Creating Static Results Maps (Shapefiles or Rasters) using RAS Mapper

Written by Mikell Warms  |  WEST Consultants
Copyright © The RAS Solution.  2016.  All rights reserved.

Many readers have been asking how to create shapefiles and other static maps in RAS Mapper. One of the main differences between RAS Mapper in RAS 4.1 and RAS 5.0 is the existence of Dynamic Maps. What makes these maps dynamic is that when you have that Results Layer selected in RAS Mapper, you can use the slider bar (top right) to animate through the simulation and see the results of that layer at each mapping output interval (or each profile for steady flow models). These maps are not saved to the disk, they are temporarily stored in memory.

With this change, you can no longer “Export Layer to Shapefile” as you could previously, due to the fact that these dynamic layers are not one map, they are many maps.

To create static maps, such as shapefiles or rasters, we must first tell RAS Mapper what type of static map we want (Inundation Boundary, Velocity, Shear Stress, etc.) and whether we want the data from a specific timestep, or max/min. To do this, right click on the bold “Results” heading in the Layer Manager in RAS Mapper, then choose “Manage Results Maps”.  All of your plans and default layers will load (like below):

Choose the plan you are interested in, and click on “Add New Map.”

If you’re running a Steady model, the window that pops up will look like this: 

If you’re running an Unsteady model, the window that pops up will look like this: 

Choose the Map Type you are interested in creating; in this case we are creating a maximum Inundation Boundary. Notice we have chosen “Maximum” under the Unsteady Profile options, but we could have chosen “Minimum” or a specific point in time. On the right hand side of the window, make sure to change the Map Output Mode to one of the “Stored (saved to disk)” options, depending on your needs. In this case, we are creating a shapefile polygon. Then click Add Map.

One last step. The Manage Results Maps layer should now look like below:

Notice the static map we have added has appeared. However, the Inundation Boundary map status says “Map Not Created”. You will need to select that map, and click on “Compute/Update Stored Maps” at the top right. If you have multiple static maps, you can select them all by holding the CTRL key and selecting multiple maps prior to computing them.

Once the computations have completed, the status will change to “Map files up to date” and RAS will save your shapefile in your HEC-RAS project folder, in a subfolder that has the same name as the plan from which the shapefiles were created.

Post-Processing: Creating Inundation Maps with very Large Terrain

Written by Mikell Warms  |  WEST Consultants 
Copyright © The RAS Solution 2016.  All rights reserved.   

We often have to deal with very large models covering hundreds of river miles.  The terrain data associated with these models can be equally massive, which can cause memory/processor issues when trying to delineate inundation maps.

This post is not concerned with pre-processing our model geometry. Instead, we have a completed model with results we are happy with, and now we want to make inundation shapefiles. This is often necessary when completing dam breach analyses/flood analyses/etc. 

There are typically two ways in which flood inundation shapefiles are created: (1) using HEC-GeoRAS and (2) RAS Mapper. Both methods can face uphill battles when terrain data begin to exceed 20-30 gigabytes, depending on performance characteristics of your computer. Below are some typical errors you may see when trying to create inundation shapefiles with RAS Mapper on very large terrain.

Figure 1: RAS Mapper Memory Error Messages

There IS a way to get around this using RAS Mapper. The first thing you’ll need to do is

The Advanced Hydrologic Prediction Service for Chehalis Washington

A great example of where flood inundation maps and accessible flood warning systems can help a community prepare for floods.

 

Contact:               Brent Bower                                                                      FOR IMMEDIATE RELEASE 

206-526-6095 x228                                                           December 15, 2015

                               

Flood Inundation Maps to Enhance Flood Forecasts for the Chehalis River

People living along the Chehalis River have a new tool from the National Weather Service to help them understand their risk during floods. A large section of the river is now depicted on flood maps that show people where the water will flow and what it will look like in their community when the river crests beyond its banks. The new flood inundation maps will also help local officials reduce flood impacts to communities by giving them more advanced information for planning.

Web Imagery for RAS Mapper in Version 5.0

Written by Christopher Goodell, P.E., D.WRE  |  WEST Consultants
Copyright © The RAS Solution 2014.  All rights reserved.

There are a lot of new features in Version 5.0.  We’ve discussed quite a bit the new two-dimensional capabilities.  But a real pleasant surprise for me was how great the new RAS Mapper is.  I’m going to try to highlight some of these new Mapper features over the next few months, but in this post I’ll share perhaps my favorite added tool:  Web Imagery. 
RAS has had the ability to add background images for quite a while now.  And when RAS Mapper was introduced in Version 4.1, it too had that feature.  But if you wanted to add aerial photographs behind your project, you had to go and find them.  There are many sources on-line for that:  some good, some not-so-good.  But, once you found the aerial photos, it was common to have to spend some time re-projecting them into the geographic projection and coordinate system you are using.  That all took time working in a GIS program, and frankly, some skill that I don’t have a lot of. 
In RAS Mapper in 5.0 a new feature called Web Imagery is added.  Web Imagery allows you to choose from 21 different web-based map types: Imagery, street maps, physical maps, topo maps, even infrared maps.  You can select these background images right from the RAS Mapper and they are re-projected on the fly. These come from a variety of hosts like ArcGIS, Bing, Google, NASA, and the USGS.  And each have worldwide coverage.  Some of these maps/images will work well for you, some won’t, depending on the scale and location of your project.  I have found that Google and Bing have excellent worldwide satellite coverage. 
And here’s where it gets really cool:  All of these maps and images are on the web, not your computer.  Just like in Google Earth as you zoom out, different, and less detailed images are used, so that you are not unnecessarily downloading more detail than you need.  As you zoom in, more detailed images are used so that you always have a nice crisp view.  This is all done seamlessly and very quickly.  And RAS only downloads what you need from the web for the current view extents you are at.  Take the Muncie demonstration dataset that comes with HEC-RAS 5.0.  I can zoom out to the full extent of the project and with Bing Satellite activated as my background image I have very nice coverage:

Now, I can also zoom in to a city block and have all the detail and precision I need. 

By the way, the time it took RAS to redraw the inundation, download and clip the more detailed image, and reproject the new image was only 2.5 seconds on my computer. 

To access the web imagery in RAS Mapper, first make sure your model is projected to a recognized projection system.  At the top of RAS Mapper, select Tools…Set Projection for Project…Here you’ll select a projection file (*.prj – NOT to be confused with a RAS project file!).  If it’s a proper projection file, you’ll see the Metadata show up in the window below.

Once your model has a defined projection, you can add web imagery by right-clicking on Map Layers in the Layer Manager and selecting “Add Web Imagery layer…” or by selecting “Web Imagery…” from the Tools menu item.  Once selected the following window will appear and you can choose any or all of the 21 available maps/images (you can only add one at a time though).


For most projects, you’ll probably be using Bing Satellite, ArcGIS World Imagery, Google Satellite, and perhaps some of the topo maps.  The quality and usability of these different maps will depend on your location and viewing scale (as you zoom in closer and closer, some of the maps will no longer load). 
Requirements for using Web Imagery in HEC-RAS 5.0:
1.  Your RAS model must be set to a known projection. 
2.  You have to have internet access (high speed is obviously better).

For more information about Web Imagery in HEC-RAS Version 5.0, check out the document “Combined 1D and 2D Modeling with HEC-RAS”. 

Get the lastest beta release of HEC-RAS Version 5.0 here.