What’s New in HEC‐RAS 5.0 Beta Since the last test release of HEC‐RAS (Version 4.2 Alpha2), we have added many new capabilities and speeded up the computations for both 2D and 1D. The following is a list of what is new since the last release: 1.
2D Only Computations and Multiple 2D areas
You can now run HEC‐RAS with only 2D Flow Areas (1 or more) and no 1D elements if you want. So HEC‐RAS can now do 1D only (multiple 1D elements); 2D only (1 or more 2D areas); and Combine 1D /2D with multiple 1D elements (1D reaches and storage areas) and 2D Flow Areas (as many as you want). 2.
Several New Ways to Link 2D Flow Areas to 1D Elements
In the previous release, you could only link a 2D area to a 1D Reach using a Lateral Structure. You can now link 2D Flow Areas in all the same ways you can a storage area. The following list is all the different ways that a 2D Flow Area can be linked to 1D elements: a.
Lateral Structure – 2D Flow areas can be connected to a 1D river Reach with a lateral structure (Same as before).
b.
SA/2D Area Conn – This is a hydraulic connection that use to be for Storage Areas. Now it can be used to link a storage area to a 2D area, 2D area to another 2D area, and a storage area to another storage area.
c.
1D reach to 2D Area – you can now directly connect a 1D reach into a 2D area. This is accomplished the same way as connecting a 1D reach to a storage area.
d.
2D Flow Area to a 1D Reach – You can also have a 2D area upstream and have 1D reaches coming out of it.
3. Hydraulic Structures Inside of 2D Flow Areas – We have added the capability to add hydraulic structures directly inside of a 2D Flow Area. Hydraulic structures must line up along 2D Flow Area Faces. Users can put in Station – Elevation data higher than the terrain, as well as add Gates, Culverts, weirs, etc… The SA/2D Area Conn (storage area and 2D area hydraulic Connector) can be used to put a hydraulic structure directly inside of a 2D area. For more information on how to connect a 2D Flow Area to 1D elements, please review the document “Combined 1D and 2D Modeling with HEC‐RAS” that was sent out with the software. 1
4.
Improved Computational Speed for 2D and 1D
We have put a lot of effort into improving the computational speed of HEC‐RAS, both for 2D computations and also 1D. The following two tables are a few of the data sets I run on a regular basis to check both speed and computational accuracy. Here are the results of our speed improvements on a few data sets. 2D Computational Tests 2D Test Data Alpha 2 Diff Wave Donut Hole 2D 5 min 31s Muncie 1D/2D 15 min 7s Ohio/Miss 20 min 19s 1D/2D Natomas 18 min 53s 1D/2D Saint Paul 1 min 46s 1D/2D Cherry Creek 21 min 36s Dambrk 2D Yolo Bypass 25 min 4s 1D/2D Average Speed Increase
5.0 Beta Diff Wave 1 min 47s 4 min 48s
Speed Increase 3.1 3.1
Alpha 2 Full Equations 10 min 41s 59 min 59s
5.0 Beta Full Equations 5 min 8s 9 min 21s
Speed Increase 2.1 6.4
8 min 53s
2.3
111 min 37s
62 min 42s
1.8
5 min 28s
3.5
20 min 24s
7 min 17s
2.8
1min 9s
1.5
3 min 28s
2 min 7s
1.6
8 min 32s
2.5
114 min 46s
55 min 13s
2.1
11 min 25s
2.2
52 min 28s
23 min 5s
2.3
2.6
2.7
1D Computational Tests Test Name Lower Columbia River ‐ 1984 Flood Natomous 1D ‐ 500 yr event Red River of the North ‐ 500 yr event Ohio River Model ‐ May 2011 Flood South Platte Dambreak Model
4.2 Beta
5.0 Beta
Speed Increase
31 min 53s 17 min 48s 89 min 5s 5 min 43s 15 min 53s
22 min 13s 5 min 28s 71 min 8s 4 min 26s 13 min 50s
1.4 3.3 1.3 1.3 1.15 1.7
Average Speed Increase
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5.
New HEC‐RAS Mapper Features and Output Capabilities
Many advancements have been made to HEC‐RAS Mapper. The following is a list of those changes:
a.
New Terrain File Format – We have changed the file format for the HEC‐RAS Terrain data from our own Tiled Mapping System (*.tms) to a GeoTiff file format (*.tif). GeoTiff files are tiled, pyramided, and compressed, just like our own format was. So it has all the same benefits of the TMS files. However, GeoTiff is a standard file format, which you can drag and drop into ArcGIS, or other software. So for compatibility with other industry standard software, we have changed how we make and store terrain data. We have also switched all of our output grids to the GeoTiff format to make it easier for user’s to get the results into a GIS or other piece of software.
b.
Additional Spatial Output Variables for Mapping – We have added several new variables in addition to water depth, that can now be visualized in RAS Mapper. These include: Depth, Water Surface Elevation, Flow, Velocity, Depth times Velocity, Arrival Time, and Flood Duration.
c.
Time Series Plots and Tables – you can now click on the map and request various time series data plots and tables for the spot you are clicking on. For 2D Flow Areas you can get depth, water surface elevation, average Face velocity, point velocities at Face Nodes, and average shear stress at cell faces.
d.
Query Active Map Layers – You can now set a map layer as the active map. Then when you move the mouse pointer over it is automatically displays the point values of the layer at that location.
e.
Merge Cross Section Data with other Terrain Layers – You can now make a terrain model from the cross sections (Channel only or entire sections), the river and bank lines, and the cross section interpolation surface. Elevations between the cross sections are interpolated using the interpolation surface and the cross section elevations. This terrain model can then be combined with your other terrain data (overbank/floodplain) to make a new terrain model in which the channel/cross section data is now burned into the overall terrain model.
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6.
New Computational Options for 2D and 1D
We have added several now computational options for 2D flow areas and also some for 1D computations. These options include new computational features, iterations for 1D/2D connections, time slicing for 2D Flow Areas, and two new features for 1D computations to improve speed. Please see the “Combined 1D and 2D Modeling with HEC‐RAS” document that was sent out with the software for more information on this. 7.
Improved Speed and Memory Usage of the 2D Pre‐Processor
We have improved the computational speed and the memory usage of the 2D Pre‐ Process. So now larger data sets can be processed, and the pre‐processing is much faster than it was. 8.
Additional 2D Flow Area Initial Conditions Options
We now have several ways to set the initial conditions in a 2D flow area. These include:
a.
Dry Initial Conditions
b.
Single Water Surface Elevation
c.
Use a Re‐Start file from a previous run
d.
Using the 2D Flow Area Initial Conditions Ramp‐up Time Option.
9.
Bank Erosion and Failure Capabilities (USDA‐ARS Bank Stability and Toe Erosion Model (BSTEM))
In previous versions of HEC‐RAS the sediment transport computations have been limited to vertical cross section adjustments that can simulate deposition and incision. The sediment capabilities in 5.0 have been coupled with the USDA‐ARS Bank Stability and Toe Erosion Model (BSTEM) which computes lateral scour and bank failure as well. Now the sediment transport model can simulate the interactions between three processes:
‐Incision/Deposition
‐Lateral Scour
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‐Geotechnical Bank Failure
The sediment module in HEC‐RAS will then route the material failed or scoured from the banks through the rest of the model. Complete User and Technical Reference Manuals as well as example data sets are available by contacting Stanford Gibson (
[email protected]) at HEC. 10.
Unsteady Sediment Transport
HEC‐RAS 5.0 can perform sediment transport studies with unsteady flow hydraulics in addition to the quasi‐unsteady option from previous versions. To get a Start Up Guide to describe how to set up an unsteady sediment model, contact Stanford Gibson (
[email protected]) at HEC.
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