# My dam break analyses - let me show you them! **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 3, 2008, 11:13pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940 "2008-05-03T23:13:50Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 3, 2008, 11:13pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/1 "2008-05-03T23:13:50Z")
Over the last few years I’ve been doing a lot of dam breach analyses. We use a Corps of Engineers computer program which models the breach flow leaving the dam and routes it through the downstream valley. The program has a very groovy feature where you can animate the flow in a pseudo-3D setup. Recently they added the capability to record .avi files of the animation. In other words, cute dam mini-movies! Here is a [simple one](http://s70.photobucket.com/albums/i84/NinetyWt/?action=view¤t=Serene.flv). One with a [steep valley](http://s70.photobucket.com/albums/i84/NinetyWt/?action=view¤t=Ras.flv). A rather [large lake](http://s70.photobucket.com/albums/i84/NinetyWt/?action=view¤t=Spring.flv) with highway downstream. This model has [two lakes](http://s70.photobucket.com/albums/i84/NinetyWt/?action=view¤t=Chestnut.flv)in it. I’ve breached the upper lake; it overtops the second dam so that one must be breached also. This also has a highway downstream. Aren’t they neat? 🙂 ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 3, 2008, 11:57pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/2 "2008-05-03T23:57:32Z")
Very cool, but the simulation really needs in include cows on roofs, [like this](http://www.prisonflicks.com/images/OBCow.jpg). ---
**Author:** ![DistendedPendulousFrenulum](https://avatars.discourse-cdn.com/v4/letter/d/43a26b/32.png) [@DistendedPendulousFrenulum](https://boards.straightdope.com/u/DistendedPendulousFrenulum)\ **Post date:** [May 4, 2008, 12:09am UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/3 "2008-05-04T00:09:54Z")
The Corps needs to add houses being swept away and hapless stick figures waving their arms and yelling HELP! ---
**Author:** ![Spoons](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spoons/32/3141_2.png) [@Spoons](https://boards.straightdope.com/u/Spoons)\ **Post date:** [May 4, 2008, 12:30am UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/4 "2008-05-04T00:30:09Z")
Interesting! And now I know who to ask if I have any dam questions. 🙂 Seriously, that is pretty cool. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 4, 2008, 2:48pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/5 "2008-05-04T14:48:19Z")
[QUOTE=beowulff] Very cool, but the simulation really needs in include cows on roofs, [like this](http://www.prisonflicks.com/images/OBCow.jpg). [/QUOTE] Ha! What’s that from? [QUOTE=DistendedPendulousFrenulum] The Corps needs to add houses being swept away and hapless stick figures waving their arms and yelling HELP! [/QUOTE] You know, these little movies are just a bunch of still bmp’s, apparently. I wonder if I could edit them to include tiny people running away from the water … ---
**Author:** ![mhendo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mhendo/32/3159_2.png) [@mhendo](https://boards.straightdope.com/u/mhendo)\ **Post date:** [May 4, 2008, 3:13pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/6 "2008-05-04T15:13:02Z")
[QUOTE=NinetyWt] Ha! What’s that from? [/QUOTE] Pretty sure it’s from the Coen Brothers film, _O Brother, Where Art Thou?_ ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 4, 2008, 3:13pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/7 "2008-05-04T15:13:53Z")
[QUOTE=mhendo] Pretty sure it’s from the Coen Brothers film, _O Brother, Where Art Thou?_ [/QUOTE] Bingo! ---
**Author:** ![Astroboy14](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Astroboy14](https://boards.straightdope.com/u/Astroboy14)\ **Post date:** [May 4, 2008, 9:49pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/8 "2008-05-04T21:49:38Z")
So I live right smack in the middle of this page [here](http://maps.google.com/maps?f=q&hl=en&geocode=&q=jack's+creek+rd,+escondido,+ca&sll=33.154978,-117.033534&sspn=0.025078,0.040169&ie=UTF8&ll=33.152284,-117.03671&spn=0.025079,0.040169&t=p&z=15); just how screwed are me and wifey when the dam goes? ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [May 4, 2008, 9:57pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/9 "2008-05-04T21:57:18Z")
This should be a lot of fun. I don’t have time now but will bookmark the page. As a non-engineer, it’s nice to have one show us what you’re all about. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 4, 2008, 10:42pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/10 "2008-05-04T22:42:51Z")
Well, those all look pretty mild. I’m now convinced that all those people who lived downstream from dam breaks are whiners who don’t want a nice bath. The dead ones are slackers who can’t be bothered to get up and walk uphill a bit. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [May 4, 2008, 11:10pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/11 "2008-05-04T23:10:26Z")
Remind me not to live downstream of your dams. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 5, 2008, 12:09am UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/12 "2008-05-05T00:09:28Z")
[QUOTE=Astroboy14] So I live right smack in the middle of this page [here](http://maps.google.com/maps?f=q&hl=en&geocode=&q=jack's+creek+rd,+escondido,+ca&sll=33.154978,-117.033534&sspn=0.025078,0.040169&ie=UTF8&ll=33.152284,-117.03671&spn=0.025079,0.040169&t=p&z=15); just how screwed are me and wifey when the dam goes? [/QUOTE] The breach inundation map for that dam should be a matter of public record. For California, the agency in charge is Dam Safety: [www.damsafety.water.ca.gov](http://www.damsafety.water.ca.gov) . I found this about Dixon Lake: Dam No. : 834-002 Name: Dixon Owner: City Of Escondido County: San Diego Lat-Long: 33.158 -117.04 Stream: Tr Escondido Cr Year Built: 1970 Volume: 2500 acre-feet That’s a fairly good sized reservoir, there. Someone at Dam Safety should be able to point you to the inundation map. Also, it should have an Emergency Action Plan (EAP) in place; this tells you what steps are taken in the case of imminent failure, or after a failure, or in the case of the owner releasing large amounts of water for any reason (should include evacuation routes for downstream areas). Some EAPs will also show expected times of peak flows at points along the downstream valley. [QUOTE=Boyo Jim] Well, those all look pretty mild. I’m now convinced that all those people who lived downstream from dam breaks are whiners who don’t want a nice bath. [/QUOTE] Well, we are _always_ concerned that it might drown the fish. 😉 ---
**Author:** ![Mithril](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mithril/32/3517_2.png) [@Mithril](https://boards.straightdope.com/u/Mithril)\ **Post date:** [May 5, 2008, 3:56pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/13 "2008-05-05T15:56:12Z")
Hey, I use DAMBRK at work, too. But I haven’t made .avi movies. I’ll have to give it a try. Are you with the government or in consulting? ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 5, 2008, 4:13pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/14 "2008-05-05T16:13:09Z")
[QUOTE=Mithril] Hey, I use DAMBRK at work, too. But I haven’t made .avi movies. I’ll have to give it a try. Are you with the government or in consulting? [/QUOTE] That is HEC-RAS that I’m using, but I’ve used DAMBRK as well. I’m in consulting, currently. I recently realized that I’ve spent time in all areas: 2 yrs research, 4 years government, 15 yrs private, and even taught a class or two at the Junior College. It’s been fun. [QUOTE=Spectre of Pithecanthropus] As a non-engineer, it’s nice to have one show us what you’re all about. [/QUOTE] Thanks. I think everyone loves their own corner of geekery. It’s not often that mine is of interest to others. 😉 ---
**Author:** ![Mithril](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mithril/32/3517_2.png) [@Mithril](https://boards.straightdope.com/u/Mithril)\ **Post date:** [May 5, 2008, 4:15pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/15 "2008-05-05T16:15:39Z")
[QUOTE=Mithril] Hey, I use DAMBRK at work, too. But I haven’t made .avi movies. I’ll have to give it a try. Are you with the government or in consulting? [/QUOTE] Oops, after looking at the video, it seems that the program is HEC-RAS, not DAMBRK. Still cool. I haven’t used it much, but my co-workers do. ---
**Author:** ![Astroboy14](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Astroboy14](https://boards.straightdope.com/u/Astroboy14)\ **Post date:** [May 5, 2008, 5:31pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/16 "2008-05-05T17:31:53Z")
[QUOTE=NinetyWt] That’s a fairly good sized reservoir, there. Someone at Dam Safety should be able to point you to the inundation map. Also, it should have an Emergency Action Plan (EAP) in place; this tells you what steps are taken in the case of imminent failure, or after a failure, or in the case of the owner releasing large amounts of water for any reason (should include evacuation routes for downstream areas). Some EAPs will also show expected times of peak flows at points along the downstream valley. [/QUOTE] In other words, REALLY screwed! 🙂 If we have any warning, I know just where to go. But if it fails in the middle of the night we’re toast. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [May 5, 2008, 5:40pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/17 "2008-05-05T17:40:44Z")
How does a highway downstream affect your analysis compared to an inhabited area? ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 5, 2008, 6:12pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/18 "2008-05-05T18:12:08Z")
[QUOTE=Astroboy14] In other words, REALLY screwed! 🙂 If we have any warning, I know just where to go. But if it fails in the middle of the night we’re toast. [/QUOTE] Soggy toast! 😛 Seriously, the City’s [risk management department](http://www.ci.escondido.ca.us/depts/rm/index.html) might know more, such as predicted water depths along your street. You could compare that to your home’s floor elevation and see how you stand. [QUOTE=Santo Rugger] How does a highway downstream affect your analysis compared to an inhabited area? [/QUOTE] Do you mean from an emergency response perspective or a hydraulic modeling perspective? From an emergency response perspective, I can see that closing a road for a few hours would probably be easier than evacuating 100 houses. From a hydraulic perspective, usually highway crossings are modeled to see if they can pass the water; also we can see if the water will be ankle-deep or neck-deep if it does indeed cross the road. Dense urban areas typically have lots of little culverts which are not going to be able to handle the water - we often omit them from the model since they aren’t relevant. A related point is gathering data such as finished floor elevations of buildings - if the buildings are many we typically won’t do that. If only a handful are affected, we might include that in our data gathering. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [May 5, 2008, 6:24pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/19 "2008-05-05T18:24:04Z")
I meant the hydraulic modeling perspective. It makes sense that culverts would be deemed negligible. When you say, “pass the water”, do you mean it would flow over the highways without damaging them, that the highway drainage system would handle and divert the water, or something else? ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 5, 2008, 10:29pm UTC](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940/20 "2008-05-05T22:29:54Z")
[QUOTE=Santo Rugger] I meant the hydraulic modeling perspective. It makes sense that culverts would be deemed negligible. When you say, “pass the water”, do you mean it would flow over the highways without damaging them, that the highway drainage system would handle and divert the water, or something else? [/QUOTE] Ah, ok. I mean that the highway structure (be it bridge, box culvert, what have you) would pass the water from upstream to downstream without the water overtopping the highway. Some of the larger structures are capable of this, and/or if the volume coming from the dam is close to the design flow, it will be ok. Overtopping is a problem for two reasons. One is the traffic - one can imagine the havoc if the interstate suddenly has a foot or more of water over it. The other is damage to the embankment. If the water is less than a foot deep and the duration of the flow is less than half an hour, that would not be as great of a concern. Greater depths and longer durations will damage the embankment, and can wash them completely out. [Next page](https://boards.straightdope.com/t/my-dam-break-analyses-let-me-show-you-them/447940.md?page=2)