Calgary and Area Flood Thread

[nik-]

Originally Posted by Drummer

Here is how much snow has to melt still:
https://www.skilouise.com/conditions/mountain-cam.php
Some live cameras at Lake Louise.

You can also look at the data. Since it's hard to gauge from pictures.

http://environment.alberta.ca/apps/b...StationID=SUNS

http://environment.alberta.ca/apps/b...StationID=SKOK

[Otto-matic]

Bow River levels are now slightly above the Normal Range for it at this time of year.

http://www.environment.alberta.ca/ap...ionID=RBOWCALG

[nik-]

Taking the saran wrap off my apartment tonight.

[Bigtime]

Flood protection walls planned for Bowness:

http://www.cbc.ca/beta/news/canada/c...ness-1.4488813

I wonder if it will be similar to the wall put in around the zoo? Big metal plates hammered into the ground and the section still above ground was filled in with larger rocks/boulders. It actually doesn't look that bad when fully finished. Rustic but still slightly natural.

[CorsiHockeyLeague]

Uhhhhhh... so, question. In the event of a flood that would otherwise have flooded Bowness, and now will be prevented by those walls... won't that water simply be pushed down into the next community? In other words, isn't Shouldice Park and half of Montgomery going to end up a rather large swimming pool as a result of this "mitigation" exercise? It's not as if that area fared particularly well last time, either.

[Bigtime]

There is definitely that factor to be considered in any walls, it can simply displace the water further downstream, and also speed it up. I'd hope the city/province is looking at these effects as well for the proposed walls.

[CorsiHockeyLeague]

I mean, the fact that they're only having a community meeting about it in Bowness - which is the community positively impacted, rather than neighbouring communities - seems like a pretty big red flag.

[Fuzz]

I can't imagine a flood wall is going to cause much issue downstream. The storage capacity of Bowness as a flood plain is pretty small given the volume of water during flooding.

[CorsiHockeyLeague]

Look at the 100 year flood map on the city website. It wouldn't take much of an incremental impact for a bunch of Montgomery to be in trouble. Not to mention that even if you don't live in the area, we just spent millions of dollars of your money rebuilding shouldice park and its athletic facilities...

EDIT: This is what I'm talking about. What is the impact on the area circled in red?

[Bownesian]

From the article:

Coun. Ward Sutherland said city officials will be providing an update on the project at the meeting.

"It is going to happen. We are going to do it," said Sutherland. "There will be a wall."

...and Montgomery is going to pay for it!

Even if all the area CHL outlines gets flooded, that's a couple dozen homes rather than hundreds that were affected by the 2013 flood, so I can see a government making the decision to accept a bigger floodway downstream.

I'll be at the meeting so I'll ask if there is anything planned for the east side of Shouldice bridge. It wouldn't take too much of a berm between the swimming pool and the playground there to funnel any future flood water under the bridge and beyond.

Contrary to the article though, I expect that there will be some pushback from the people across the street from me who may have a 1-2m wall where their view of the river used to be.

[Fuzz]

I'm sure someone could run the numbers, but I still would contend that under a flood situation with the Bow flowing at 2000m³/s that the volume of water held in Bowness would be insignificant to any downstream areas. We aren't talking about filling up a static bathtub here. Yes, filling in floodplains is not an ideal plan, but in this case with it already developed I'd say it is a decent solution that would have minimal impacts downstream.

[octothorp]

Without knowing the costs involved, it seems like money is always going to be better spent on upstream control and mitigation aimed at keeping the overall levels of the river lower, which benefits every neighbourhood along the river without picking favorites.

[Bigtime]

Yeah, I will continue to leave my basement undeveloped.

The idea of a new reservoir on the bow upstream of Calgary is still our best bet, with the added bonus of helping us control a resource that could face scarcity issues in the future.

[Fuzz]

OK, so I just ran the numbers....

That section of Bowness is approximately 200,000 square metres. Lets assume for simplicity it is filled evenly to a depth of 1 metre. The full flow of the Bow at 2000m³/s. So Bowness could hold 100 seconds worth of 100 year flood water. Blocking that will have very little affect downstream.

How much money would you spend on a reservoir that could hold 100 seconds worth of water to protect a park?

[CorsiHockeyLeague]

Originally Posted by Fuzz

How much money would you spend on a reservoir that could hold 100 seconds worth of water to protect a park?

It's more "why not just build a few hundred extra metres of length on this wall so that it extends to the Trans Canada bridge, thereby pushing the worst case scenario down to a point where all it impacts is the park, and people aren't driven from their homes"? Isn't there a solution here that actually saves not only the inundated blue area in Bowness, but also the inundated blue area in Montgomery, rather than making one better while making the other worse (even if it's not catastrophically worse)?

They're just going to have to spend money later to do mitigation to protect that latter area, so why not do it now.

[Bownesian]

Agreed.

The run from Bowness Road to 16th ave is a park and so would be simple and cheap to berm, especially since they already have the ground torn up there because of the Bowness Rd/Hextall Bridge underpass restoration. The road that runs under the bridge would have to be terminated or built over the berm.

[Fuzz]

I assume you would have to build a wall all the way down the red area on your map, which might not be worth the cost. Or maybe it is. I assume protecting Bowness first makes the most sense, as that is the most impacted area, and they might look at the other side later? No reason it has to be in one project.

[CorsiHockeyLeague]

Well, there is a reason; it's cheaper to do it all at once and it protects the whole area now, rather than some now and some later. I don't know that there's any major risk of flooding this summer, but I don't know that there isn't, either.

Also my intuitive reaction is that you'd just build it down to the transcanada bridge (which is a few hundred additional metres), and then any flooding that happens would be contained south of the highway for the most part. But I'm not an engineer, so maybe that's nonsense.

[Bownesian]

[Barnes]

Calgarypuck. Where Hockey and amateur hydrology collides.