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Re: Bear Cr Jumps Into Road During Flood

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From Oxford, Chester Co., PA
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According to the 2012 post-flood report 75% of the stream "restoration" structures on Big Bear creek were destroyed by the flood. That turned out to be a very expensive demonstration project. But hey, lessons learned.

Posted on: 3/19 14:28


Re: Bear Cr Jumps Into Road During Flood

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One of the stated goals of the BB Cr restoration project was to increase brook trout numbers in the stream. The 2010 post-restoration fish survey indicates that BT outnumbered ST by 2 or 3 to 1. However, after the 2011 flood destroyed most of the restoration structures, the ST popn appears to be rebounding. How can that be?

On the other hand, we don't have a pre-project comparison of BT/ST numbers, so we can't assume any cause and effect relationship.

Posted on: 3/19 14:41


Re: Bear Cr Jumps Into Road During Flood

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My gut tells me that V-weirs and J-Hooks favor brown trout (BT) over brook trout (ST). These structures are designed to create deep scour holes on the downstream side. It is my experience that BT are much more dependent upon deep holes than are ST. Now that the weirs and jhooks are gone, the BT no longer have such a habitat-based advantage.

Posted on: 3/19 14:53


Re: Bear Cr Jumps Into Road During Flood

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Quote:

Yes. Thanks.

Posted on: 3/19 15:43


Re: Bear Cr Jumps Into Road During Flood

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TB: In your opinion, from an ecological perspective, is stream avulsion good, bad or indifferent?

Posted on: 3/19 16:39


Re: Bear Cr Jumps Into Road During Flood

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Tups wrote:
My gut tells me that V-weirs and J-Hooks favor brown trout (BT) over brook trout (ST). These structures are designed to create deep scour holes on the downstream side. It is my experience that BT are much more dependent upon deep holes than are ST. Now that the weirs and jhooks are gone, the BT no longer have such a habitat-based advantage.


i'd agree with that - BT like deep holes for cover, whereas ST will ise anything for cover.

Posted on: 3/19 16:59


Re: Bear Cr Jumps Into Road During Flood

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Tups wrote:
TB: In your opinion, from an ecological perspective, is stream avulsion good, bad or indifferent?

I don't know what TB thinks, but it isn't good for the road or the people that depend on the road. On the other hand, back in the late 60' and 70's the state took it upon itself, to straighten a lot of roads out and minimizing the number of bridges along streams. In the process they also channelized streams to help accomplish the straightening of roads.
This straightening may have contributed to problems during subsequent floods, including the Irene/Lee floods. I myself feel stream avulsions are probably good for the streams, if the streams move back to their former channel, but only if then left alone by the dopes that think streams should be straight and channelized.

Posted on: 3/19 17:13


Re: Bear Cr Jumps Into Road During Flood

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Chaz: I've never been to BB Creek, but viewing Google Earth it appears that the Big Bear Creek valley is largely undeveloped. The Big Bear Creek Sportsman's Club and one other residence may be the only people served by Dunwoody Road. So yes, the washout of Dunwoody Rd affected those folks. But the road has been replaced in situ. In this case, and at the location where the avulsion occurred, Dunwoody Road is located in perhaps the best possible place; at the very edge of the valley.

Agreed, channelization for road work or flood control or any other reason is rarely a good thing. It oftentimes creates more problems than it solves.

But I am also wondering if stream restoration projects don't often create their own set of ecological and hydrological problems as well. I've seen quite a few failed ecological-based stream restoration projects. Big Bear Creek is a very good example of such a failure and should be studied carefully by restoration advocates (of which I am one).

Posted on: 3/19 17:26


Re: Bear Cr Jumps Into Road During Flood
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I have never seen the word avulsion used so many times in my life...I feel dirty.

Regarding the avulsion. I am not sure whether the stream was straightened when the road was built or not. Nor am I aware of how much use the road had prior to the avulsion. So I am speculating here but it seems to me that if the crik took the road for a few hundred feet and the road won;t be missed that much, leave it be and address the stabilization issues.

If however the road was necessary for local residents. Put the stream back and build the road at a higher elevation to prevent future infrastructure disruptions.

The trouts will make their home where ever you direct them.

Posted on: 3/19 17:34
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Don't hit me with them negative waves so early in the morning. Think the bridge will be there and it will be there. It's a mother, beautiful bridge, and it's gonna be there. Ok?


Re: Bear Cr Jumps Into Road During Flood

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Tups wrote:
TB: In your opinion, from an ecological perspective, is stream avulsion good, bad or indifferent?


Avulsions are a normal part of the system. And good for trout habitat, and other creatures and plants, not just in the stream, but the whole way across the stream / floodplain system.

But if you have a road, or other developments such as buildings, in the floodplain, then of course you have a conflict.

During a flood, the stream jumps into the road grade, and you have a real mess, as seen in the video.

If you look at the topo map of Bear Creek, you will see that a stretch of the road and stream are both there in the floodplain, at about the same elevation.

Probably the best solution there is to relocate the road out of the floodplain, and put it on the adjacent hillslope.

As you drive around in forested areas, notice where the roads are located. Some are located right down in the floodplain, so they get flooded. Frequently.

But you'll also see that many of the roads that parallel streams have long sections that are NOT in the floodplain. But instead located on cut-and-fills in the hillslope. So, they never flood.

Many of these roads go up and down, with sections down in the floodplain, then going back up on the hillslopes.

With many of these roads, I think they could connect the sections that are already on the hillslopes, and get rid of as much road mileage in the floodplains as possible.

Posted on: 3/19 17:38

Edited by troutbert on 2014/3/19 17:58:47


Re: Bear Cr Jumps Into Road During Flood

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Maurice: "Avulsion" is not a dirty word! Based on Google Earth and the PGC Mapper, it appears that before the storm the stream flowed through the center of the valley. However, the pre-storm aerial indicates an old, abandoned (orthofluvial) channel located along the northern edge of the valley. Dunwoody Road is also located along this northern edge of the valley. The stream avulsed back into its old channel taking about 1500 LF of road with it. The road could theoretically be moved to a higher elevation, but the valley wall on the north side is very steep and likely could not be done without great expense. I would be opposed to returning the stream to its pre-flood channel.

Posted on: 3/19 17:44


Re: Bear Cr Jumps Into Road During Flood

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Maurice wrote:
I have never seen the word avulsion used so many times in my life...I feel dirty.


Avulsion revulsion??!!

Posted on: 3/19 18:11


Re: Bear Cr Jumps Into Road During Flood

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Tups wrote:
Chaz: I've never been to BB Creek, but viewing Google Earth it appears that the Big Bear Creek valley is largely undeveloped. The Big Bear Creek Sportsman's Club and one other residence may be the only people served by Dunwoody Road. So yes, the washout of Dunwoody Rd affected those folks. But the road has been replaced in situ. In this case, and at the location where the avulsion occurred, Dunwoody Road is located in perhaps the best possible place; at the very edge of the valley.


There is another route into the Dunwoody Camp, i.e. coming in "from the top."

They could abandon the section of road that is there in the floodplain that's causing the problems.

Posted on: 3/19 18:17


Re: Bear Cr Jumps Into Road During Flood
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Tups wrote:
Maurice: "Avulsion" is not a dirty word! Based on Google Earth and the PGC Mapper, it appears that before the storm the stream flowed through the center of the valley. However, the pre-storm aerial indicates an old, abandoned (orthofluvial) channel located along the northern edge of the valley. Dunwoody Road is also located along this northern edge of the valley. The stream avulsed back into its old channel taking about 1500 LF of road with it. The road could theoretically be moved to a higher elevation, but the valley wall on the north side is very steep and likely could not be done without great expense. I would be opposed to returning the stream to its pre-flood channel.


So when it jumps back...and it will. (Or do I need to say avulses) will it be OK to rebuild the road?

Posted on: 3/19 18:18
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Don't hit me with them negative waves so early in the morning. Think the bridge will be there and it will be there. It's a mother, beautiful bridge, and it's gonna be there. Ok?


Re: Bear Cr Jumps Into Road During Flood

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2006/9/18 16:54
From Oxford, Chester Co., PA
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As I said, the road has already been re-built, so that's no longer an issue. Of course now the stream channel is located at the toe of the road slope and whoever is responsible for road maintenance (probably Plunkett Cr. Twp.) will have headaches in the future. Perhaps at some point the Twp will be faced with the political decision to close the road at the bottom and require entrance only from the top, but that is a very long drive, and long one-way-out roads are generally not desirable from an emergency stand-point.

Maurice: It is inevitable that the stream will some day avulse again at this location (perhaps back into its pre-2011 channel, perhaps creating an entirely new channel), but it may be 50 or 100 years before that occurs. Avulsion is a natural occurrence. My point is that artificially forcing the stream back into its pre-2011 channel is not a good idea from an ecological standpoint.

TB: Never mind avulsion revulsion, you started this!

It's a great topic btw.

Posted on: 3/19 19:18



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