Groundwater Flow and Solute Transport Modelling
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:
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.
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.
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.
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.
Hydrologic Evaluation of Landfill Performance - is a specialised
landfill model used to predict leachate generation rates and assess
landfill cover performance.
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
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 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 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.