Hydraulic model, hydraulic models, hydraulic modeling, and hydraulic modelling software - GMS (Groundwater Modeling System
Coordinate Transformations
A typical groundwater modeling project involves data from a variety of sources including base maps, CAD drawings, GIS data, borehole logs, and survey data. These data are often defined in multiple coordinate systems. In order to build a model in GMS, the data must all be converted to a common coordinate system. GMS features a powerful tool for performing such coordinate transformations.
Current Coordinates
The first step in dealing with multiple coordinate systems is to set the current coordinate system used by the project. The selected coordinate system is saved with the project and is used as a reference when converting to a new system. The coordinate system is defined by selecting the Current Coordinates command in the Edit menu. This command brings up the Coordinates dialog. A coordinate system is selected for both the horizontal and vertical directions. The values that must be defined (zone, hemisphere, etc.) depend on the coordinate system. The following horizontal coordinate systems are supported:
Local
Geographic
Geographic NAD 27 (US)
Geographic NAD 83 (US)
Geographic HPGN (US)
UTM
UTM NAD 27 (US)
UTM NAD 83 (US)
UTM HPGN (US)
State Plane NAD 27 (US)
State Plane NAD 83 (US)
State Plane HPGN (US)
CPP
For the state plane options all 50 US states are supported as well as Puerto Rico/Virgin Islands, St. Croix, American Somoa, and Guam. For the Geographic and UTM options, 32 different ellipsoids are supported, covering most of the globe.
Coordinate Conversions
The coordinate system for a project can be converted to a new system by selecting the Coordinate Conversions command in the Edit menu. This command brings up the Coordinate Conversion dialog. The top section of the dialog illustrates the coordinate system currently associated with the project. The Current Options button can be used to reset the current system if desired. The bottom section of the dialog is used to define the new coordinate system for the project. When the Convert button is selected, all geometric data associated with the project is converted to the new coordinate system.
Local Coordinate Systems
When dealing with local coordinate systems, special care must be taken when making the conversion. Three scenarios are possible when dealing with local coordinate systems:
Global to Local
When converting from a global to a local coordinate system, the global coordinates of the origin of the local coordinate system must be defined using the Local Origin button in the lower portion of the dialog. This dialog can also be used to enter the angle of rotation of the local coordinate axes relative to the global coordinate axes. The angle is measured ccw from the positive x-axis.
Local to Local
When converting from one local coordinate system to another local coordinate system, the same approach is used as when converting from a global to local coordinate system. The Local Origin dialog is used to define the coordinates of the origin of the new coordinate system relative to the old coordinate system.
Local to Global
When converting from a local to a global coordinate system, the Local Origin dialog is used to enter the coordinates of the local coordinate system (which is the old system in this case) relative to the new global coordinate system.
Converting a Portion of Your Data
At times it is necessary to perform a coordinate transformation on a portion, but not all, of your project data. The conversion process described above changes the coordinates of all the data in your project. To change the coordinates for only a portion of your data, read that data into GMS without reading in the rest of your project. This can typically be accomplished by selecting the Open command from the File menu, changing the file filter to the appropriate type, and opening the file containing the data you wish to convert. Once the desired data are in memory, perform the conversion, and then read the rest of your project into GMS.
Hydraulic model, hydraulic models, hydraulic modeling, and hydraulic modelling software - GMS (Groundwater Modeling System
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