Aquaveo & Water Resources Engineering News

Tips for Long Term Precipitaiton Simulations

By aquaveo on February 27, 2024

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

By aquaveo on February 20, 2024

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.

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

By aquaveo on February 13, 2024

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

By aquaveo on February 6, 2024

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.

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.

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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