Brief Introduction of

Visual MODFLOW

Visual MODFLOW is the USGS's three-dimensional (3D) finite-difference groundwater model thatwas first published in 1984.Visual MODFLOW is the most complete, and user-friendly, modeling environment for practical applications in three-dimensional groundwater flow and contaminant transport simulation.

Introduction

CharacteristicsWidely used ground-water flow simulation program that runs on any platform (Windows, Unix, Linux,); Open source (Anyone can check and change the source code);A modular structure that allows it to be easily modified to adapt the code for a particular application (Processes and Packages).

Some modules

Public domain/open sourceMT3DMS (multi-species solute or heat transport, some reactions, dual porosity) (Chunmiao Zheng, U Alabama)MODPATH (particle tracking) (Dave Pollock, USGS)SEAWAT (density-dependent transport using MODFLOW and MT3DMS) (Chris Langevin, USGS)CommercialMODHMS-Surfact (Integrated sw/gw/unsat)GUIs: Visual MODFLOW, Groundwater Vistas, GMS, PMWin, Programs based on MODFLOW

Governing EquationsConfined Aquifer

Unconfined Aquifer

. A simplified representation of the physical hydrogeological setting. The geologic and hydrologic framework;Media type;Hydraulic properties;Sources and sinks of flow;

Conceptual model

Recharge, discharge, and runoff of groundwater

Input of Visual MODFLOW.1. BoundaryMathematical statements specifying the dependent variable (head) or the derivative of the dependent variable (flux) at the boundaries of the problem domain.

1) Specified head boundaries (Dirichlet conditions) for which head is given.2) Specified flow boundaries (Neumann conditions) for which the derivative of head (flux) across the boundary is given. An no-flow boundary condition is set by specifying flux to be zero.3) Head-dependent flow boundaries (Cauchy or mixed boundary conditions) for which flux across the boundary is calculated given a boundary value. Input of Visual MODFLOW

Constant HeadRiverStreamGeneral HeadEvaporationDrainLakeWallRechargeBoundary Setting in Visual MODFLOW

Input of Visual MODFLOW.2. Source and sinkAmong the many problems in heat-conduction analogous to those in ground-water hydraulics are those concerning sources and sinks, sources being analogous to recharging wells and sinks to ordinary discharging wells.

--- C.V. Theis, 1935

Input of Visual MODFLOW.3. GridThe Grid module allows the user to define and discretize the modeling domain. The user can add or delete gridlines, change cell or layer elevations, or remove cells from the computations.

Input of Visual MODFLOW.Other InputWellsPropertiesParticles(MODPATH)LeakageZone budget

Output of Visual MODFLOWThe output allows the user to visualize, print, and export the simulation results.Five types of maps: Calibration Residual Maps Contour Maps Pathline Maps Velocity Vectors Maps Zone Budget MapsFour types of graphs: Calibration Graphs Time-Series Graphs Mass Balance Graphs Zone Budget Graphs

USGS Software website:http://water.usgs.gov/ogw/modflow/MODFLOW.htmlhttp://water.usgs.gov/nrp/gwsoftware/

Online Visual MODFLOW manual:http://water.usgs.gov/nrp/gwsoftware/modflow2000/MFDOC/guide.html

Some useful website

Thank you for your attention!

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