GMS has the capability to import and export shapefiles.
When a shapefile is saved from ArcGIS, multiple files are saved. The files are described in the following table. When the shapefile (*.shp) is imported to GMS, the database file (*.dbf) and (*.prj) files are automatically imported at the same time.
|This file contains the geometry of the points, lines, or polygons.|
|This is a relational database file. The properties of the feature objects are stored in this file.|
|This is an index file. It is ignored by GMS.|
|Projection file [optional]. Contains the projection information for the data which GMS uses to project the data on-the-fly.|
Shapefiles are imported to GMS using Open command in the File menu and selecting the *.shp extension. Drag-and-drop is also supported. Shapefiles are handled in GMS by the GIS module and are listed in the Project Explorer under GIS Layers.
GMS can export the following object types as shapefiles:
The Export command can be found by right-clicking on the object in the Project Explorer.
Exporting Feature Objects
In GMS, a single coverage can contain points, nodes, arcs and polygons. Shapefiles, however, can only contain one type of attribute. Thus, when exporting a coverage as a shapefile, GMS can export up to three shapefiles depending on the type of objects in the GMS coverage. For example, if the GMS coverage contains arcs, points and nodes, export the arcs to one shapefile and the points and nodes to a separate point shapefile. It is possible to control which shapefiles GMS will create when more than one is possible. The names for the shapefiles come from the prefix listed at the top of the dialog, appended with "_pts" for the point shapefile, "_arcs" for the arc shapefile, and "_polys" for the polygon shapefile.
With the current version of GMS, only steady state data can be exported to a shapefile. Transient properties are not saved to the file.
The table of attributes that is exported matches the table that is displayed in the properties dialog when editing feature objects.
Currently, only one coverage at a time can be exported to shapefiles.
Converting Shapefiles to Other Object Types
Shapefiles can be converted to the following types of objects:
Conversion to Feature Objects
When converting a shapefile to feature objects the GIS to Feature Objects Wizard is used.
The tables below indicate how GMS imports and exports shapefile properties. A "type" field must exist as an attribute when importing so GMS knows what kind of attribute to assign to the object. If the "type" field is not found, GMS will import the objects as generic objects without properties and the Map Shapefile Properties dialog will not appear.
A single shapefile may contain objects with different attribute types. Different attribute types require different fields, as shown in the tables. The X's in the table indicate which fields correspond with which attribute types. GMS writes -999 to empty cells when exporting because shapefiles have no way of flagging "null" or "no data" fields. If a field is not required based on the attribute types of the objects to be exported, the field will not be included.
GMS only supports importing of steady state data (one moment in time) from shapefiles.
MODFLOW/MT3D Local Sources Sinks Coverage
For MODFLOW/MT3D local source/sink coverages, if a node is attached to more than one arc, it can have more than one attribute type. When GMS exports these nodes, it exports one node for every attribute type the node has. So the shapefile might end up with several points in the same location, each with different properties. When importing, GMS will resolve all nodes found in the same location to one node and assign the node the union of the properties of all the nodes.
Note that the following options only work for steady state data. Transient well data can be imported using the pumping well data file formats.
Point Properties For MODFLOW/MT3D Local Source/sink Coverage.
Node Properties For MODFLOW/MT3D Local Source/sink Coverage.
Polygon Properties for MODFLOW/MT3D Local Source/sink Coverage.
MODFLOW/MT3D Areal Coverage
The fields exported for MODFLOW/MT3D layer coverages depend on what properties are defined for the polygons. They also depend on which flow package (LPF, BCF or HUF) is selected in the Coverage Properties dialog. Similarly when importing GMS looks for the appropriate fields based on the selected flow package.
The following table lists the attributes that go with each flow package.
|Type||The attribute type ("Layer")||X||X||X|
|Kh||Horizontal hydraulic conductivity||X||X|
|KV||Vertical hydraulic conductivity||X|
|Pstore||Primary storage coefficient||X|
|Sstore||Secondary storage coefficient||X|
Polygon Properties for MODFLOW/MT3D Layer Coverage.
When importing shapefiles into an observation coverage, information should exist in the Int (interval) and Conf (confidence) fields, or in the Stdev (standard deviation) field but not both. The confidence value should be an integer between 0 and 100 (i.e., 95 means 95% confidence). GMS will assign default values if there is any information missing.
Point Properties for Observation Coverage.
GMS – Groundwater Modeling System
|Modules:||2D Grid • 2D Mesh • 2D Scatter Point • 3D Grid • 3D Mesh • 3D Scatter Point • Boreholes • GIS • Map • Solid • TINs • UGrids|
|Models:||FEFLOW • FEMWATER • MODAEM • MODFLOW • MODPATH • mod-PATH3DU • MT3DMS • MT3D-USGS • PEST • PHT3D • RT3D • SEAM3D • SEAWAT • SEEP2D • T-PROGS • ZONEBUDGET|