Aquaveo & Water Resources Engineering News

The Ground-water Modeling System (GMS) 10.8 beta includes a model interface that is brand new to the software. HydroGeoSphere (HGS) is a unique three-dimensional control-volume finite element simulator developed by Aquanty that is meant to be able to handle all parts of the terrestrial water cycle. It uses a globally-implicit approach to simultaneously solve the 2D diffusive-wave equation for overland/surface water flow and the 3D form of Richards’ equation for variably saturated groundwater flow. This is different from the many other models that simulate only a portion of the hydrologic cycle. HGS includes components for precipitation, evaporation, overland flow, infiltration, recharge, and more. HGS can simulate both surface and subsurface water flow simultaneously for each time step.

In GMS, the base components for an HGS model include: an unstructured (UGrid), HGS coverages, and an HGS simulation. GMS allows multiple HGS simulations to exist in a single GMS project. A 3D UGrid of the project area is required before building an HGS simulation. There can also be multiple UGrids in one project, although only one UGrid can be assigned to each simulation.

The coverages specific to HGS are boundary conditions, observations, and hydrographs. GMS uses feature objects to define the boundary conditions on an HGS boundary conditions coverage. This includes points, arcs, and polygons. The observations coverage allows you to set observation points that will collect time series information during the simulation run. The hydrograph coverage records hydrograph data during the simulation run.

HGS defines materials with domains and zones. The domain contains information about the type of material. The domain is then assigned a zone number, which is then assigned to a polygon. Multiple domains can be assigned to the same zone.

There’s a lot more to HydroGeoSphere than we can cover in one blog post. If you’d like to learn more about HGS, Aquanty has numerous resources on their website. You can look at the HGS Theory Manual or the HGS Reference Manual. They regularly post webinars on their blog and on their LinkedIn. You can also find videos about how to use HydroGeoSphere as well as presentations that have been made by Aquanty’s staff on their YouTube page. We also have our own HGS tutorials that can walk you through the steps of building an HGS model.

We hope you’re excited about the addition of HydroGeoSphere into GMS 10.8, because we certainly are! Download GMS 10.8 to try out HGS today!

When creating a surface-water model, your model will make use of bathymetry data as either elevation or depth. Knowing how the Surface-water Modeling System (SMS) represents depth versus elevation is vital when it comes to creating, running, and understanding a model. SMS uses several different numerical models, and some models require that depth be negative and elevations be positive, while other models require the opposite.

It can become confusing when trying to remember what is needed for each model, which is why the decision was made to standardize how SMS treats elevation and depth across all models. SMS treats all depth values as negative and all elevation values as positive. That way you don’t have to remember how data needs to be entered for each model. If depth data is entered with positive values, SMS will read the data as part of the land elevations, which will produce incorrect calculations.

Some of the most used models where you may see that the elevation values have been changed to fit SMS’s conventions after importing are CMS-FLOW, CMS Wave, and CGWAVE. If you’re not sure whether or not the imported elevation data has been changed and would like to check, then this is a great time to make use of the Mesh module’s find function. Under both the Nodes menu and the Elements menu you’ll see a Find… option listed. You can use this to quickly locate a specific node or element inside of SMS to compare the elevation data with the model’s files outside of SMS.

If SMS has changed the values of the elevation data to account for the required negative depth value, there is no need to be concerned about how this will affect the end result for your model. SMS automatically adjusts the data to match the convention of the model when the project information is exported to the model executable.

Take this information and head over to SMS, more confident that your project’s elevation data will be handled correctly.