and pollution, D. Reidel Publishing Company, Dordrecht, Holand, 414pp. Brouyère S. 2008. Modeling tracer injection and well-aquifer interactions: a new mathematical and numerical approach. Water Resour. Res, 39(3), 1070-1075. Drost, W., D. Klotz, A. Koch, H. Moser, F. Neumaier, and W. Rauert, 1968. Point dilution methods of investigating ground water flow by means of radioisotopes. Water Resour. Res., 4(1), 125-146. Fetter C.W., 2001. Applied Hydrogeology. Prentice Hall Inc. New Jersey 07458, 598pp. Hall, S.H., 1996. Practical single-well tracer methods for aquifer testing, In: Tenth National Outdoor Action Conference and Exposition, National Groundwater Association, Colombus, Ohio, USA, 11pp. Huyakorn P.S., and Pinder G. F., 1983. Computational Methods in Subsurface Flow. Academic Press, New York, 473pp. Nguyen Van Hoang, 2016. Modeling of pollutant transport in water environment. Vietnam Academy of Science and Technology Publishers, 201pp. Nguyen Van Hoang (project head) (2014-2017). Science and Technology Proposal: Study on the finite element modeling software for simulation of groundwater flow and solute transport by groundwater-application to aquifer in Central plain of Vietnam" codded ĐT.NCCB-ĐHƯD.2012-G/04 supported by NAFOSTED-MOST. Nguyen Van Hoang, Dinh Van Thuan, Nguyen Duc Roi, Le Duc Luong, 2012. Study on the impact of the Tri An reservoir on its downstream groundwater level regime. Vietnam Journal of Earth Sciences, 34(4), 465-476. Nguyen Van Hoang, Pham Lan Hoa, Le Thanh Tung, 2014. Study on the accuracy of the numerical modeling of the groundwater movement due to spatial and temporal discretization. Vietnam Journal of Earth Sciences, 36(4), 424-431. Nguyen Van Hoang and Nguyen Duc Roi, 2015. Finite element method in estimation of lag time of rainfall recharge to Holocene groundwater aquifer in Hung Yen province. Vietnam Journal of Earth Sciences, 37(4), 355-362. Nguyen Van Hoang, Nguyen Thanh Cong, Pham Lan Hoa, Le Thanh Tung, 2016. Study on the characteristics of salinity transport in 2D cross-section unconfined aquifer. Vietnam Journal of Earth Sciences, 38(1), 66-78. Novakowski, K.S., 1992. An evaluation of boundary conditions for one-dimensional solute transport, 1, Mathematical development. Water Resour. Res., 28(9), 2399-2410. Polubarinova-Kotrina P. IA., 1977. Theory of Groundwater. Moscow Science Publishers. 664pp. Tong Thanh Tung, 2015. Specialized report: Interpretation and analysis of aquifer parameters for pumping test at group-well test CHN5 in Nghiem Xuyen-Thuong Tin-Hanoi. Project "Groundwater protection in large cities (city: Hanoi)". Vietnam National Center for Water Resources Planning and Investigation-MoNRE, 16pp. Trieu Duc Huy (Project head), 2015. Science and Technology Proposal: Groundwater protection in large cities (city: Hanoi) approved by MoNRE Minister in Decision 1557/QD-BTNMT dated 30th Aug. 2013. Vietnam National Center for Water Resources Planning and Investigation-MoNRE. Vitaly A. Zlotnik and John David Logan, 1996. Boundary Conditions for Convergent Radial Tracer Tests and Effect of Well Bore Mixing Volume. Papers in the Earth and Atmospheric Sciences, 159pp. Zienkiewicz O. C. and Morgan K., 1983. Finite Elements and Approximation. Academic Press, 328p.

Predicting the particle size distribution of eroded sediment using artificial neural networks.

Water erosion causes soil degradation and nonpoint pollution. Pollutants are primarily transported on the surfaces of fine soil and sediment particles. Several soil loss models and empirical equations have been developed for the size distribution estimation of the sediment leaving the field, including the physically-based models and empirical equations. Usually, physically-based models require a large amount of data, sometimes exceeding the amount of available data in the modeled area. Conversely, empirical equations do not always predict the sediment composition associated with individual events and may require data that are not always available. Therefore, the objective of this study was to develop a model to predict the particle size distribution (PSD) of eroded soil. A total of 41 erosion events from 21 soils were used. These data were compiled from previous studies. Correlation and multiple regression analyses were used to identify the main variables controlling sediment PSD. These variables were the particle size distribution in the soil matrix, the antecedent soil moisture condition, soil erodibility, and hillslope geometry. With these variables, an artificial neural network was calibrated using data from 29 events (r2=0.98, 0.97, and 0.86; for sand, silt, and clay in the sediment, respectively) and then validated and tested on 12 events (r2=0.74, 0.85, and 0.75; for sand, silt, and clay in the sediment, respectively). The artificial neural network was compared with three empirical models. The network presented better performance in predicting sediment PSD and differentiating rain-runoff events in the same soil. In addition to the quality of the particle distribution estimates, this model requires a small number of easily obtained variables, providing a convenient routine for predicting PSD in eroded sediment in other pollutant transport models.

Numerical study on pollutant transport in Dalian bay based on hydrodynamic model

Based on the depth-averaged two-dimensional shallow water and pollutant transport equation, the coupling model of water flow and water quality with explicit scheme is developed in this study. The unstructured triangular grid is adopted to locally refine the mesh around sewage outlet or in high-gradient regions of terrain change for the coupling model. The finite volume method is applied to ensure the conservation of mass for each element. This hydrodynamic model applies the Roe solver approximate Riemann solution with second-order accuracy to compute the water momentum flux on the grid interface. Taking Dalian Bay as the research object, the numerical model established is used to simulate the hydrodynamic characteristics and pollutant transport process. The computed results of the tide level, flow current and flow direction agree well with the measured data in Dalian Bay. The spatial and temporal distribution of pollutant in water are analyzed and discussed in this study. Simulated results show that the two-dimensional hydrodynamic and pollutant transport model can accurately simulate the mass transport in coastal waters, and it can provide a scientific basis on coastal water environment protection for the research water.

Some remarks about a community open source Lagrangian pollutant transport and dispersion model

Nowadays fishes and mussels farming is very important, from an economical point of view, for the local social background of the Bay of Naples. Hence, the accurate forecast of marine pollution becomes crucial to have reliable evaluation of its adverse effects on coastal inhabitants’ health. The use of connected smart devices for monitoring the sea water pollution is getting harder because of the saline environment, the network availability and the maintain and calibration costs2. To this purpose, we designed and implemented WaComM (Water Community Model), a community open source model for sea pollutants transport and dispersion. WaComM is a model component of a scientific workflow which allows to perform, on a dedicated computational infrastructure, numerical simulations providing spatial and temporal high-resolution predictions of weather and marine conditions of the Bay of Naples leveraging on the cloud based31 FACE-IT workflow engine27. In this paper we present some remarks about the development of WaComM, using hierarchical parallelism which implies distributed memory, shared memory and GPGPUs. Some numerical details are also discussed.

ANALISIS MODEL SEBARAN BAHAN PENCEMAR Dl PERAIRAN SELAT NGUAN, BATAM

Analysis of the pollutant transport model was conducted to understand themagtitude, their pattern and spreading speed of the pollutant at Nguan narrowchannel of Batam. The RMA2 (Resource Management Associates) analysis wasemployed to solve those phenomena. The target analysis of the pollutant issuspended particulate matter (sediment), a rnost dominant pollutant matter withinthis area. The result shows that the spreading pollutant was strongly associatedwith the monsoonal system, current speed, tidal system and the pollutant source.The southward direction of sediment transport was inluenced by the northwestmonsoon and the tidal flood. While the northward direction was affected by thethe southeast monsoon and the ebb tide. The current speed was identified asmain factor causing the flushing out magnitude of the water mass at the channel, inwhich the flushing out in the northwest monsoon was faster than that in the southeastmonsoon. As consequence, the water resident time was to be short, the pollutantwas easily to be cleaned out and as the result, the water quality within the channelwas to be excellent.

Sensitivity analysis applied to a variational data assimilation of a simulated pollution transport problem

SummaryUnderstanding the impact of the changes in pollutant emission from a foreign region onto a target region is a key factor for taking appropriate mitigating actions. This requires a sensitivity analysis of a response function (defined on the target region) with respect to the source(s) of pollutant(s). The basic and straightforward approach to sensitivity analysis consists of multiple simulations of the pollution transport model with variations of the parameters that define the source of the pollutant. A more systematic approach uses the adjoint of the pollution transport model derived from applying the principle of variations. Both approaches assume that the transport velocity and the initial distribution of the pollutant are known. However, when observations of both the velocity and concentration fields are available, the transport velocity and the initial distribution of the pollutant are given by the solution of a data assimilation problem. As a consequence, the sensitivity analysis should be carried out on the optimality system of the data assimilation problem, and not on the direct model alone. This leads to a sensitivity analysis that involves the second‐order adjoint model, which is presented in the present work. It is especially shown theoretically and with numerical experiments that the sensitivity on the optimality system includes important terms that are ignored by the sensitivity on the direct model. The latter shows only the direct effects of the variation of the source on the response function while the first shows the indirect effects in addition to the direct effects. Copyright © 2016 John Wiley & Sons, Ltd.

Damages and Expected Deaths Due to Excess NOx Emissions from 2009 to 2015 Volkswagen Diesel Vehicles.

We estimate the damages and expected deaths in the United States due to excess emissions of NOx from 2009 to 2015 Volkswagen diesel vehicles. Using data on vehicle registrations and a model of pollution transport and valuation, we estimate excess damages of $430 million and 46 excess expected deaths. Accounting for uncertainty about emissions gives a range for damages from $350 million to $500 million, and a range for excess expected deaths from 40 to 52. Our estimates incorporate significant local heterogeneity: for example, Minneapolis has the highest damages despite having fewer noncompliant vehicles than 13 other cities. Our estimated damages greatly exceed possible benefits from reduced CO2 emissions due to increased fuel economy.

Flow and dispersion analysis of shallow water problems with Froude number variation

A shallow water flow model and a pollutant transport model were developed, and this study highlighted the practical applications of the coupled flow and dispersion models in terms of general properties. The flow model used the Petrov–Galerkin method in which the test functions are deformed by the current direction to introduce balancing diffusion only in the flow direction. The developed flow model was coupled to the pollutant transport model with a spatially varied dispersion tensor to demonstrate soluble constituent mixing. Three applications were considered to test the model performance under various Fr numbers. In the first application, the flow passing through a flume with an abrupt sidewall expansion was considered, and the model prediction was verified by experimental values, focusing on recirculation and the pollutant cloud trap. In the second and the third applications, the trans-critical and super-critical flow regimes evolved in non-uniform channels with an expanding or converging sidewall were reproduced, and pollutant mixing by a spatially varied dispersion tensor was investigated.

Modelling transport polluting substances into alluvial sediments of the Danube River near Novi Sad

The paper analyzes the behavior and interaction of water and the environment in different conditions of groundwater regime. Based on the quality of groundwater i.e. physical-chemical and microbiological characteristics of water from source in the alluvions of the Danube and water quality of the Danube River, we can assume the possible impact on the quality of the river water source in Novi Sad. Good knowledge of the sources and quantities of accumulated pollutions in the sediments and hydrogeological conditions in aquifers in a particular period are crucial for proper placement of the conceptual model of the aquifer. Properly set conceptual model has a crucial role for good mathematical model of pollution transport in aquifer. Water source Štrand near Novi Sad has been selected for the modeling because the data on the water quality of this water source and characteristics of alluvial sediments are very well researched.

Hydrological monitoring at international rivers and basins

The objectives and principles of organization of hydrological monitoring at international (transboundary and boundary) rivers of Russian Federation are discussed. We developed an international rivers classification which concern their location in relation to national boundaries and further used for the optimization of hydrological monitoring network. Rivers in the basin of the Amur and the Selenga are used as an example to discuss the problems of introducing special technologies into the practice of hydrological monitoring under the incomplete hydrometric knowledge of international rivers. Perspectives of the application of methods of water regime assessment, remote sensing application to river hydrology, and mathematical models of pollutant transport are demonstrated.

Experiments and numerical simulations on transport of dissolved pollutants around spur dike

The flow field around a spur dike has three-dimensional characteristics. In order to analyze the influence of the flow field on pollutant transport, based on a compressive volume of fluid (VOF) scheme, the three-dimensional transient compressive pollutant transport model (CPTM) and the cubic equation (CE) bounded differencing scheme were developed. For the calibration and validation of CPTM, laboratory experiments were carried out in a flume with a non-submerged spur dike. The spur dike was angled at 60°, 90°, and 120° from the upstream direction. The simulation results agreed with the experimental results. The simulations and experiments showed that the distribution of pollutant concentration was determined by circumfluence and the main flow. Concentration decay in the circumfluence zone was slower than that in the main flow. Downstream of the spur dike, the concentration fluctuation became intensive with the increase of spur dike angle.

A dynamic coupling numerical model for pollutant transport under wave condition

In order to study the diffusion, migration, and distribution of pollutants among overlying water-body and porous seabed under wave conditions, a dynamic coupling numerical model is proposed. In this model, the coupling between wave field of overlying water-body and seepage of porous bed, the capture and release of pollutants in porous media, and the transport process between the two different regions are taken into account. We use the unified equations for pressure correction and pollutant concentration to solve the numerical model, which avoids repeated iteration on the interface boundary. The model is verified by several case studies. Afterwards, the processes involving release of pollutant from porous seabed and transportation to overlying water-body under different wave conditions are investigated. The results show that the water depth, wave height, and wave period have great influences on the release, capture, and transport processes for phosphorus pollutant.

Deoxygenation andReaeration Coupled hybridMixing cells Based Pollutant Transport Model to Assess water Quality Status of a River

Prediction of spatial and temporal variation of water quality is vital for managing pollutantsdisposal into the rivers. Depletion of dissolved oxygen (DO) takes place due to the consumption of oxygen bymicrobes to digest bio-degradable pollutants which enter a water course. Reaeration takes place in a specificrate depending on DO deficit. Many investigators have formulated models as an alternative to the FickianModel for the advection dispersion pollutant transport. Since Streeter-Phelps research on BOD-DO modeling,many researchers have studied fate of pollutant considering first order reaction along with only advection. TheStreeter-Phelps dispersion model includes deoxygenation and reaeration along with advection and dispersionand which has been solved by defining an axillary variable relating DO deficit and BOD concentration. Thusthis paper considered first order decay and reaeration along with advection and dispersion to simulate spatialand temporal variation of DO concentration using a hybrid mixing cells model. The proposed model has beensuccessfully applied for a hypothetical flow conditions and the River Brahmani, India. River flow requirementand regulation for pollutant disposal with pre-treatment were optimized using the responses of proposedmodel for this River. This research analyzed the selected river reach using proposed model having a particularflow and channel characteristics and found that release of 1180m3/s from Rengali Dam is required to avoidpollution problem. However, in absence of this flow at least 50% of pretreatment pollutants are requiredbefore released into river Tikira.

A hybrid inverse-modeling technique to estimate circulation in a steady wind driven open channel flow

A pollutant transport model for small water bodies is proposed in this paper. This novel model uses kriging and a simple neural network in combination with limited physics to model transport of pollutants in water body instead of trying to model all natural hydrodynamic processes. This technique helps to keep the unknown parameters in the model to fewer numbers compared to models with similar spatial resolution. As such, the model is suitable for ‘inverse modeling’ and predicting the pollutant distribution in water bodies. The model is validated with extensive simulated data and lab scale experiments.