Aquaveo & Water Resources Engineering News

Understanding SRH-2D No Flow Boundaries

Do you want to understand more about how SRH-2D uses no flow boundaries? Occasionally, you can encounter various challenges regarding no flow boundaries. This post will review how no flow boundaries interact with SRH-2D in order to avoid potential issues with your SRH-2D model.

Examples of no flow boundaries in SRH-2D

SRH-2D includes different types of no flow boundaries such as:

  • Boundary condition arcs assigned to be a "wall".
  • The elements touching a void in a mesh.
  • The boundaries of a mesh that are not assigned to be inflow, outflow, etc.

Make certain to review all of your no flow boundaries. In particular, if you used a shapefile or another coverage to create your boundary condition coverage review all of the arcs on the coverage. In SMS, the default SRH-2D boundary condition is a "wall", so any arcs on the boundary condition coverage that are not meant to be no flow arcs should be changed or removed.

An important aspect to understand for no flow boundaries is that for every element they touch, SRH-2D is essentially being told that water can't flow past the boundary. This changes how SRH-2D computes the flow of water through the model. Large elements that are part of no flow boundaries can impact the model flow more than desired, because the smallest unit SRH-2D can process is a single element. SRH-2D is not designed to assign multiple flow values to a single element.

With this restriction on flow for single elements in mind, large elements can have a disproportionate effect on the model if left in key areas. Therefore, in most cases it is important to make sure that elements around key areas of the model should be more refined. Larger elements should be left in less important areas where they will have less impact.

Now that you understand a little more about no flow boundaries, try out SRH-2D in SMS 13.1 today!

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Using the Equal Color Segment Height Legend Option

Have you wanted the legend to better represent the scale of your contours in your GMS projects, especially if your intervals are logarithmic? Having a well-configured legend can be very helpful in interpreting the contours of your project in the Graphics Window. And a logarithmic scale for your legend can be useful when you have wide-ranging values in your model that you want to represent in a compact and nuanced way. This post will review how to modify your contour legend options and how your legend is scaled.

To access the GMS Contour Legend Options:

  1. First, contour options can be accessed either through relevant parts of the Display Options dialog (accessed from the Display Options macro) or through clicking on the Contour Options macro directly.
  2. Look to the bottom-left of the dialog and turn on the Legend checkbox.
  3. Click the Options button to bring up the Contour Legend Options dialog where all the contour legend options will be. This post won’t go into most of these options, but they include such options as setting the legend’s height and width, setting where in the graphics window it will be situated, and customizing its font.
Countour legend using an equal height option

The focus of this post will be the option to turn on Equal Color Segment Height. If the Contour Interval has been set to Number or Specified Interval, this option might not seem so useful, as the values for the contours should already be equally separated. But if the Contour Interval has been set to Specified Values, the Populate Values button will be clickable. This brings up the Value Population Method dialog, where different methods can be used to populate the values of the contours, including a Log Scale Method that will create a logarithmic rather than linear scale to the contours and their legend.

Normally, when a logarithmic scale is used for the contours, the legend will be as well, leading to a lot of the space on the legend being taken up by the higher values and a small amount of space being taken up by the more crowded lower values. Turning on Equal color segment height in the Contour Legend Options dialog can correct this, if that is how you want the legend to be displayed. This option will make the legend display logarithmically, with each logarithmic value displaying equally distant from each other. This means that the legend is no longer a linear gradient, but it better reflects the spread of a logarithmic scale when one is used.

Try experimenting with logarithmic contour intervals and other contour options in GMS 10.5 today!

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How to Change the Temp Directory for WMS

Have you needed to specify the location of a temp directory when working with WMS? Starting in WMS 11.1, you can do this when necessary. It isn’t a feature many users will likely need to bother with, but it will come in handy when you need it. This post will review how to specify the temp directory that WMS will use, and why you might want to.

So what is the significance of temp files and temp directories? Temp files are often used in programs that are dealing with files that use larger amounts of data, such as graphics or video editing software. They help save changes, help programs run efficiently, and can restore progress in the case of a sudden crash or shutdown. They are also designed so that they will be deleted automatically when they are no longer needed.

Your computer should have automatic temp directories that it uses, but sometimes it is required to work with these directories yourself. This may be required for security purposes, to troubleshoot issues, to fulfill legal requirements, or for some other reasons.

This can be done by using the following workflow:

  1. Within WMS, click on Edit | Preferences... to bring up the Preferences dialog.
  2. Go to the General tab of the dialog.
  3. Towards the bottom of the dialog, activate the checkbox for Temporary directory.
  4. Click the Select… button that has now been made active to bring up the Browse For Folder dialog.
  5. Use this dialog to locate which folder will be the new temp directory. This dialog also allows a new folder to be added to your file directory with the Make New Folder button.
  6. The textbox next to the Temporary directory should now be populated with the new temp directory address.
  7. It is recommended to restart WMS for the changes to take effect.
The Temporary direction option in the Preferences dialog

Please note that most users should not play around with this feature. Changing the temp directory typically does not speed up performance or improve functionality. Unless you have a specific reason to change the temp file directory, do not change it as doing so indiscriminately can cause some of WMS’s functionality to stop working.

Besides being able to change the temp directory, check out what else can be done with the Preferences in WMS 11.1 today!

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Using BCDATA Lines with SRH-2D

Have you needed to modify how SRH-2D calculates flow around a structure? Using BCDATA lines in SMS may be able to help. New to SMS 13.1, the BCDATA line feature lets you specify a location where a water level or flow rate is extracted for a variable boundary condition.

The BCDATA line is primarily used to adjust how flow is calculated going into or leaving a structure. If there is high skew or rapid drawdown at the entry or exit of the structure then you should consider using a BC Data line. It indicates that rather than performing flow computations directly at the site of the structure, they should be performed at the location of the BCDATA line.

There are a few applications for a BCDATA line. For instance, it can be used on a structure such as a weir or culvert. When SRH-2D computes flow through or over a structure, it uses an average water surface elevation. When no BCDATA line is present, SRH-2D computes right along the nodes where the upstream boundary condition arc has been mapped. If an upstream or downstream BCDATA line exists, the water level can be computed there rather than at the actual edges of the structure. The BCDATA line should typically be located one or two cells upstream or downstream from the structure to get out of the zone of influence of the structure itself. This avoids drawdown caused by the flow going through or over the structure.

To create a BCDATA line and assign it to a structure, use the following workflow:

  1. Use the Create Feature Arc tool to create a line a few elements long, ideally about 1 to 2 elements away from the upstream or downstream arc. Create it perpendicular to the arc and along the centerline.
  2. Using the Select Feature Arc tool, select the line you have just created, right-click it, and select Assign BC… to bring up the SRH2D Assign BC dialog.
  3. Set the BC Type to Bc Data. Make sure to provide a label name that is unique in the coverage. Then click OK to close the dialog.
  4. Now select the upstream or downstream arc that is meant to be associated with the BCDATA line, right-click it, and select Assign BC… to bring up the SRH2D Assign BC dialog.
  5. Scroll down to the General structure options section at the bottom. Depending on whether the arc selected is upstream or downstream, check the box by the appropriate BCDATA line option.
  6. Use the drop-down that populates to select the label you previously specified for the BCDATA line. Then click OK to close the dialog.

The BCDATA line will now be assigned to the structure.

Example of a BCDATA Line

It can also be used on a Link or an EXIT-H boundary condition that you have specified using a rating curve. Normally, without a BCDATA line, SRH-2D computes the average flow directly at the line and then extracts the water level from the curve. When a BCDATA line does exist, the flow rate (Q) is computed across the BCDATA line, like a monitor line, rather than exactly at the boundaries.

Try using BCDATA lines with SRH-2D in SMS 13.1 today!

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Using A Well Pumping Rate to Calibrate a Model

Have you needed to know how to use a well pumping rate as a calibration parameter in a PEST run? For example, this might be useful in estimating a probabilistic capture zone. We have a workflow that can help with this, utilizing an extraction well and the WEL package for model calibration. This post will review how you can set your MODFLOW parameters in GMS to incorporate well information to be used for parameter estimation.

To do so, use the following steps:

  1. In a well coverage, create a well and give it a constant pumping rate (negative for extraction).
  2. Go to MODFLOW | Parameters... to bring up the Parameters dialog and click the New button to create a new parameter.
  3. Turn on the Show all columns checkbox at the top of the dialog and change the Type value to WELL.
  4. Enter the value that was used for step 1 as the Key, and enter its inverse as the Value.
  5. Enter values for Min and Max that are greater than 0.0. These values and Value will be multiplied by the Q factor later on, which will be -1.0, so positive values listed here will actually become negative.
  6. Turn on the Log Xform checkbox and close the dialog.
  7. Go to MODFLOW | Optional Packages | WEL - Well… to bring up the MODFLOW Well Package dialog.
  8. Enter a Q factor of -1.0 and close the dialog.
  9. Go to MODFLOW | Global Options… to bring up the MODFLOW Global/Basic Package dialog.
  10. Under the Run options section, select Parameter Estimation and close the dialog.
  11. Create a new Observed Flow coverage with Observation Points set to Head in the Coverage Setup dialog, and create a head observation with the Map module active.
  12. Save the project and then click Run MODFLOW to run the PEST Parameter Estimation. When the run is complete, make sure to read the solution into your GMS project.
Example of PEST running using pumping rate as a parameter

Following the above steps will generate solution data where you can use any of the post-processing tools in GMS to review and adjust your model. Try out using well pumping rates in model calibration in GMS 10.5 today!

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Using a Shapefile with the Fast Flood Tool

Do you have a shapefile with water surface elevation data you would like to use towards quickly generating floodplain data? WMS can help you with this. The Map Flood tool, sometimes called the Fast Flood tool, has a new feature we have developed that will allow you to use shapefiles as part of the process of generating floodplain data. This post will review how to use shapefiles for fast flood mapping in WMS.

Using a shapefile with the Map Flood tool can be done by using the following workflow:

  1. Use any of the methods to open files to import your shapefiles into your WMS project. If your shapefile coordinates are geographic, WMS may ask you to convert them to a planimetric coordinate system for computational use, in which case, click OK to accept this.
  2. The shapefile should now be visible under GIS Data. Click on the Map Flood macro to open the Floodplain Mapping Options dialog.
  3. Under the Water Surface Elevations section of the dialog, click on Use FEMA Floodplain Boundary and select your shapefile from its associated drop-down and after making any other changes, click OK to close the dialog.
  4. Example of using a shapefile with the Map Flood tool
  5. The Virtual Earth Map Locator may appear if there is not a set projection. Use it to navigate to the location of your shapefile then click OK after making any other changes. Navigation can either be done by inputting latitude and longitude or typing in the location you wish to observe.
  6. A message may appear saying that the feature requires a global projection. Click OK on this to bring up the Display Projection dialog.
  7. Review the projection to make certain it is correct, click OK to close the Display Projection dialog and run the floodplain delineation.
  8. After the Map Flood tool finishes, you will have all the necessary data downloaded, and the floodplain will have been generated.

Importing a shapefile into the project will have allowed it to be used with the Map Flood tool instead of needing to download the shapefile. This can save you time and provide consistency when generating multiple floodplains using the Map Flood tool. This also allows you to use a shapefile generated from the first use of Map Flood tool for additional floodplain generation in the same area.

Try out using shapefiles for fast flood mapping in WMS 11.1 today!

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Viewing a 3D Bridge in a Plot

Have you had difficulty determining where in your plots your 3D bridges are located? At times it can be challenging to determine where objects lie along a generated line plot. This is why SMS has the functionality to be able to tell the plot to display the location of a 3D Bridge. This post will review how to view the location of a 3D bridge in a plot.

3D bridge plot example

The Plot Data coverage provides the ability to locate structures on a profile plot, which could be used to map the location of a 3D Bridge. However, SMS also allows using the Bridge coverage to help see where the 3D bridge is located on the profile plot. It is important to note that a 3D bridge defined within a 3D Bridge coverage will have to be used, as a UGrid will not suffice.

Once you have all your 3D bridges created and defined, you will need to make a profile plot. This is done by using an observation arc within an Observation coverage that intersects the 3D bridge so that it will eventually be visible in the plot. Select that observation arc, and then right-clicking the arc, you must select the Show Observation Plot command to open a Plot window. This plot will automatically update based on which of the datasets and time steps are selected. This plot shows the data values along the observation arc, but by default does not show where a 3D bridge or other structures intersect with the observation arc.

After the profile plot has been generated, right-click within the Plot window and select the Plot Data command to bring up the Data Options dialog. Notice the options in the Components section related to the 3D bridge coverage. Turn on the check boxes for the 3D bridge coverage in any of the relevant rows.

When everything has been set up correctly, the plot will have properly updated itself and you will be able to see a representation of the selected 3D bridges within the Plot window at this point. Now you will be able to properly keep track of where your 3D bridges come into contact with your profile plots.

Try out viewing 3D bridges in a plot in SMS 13.1 today!

Mapping Multiple Coverages in GMS

Do you have a conceptual model project in GMS where you have multiple map coverages with values for the same MODFLOW package? Are you wondering how GMS maps values from multiple coverages over to the MODFLOW packages?

It's not unusual for some projects to require the same attributes to be in separate coverages rather than having all the attributes in a single coverage. For example you might want to use recharge attributes from different sources and have placed the values on different coverages. But how exactly does GMS handle this? This post should hopefully give you a better sense of what GMS is doing behind the scenes.

Normally, the values for a particular MODFLOW package, such as recharge, are placed on one coverage that uses multiple polygons. In this case, a single value can be calculated, taken only from the predominant polygon, as it is expected that the polygons will all be within the same coverage. Also in this case, the methodology is designed to accommodate polygons being used to calibrate recharge zones in PEST, as opposed to calibrating with pilot points. If using gradient recharges, it is recommended to use scatter points to interpolate recharge values to MODFLOW layers.

You may have a case where you have the values for a package, such as recharge, on polygons on different map coverages. This could be because you imported the values from different sources. In cases where the polygons on different map coverage overlap, the attribute types with different values will have those values summed up when they are applied all at once if you map all of the coverages at the same time. If you don’t want them summed up, make sure that rather than applying them all at once, the value you want is the last value mapped over. This is because when multiple coverages are applied at once, GMS sum the values cumulatively, but when done individually, GMS overwrites the value with the most recently mapped coverage.

Mapping multiple coverages

It is important to note that hydraulic conductivity is not cumulative, though the sources may be. Hydraulic conductivity is overwritten every time, so the values MODFLOW receives are the values of the last polygon that intersected an individual cell.

Items in the Project Explorer are mapped in descending order, so changing the order of the coverages can change the end results.

You can also find more information on how objects are mapped to MODFLOW at the Aquaveo XMS Wiki.

Try mapping multiple coverages in GMS 10.5 today!

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Viewing Multiple GSSHA Scenarios in a Hydrograph

Have you needed to compare multiple GSSHA scenarios using a single hydrograph? New functionality has been added to WMS that now allows for hydrographs that can display results from multiple GSSHA scenarios. This post will review how multiple GSSHA scenarios can be added to hydrographs, a feature newly introduced in WMS 11.1.

Hydrograph showing multiple GSSHA scenarios

Hydrographs that show multiple GSSHA scenarios plot them all out within the same hydrograph. A legend below the graph will indicate which GSSHA scenario run is which in the hydrograph, as each run should be in a different color and potentially a different line style. The dimensions of the hydrograph will be such that all of the different runs will all be able to be displayed.

To be able to work with hydrographs that show multiple GSSHA scenarios, multiple GSSHA scenarios will need to be loaded into WMS to be compared with each other. This can be done by loading multiple GSSHA projects that use the same area into WMS. These can be saved together as a single GSSHA Group Project (GGP) file if needed.

When these GSSHA scenarios will be run, rather than using the typical Run GSSHA command, instead go to the GSSHA | Run GSSHA Group Command. This will open up the Save and Run GSSHA Group dialog. Here, the projects that will run can be selected, as well as the group filename. When the projects have been selected, clicking OK will close out the dialog and bring up the Model Wrapper dialog. This will be brought up for every scenario that will be run, along with the necessary loading of the data into WMS. This will likely take some time, depending on the nature of the GSSHA scenarios, the amount of data to be loaded in, and the amount of different scenarios that will all need to be run.

Once the entire group of GSSHA scenarios has been run, selecting the hydrograph for viewing should display plots of all of the relevant hydrograph scenarios that have been run. Feel free to examine the data, and potentially experiment with different combinations of geographically related runs.

Try out multiple scenario hydrographs in WMS 11.1 today!

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Using SRH-2D Monitor Plots and Structure Plots

With the release of SMS 13.1, we have added the ability to generate monitor plots and structure plots from the solution of a successful SRH-2D model run. This post will offer a brief rundown of these new features and a brief explanation of how to use them.

SMS now has the ability to generate solution plots at monitoring locations or structure locations, using solution datasets generated during the model run. If you make any edits to the coverage after running SRH-2D, make sure to rerun SRH-2D with the updated coverage to keep the plots consistent with the SRH-2D outputs.

For both plots, they will be displayed in an SRH-2D Solution Plots dialog, and they will have similar options in both cases. These options include:

  • Simulations: contains a list of all available simulations where the monitor or boundary conditions coverages were included during the simulation run. Select which solution set to use for the plot.
  • Plots: contains a list of all available solution datasets from the model run. Datasets you select will appear in the plot.
  • Specify time range: specify the time range for the plot to display. The possible range will be from 0 to the length of the entire simulation.

To use the monitor plots:

  1. Make sure you are in the monitor coverage and select a monitoring point or line.
  2. Right-click to select the Monitor Points Plot or Monitor Lines plot command.

This will open the SRH-2D Solution Plots dialog. Note, you need to make sure the monitor coverage was included in the simulation run, and that only one point or line is selected.

To use the structure plots:

  1. Make sure you are in the boundary conditions coverage and select a structure arc.
  2. Right-click to select the Structure Output Plots command.

This will open the SRH-2D Solution Plots dialog. Note that you need to make sure the boundary conditions coverage was included in the simulation run, and that only one structure arc is selected, even for structures that require two arcs.

Structure plot example

Try using monitor plots and structure plots in SMS 13.1 today!

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