Aquaveo & Water Resources Engineering News

Using Internal Sinks and Links in SRH-2D

Do you have an SRH-2D project that requires placing a drain inside the mesh? Or perhaps you have two seperate meshes in your project where you need to have water flowing between them? Both of these scenarios can be resolved by respectively using the internal sink and link boundary conditions.

Internal Sink Boundary Condition

The internal sink boundary condition is assigned to an arc on an SRH-2D boundary condition map coverage. Unlike an inflow or outflow boundary condition, an internal sink is assigned to an arc that is inside the mesh boundaries.

An internal sink can simulate wells, drains or other points of outflow. It can also simulate a source by specifying a negative number for the flow.

It should be noted that an internal sink boundary condition should not be used as a model’s primary source of inflow or outflow. Inflow and outflow boundary conditions should be placed on the mesh boundary.

Links

Link boundary conditions can be used to simulate moving water between two different meshes or two different areas of the same mesh. Links can sometimes be used to make a simple representation of a pipe or similar structure connecting two areas.

Links are made by making two arcs on an SRH-2D boundary condition coverage. Both arcs are selected when assigning the Link property type. One arc should be assigned as the link inflow boundary condition and the other arcs should be assigned as the link outflow.

Example of an link boundary conditions

It should be noted that link boundary conditions should not be used to model culverts or other such structures. Also, link boundary conditions should not be used as the primary inflow or outflow source for a project.

Now that you know a little more about using internal sink and link boundary conditions, try using them in your SRH-2D projects in SMS.

Blog tags: 

Using MODFLOW Native Files

If you have been using MODFLOW with GMS for any amount of time, you have likely noticed that GMS uses a modified version of the MODFLOW files. This is so that the MODFLOW files can be used more efficiently by the GMS interface.

However, there are times when a project may require using the native MODFLOW files. This is often necessary when opening a MODFLOW project that was not originally created in GMS, or when sharing a project with someone who does not have access to GMS.

When importing native MODFLOW files into GMS, there are some important concepts to keep in mind:

  • You will need to start by importing either the NAM file or MFN file. These files contain a directory for the other files in the MODFLOW project and how they should be opened.
  • It is important to keep all of the MODFLOW files together in the same directory. Having only the NAME or MFN file will not be enough to open the MODLOW project.
  • Files for the packages used with the project will typically have a file extension that matches the package. For example, the Wells package will have the extension "*.wel".
  • All native MODFLOW files can be opened and reviewed using a text editor if needed. See the MODFLOW user guide for information on the file format.
The Save Native Text Copy option

Native MODFLOW files can be exported from GMS by turning on the Save Native Text Copy option in the MODFLOW Global/Basic Package dialog. When exporting native MODFLOW files, keep the following in mind:

  • GMS will create a separate directory with the native MODFLOW files. This directory will typically be the project name with "_text" appended to it. For example, if the project is named "Aquifer", the directory will be named "Aquifer_text".
  • All files in this directory should be kept together.
  • As mentioned before, the files can be reviewed using a text editor.

With GMS 10.4, MODFLOW 6 native files can be imported and exported.

Being able to use native MODFLOW files can greatly enhance collaboration with projects. Try out importing and exporting native MODFLOW files in GMS today!

Blog tags: 

Obtaining Nonstandard Data for Curve Numbers

Calculating curve numbers is a necessary process for many WMS projects. WMS contains a number of tables with suggested soil and land use data for use in calculating the curve number. These are not comprehensive lists of every possible soil data resource, however. These are, only those that are readily downloadable through WMS.

So what do you do if you need to use soil or land use data from a location without data readily available in WMS? You can use nonstandard soil or land use data by creating a file with the data formatted as a table. The format of those land table files can be applied to create a table for any soil data source, such as local shapefiles developed for specific projects.

Example of a land use shapefile

The format for these files is a set of columns as follows:

  1. Soil ID number
  2. Category Label
  3. Hydrologic soil group A
  4. Hydrologic soil group B
  5. Hydrologic soil group C
  6. Hydrologic soil group D

Once you have created a text file with your soil or land use data, import it into WMS as you would any other soil or land use data.

If you’re building your own table for your soil data, there are sources for the tables and charts to help facilitate estimating the curve numbers to put into the table.

For an explanation of or introduction to SCS or runoff curve numbers, a good source is the National Conservation District Employees Association. Their guidance may help clarify the process of creating your own curve numbers.

Additional sources can also be found for soil or land use data. Use whichever data source you feel is appropriate for your project. As long as the data is formatted correctly, WMS should be able to import it.

Try out importing soil and land use data from locations around the world using WMS today!

Blog tags: