MODFLOW SURFACT

MODFLOW-based ground-water flow and contaminant transport model

MODFLOW SURF/MODFLOW SURFACT DESCRIPTION

A new flow and transport model, MODFLOW SURFACT, is based on the USGS MODFLOW code, the most widely-used ground-water flow code in the world. MODFLOW, however, has certain limitations in simulating complex field problems. Additional computational modules have been incorporated to enhance the simulation capabilities and robustness.MODFLOW SURFACT is a seamless integration of flow and transport modules.

1-D Transport. Note the superior performance of MODFLOW SURFACT.

Steady unconfined flow with drained nodes (red grid).

Transport in radial flow (injection/pumping).

MODFLOW SURF
MODFLOW SURF Features
MODFLOW SURFACT
MODFLOW SURFACT Features
MODFLOW SURFACT Input
MODFLOW SURFACT Requirements

MODFLOW SURF and MODFLOW SURFACT

MODFLOW SURF

MODFLOW SURF FEATURES

The flow module, MODFLOW SURF, incorporates the following new features:

S - Robust and efficient solution Schemes with axisymmetric simulation options, adaptive time stepping, and enhanced output control features.

U - Rigorous treatment of Unconfined flow with complete drying/rewetting capabilities taking into account unsaturated flow and delayed yield effects.

R - Treatment of non-ponding/limited-ponding Recharge and seepage face conditions.

F - Fracture well package to provide rigorous treatment of wells by superimposing tubular fracture elements to the discretized system. MODFLOW SURF automatically determines the contributions from various nodal layers to a total pumping rate, adjusts these contributions based on aquifer conditions, adjusts the total pumping rate of the system when demand exceeds supply, and includes wellbore storage effects.

MODFLOW SURF is fully compatible with previous versions of MODFLOW and includes all additional packages implemented in later versions of MODFLOW. Input data formats for MODFLOW SURF are similar to MODFLOW and inputs for the new packages may be created with minimal effort.

MODFLOW SURFACT

MODFLOW SURFACT FEATURES

Recognizing that few contaminant transport codes compatible with MODFLOW are available, new transport modules were developed and integrated into MODFLOW SURFACT. The new transport modeling features of MODFLOW SURFACT include:

Advective-dispersive transport of up to five species.

Linear/non-linear retardation.

First-order biochemical degradation in soil and/or water, including generation of transformation products.

MODFLOW SURFACT overcomes several limitations of other available transport counterparts of the MODFLOW code. These limitations concern mass balance problems, excessive numerical dispersion and/or oscillations, and the implicit assumption of negligible impact of transient flow storage effects on transport.

MODFLOW SURFACT utilizes robust and efficient flux-limiting transport schemes with Total Variation Diminishing (TVD) properties. These TVD schemes are not only mass-conservative but are also capable of accurately simulating steep concentration fronts. They are used in conjunction with an adaptive time-stepping procedure.

For the sake of completeness, MODFLOW SURFACT also offers standard finite-difference schemes including upstream, central, and combined central-upstream differencing with the Crank-Nicolson or fully-implicit time stepping. All schemes used in MODFLOW SURFACT are strictly mass conservative producing numerical solutions with negligible mass balance errors.

MODFLOW SURFACT Input

Input preparation for MODFLOW SURFACT is straightforward and follows the MODFLOW format structure. Transport simulations make use of all MODFLOW data sets, and duplication of these data is eliminated. An additional data set, including all transport parameters, is required, and boundary conditions are implemented easily through the MODFLOW boundary data sets.

MODFLOW SURF and MODFLOW SURFACT Requirements: PC 486/Pentium with 16 MB RAM and Microsoft Windows V 3.1 or later.

Τελευταία Ενημέρωση 27 Ιουλίου 2004 - Last Revised on July 27th 2004

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