2D Troubleshooting – Fragmented Inundation

Written by Christopher Goodell, P.E., D.WRE  |  WEST Consultants
Copyright © The RAS Solution 2015.  All rights reserved.

(Initial post 19 Feb., 2015.  Updated 20 Feb., 2015).  I continue to be more and more impressed with how user-friendly and robust the new 2D feature is in HEC-RAS.  However, there are some issues to be aware of, particularly in how results are mapped.  I want to take the next two blog posts to highlight two of the more important mapping problems to be aware of.  Today’s post covers what I call “Fragmented Inundation”, or fragmented mapping.  If you’ve run some 2D data sets already, you are likely to have seen this, especially if your 2D area starts off dry, you have steep terrain, and/or your cell size is too large.  Fragmentation usually shows up just as a part of a 2D area becomes wet (i.e. very shallow depths), and tends to go away as depths increase.  Very rarely do you see fragmentation in the maximum water surface plot.  Here’s an example of fragmented inundation:

Notice the isolated “ponds” of water in some cells, disconnected from the water in its neighboring cells.

HECRASController VBA Code-Companion to “Breaking the HEC-RAS Code”

Written by Christopher Goodell, P.E., D.WRE  |  WEST Consultants
Copyright © The RAS Solution 2015.  All rights reserved.

There has been a lot of demand from new owners of the book “Breaking the HEC-RAS Code” for example code in VBA form.  So…here it is!  Aside from the obvious fact that you wont have to re-type code from the book into your own Excel VBA modules, this Excel Workbook provides the benefit of seeing how each and every procedure in the HECRASController works.

 
That’s right, every subroutine, and every function are documented in this workbook, along with example code from a wide range of HEC-RAS automation procedures and some code snippets for error catching and string manipulation-very important when reading/writing HEC-RAS input files.  In total, there are over 150 procedures and over 8000 lines of code for you to use for help while you create your own HEC-RAS automation projects.


Each procedure from the HECRASController is demonstrated in either a subroutine or function in this Excel Workbook.  Each demonstration provides up-front commentary including the procedure's name, what it does, cautions and pitfalls to look out for, as well as what standard HEC data set it was tested with (i.e. Bald Eagle Creek, Beaver Creek, etc.). 



There’s also commentary all throughout each demonstration so that you’ll know exactly what each block of code does.  

The HECRASController VBA Code Excel Workbook will make a valuable companion to “Breaking the HEC-RAS Code”.  Every bit of code presented in the book is available in digital form in the Excel Workbook.  The HECRASController VBA Code is optimized for Version 5.0 of HEC-RAS. It will work right now with the current beta release, and will work with the official version when it is released.  

The HECRASController VBA Code Excel Workbook is available here:

BUY NOW

HEC-RAS 2D - Upcoming Training Courses!

Don't miss out on these opportunities to be among the first to get training on HEC-RAS 2D!


2D Free Surface Flow Modeling
SANCOLD 2015 Conference in Pretoria, South Africa.  February 2-6, 2015


http://www.sancold.org.za/images/2D_Free_Surface_Flow_Modeling_Course.pdf




Two-Dimensional Modeling using HEC-RAS
ASCE Live Seminar, Tampa, Florida USA, February 25-27, 2015

http://mylearning.asce.org/diweb/catalog/item/id/242087/q/c=79&q=hec-ras&t=2122&t=2115




2D HEC-RAS Workshop
Floodplain Management Association, McClellan, California, March 10-12, 2015.

http://membersfloodplain.site-ym.com/events/event_details.asp?id=569705

HEC-RAS Model with 2D Mesh Only.

Written by Christopher Goodell, P.E., D.WRE
Copyright © The RAS Solution 2015.  All rights reserved.

There have been many questions lately about whether HEC-RAS 5.0 can perform a simulation with ONLY a 2D mesh (i.e. no cross sections).  The answer is yes.  In fact, in many ways it’s a lot easier.  In this example, the standard Muncie project offered by the Hydrologic Engineering Center has been converted first to SI units, then to a single 2D mesh.  To keep things simple, the levee breach was removed and flow moving into the overbank areas is purely due to overtopping of the levee.  The following figure presents the geometry file for Muncie when modeled with a single 2D area.   




Once you’ve drawn your 2D area boundary and have assigned a mesh cell center spacing (DX and DY) and Manning’s roughness value(s), really all that is left is to

Updated Errata Sheet for Breaking the HEC-RAS Code.

For all of you who have a copy or are planning to get a copy of "Breaking the HEC-RAS Code", there's an updated Errata Sheet on the bottom of the "Book" page of this blog.  Although I spent a LOT of time hunting down and correcting errors before publishing, it's inevitable that some of these will show up.  As always, please let me know if you find any more.

And also, many of you have already emailed me with examples of code you've written by using the techniques presented in the book.  I love it!  Thanks.  Keep up the good work and if you've written something you think will be useful to others, or you just want to show off :-), please post it in the forum under the HECRASController sub-forum.

New HECRASController Forum

Happy New Year RAS Modelers-

I've added a new sub-forum for HECRASController users to post questions and comments specific to the HECRASController and to submit sample code that you would like to share with others.  As you do more and more programming with the HECRASController, please consider sharing some of your useful code with others.  I plan to periodically post code both from the book "Breaking the HEC-RAS Code", and from real projects I've worked on.  A good primer for controlling HEC-RAS using the HECRASController is located here.

The new forum can be found in the forum tab on the top of this page, or by following this link.  "Breaking the HEC-RAS Code" is available from my e-store and from Amazon and other on-line book retailers.

Have fun!

Including Channel Bathymetry into your Terrain.

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

Let’s say you have a digital terrain model of the area you want to model with 2D HEC-RAS.  ONLY 2D RAS.  In other words, you want to lay out a grid, but do not want to have do to any 1D computations-all 2D.  The problem is the area you want to model includes one or more rivers and streams that have no bathymetric (under water topography) data represented in the digital terrain model.  This is a common problem as many sources of terrain data are collected today using LiDAR (Light Detection And Ranging).  As great as LiDAR is for collecting surface data, conventional forms of LiDAR do not penetrate water. 

To adequately model 2D in RAS,