Aquaveo & Water Resources Engineering News

Streamlining Watershed Analysis with AGWA

If you work with GSSHA, then you'll definitely want to check out the Automated GSSHA Watershed Analysis, or AGWA, app. AGWA is an online web application for managing proposed changes to watershed models. The app is powered by GSSHA--a hydrologic model developed by the U.S. Army Corps of Engineers.

Example of the AGWA Workflow

AGWA is web-based and therefore can be used from anywhere as long as you have an internet connection and a web browser. It includes simple step-by-step workflows to help you break down a more complex watershed analysis. These workflows can be applied to any number of GSSHA projects. The current workflows include:

  • Detention Basin Analysis
  • Culvert Resize Analysis
  • Find Discharge Tool
  • Land Use Change Analysis

AGWA uses the Tethys platform for managing accounts and access to projects. The GSSHA Models page in AGWA shows a list of all the GSSHA projects that are available for your account. The list includes the project name, project creator, description, and date of creation for each project. You can also view details about the model or the model map from the GSSHA Models page.

Clicking the launch button next to a GSSHA project on the GSSHA Models page will take you to the Model Summary page, which includes two tabs: the Summary tab and the Workflows tab. The Summary tab shows a summary of the GSSHA model including the name and description, map preview, creation date, and a list of scenarios. The Workflows tab shows all workflows that have been created or started, and is where you can create a new workflow.

All completed AGWA workflows have options to view the output data as plots. You can also download the flow and time series data as a CSV file so that you can use the results of your finished workflow outside of AGWA.

Check out AGWA, the app that lets you use GSSHA from anywhere! Follow this link to see a more complete list of the components of AGWA.

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Tool to Fill a Hole in an Unstructure Grid

Have you ever found yourself working on a mesh in the Surface-water Modeling System (SMS) that has holes in places you don’t want them? Then you may want to check out the new Fill Holes in UGrid tool in the SMS toolbox. This tool can be a quick and easy way to fill in any undesirable voids in your 2D mesh or unstructured grid (UGrid).

Example of a UGrid before using the Fill UGrid tool

The Fill Holes in UGrid tool can be found in the SMS toolbox under the Unstructured Grids folder. From there, all you need to do is select the mesh or UGrid that has holes or voids you want filled from a dropdown list, give the new mesh a name, and run the tool. From there, SMS will create a duplicate of the input mesh, only now the mesh will have elements where the holes used to be.

Example of a UGrid after using the Fill UGrid tool

But what if you want to keep some of the voids in your mesh? That’s where the Extract Subgrid tool comes in handy. The Extract Subgrid tool can isolate a portion of a mesh, which is useful if the mesh is particularly large, or if you want to confine any changes to one specific area.

To create a subgrid, first you need to create an Area Property coverage with a polygon outlining the area you want to isolate. Then open the toolbox and find the Extract Subgrid tool, which is located in the Unstructured Grids folder. Select the mesh from the “Grid” dropdown, the coverage from the “Subgrid boundary coverage” dropdown, and enter a name for the new mesh. Now you can use the Fill Holes in UGrid tool to fill the voids in just the isolated portion of the mesh.

If you use the subgrid method to fill the voids in your mesh, there is one more tool you’ll want to know about: the Merge 2D UGrids tool. You can use this tool to merge the subgrid back with the original mesh. This tool is also in the toolbox under the Unstructured Grids folder. To use this tool, select the subgrid from the “Primary grid” dropdown, the original mesh from the “Secondary grid” dropdown, and choose a name for the new mesh.

The Fill Holes in UGrid, Extract Subgrid, and Merge 2D UGrids tools can help simplify and smooth the mesh editing process, no matter the project. Open SMS 13.3 and check out what these three tools can do for you today!

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New MODFLOW-USG 3D Dataset to Array

While most groundwater projects typically only need a 2D dataset to define arrays, 3D datasets are becoming more available. There’s a new feature in the Ground-water Modeling System (GMS) version 10.8 for MODFLOW-USG and MODFLOW-USG Transport models. MODFLOW-USG and MODFLOW-USG Transport are MODFLOW models that were designed specifically to be used with unstructured grids, or UGrids. The Recharge (RCH), Evapotranspiration (EVT), and EvapoTranspiration Segments (ETS) packages in MODFLOW-USG now have the option to use a 3D dataset to define the input arrays. Previous versions of GMS only had the option to use a 2D dataset with a matching 2D structured grid.

Example of the 3D Dataset to Array option

You can find the 3D Dataset → Array button in the properties dialog of the Recharge (RCH), Evapotranspiration (EVT), or EvapoTranspiration Segments (ETS) package. In order to use the 3D Dataset → Array button, the 3D dataset in the MODFLOW-USG model has to have the same number of rows and columns as the 3D grid. If the rows and columns don’t match the 3D grid, then the button will be grayed out and you won’t be able to use it.

Clicking the 3D Dataset → Array button will bring up a Select Dataset dialog with a list of all the datasets associated with the current 3D grid. You can then select the relevant dataset to assign values to the MODFLOW-USG package. 3D datasets are often created using the 3D Scatter Point tool, which can help you interpolate rainfall data to the cells on your grid. If you are using a transient dataset, then the dataset values will be interpolated linearly to each stress period when they are copied to the array. You can learn more about using the 3D Scatter Point tool on this page of our wiki.

Now head over to GMS 10.8 and try using the new 3D Dataset → Array button in your MODFLOW-USG or MODFLOW-USG Transport project today!

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Differences Between AHGW and AHGW Pro

The Arc Hydro Groundwater tools developed by Aquaveo help you manage groundwater and subsurface data within ArcGIS. When ESRI released ArcGIS Pro as the successor to the ArcGIS Desktop applications, we made some changes to the AHGW tools to adapt to the interface of the new ArcGIS application. Today we’ll talk about some of the differences you should expect when making the switch to AHGW Pro. If you're curious about ArcGIS Pro in general, you can follow this link to learn more about it.

Example of the AHGW Pro ribbon

One of the major visual differences between AHGW in ArcGIS Desktop and ArcGIS Pro is the location of the tools. All the AHGW tools in ArcGIS Desktop are located on an AHGW toolbar that can be either docked or floating. In ArcGIS Pro, the AHGW toolbar has been replaced with an AHGW Pro ribbon which includes only some of the tools that were on the old AHGW toolbar. The rest of the subsurface and groundwater analyst tools are imported as a python toolbox. Additionally, AHGW wizards have been converted to panes, which contain all pages of the wizard.

Some of the tools that were previously available in the AHGW desktop applications are not available in AHGW Pro. Some of these tools will be included in upcoming iterations of AHGW, but there are some that will get left behind. Most notably, we have no plans to include any of the AHGW MODFLOW analyst tools in ArcGIS Pro. You may also notice that other file import and export options have been removed.

We made functional changes to some of the AHGW tools in ArcGIS Pro as well. AHGW Pro has moved away from using raster catalogs, using mosaic datasets instread. This may be a little confusing at first, as the tools still have "raster" in the name. Just know that when it says raster, it means mosaic dataset. There are lots of tools that can help you create and modify mosaic datasets inside of ArcGIS Pro, which you can easily find just by typing "mosaic dataset" in the search bar at the top of the window.

Go to ArcGIS Pro and check out the new AHGW Pro tools today!

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Using the Mask Subset Smoothing Option

The Surface-water Modeling System now includes two new tools in the toolbox to help you when your project requires any amount of dataset smoothing. Previous versions of SMS had you use the Dataset Toolbox to smooth a dataset. These new tools can do everything that the Dataset Toolbox used to do, and more.

Both the Smooth Datasets and Smooth Datasets by Neighbor tools are used to eliminate extreme slopes in a dataset, but they require different inputs, which will tell SMS how to incorporate the relationship between nodes. The Smooth Datasets tool uses an anchor and either an elemental area change or maximum slope for its calculations. Smooth Datasets by Neighbor uses the relationship between neighboring nodes and a selected interpolation method: average or inverse distance weighted. Note that the current version of these tools are designed to be used on node-based datasets, so they will only work on a mesh.

Both of the dataset smoothing tools have the option to include a subset mask. A subset mask dataset is great if there are nodes or elements in your mesh that you don't want included in the smoothing process. Here's some things you need to know when using a subset mask in your project.

Before you begin making changes, your subset mask dataset needs to have the same number of values in the same locations as the dataset being smoothed. A simple way to do this is to right-click on the original dataset in the Project Explorer and select Duplicate. Then you can make changes to the duplicate to create your subset mask dataset.

Example of using the mask subset option

All the nodes you want to have included in the smoothing process need to be set to an S value of "1.0", and the nodes that should be excluded need an S value of "0.0". You can do this in any way you'd like, as long as all nodes get assigned one value or the other. There is a quick method that you may consider using to assign these values. With the Select Mesh Node tool active, right-click in the Graphics Window and choose Select All. With all nodes selected, enter either "1.0" or "0.0" in the S value field depending on whether the majority of nodes should be included or excluded. Then manually select the nodes that should be excluded from the smoothing process by either clicking and dragging a box around the nodes, or by holding down the Shift key and selecting nodes, so that you can select multiple nodes at the same time.

Now this dataset is ready to be used as a subset mask. Open the tool's dialog and select the dataset from the Subset mask dataset dropdown in the tool dialog and enter any other necessary inputs, then run the tool.

To see all the changes, go to the Data menu, select Map Elevation, and select the new smoothed dataset. This will apply the changes that the smoothing tool made to the mesh in the Graphics Window.

Head over to SMS and try including a subset mask dataset with the Smooth Dataset tool today!

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Understanding Pass Through Cells

Starting with version 10.8, the Groundwater Modeling System (GMS) has the ability to handle pass through cells in MODFLOW-USG and MODFLOW-USG Transport projects. What are pass through cells? If you have a 3D UGrid with multiple layers, you can have middle layers with pinchouts or other features that cause that middle layer to not extend through the entire range of the other layers. For example, if you have a three-layer unstructured grid with a pinchout in layer two, then you will have an area where the cells of layer one and layer three are supposed to meet. This area where a middle layer is missing for some of the cells is where pass-through cells are needed.

In actuality, there is a thin cell between the layers. Because of this, in areas where a middle layer is missing a barrier would be formed when running MODFLOW-USG. If you don’t want a barrier in that area, then you will need to add a pass through cell to allow water to flow through the area. This means you need to have the Ibound be greater than zero or the water will not be able to pass through the middle layer and create a “no-flow zone.”

By switching between layers you can see which layers have a thickness of zero and which do not. To inactivate the cells with a thickness do the following:

  1. Open the MODFLOW Global/Basic Package dialog.
  2. Select the Set Pass Through… button.
  3. A message will appear explaining parameters used to determine pass through cells.
  4. In the Pass Through Thickness dialog, set the maximum cell thickness.
Example of setting pass through cells

After assigning the maximum cell thickness, cells that are below that thickness will be designated as pass through cells. The pass through cells will have an inactive IBOUND and will be ignored when making vertical connections in the DISU package.

Note that setting pass through cells requires a stacked grid.

Now that you know about pass through cells, make use of them in your MODFLOW-USG and MODFLOW-USG Transport projects in GMS today!

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Tips for Long Term Precipitaiton Simulations

The Watershed Modeling System (WMS) has several options for modeling rainfall events, however many of them are built to model only single rainfall events. If you are looking to create long term simulations that include precipitation, the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) models may be the best fit for your projects. GSSHA was engineered with long term simulations in mind. GSSHA is a product of the US Army Engineer Research and Development Center (ERDC) Hydrologic Modeling Branch, in the Coastal and Hydraulics Laboratory. This blog post covers some information that may be helpful for the next time you build a long term simulation with precipitation.

Example of Long Term Precipitation Results in WMS

While HEC-HMS models are also capable of running long term simulations with precipitation, unlike GSSHA, long term projects are not the main focus of the model. If you’ve already gotten started with HEC-HMS, you may want to consider converting your project to GSSHA. We even have a tutorial that can walk you through doing just that.

There are multiple methods you can use to define precipitation data in GSSHA: Uniform, Gage, Hyetograph, and Nexrad Radar. This is done in the GSSHA Precipitation dialog. Rainfall data for GSSHA models are input as a series of single rainfall events. WMS calculates evapotranspiration between each event, which makes evapotranspiration data a required component of the simulation. There’s no limit to how many times the pattern of rainfall events and evapotranspiration can be repeated, or for what duration, as long as you have enough data.

If your model is not running as expected, there are a couple simple things you can check first when trouble-shooting your project. Be sure to check that you have included enough precipitation and hydrometeorological data. Not including enough data in your project can result in a faulty output. Each data point must be tied to a single point in time, down to the minute.

GSSHA uses gage and HMET files for precipitation and hydrometeorological data, respectively. This data can be prepared using the Time Series Data Editor application so that it can be imported into WMS for use in a long term simulation. Formatting this data properly can be a bit finicky at times, so you may need to double-check that everything is getting read in correctly. We have a tutorial that can show you how this process works, as well as many other tutorials covering different aspects of GSSHA in the WMS Learning portion of our website.

Head over to WMS and try these tips to keep your long term GSSHA simulation running smoothly.

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Incorporating Rubble Mounds in CMS

CMS-Flow and CMS-Wave are two of the principal components of the Coastal Modeling System. Rubble mounds are an important part of some coastal modeling projects. They are a common engineering structure used as jetties, breakwaters, seawalls, and groins for shoreline protection as well as flow and sediment transport control.

The way rubble mounds are implemented in the Surface-water Modeling System (SMS) is different depending on which CMS model you pick. Rubble mounds in CMS-Flow simulations focus primarily on sediment transport and morphology changes, while CMS-Wave focuses on wave processes. Both of these CMS models have their own coverages and sets of requirements in order to add rubble mounds to the project.

Rubble mounds can be added to CMS-Flow simulations through the CMS-Flow Rubble Mound Jetties coverage. Once this coverage is added, you can create a polygon in the Graphics Window that represents the rubble mound. Double-clicking on the rubble mound polygon opens the Rubble Mound Jetty Attributes dialog where you can define the parameters of the rubble mound structure. This dialog includes inputs for the name, the rock diameter, the porosity, the base depth, and the calculation method. After defining all the parameters, the coverage is ready to be added to the CMS-Flow simulation. Finally, make sure that Calculate sediment transport is turned on in the Model Control , otherwise your rubble mound is just a random polygon that has no effect on the final simulation.

Example of a rubble mound in CMS-Wave

Rubble mounds in CMS-Wave simulations work a little differently than CMS-Flow. CMS-Wave doesn't have a specific rubble mound coverage like CMS-Flow does. Instead, rubble mounds are defined on a CMS-Wave structures coverage. This behaves somewhat similarly to materials coverages that you may be familiar with in other SMS models. Double-click the polygon representing the rubble mound to bring up the Assign Structure dialog. Then you'll add a structure with the green plus sign, select "Rubble-mound" from the structures dropdown, and then whether or not you want to modify the rubble mound by elevation. If you'd like, you have the option of customizing the color and texture SMS will use to fill your polygon structure to something that best suits your project.

CMS-Flow and CMS-Wave each require their own simulations, but you have the option to couple them using inline steering. This is a great option if you're building a comprehensive coastal model.

Head over to SMS and try out adding rubble mounds to your CMS project today!

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Generating a 3D Grid from Raster Data

Have you heard about the 3D UGrid from Rasters tool that’s new to the Groundwater Modeling System (GMS)? Previous versions of GMS required you to build a raster catalog and then use the “Horizons to Solids” command in order to generate a 3D unstructured grid (UGrid) when modeling stratigraphy. The 3D UGrid from Rasters tool, which is in GMS’s toolbox under the “Unstructured Grids” folder, streamlines this process by allowing the two previously separate processes to be set up in the same place and executed simultaneously.

Example of a 3D UGrid generated from rasters

The base components for creating a UGrid with the 3D UGrid from Rasters tool are a 2D UGrid and multiple rasters. The rasters are then added to a table and assigned a horizon number. The term “horizon” refers to the top of each stratigraphic unit that will be represented in a corresponding solid, HUF unit, or 3D mesh layer. Horizons are ordered from the bottom up. For each raster you can choose to fill or clip the layer. Choosing “fill” tells GMS to use the raster to create a UGrid layer. Choosing “clip” tells GMS that any lower surfaces should truncate at that layer. You also have the option of creating sublayers between any rasters that have the “fill” option turned on. You can then set the relative size of each of the sublayers so that they are all proportional, or of differing sizes.

After setting all of the parameters for your UGrid in the rasters table, you then need to set a target location so that GMS knows to calculate elevations at the UGrid cell tops and bottoms or at the points. Lastly, you’ll need to define the minimum thickness that every layer must have, and choose a name for your new UGrid.

If you want more details about how the 3D UGrid from Rasters tool works, you can check out this page of our wiki. You can also look at the newest version of the Horizons with Rasters tutorial.

Head over to GMS, and use this new tool to simplify the stratigraphy modeling process.

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Deciding between SRH-2D 2D Bridges and 3D Bridges

In the Surface-water Modeling System, you have the option of adding either a 2D or a 3D bridge to your SRH-2D model. But what are the differences between 2D and 3D bridges, and how can you know which one is the best fit for your SMS project? There are pros and cons to each, so we will briefly explore each option, and hopefully by the end you’ll have a better idea of what works best for you.

Starting in SMS 13.3, the 3D Bridge component that was used in previous versions was retired in favor of 3D Structures. 3D Structures can be used to build 3D bridges as well as culverts, and can also be used to calculate overtopping, an option that wasn’t available with 3D Bridges.

SRH-2D 2D bridge example

For 2D bridges, you have many options to help you customize your bridge, such as setting the bridge width, type and number of piers, abutments, etc.. (For the full list, go to this page of our wiki). All of the options that exist for 2D bridges are also available when building a 3D bridge. Using the 3D structures coverage to build your bridge allows for even more customization, including being able to shape the bridge ceiling so there is variation rather than being a constant along the full length.You can also use the 3D structures dialog to add a UGrid to the Project Explorer so that you can see what the bridge will look like with the mesh. The 3D structures coverage dialogue is able to generate a mesh footprint for your bridge, which automatically includes voids in the mesh for your piers so you don’t have to create them manually.

SRH-2D 3D bridge example

If you have questions about the specifics of building a 3D bridge, check out the new 3D Structures tutorials, or our wiki page on 3D Structures to get a more thorough introduction.

Building a 3D bridge into your project is an excellent option when you want to go the extra mile with the visual representation of the bridge. Although the idea of using a 3D bridge for everything may sound great because of the extra visualization options, a 3D bridge isn’t going to be necessary, or even practical, for every project. SMS’s calculations will turn out the same regardless of which bridge type you pick. 2D bridges are often a better choice if you’re looking for just a quick representation for your bridge, or if you’re modeling multiple bridges at the same time. Having multiple 3D bridges can slow down the processing speed in a way that having multiple of their 2D counterparts wouldn’t.

Head over to SMS and try out the 2D and 3D bridge building tools in 13.3 today!

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