GeoHECRAS (March 25, 2021 Release)

Find Address command

The Find Address command allows the user to select a location on the Map View and retrieve the corresponding street address.

Selecting this command will display the following dialog box:

HEC-RAS 2D Multi-Resolution Elevation Raster Support

When dealing with larger 2D model areas whereby the use of a high-resolution elevation terrain surface is too large and will utilize too much memory, a multi-resolution elevation raster allows the selective application of additional detail where required.

For example, when defining a building footprint or bridge support piers, the original elevation raster that HEC-RAS uses in its 2D flow computations may be too coarse. This may cause the flow around the structure to appear jagged and not truly representative of actual conditions, as shown below.

Enabling the Use VRT refinement grid option in the Unsteady Flow Computational Options dialog box 2D Flow Options tab directs the software to automatically create a higher resolution elevation raster in those areas of the 2D flow area model domain where necessary. The software will automatically recognize bridge piers, conveyance obstructions, flow training structures and more and generate a VRT (Variable Resolution Terrain) elevation raster in those areas of interest.

As shown below, the updated HEC-RAS model more accurately depicts the flow around structures in the 2D flow area domain when using a VRT elevation raster.

Cross Section Data dialog box — Highlight station point on Map View
When the user selects a cross section point in the Cross Section Geometry table of the Cross Section Data dialog box, the point is highlighted in the cross section plot and on the Map View cross section.

Merge DEMs command — Overlapping Cells Mosaic Merging option

The Merge DEMs command has been improved to mosaic merge multiple terrain surface DEMs.

When working with elevation data and terrain surfaces, various survey methods are used to capture elevation data of the study area. Due to data capture limitations for these different survey methods, multiple terrain surfaces from these different survey methods need to be merged as a single terrain surface. However, merging terrain surfaces presents issues at points where the terrain surfaces overlap each other. The mosaic merge capability that has been added to this command allows the user to define how the two surfaces should be merged at points where this overlap occurs.

As shown in the below profile plot, DEM 1 and DEM 2 represent a cross section of two elevation terrain surfaces. DEM 1 represents a lidar terrain surface created by an aerial survey. You can see that it lacks the channel geometry of the river. DEM 2 represents a bathymetric survey terrain surface. However, it lacks the overbank geometry outside of the river channel. By selecting the Use minimum elevation option, the merged terrain surface represents the minimum elevation where the two terrain surfaces overlap.

The following options are provided for the mosaic merge operation:

• Use minimum elevation – The merged cell elevation for the overlapping areas will be the minimum elevation contained in the original terrain surfaces.
• Use maximum elevation – The merged cell elevation for the overlapping areas will be the maximum elevation contained in the original terrain surfaces.