Import MODFLOW-2005 or -NWT Model Dialog Box

The Import MODFLOW-2005 or -NWT Model dialog box is used to import an existing MODFLOW-2005 or MODFLOW-NWT model into ModelMuse. It is displayed either by selecting File|Import|Import MODFLOW-2005 or -NWT Model... in the Main Window or by selecting Import MODFLOW-2005 or MODFLOW-NWT model in the Start-Up dialog box.

The dialog box has two tabs: Model and Extract Submodel. The Model tab is always used. The Extract Submodel tab is used when the user wishes to create a new model that represents a portion of an existing model.

Model tab

X Origin and Y Origin represent the corner of the grid at row 1, column 1 (the upper, left corner). Grid angle represents the angle in degrees that the grid is rotated counterclockwise. When extracting a submodel, the X Origin and Y Origin represent the coordinates of the corner of the full model - not the submodel. The Name file is the MODFLOW input file that lists the names of the other input and output files for MODFLOW. The MODFLOW name file is not required to have any particular extension, however, the extensions .nam, .mfn, and .modflow.in are sometimes used.

The imported model will have a series of objects that define the properties and boundary conditions of the model. All of these objects will be hidden initially. Once imported, the user can edit or execute the model in the normal way.

For array data such as hydraulic conductivity or recharge rate, there are two different ways in which the data can be assigned. The best method depends on how the model will be used. If the grid might be changed, it is better to use interpolation to ensure that all cells are assigned appropriate values. If the grid will not be changed, assigning cells intersected by an object will allow the values to be assigned faster than assigning them by interpolation.

Although, ModelMuse can import MODFLOW models, it has some intrinsic limitations. Boundary conditions, such as wells, will be imported as points at the centers of cells. The exact coordinates of the wells are not preserved in the MODFLOW input files. Similarly, rivers are imported as a series of points rather than linear features because they are represented as a series of cells in MODFLOW rather than as line segments.

The following packages or input files are imported: Discretization input file, Basic package, Zone arrays input file, Multiplier arrays input file, BCF, CHD, CHOB, DE4, DRN, DROB, DRT, DE4, EVT, FHB, GAGE, GBOB, GHB, GMG, HFB, HOB, HYD, NWT, MNW1, MNW2, MNWI, PCG, PCGN, PVAL, RCH, RIV, RVOB, SFR, SIP, STOB, STR, SUB, SWI, SWR, SWT, UPW, and WEL.

The way that data are specified in MODFLOW can limit the ways in which an imported model is modified. For instance, most of the boundary condition packages such as the Well, River, Drain, and General-Head Boundary packages, define the locations of the boundary conditions using layer, row, and column numbers. If the grid is changed after importing a model, these boundary conditions may no longer be located appropriately. When importing boundary conditions defined by lists of cells such as the Well, River, Drain, and General-Head Boundary packages, separate objects are imported for each stress period. If some of these boundary conditions need to be deleted or have their values changed, it may prove easier to delete the objects that define the boundary conditions entirely and to redefine them based on the original data than to edit them. Adding additional boundary condition objects, on the other hand, can be done with little difficulty. Properties that are defined by arrays in MODFLOW, such as hydraulic conductivity, are less of a problem because a value will be assigned to every cell. However, in some cases, it may be desirable to change the interpolation method used in certain imported data sets. The Nearest Point interpolation method is typically used in imported data sets.

The program MF2005_Importer.exe is used during the process of importing MODFLOW models. It is based on MODFLOW-2005. It reads data in the same way MODFLOW-2005 does and then writes that data in a simple format to the listing file for the model. ModelMuse then reads the data from the listing file. Thus, in the process of importing the model into ModelMuse, the existing listing file is replaced by one created by MF2005_Importer.exe. If the user wishes to preserve the existing output files from the model, a copy of the model should be imported rather than the original version of the model.

Many MODFLOW-2000 models can be imported into ModelMuse in just the same way as the MODFLOW-2005 model. However, because of some differences in the input structure between MODFLOW-2000 and MODFLOW-2005, some MODFLOW-2000 models will have to be converted to MODFLOW-2005 models to be imported into ModelMuse. The program MF2KtoMF05UC can be used to convert MODFLOW-2000 to MODFLOW-2005 models. MF2KtoMF05UC can be obtained from http://water.usgs.gov/nrp/gwsoftware/mf2ktomf05uc/mf2ktomf05uc.html.

MODFLOW-96 models can not be imported into ModelMuse in the same way as MODFLOW-2005 models. However, the program mf96to2k.exe, which is distributed with MODFLOW-2000, can convert MODFLOW-96 models to MODFLOW-2000 models, which could then be imported as described above. MODFLOW-2000 can be obtained from http://water.usgs.gov/nrp/gwsoftware/modflow2000/modflow2000.html. In many cases, it will be necessary to provide the elevations of the tops and bottoms of the layers in order to convert MODFLOW-96 models to MODFLOW-2000 models because those elevations are not necessarily included in the MODFLOW input.

If you wish to import just the MODFLOW grid, edit the name file so that all the files except the LIST, BAS and DIS file and any DATA or DATA(BINARY) files are commented out. You can also comment out any DATA or DATA(BINARY) files if they are used as output. Any line in the Name file that starts with "#" is considered a comment.

Some commercial versions of MODFLOW produce models that can not be read by the USGS version of MODFLOW. These will need to be modified to allow them to be run. Some common changes that might need to be made include the following.

1.Avoid using a unit numbers of 5 or 6.

2.File names must not be surrounded by quotation marks.

3.File names must not include spaces.

4.The USGS version of MODFLOW does not support the H5 format used by GMS.

5.Lines that refer to packages not included in the USGS version of MODFLOW-2005 or MODFLOW-NWT should be commented out. Some examples include:

a)WHS

b)NDC

c)ASP

d)CLB

Extract Submodel

The Extract Submodel tab is used to create a new model representing a portion of an existing model. Such a model might be used in either of two ways.

1.As a completely independent model.

2.As a child model in MODFLOW-LGR (Local Grid Refinement).

When extracting a submodel, the X Origin and Y Origin represent the coordinates of the corner of the full model - not the submodel.

There are two ways to specify the outline of the submodel area.

1.Using a polygon Shapefile that outlines the area to be included. (The Shapefile must be in the same projection used for the MODFLOW model.)

2.Using starting and ending row and column numbers. If the submodel will be a MODFLOW-LGR child model, this method should be used.

A polygon can be used to outline an irregular model outline. This is typically inappropriate for models intended to be child models in MODFLOW-LGR. If the model is intended to be a child model in MODFLOW-LGR, it is better to use starting and ending row and column numbers.

If the model is to be completely independent of the original model, specified head or specified flow boundaries along the edge of the submodel can be read from output files generated by the original model. However, this should not be done for models that will be used as child models with MODFLOW-LGR. In MODFLOW-LGR, the parent model supplies the boundary conditions along the edge of the child model grid automatically.

If the edge boundary conditions are to be read from the original model output files, either specified head or specified flow boundaries should be used but not both. If both are used, the specified head boundaries will override the specified flow boundaries. When a file is used to supply the edge boundary conditions, it is best for it to contain data for every time step.

The edge boundary conditions will be specified with the "Flow and Head Boundary" packages.