Friday, March 30, 2018

Webinar: The HECRAS Controller, A Powerful Feature of HEC-RAS Exposed

I'll be giving a free webinar on the HECRAS Controller through the Australian Water School on April 18 at 7:00 PM (pacific daylight time) which is April 19 11:30 AM (local time in Adelaide, Australia). 

https://www.icewarm.com.au/australian-water-school/short-courses/course/powerful-hec-ras-features-exposed/


Unlock a multitude of custom applications for controlling and automating HEC-RAS


In this webinar, Chris explains the HECRASController, an application programming interface (API) that communicates with HEC-RAS, through a comprehensive library of programming procedures. You will gain an understanding of how to work with the HECRASController that are not otherwise available through the standard version of HEC-RAS. He also covers custom applications including an analysis example that allows the implementation of selected Australia Rainfall and Runoff (ARR2016) guidelines. As Chris is fond of saying, "if you can imagine it, it's likely you can do it with the HECRASController and a little programming skill".

Monday, January 22, 2018

Bridge Momentum: Understanding the Weight Component

Written by James Woidt, P.E.  |  Woidt Engineering and Consulting
Copyright © The RAS Solution 2018.  All rights reserved



Take a look at the water surface profile in Figure 1 below. The two profiles are for Class A low flow (subcritical throughout) with identical boundary conditions, flow conditions, and geometry. The only difference is the bridge modeling approach: the blue line is calculated using the energy method; the red line is calculated using the momentum method. For this example, which is a simple rectangular channel, the difference in computed water surface elevation and energy grade line from the downstream cross-section to the upstream cross-section is 0.10 feet and 0.16 feet for the energy method, respectively; those differences increase to 1.64 feet and 1.64 feet, respectively, for the momentum method. Those of you well-versed in the applicability of the various bridge modeling approaches (see page 181 of the HEC-RAS River Analysis System, version 5.0, Hydraulic Reference Manual [Brunner, 2016] for a great discussion on this topic), will answer: “the momentum method accounts for the drag imparted by bridge piers on the flow and should be used when pier losses are significant; that’s why.” But check out Figure 2. There are no piers. The bridge doesn’t even touch the water surface!


Figure 1: Comparison of bridge modeling results between energy and momentum methods

Figure 2: Representative cross-section of modeled bridge

From a hydraulic perspective, the bridge is doing nothing in this model. We could ignore it, stick in two cross-sections, press “run”, use the tried-and-trusted energy equation, and be on our way. However, “momentum” has been as familiar and comfortable a term as “energy” ever since we first smashed two model cars in physics class. We know the one-dimensional form of the conservation of momentum equation backwards-and-forwards, have solved the above problem by hand in our open channel hydraulics class, and know that the momentum equation should give us an answer similar, if not identical, to the energy equation. Even though the title of this post gives away the reason for the difference, I’m going to let the suspense build and provide some background to understand the implementation of the momentum equation in HEC-RAS at bridges for steady discharge.

Tuesday, January 2, 2018

Considerations of River Ice Breakup Uncertainties in HEC-RAS

A fantastic blog post by Mr. Juha Aaltonen of the Freshwater Centre of Finnish Environment Institute SYKE.  In his post, Mr. Aaltonen discusses river ice breakups and the advantages of incorporating uncertainty into river ice modeling in HEC-RAS.  He was able to do this by harnessing the power of the HECRASController as detailed in "Breaking the HEC-RAS Code".

While his post is specific to river ice breakup modeling, uncertainty can be used for just about any HEC-RAS application.  Give Mr. Aaltonen's post a read here:

http://www.hyokyaaltonen.fi/consideration-of-river-ice-breakup-uncertainties-in-hec-ras/


Friday, December 29, 2017

River Ice Modeling using HEC-RAS. New Forum!


Image courtesy JLH3Photography via Creative Commons.
license
Hello to everyone in the international River Ice Community! The RAS Solution has a new forum dedicated to river ice modeling with HEC-RAS.  This forum was developed for those who use HEC-RAS to simulate river ice covers and river ice jams. Please post your questions, comments, and insights in the HEC-RAS River Ice Modeling sub-forum which can be found here.  The RAS Solution is especially interested to hear how you have addressed difficult ice problems with HEC-RAS. 



HEC-RAS allows the user to model ice-covered channels with known ice properties, or to simulate wide-river jams. In the first case, the user specifies the ice cover thickness and roughness at each cross section. Different ice cover thicknesses and roughnesses can be specified for the main channel and for each overbank, and both can vary along the channel. In the second case, the ice jam thickness is determined at each section by solving the ice jam force balance equation. The ice jam can be confined to the main channel or can include both the main channel and the overbanks. The material properties of the wide-river jam can be selected by the user and can vary from cross section to cross section. The user can specify the hydraulic roughness of the ice jam or HEC-RAS will estimate the hydraulic roughness on the basis of empirical data. 


Image courtesy of Steven F.Daly, Ph.D., USACE ERDC/CRREL

The river ice capabilities of HEC-RAS were developed over 20 years ago through a joint effort by the HEC-RAS team at HEC and the Corps of Engineers’ Cold Regions Research and Engineering Laboratory (CRREL). Since that time, HEC-RAS with ice has been applied in rivers all around the world. It has been applied in river systems larger and more extensive than were imagined at the start. Recently, the HECRASController has been used to systematically vary the ice parameters over the course of hundreds (if not thousands) of separate simulations. 

Image courtesy of Steven F.Daly, Ph.D., USACE ERDC/CRREL




Tuesday, August 29, 2017

Having fun with HEC-RAS?

Written by Krey Price  |  Director, Surface Water Solutions
Copyright © The RAS Solution 2017.  All rights reserved. 


I’ve been seeing some cool applications of HEC-RAS from around the world lately. Here are some articles showing a few ways we’ve been putting HEC-RAS to use down under.

Making Middle Zealand
Did you know that the only thing keeping New Zealand’s two main islands from being split into three is a little 2-km wide piece of land just south of Auckland? What do you think would happen if you dug a ditch through this strip? Last time I drove across it, I asked myself that question…and then I let HEC-RAS tell me the answer! This article covers terrain manipulation and tidal boundary conditions in HEC-RAS with the construction of a canal that severs Northland from New Zealand’s North Island. The tides on either side of the island are out of phase with each other, so you get some really cool mixing with the alternating current. Have a read and give it a shot yourself!


  
Creating Rating Curves in HEC-RAS 2D Models
HEC-RAS does a great job providing you with rating curves for 1D models, but how about 2D? It takes a bit of additional effort, but this article walks you through the process of generating a rating curve from your existing 2D model. You may find – as we did in the example covered in the article – that the uncertainties in your rating curve are greater than you thought. Try it yourself by following along with this example, and see if you find yourself wanting to recalibrate your gauge!














Disappearing Terrain?
Do you get frustrated when your terrain disappears in HEC-RAS? Don’t fret, here are some simple workarounds for getting it back!  
 
My HEC-RAS Wish List
Speaking of workarounds, the HEC Spring 2017 Newsletter included a preview of what's new in Version 5.1 (see article on Page 20). They'll be adding some handy new features, but here's my HEC-RAS wish list that includes a compilation of suggestions gathered from hundreds of course attendees over the last year and a half since Version 5.0 was released. You may wish to submit your own on the Forum Page of the The RAS Solution.



Wednesday, August 16, 2017

1D/2D HEC-RAS Workshop in Brisbane Australia

ICE WaRM joins with internationally respected HEC-RAS authors and mentors to offer training in Version 5.0 of HEC-RAS, a highly regarded global water modelling package, available for free download and support from the US Army Corps of Engineers.

The new HEC-RAS Version includes two-dimensional floodplain modelling, unsteady sediment transport, bank erosion, water quality, and the RAS Mapper GIS interface.

Join us for a hands-on, 1-week overview of this latest version of HEC-RAS 1D+2D.  The week consists of five courses, run consecutively; that's 1 course per day for 5 days.  You can attend any combination of courses with respect to your level of experience and understanding.

WHAT:                 HEC-RAS Water Modelling: 1D+2D Hands-On Workshops
WHEN:                 Mon 11th - Fri 15th Sept 2017
WHERE                 BRISBANE, Queensland, AUSTRALIA
PRESENTERS:     Krey Price, Mark Forest, Rob Keller
REGISTRATION: 20% Discount for Early Bird Registrations by Mon 21st August 2017.
                              To gain another 20% Discount please add to Comments Field: “TP Aug Blog”
FULL DETAILS:    Click here.
FLYER:                  Click here.
CONTACT:            Trevor Pillar: tpillar@icewarm.com.au

See examples below:





    


Friday, June 23, 2017

New Geospatial editing tools coming in HEC-RAS Version 5.1

Written by Chris Goodell  |  WEST Consultants, Inc.
Copyright © The RAS Solution 2017.  All rights reserved


New geospatial editing tools are currently in development for the next version of HEC-RAS-Version 5.1.  While no date has been set for the release of Version 5.1, it is expected sometime within the next year or two.  But no guarantees!  This will be an exciting new addition to HEC-RAS in that users will no longer be reliant on 3rd party software like ArcGIS or AutoCAD to develop geometric features like cross sections, river lines, flow lines, storage and 2D areas, etc.  All of this will be done within the HEC-RAS program environment.  And this will effectively eliminate the need for HEC-GeoRAS.

HEC recently published it's Spring 2017 Newsletter, which has a very nice article by Cameron Ackerman ,P.E., D.WRE on some of the new tools and capabilities that will be available within HEC-RAS Version 5.1 for extracting GIS information from digital terrain models.  The newsletter can be read here: 

http://www.hec.usace.army.mil/newsletters/HEC_Newsletter_Spring2017.pdf

Cameron's article on new geometric editing features in Version 5.1 starts on page 20.  

The new geospatial editing toolbar will serve as the base point for adding and editing geospatial features in HEC-RAS and will be docked to the RAS Mapper window.  It includes editing tools for adding new features, selecting/editing features, undo and redo, and  plotting terrain profiles.



With these tools, you'll be able to add geospatial features and interact with them directly within HEC-RAS.  Here you see the ability to move stream centerline points in RAS Mapper:



HEC also plans to have interactive help messaging while working in the geospatial environment to help the user identify errors in the geometry setup.  The following figure shows help messages for locations where bank lines do not intersect cross sections, which would result in missing bank stations.



These new features will make it much easier to identify problems with your model construction and fix those problems without having to leave HEC-RAS.  Here we see a poor definition of study limits not allowing for proper mapping of the flood inundation zone.  By quickly adjusting the study limit polygon, a more appropriate inundation map can be drawn.


This is just a brief preview of all of the exciting geospatial editing tools HEC-RAS will include in Version 5.1.  Please read the article by Cameron Ackerman in the HEC Spring 2017 Newsletter for more information.