Novel Approach to Groundwater Contaminant Transport Modelling

2021 ◽  
Vol 23 (07) ◽  
pp. 281-292
Author(s):  
Manoj Kumar ◽  
◽  
Anunay Gour ◽  
Keyword(s):  
Contaminant Transport ◽  
Groundwater Resources ◽  
Solute Concentration ◽  
Flow Mechanism ◽  
Precise Description ◽  
Transport Modelling ◽  
Novel Approach ◽  
Programming Tools ◽  
Flow Gradient ◽  
Modelling Techniques

This paper comprehensively investigates literature about modelling techniques used in groundwater contaminant transport modelling. Modelling of groundwater is a useful way for the management of groundwater resources, also assessing the fate of contaminants and their remediation. Models very conveniently help to study complex real conditions and examine specific phenomena in addition to predicting the future behaviour of any problem. The use of groundwater simulation programming tools such as MODFLOW, MT3DMS, RT3D, FEFLOW, and MODPATH to model multi-directional contamination transport yields accurate results. Movement, storage, and change of solute concentration are largely regulated by groundwater flow gradient. As a result, a precise description of the flow mechanism is very important. If models are not properly constructed and interpreted, they can become complicated and may generate wide errors. Well-defined and clear modelling objectives produce suitable models for efficient error-free modelling processes. The study will assist modellers to clearly define their model objective and select appropriate modelling tools.

scholarly journals Probabilistic Groundwater Flow, Particle Tracking and Uncertainty Analysis for Environmental Receptor Vulnerability Assessment of a Coal Seam Gas Project

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3177
Author(s):  
Dennis Gonzalez ◽  
Sreekanth Janardhanan ◽  
Daniel E. Pagendam ◽  
Daniel W. Gladish
Keyword(s):  
Risk Assessment ◽  
Coal Seam ◽  
Groundwater Flow ◽  
Contaminant Transport ◽  
Particle Tracking ◽  
Gas Wells ◽  
Coal Seam Gas ◽  
Transport Pathway ◽  
Transport Modelling ◽  
Contamination Risk

The production of coalbed methane, or coal seam gas (CSG) in Australia increased 250-fold since the 1990s to around 1502 petajoules in 2019 and continues to expand. Groundwater flow in the aquifers intersected by gas wells could potentially facilitate a transport pathway for migration of contaminants or poorer quality water from deeper formations. While regulatory and mitigation mechanisms are put in place to minimize the risks, quantitative environmental impact assessments are also undertaken. When many gas wells are drilled in a wide area where many potential receptors are also spatially distributed, potential source-receptor combinations are too numerous to undertake detailed contamination risk assessment using contaminant transport modelling. However, valuable information can be gleaned from the analysis of groundwater flow directions and velocities to inform and prioritise contamination risk assessment and can precede computationally challenging stochastic contaminant transport modelling. A probabilistic particle tracking approach was developed as a computationally efficient screening analysis of contamination pathways for a planned CSG development near Narrabri in northern New South Wales, Australia. Particle tracking was run iteratively with a numerical groundwater flow model across a range of plausible parameter sets to generate an ensemble of estimated flow paths through the main Great Artesian Basin aquifer in the area. Spatial patterns of path lines and spatial relationships with potential receptors including neighbouring groundwater extraction wells and hydrologically connected ecological systems were analysed. Particle velocities ranged from 0.5 to 11 m/year and trajectories indicated dedicated contaminant transport modeling would be ideally focused at the local scale where wells are near potential receptors. The results of this type of analysis can inform the design of monitoring strategies and direct new data collection to reduce uncertainty and improve the effectiveness of adaptive management strategies and early detection of impacts.

scholarly journals A Generic Method for Predicting Environmental Concentrations of Hydraulic Fracturing Chemicals in Soil and Shallow Groundwater

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 941 ◽  
Author(s):  
Dirk Mallants ◽  
Elise Bekele ◽  
Wolfgang Schmid ◽  
Konrad Miotlinski ◽  
Andrew Taylor ◽  
...  
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Shallow Groundwater ◽  
Solute Concentration ◽  
Coal Seam Gas ◽  
Transport Modelling ◽  
Environmental Concentrations ◽  
Modelling Framework ◽  
Recharge Rates ◽  
Migration Pathways

Source-pathway-receptor analyses involving solute migration pathways through soil and shallow groundwater are typically undertaken to assess how people and the environment could come into contact with chemicals associated with coal seam gas operations. For the potential short-term and long-term release of coal seam gas fluids from storage ponds, solute concentration and dilution factors have been calculated using a water flow and solute transport modelling framework for an unsaturated zone-shallow groundwater system. Uncertainty about dilution factors was quantified for a range of system parameters: (i) leakage rates from storage ponds combined with recharge rates, (ii) a broad combination of soil and groundwater properties, and (iii) a series of increasing travel distances through soil and groundwater. Calculated dilution factors in the soil increased from sand to loam soil and increased with an increasing recharge rate, while dilution decreased for a decreasing leak rate and leak duration. In groundwater, dilution factors increase with increasing aquifer hydraulic conductivity and riverbed conductance. For a hypothetical leak duration of three years, the combined soil and groundwater dilution factors are larger than 6980 for more than 99.97% of bores that are likely to be farther than 100 m from the source. Dilution factors were more sensitive to uncertainty in leak rates than recharge rates. Based on this dilution factor, a comparison of groundwater predicted environmental concentrations and predicted no-effect concentrations for a subset of hydraulic fracturing chemicals used in Australia revealed that for all but two of the evaluated chemicals the estimated groundwater concentration (for a hypothetical water bore at 100 m from the solute source) is smaller than the no-effect concentration for the protection of aquatic ecosystems.

scholarly journals Recursive modular modelling methodology for lumped-parameter dynamic systems

2017 ◽  
Vol 473 (2204) ◽  
pp. 20160891 ◽  
Author(s):  
Renato Maia Matarazzo Orsino
Keyword(s):  
Dynamic Systems ◽  
Recursive Algorithm ◽  
Complex Model ◽  
Projection Operators ◽  
Novel Approach ◽  
Lumped Parameter ◽  
Modelling Methodology ◽  
Modelling Techniques ◽  
Single Complex ◽  
The One

This paper proposes a novel approach to the modelling of lumped-parameter dynamic systems, based on representing them by hierarchies of mathematical models of increasing complexity instead of a single (complex) model. Exploring the multilevel modularity that these systems typically exhibit, a general recursive modelling methodology is proposed, in order to conciliate the use of the already existing modelling techniques. The general algorithm is based on a fundamental theorem that states the conditions for computing projection operators recursively. Three procedures for these computations are discussed: orthonormalization, use of orthogonal complements and use of generalized inverses. The novel methodology is also applied for the development of a recursive algorithm based on the Udwadia–Kalaba equation, which proves to be identical to the one of a Kalman filter for estimating the state of a static process, given a sequence of noiseless measurements representing the constraints that must be satisfied by the system.

Design of a hydrodynamic leachate containment system

1989 ◽  
Vol 16 (5) ◽  
pp. 615-626 ◽  
Author(s):  
M. D. Haug ◽  
D. J. L. Forgie ◽  
S. L. Barbour
Keyword(s):  
Contaminant Transport ◽  
Water Table ◽  
High Water ◽  
Groundwater Table ◽  
Cutoff Wall ◽  
Transport Modelling ◽  
High Water Table ◽  
Cutoff Walls ◽  
A Site

This paper presents the design concept for a case study sanitary landfill on a site that would not normally have been approved owing to the presence of a high water table. In this design, the base of the landfill was intentionally placed below the water table. A massive 2.5 m wide, 2.5 m high cutoff wall and a 0.3 m thick liner with hydraulic conductivities of approximately 5 × 10−10 m/s were constructed of recompacted glacial till to limit both groundwater intrusion into the landfill and leachate migration out of the landfill. In this case study, the landfill base was placed below the water table to (i) provide a relatively inexpensive source of cover material and (ii) use the hydrodynamic gradient from the high water table to help contain the leachate. Finite element modelling of the seepage and contaminant transport, for alternate designs for lined and unlined landfills placed above and below the groundwater table, is shown to confirm a previous, less-sophisticated, estimation that placing a lined landfill below the groundwater table has definite advantages in reducing both leachate seepage and contaminant transport. Key words: landfill, leachate, hydrodynamic containment, liners, compacted earth cutoff walls, seepage and contaminant transport modelling.

DISPOSABLE GROUNDWATER RESOURCES OF RIVER BASINS IN POLAND IN THE LIGHT OF SUSTAINABLE MANAGEMENT

2016 ◽  
pp. 0-0
Author(s):  
Andrzej SADURSKI ◽  
Elzbieta Przytuła
Keyword(s):  
Water Management ◽  
Sustainable Management ◽  
Groundwater Resources ◽  
Groundwater Exploitation ◽  
Ore Bodies ◽  
Catchment Areas ◽  
Management Plans ◽  
Water Management Plans ◽  
Modelling Techniques ◽  
Analytical Approaches

The term groundwater resources was introduced to hydrogeology from economic geology similarly to the resources of ore bodies almost a hundred years ago. It has been used for the need of physical planning, investment in new water intakes, and water management. Discussion on the groundwater resources started in the past after implementation of new methods of their evaluation, e.g. analytical approaches, and physical and then numerical modelling techniques. The ecological aspects of water demand, indicated in the Water Framework Directive, oblige the EU countries to introduce a new idea for the estimation of groundwater resources. This idea is also presented in the water management plans for river catchment areas. Distribution of available groundwater resources in the country and comparison with the groundwater exploitation is the background of proper, sustainable management of its resources. Available groundwater resources of the country, understood as a total amount of disposable and prospective groundwater resources, is 36.4 million m3/day (as of December 31, 2015), including 21.4 million m3/day of disposable resources, and 15 million m3/day of estimated prospective resources.

scholarly journals The Tournemire industrial analogue: reactive-transport modelling of a cement–clay interface

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 167-184 ◽  
Author(s):  
C. Watson ◽  
D. Savage ◽  
J. Wilson ◽  
S. Benbow ◽  
C. Walker ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Reactive Transport ◽  
Transport Model ◽  
Surface Complexation ◽  
General Purpose ◽  
Transport Modelling ◽  
Mineralogical Characterization ◽  
Modelling Techniques ◽  
Materials Used ◽  
Set Up

AbstractIn the post-closure period of a geological disposal facility for radioactive waste, leaching of cement components is likely to give rise to an alkaline plume which will be in chemical disequilibrium with the host rock (which is clay in some concepts) and other engineered barrier system materials used in the facility, such as bentonite. An industrial analogue for cement-clay interaction can be found at Tournemire, southern France, where boreholes filled with concrete and cement remained in contact with the natural mudstone for 15–20 years. The boreholes have been overcored, extracted and mineralogical characterization has been performed. In this study, a reactive-transport model of the Tournemire system has been set up using the general-purpose modelling tool QPAC. Previous modelling work has been built upon by using the most up-to-date data and modelling techniques, and by adding both ion exchange and surface complexation processes in the mudstone. The main features observed at Tournemire were replicated by the model, including porosity variations and precipitation of carbonates, K-feldspar, ettringite and calcite. It was found that ion exchange needed to be included in order for C-S-H minerals to precipitate in the mudstone, providing a better match with the mineralogical characterization. The additional inclusion of surface complexation, however, led to limited calcite growth at the concrete-mudstone interface unlike samples taken from the Tournemire site that have a visible line of crusty carbonates along the interface.

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