GMS

Importing and Exporting Shapefiles

By aquaveo on January 8, 2020

If you have data in GMS, SMS, or WMS that needs to be shared with another application, one of the easiest ways to share this data is through shapefiles. GMS, SMS, and WMS can all import and export shapefiles, though there are some differences between them. This article goes over some of those differences.

Importing Shapefiles

When you import shapefiles into GMS, SMS, or WMS, they will be loaded under the GIS module. Shapefiles can be imported just like any other file using the File | Open command, the Open File macro, or dragging the file icon on the interface. From there, you can use the conversion commands to move the shapefile data into other modules.

Exporting Shapefiles

Though GMS, SMS, and WMS have a lot of similarities they each vary from the other when it comes to saving a shapefile. In general DEMs, TINs, feature objects, and grids can be saved through the right-click menu in GMS; the file menu in SMS; and through both the right-click menu and file menu in WMS.

GMS
Export command

Shapefiles can be exported through the right-click menu.

  1. Right-click on the item in the Project Explorer and select Export to bring up the Export dialog.
  2. In this dialog you can change the "Save as type" to "Shapefile (*.shp)".

The following items can be exported as shapefiles.

  • TINs
  • 3D Grids
  • Feature Objects
  • DEMs
SMS

Shapefiles can be exported through the File menu.

  1. Select the item in the Project Explorer, then File | Save As to bring up the Save As dialog.
  2. In this dialog you can change the "Save as type" to "Shapefile (*.shp)".

The following items can be exported as shapefiles.

  • Scatter Sets
  • 2D Grids
  • Feature Objects
  • Raster Files
WMS

Shapefiles can be exported through the right-click menu and through the File menu.

  1. Select the item in the Project Explorer, then File | Save As to bring up the Save As dialog.
  2. In this dialog you can change the "Save as type" to "Shapefile (*.shp)".
  3. Alternatively, you can right-click and select Save As to bring up the same dialog.
The following items can be exported as shapefiles.
  • TINs
  • 2D Grids
  • Feature Objects
  • DEMs

Now that you know a little more about using shapefiles in XMS, try using them in your GMS, SMS, or WMS projects today!

Blog tags: 
GMS
SMS
WMS

Understanding Projections vs. Reproject

By aquaveo on December 18, 2019

Have you ever wondered what the difference between projection and reprojection is? Have you ever needed to convert a projection from one type to another in GMS, SMS, or WMS (collectively known as XMS)? The use of projections in WMS can be confusing, so the following should provide further clarification.

Specifying Projections

Projections can be associated with individual data objects, either in the object data file itself or in an associated *.prj file. If XMS cannot find a projection, the object will be left as "no projection," or, when new objects are created, XMS will assign the display projection to it. You can specify an object's projection by right-clicking on it and selecting Projection. Note that this projection must be the same as the original projection of the data; specifying an incorrect projection will result in data issues.

Reprojecting on the Fly

"Reprojecting on the Fly" occurs when datasets or objects from multiple projections are loaded into a project, where the x and y values would not otherwise overlap (i.e., the data would be displayed in two or more distinct locations). The different projections for these data will be "reprojected on the fly" to match the display projection such that the data objects will line up. Note that this does not change any *.prj files or the projections that are set for each object; it is an automatic function internal to XMS used for display purposes.

Converting a Projection

If you need to convert from one projection to another, this can be done by right-clicking on it and choosing Reproject. To use this command, the data must first have the correct projection specified. After choosing Reproject, the command will prompt the user to select a new projection, the data will be converted to the selected projection. If a *.prj file is associated with the object (such as a TIFF), reprojecting the object will change the *.prj file. Reprojection on the fly is usually sufficient for most applications. Please note that there are some limitations for reprojecting.

Reporject Dialog Example

Once the datasets are referencing their projection correctly, XMS should reproject them on the fly to match your display projection. If you don't have a display projection set, you can do so by selecting the Display menu and choosing Projection. At that point, if you would like to reproject your scatter(s) into the same projection as the display projection, you would be able to do so.

Now that you see the differences between projection vs. reproject try them out in XMS today!

Blog tags: 
GMS
SMS
WMS
XMS

Viewing an Aquifer's Water Level

By aquaveo on December 4, 2019

After completing a MODFLOW groundwater model in GMS, have you needed to see the aquifer water level? Viewing the water level can aid in visualizing the saturated thickness of an aquifer. The water level can be viewed by doing the following:

  1. Ensure that the Ortho Mode option is toggled on.
  2. Go to Display | Display Options, choose 3D Grid Data, and go to the MODFLOW tab.
  3. Toggle on the Water Table option, and click OK.
  4. Choose either the Front View or the Side View option, or select a cross section to view the water table level.
Water Table shown in GMS

Additional information about the MODFLOW display options, including the Water Table option, can be found on our wiki.

After viewing the water table, it is possible to save the spatial 2D data for the saturated thickness (water table thickness from the aquifer base).

There isn't a shortcut way to save the 2D water table thickness. However, the desired dataset can be created by converting the head and bottom elevation datasets to 2D datasets, and using the dataset calculator to create a dataset of the difference between the two datasets. The workflow is outlined below.

  1. Right-click on your 3D grid and select Convert To | 2D grid.
  2. Select your Head 3D dataset.
  3. Go to the Grid menu, and select 3D data → 2D data.
  4. Choose the desired option in the Create dataset using dialog box selecting the option that best fits your desired dataset.
  5. Repeat steps 2–3 for the Bottom MODFLOW dataset.
  6. Select the 2D grid and go to Edit | Dataset Calculator.
  7. Create the expression: head dataset minus bottom dataset.
  8. Note: If you would like to create a dataset of all time steps, check the box next to Use all time steps before computing.
  9. Give the new dataset a name in the Result option, and click Compute.
  10. Your new dataset will appear under the 2D grid.

Now that you know how to view and save a water table, try it out in GMS today!

Blog tags: 
GMS

Tips for Flow Budget in GMS

By aquaveo on November 13, 2019

In any groundwater model, knowing how much of the groundwater is available for use determines the fate of any project planned for the area. It is often a crucial part of a model to determine an accurate water budget or flow budget. MODFLOW can calculate its own flow budget and can also make use of the ZONEBUDGET program to calculate the water budget for subregions of a model. Knowing how to use both the MODFLOW flow budget and the ZONEBUDGET program greatly enhances the value of models built in GMS.

PZONEBUDGET example

With that in mind, here are some tips for making use of a flow budget and ZONEBUDGET in GMS:

  • If ZONEBUDGET is used to calculate a budget for the entire modeled area, the values for each budget term should match the MODFLOW budget except in situations where there are multiple stresses of the same kind in the same cell (e.g. a pumping well and a recharging well in the same cell).
  • You can confirm your approach by calculating the cumulative volumes for the entire model and seeing if they match the MODFLOW outputs.
  • Computer precision could be a cause of small discrepancies between the budgets produced by ZONEBUDGET and MODFLOW. ZONEBUDGET accumulates budget totals using double precision, and MODFLOW uses single precision. Because of the use of double precision, ZONEBUDGET's output should generally be more accurate than MODFLOW's; however, differences in output are not likely to be significant except for some very large models.
  • You can find the correct cumulative volume of water entering a given zone using the flow rate. This is done by multiplying the rate by the length of the corresponding time step.
  • Rates reported are for the same duration of the matching time step. Time steps stair step, so there the value is the same for the entire time step.

For an overview of ZONEBUDGET in GMS, see our tutorial and try it out in GMS today!

Blog tags: 
GMS

Pages