## Free Webinar on Dam Breach Modeling

Written by ironcore | December 7, 2018

## Webinar: Dam Breach Modelling

Colleagues-

I’m honored to join Krey Price and Bill Syme in presenting a brief webinar on dam breach modeling hosted by ICEWaRM and the Australian Water School.  Half hour presentation followed by discussion and a Q&A session.  Please join if you can.

http://www.icewarm.com.au/australian-water-school/short-courses/course/dambreak-modelling/

A vigorous discussion with a group of highly regarded dam breach modellers
Approaches to dam breach modelling vary greatly when estimating the discharge through the breach and potential downstream inundation impacts.

This webinar will address 3 key issues:
1) upstream of the dam (reservoir) Krey Price 5 min
2) the dam itself (breach parameters) Chris Goodell 10-12 min
3) downstream of the dam (flood wave routing) Bill Syme 10-12 min

The different approaches to generating the breach hydrograph, the numerical modelling of downstream flood inundation, benchmarking of solution schemes, and uncertainties associated with the modelling will be presented and explored.

1. ### Rose Patenaude

on December 12, 2018

Hi Chris,

I just saw this and am sorry to have missed it. Are there any class notes I can review?

Thanks,
Rose

2. ### Chris Goodell

on December 13, 2018

Hi Rose. You can watch a Youtube of the webinar here: http://youtu.be/iRCYmQsWTXA

Enjoy!

3. ### Daniel

on January 23, 2019

I have a question about what HEC-RAS does when the breach bottom elevation is below the "Centerline Terrain" elevation. In my case, I have a dam that is built on bedrock that varies from an elevation 417 masl to 431 masl. I want to breach down to the bedrock, but not further. We want to see the impact of different sections (and thus different elevations) failing. If I set the Breach bottom width to 417 masl, will it "cut out" the ground even if the terrain is above 417 masl?

4. ### Chris Goodell

on January 23, 2019

Yes, it will cut into the ground if the breach elevation (or any part of it) is below ground level. Unfortunately you are limited to a regular trapezoid for your shape. I always tell people to just fit it in as best as you can.

5. ### Daniel

on January 24, 2019

In my case, it is a mass concrete dam, so we are assuming the gates fail in rectangular monoliths, with the only issue being the various depths of the gates make a more complex shape. Would it be reasonable to perhaps model multiple "mini-breaches" that go different depths to approximate the more complex shape? Sort of like how you would use rectangles to approximate the area under a curve? I know HEC-RAS can't do multiple breaches on a single structure, but do you know of a software that could do that and produce a hydrograph to input back into HEC-RAS?

6. ### Chris Goodell

on January 24, 2019

Why not try using multiple lateral structures to go with your inline structure. Each lateral structure can have its own breach. This would especially work well if you have a long-ish and flat reservoir where you can fit several lateral structures in and have the same headwater as your inline structure.

7. ### Unknown

on February 5, 2019

Hi chris Goodell I am doing 2d dam Breach modelling on Hecras.I am modelling the whole upstream and downstream of the dam as the 2D flow area but I am bit confused in assigning boundary conditions.I assigned inlet Boundary condition as Inflow Hydrograph at upstream of the dam and out let BC at downstream of Dam as Normal Depth

8. ### Chris Goodell

on February 6, 2019

9. ### Unknown

on September 17, 2019

Hi Chriss I am working on the dam breach modelling but I am struggling with the Boundary Condition.I have input inlet Boundary condition as Stage Curve as I dont have any inflow hydrograph with me.I have a reservoir volume of 22.7 Km3 and the Dam height is about 25 m.But everytime I do the dam breaching my model get unstable.

10. ### Chris G.

on September 23, 2019

Stage hydrographs are very tricky for upstream boundaries. Especially when draining a reservoir. I would suggest trying to convert those stages to flows using Uniform flow. And keep that boundary well upstream of the influence of the reservoir. Otherwise you're likely to keep getting errors and instabilities.