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Groundwater Flow and Solute Transport Modelling

plumeHydrogeologists are frequently asked to predict how groundwater behaviour may change with time, generally in response to some change in conditions brought about by human intervention. The emphasis may be on groundwater level (or pressure) and discharge volume - flow modelling - or prediction of the concentration of dissolved contaminants - solute transport modelling. C. M. Jewell & Associates Pty Ltd utilises groundwater modelling as one of the many tools available to assist hydrogeological evaluation and site contamination assessment.

The modelling approach (model code, format, resolution and levels of complexity) required is specific to the hydrogeological setting, and the objectives of the assessment. Models may range in complexity from a one-dimensional analytical equation embedded in a spreadsheet program to a multi-layered, time-variant numerical model intended to simulate changes in groundwater conditions within a complex geological setting over a time scale of several decades. Our groundwater professionals have the experience and insight to make the critical choices in designing the model approach most appropriate to the application.

We use a range of groundwater model codes and integrated modelling software suites, including:

Visual MODFLOW
This package includes the modular three-dimensional finite difference flow model MODFLOW, together with the contaminant transport packages MODPATH and MT3D, which allow extension of modelling into complex contaminant transport simulations. The public domain model MODFLOW is universally recognised among groundwater scientists, and is one of the most commonly used groundwater flow models worldwide. Visual MODFLOW utilises CAD and graphical user interface front-end software to accelerate and refine the modelling process, and 3-D Explorer to output modelling results.

SEEP/W
A two-dimensional, variably saturated, finite element code which is particularly useful for sectional modelling of seepage through embankments or into excavations, and handling difficult multi-layered flow systems where groundwater flow conditions range from unsaturated through to fully saturated, and boundary conditions are complex.

seep/w
TWODAN
An analytical element code, TWODAN utilises sophisticated pre- and post- processing to underpin the highly flexible analytical element modelling approach. Using TWODAN, effective two-dimensional groundwater flow models may be produced in a matter of hours.
PRINCE
A suite of analytical and semi-analytical compiled codes developed by Princeton University. Used by us both as stand-alone models for relatively simple conditions, and as a check on numerical models in more complex situations.

HELP
Hydrologic Evaluation of Landfill Performance - is a specialised landfill model used to predict leachate generation rates and assess landfill cover performance.

RISC
Risk-Integrated Software for Cleanups - an analytical attenuation and decay package for hydrocarbon risk assessment developed by British Petroleum. Includes the vapour transport pathway into buildings.

BIOPLUME III
BIOPLUME III is a two-dimensional, finite difference model for simulating the natural attenuation of organic contaminants in ground-water due to the processes of advection, dispersion, sorption, and biodegradation. It is based on the US Geological Survey solute transport code MOC and solves the solute transport equation six times to determine the fate and transport of the hydrocarbons, electron acceptors and reaction by-products.

BIOCHLOR
BIOCHLOR is a screening model that simulates remediation by natural attenuation of dissolved solvents at chlorinated solvent release sites. BIOCHLOR can be used to simulate solute transport without decay and solute transport with biodegradation modelled as a sequential first-order process within one or two different reaction zones.

PHREEQC
PHREEQC is a computer package designed to simulate chemical reactions and transport processes in natural or polluted water. The program is based on equilibrium chemistry of aqueous solutions interacting with minerals, gases, solid solutions, exchangers, and sorption surfaces, and can also model kinetic reactions.

PHREEQC includes a 1D transport algorithm which models dispersion, diffusion, and various options for dual porosity media. An extensible chemical data base allows application of the reaction, transport, and inverse-modelling capabilities to almost any chemical reaction that is recognized to influence the quality of rainwater, soil water, groundwater and surface water.

 

 
© C. M. Jewell & Associates Pty Ltd - 1/13 Kalinda Road, Bullaburra, NSW, 2784. PO Box 10, Wentworth Falls, NSW, 2782.
Ph (02) 4759 3251. Fax (02) 4759 3257. postie@cm-jewell.com.au