Wednesday, September 21, 2016

HEC-RAS Dam Breach course in New Zealand!

Limited-time early-bird discounts available

Registrations are now available for our dam breach course in Auckland, New Zealand to be held from 29 November to 1 December 2016.  I will be teaching this course with help from Mr. Krey Price of Surface Water Solutions.  Please come and join us!

We have fewer than ten places remaining, so please register soon to confirm your place!
A $250 early-bird discount is available using coupon code “earlybird” at checkout.
Our agenda will cover unsteady flow, level pool versus dynamic routing, breach parameters, setting up a dam breach model, diagnosing and fixing dam breach models, and presentation of 1D and 2D case studies. Hope to see you there! 

Wednesday, September 14, 2016

HEC-RAS 2D Course in Concepcion, Chile November 8-10, 2016

If you are in the neighborhood, how about joining me for a course in HEC-RAS 2D modeling at the Universidad Católica de la Santísima Concepción (Catholic University of Concepcion), Chile November 8-10, 2016.

Please visit the University's website for more information and to register.

Space will be limited, so don't delay signing up.  Hope to see you there!   

Wednesday, August 24, 2016

HEC-RAS Version 5.0.2 is now available to download!

*Update:  Please note that HEC has removed HEC-RAS Version 5.0.2 from their website due to the discovery of a significant bug.  A newer version (5.0.3) will be posted soon.  Stay tuned...

HEC-RAS Version 5.0.2 is now available to download from

In addition to a number of bug fixes there are some new features.  Here are a few:
  • Option to use 2D Flow Equations over lateral structures.
  • Flow and Volume output on profile lines in RAS Mapper.
  • Legend added to active results layer in RAS Mapper.
Please read the HEC-RAS 5.0.2 Release Notes for more detail on these and other new features, as well as a comprehensive list of bug fixes.  


Friday, August 5, 2016

Optimizing Your Computer for Fast HEC-RAS Modeling

Written by Christopher Goodell, P.E., D.WRE  |  WEST Consultants 
and Gary Brunner, P.E., D.WRE  |  Hydrologic Engineering Center
Copyright © The RAS Solution 2016.  All rights reserved. 

Now that 2D modeling is becoming widespread in the HEC-RAS community, a lot of HEC-RAS users are wanting to know what kind of computer to build to maximize computation speed when running those large 2D datasets.  I had an opportunity to interview Gary Brunner about this and he had some valuable insight I’d like to pass along.

Before moving into suggestions for 2D modeling, let me first state that in 1D modeling, multiple processing cores are NOT used.  If you plan to only do 1D modeling, having extra cores will not help you with speed.  In this case, the processor speed is everything.  So get the fastest processor you can (e.g. 3.4 Ghz or higher).

For the rest of this post, I’ll assume you want to optimize your computer for 2D HEC-RAS modeling, since those are the models that typically will take longest to run.
  •  More processing cores is not always better.  In fact, it has been found that for smaller 2D areas (e.g. less than 10,000 cells or so), 8 cores may indeed run slower than 4 or 6 cores.  The reason behind this is that there is a level of computing overhead used just to transfer data between cores.  Fortunately, HEC-RAS has an option to change the number of cores you wish to use in the Computation Options and Tolerances window (from the unsteady flow analysis window…Options…Calculation Options and Tolerances…2D Flow Options tab).  For smaller datasets, I suggest experimenting with this to optimize computation speed.  “All Available” may not necessarily be the fastest.  But for large numbers of cells, you’re going to want as many cores as you can get your hands on.  Get as many cores as you can afford, but not at the expense of processor speed.  Try to get at least 3.2 to 3.4 Ghz or higher processors, no matter how many cores you get.
  • Processor speed is still paramount.  Do NOT think you will have fast HEC-RAS model run times just because you have a computer with 16 processing cores or more.  If all of your cores have slow processor speeds, you’ll get some benefit out of the number of cores, but you will be disappointed in the overall speed for a wide range of model types (1D/2D) and sizes.  So make sure even if you get a large number of cores, you are not doing so at the expense of fast processor clock speeds.  Again, 3.2 to 3.4 GHz or higher is a good clock speed for fast running models. 
  • Your hard drive is important.  Especially if you are producing a lot of output.   Small detailed output intervals, small mapping output intervals, writing computation level output, etc.  All of these settings affect how much and how often output is written to the hard drive during run time.  Solid state hard drives (SSD) are typically going to be better than the traditional spinning hard drive (HDD).
  • RAM is important, but not as much as you might think.  While RAM is definitely important, it is not as important for 2D modeling as number of cores and processor speed.  You do want enough RAM to run your operating system and have your entire HEC-RAS model in memory, without the operating system having to swap things in and out of memory.  That being said, if you plan to do multiple HEC-RAS models at the same time, or you have a habit of keeping lots of programs open and running in the background of your computer, you may want to get a computer with a lot of RAM.    I would venture to guess that if you are buying a computer with a lot of cores with fast clock speeds, your computer will have enough RAM.  But RAM is cheap, so you might as well load up on it while you’re building the HEC-RAS computer of your dreams. 
  • Graphics card does not matter.  While some of your other programs run best on a super-charged graphics card, HEC-RAS does not.  For HEC-RAS modeling, don’t waste your money on an expensive graphics card.  However, you may seem some noticeable improvement in the snappiness of image rendering or particle tracing with a better graphics card.  If money is no object, get a top-of-the-line graphics card, but this is one area you can sacrifice if you need to save some dough. 
To sum up, my recommendation for building a computer to optimize 2D runs in HEC-RAS is as follows:
  • Get as many processing cores as you can, but do not do so in expense of processor speed. 
  • Make sure your computer has processors that are 3.2 to 3.4 Ghz or even higher (the faster the better).  
  • Get an SSD hard drive
  • Max out your RAM.  
Pretty simple really.  And by the way, 24-inch (or larger) dual monitors really helps with viewing all those HEC-RAS windows you have open.  But if you have the means, why stop at two monitors?  

Starting on page 4-11 in the HEC-RAS 2D Manual, there is an interesting discussion on the effect of number of processing cores in computations.  I suggest giving it a read.  There will be a new chapter in the RAS 2D manual due out soon (for version 5.0.2) that will discuss this topic.  

Mr. Brunner has some follow-up advice when buying a computer that has an Intel chip that uses Hyper-threading:

"Hyper-threading is an Intel technology that attempts to keep CPU resources as busy as possible.  Each real CPU core has what appears to be two cores.  However, there is really only one true core.  For example, the typical Intel I7 chip has four real CPU cores, but if you open Task Manager and go to the Performance Tab, you will see four across the top, and what appears to be four more below it.  These are virtual cores.  Each real CPU core has only one true math processing unit, but with Hyper-threading it has two instruction feeders.  Hyper-threading tries to eliminate stalls by always having another thread at the ready in a second virtual core.  If one thread stalls (not requiring the math unit) on virtual core A, virtual core B will instantly start picking up the slack, so the execution units keep working at 100%.

The RAS 2D compute engine is extremely math heavy.  So for each core it utilizes, it is almost always using 100% of the math unit.  So the second virtual core (Hyper-thread) is never used.   So back to our Intel I7 chip example.  An Intel I7 has 4 real cores, but appears to have 8 cores (4 virtual cores).  RAS will only use the four real cores, and it will keep them almost 100% busy.  However, Task Manager reports this as only 50% utilization of the CPU.  However, this is truly 100% utilization of the four real cores math units."

What has been your experience with running fast HEC-RAS simulations on your computer?  Please leave a comment and share with us what you’ve learned about how your computer performs.  In fact, if you have a good picture of your suped up machine running HEC-RAS, please share!

Thursday, July 28, 2016

HEC Software Workshop London - Oct 25-26, 2016.

Would you like to meet the Director of HEC, Chris Dunn and the lead developers of HEC-RAS (Gary Brunner) and HEC-HMS (Matt Fleming)?

They will all be coming across to London on 25 and 26 October to meet with leading users of the software. It’s a great opportunity to learn more about the software and its future development path, and to exchange knowledge on how these products are used in Europe and the USA for flood risk management and also water resources and channel restoration work.

Over the two days there will be plenty of opportunities to speak to Chris, Gary and Matt and learn from the experts. Demonstrations and interactive workshops will feature the latest thinking, giving you practical solutions to take away with you.

There is also an opportunity to showcase your projects where the HEC software has been used focusing on the new functionalities and efficiencies. If you would like to submit a poster the deadline is 31 August, please email us in the first instance to register your interest and we will send you further guidelines for the poster submission.  

During the two days you will:
  • Learn how to build a HEC-HMS catchment model from scratch
  • How to apply the HEC software in hydraulic engineering, flood forecasting, flood risk mapping and catchment modelling projects
  • Explore how HEC-RAS Sediments (and some of the ‘hidden’ utilities) can help in your hydromorphology studies, scour, bank erosion and maintenance.
  • Discover how the reservoir system simulation software (HEC-ResSim), can be used to model reservoir operations at one or more reservoirs for a variety of operational goals and constraints.
To see the full programme of the workshops clickhere

Social Event – 25 October

image courtesy of Chris Wheal via Flickr Creative Commons

On the evening of 25 October there will be an optional social event to visit the largest movable flood barrier in the world - The Thames Barrier, followed by a buffet. Your guide will cover topics including the history of the river and the risk of flooding in London, the environment and wildlife of the Thames.

When: 25 - 26 October 2016

Where: Chartered Institution of Water and Environmental Management (CIWEM), London

If you’d like to join us and would like to find out more and book your place, please visit

Chief Executive
Jeremy is the Executive Chairman of JBA Consulting.  He has over 33 years’ water engineering, management and hydrology experience working in the UK and internationally.  He has published and lectured widely on these subjects.

He has been involved in the feasibility and detailed design of irrigation, drainage, flood walls, and storage reservoirs, ranging from culvert replacements to multi-million pound flood alleviation and land drainage schemes.

Jeremy has particular interests in computational hydraulics and hydrological modelling and is an acknowledged expert on the assessment and management of scour risk to engineering structures.

Wednesday, July 27, 2016

Controlling HEC-RAS using MATLAB

Please check out this journal paper written by Professor Arturo Leon of the University of Houston and myself on using MATLAB to control HEC-RAS for gate optimization on a multi-dam river network.

The preprint can be downloaded from:

The MATLAB code can be downloaded from:

or from

Tuesday, July 26, 2016

HEC-RAS Dam Breach course in New Zealand and Round 2 of HEC-RAS 5.0 2D courses across Australia!

Dam breach course in New Zealand and Round 2 of HEC-RAS 5.0 2D courses across Australia!

We had a great turnout for our first HEC-RAS 2D course in Melbourne back in April, and I’m excited to be returning to the southern hemisphere in November to teach a 3-day HEC-RAS Dam Breach course to be held in Auckland, New Zealand.

November 29 - Dec 1, 2016

Our agenda will cover unsteady flow, level pool versus dynamic routing, breach parameters, setting up a dam breach model, diagnosing and fixing dam breach models, and presentation of 1D and 2D case studies.

Register your interest in this course here:

The course will be facilitated by Krey Price, who organised our Melbourne course and has wrapped up a full round of HEC-RAS 5.0 2D courses around Australia over the last three months; due to the overwhelming demand, Krey has now scheduled a second round of 2D courses across Australia:

·         Hobart 11-12 August 2016
·         Brisbane 25-26 August 2016
·         Sydney 1-2 September 2016
·         Adelaide 15-16 September 2016
·         Perth 6-7 October 2016
·         Melbourne 20-21 October 2016

Why not combine your HEC-RAS training with a New Zealand or Australian vacation? All courses are open for registration for local residents as well as international attendees. International participants can contact Krey for a visa invitation letter or further details.