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Re: Bear Cr Jumps Into Road During Flood

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It is a good topic.

I hope we all receive checks for our consulting.

Posted on: 3/19 20:12


Re: Bear Cr Jumps Into Road During Flood

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Trout err you mentioned Greys Run in the OP. That stream, especially in the C&R section has several channels it jumps to occasionally. Granted they aren't the road but one time I fished there and two months later I came back only to find the stream was running a different path; one that had been used before.

While the fishing was poor in that stretch, it was neat to see. I kinda wish I saw it happen live. I can't make up my mind if it happens abruptly or slowly switches channels.

Posted on: 3/19 20:37
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Re: Bear Cr Jumps Into Road During Flood

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Quote:

MKern wrote:
Trout err you mentioned Greys Run in the OP. That stream, especially in the C&R section has several channels it jumps to occasionally. Granted they aren't the road but one time I fished there and two months later I came back only to find the stream was running a different path; one that had been used before.

While the fishing was poor in that stretch, it was neat to see. I kinda wish I saw it happen live. I can't make up my mind if it happens abruptly or slowly switches channels.


I think it usually happens abruptly, during floods. During a big flood, the water is flowing over the entire width of the floodplain.

In the stream channel, the water is flowing fast and deep and moving a lot of cobble and gravel. And also transporting big branches and even whole trees, root wads and all.

When some trees, branches (large woody debris) jam up in the channel, the water is slowed there, and the cobble and gravel drop out, filling the channel partially or even completely, right up level with the floodplain.

And the water gets shunted over and takes a different path, either enlarging an already existing relict channel or secondary channel (usually). Or sometimes just forming an entirely new channel.

Often there is some water going down the old channel still, so you have a "channel split" and have two channels flowing parallel to each other for a ways.

Then the channels typically rejoin further down. Often a pool forms where the two flows converge.

Posted on: 3/19 21:01


Re: Bear Cr Jumps Into Road During Flood

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Quote:

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.

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).


I pretty much think that stream restoration work should be holistic, meaning the lowest impact possible.Nearly every in stream device fails at some point any it often is replaced, often with the thinking, it won't happen again. Faulty logic, because they all fail again if they've failed once. This is why I think the holistic approach works best, fence livestock off and plant trees and shrubs, let the trees and shrubs grow, and if they fall in the water, that's part of the program, leave it unless it threatens a bridge. If it threatens a house move the house, the house is in the flood plain.

Posted on: 3/19 22:35


Re: Bear Cr Jumps Into Road During Flood

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I'm going to take a closer look at the Big Bear Creek study and details, but for general consideration every stream shares common characteristics.
Course changes occur most frequently at alluvial points and in the low slope areas below. It's dynamic.

Hydrologic cycles have been altered in many watersheds for a variety of reasons (in many streams we now have many more caddis fly populations than mayflies because caddis can tolerate the changes in stream flow better).

As weather patterns have changed and extreme flooding has upended the bottom structure of many of our streams for the past 40 years, I suspect/hope we will be migrating toward considering stream channel structures built well back from the normal flow stream bank.

These devices would only be seen by the observer to be in effect during a flood.

Posted on: 3/20 10:43


Re: Bear Cr Jumps Into Road During Flood

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vern wrote:

I suspect/hope we will be migrating toward considering stream channel structures built well back from the normal flow stream bank.

These devices would only be seen by the observer to be in effect during a flood.


Could you tell us more about that? What sorts of devices are you referring to, and how would they function?

Posted on: 3/20 11:21


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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Vern: Like TB, I am having a hard time picturing the sort of structures you are describing. Habitat structures such as log and stone cross vanes and j-hooks are usually constructed within the channel, for obvious reasons. Bank and channel stabilization structures are typically constructed either across the channel (j-hooks, cross-vanes) or at the intersection of the bank and channel (deflectors, bendway weirs).

Posted on: 3/20 12:32


Re: Bear Cr Jumps Into Road During Flood

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Okay.

Picture some of the best, most stable fishing holes in a stream. Any stream.

They are going to be bridge holes, old dam abutment holes, projections of hard bedrock, etc. Large rock formations on the flood plain, such as glacially placed (not the lesser 20-year depositions).

If your study Rosgens' designs, he basically attempts to address flood stage flows with the largest rocks on the downstream high bank wings in order to do so.

Don't look at the stream flow as you see it on the day you are there. Look at the topography all around the site. That is what formed the flow. Build and place for flooding flows and you will get the pool basin formation you want using natural forces. After that, vegetation and instream structures, bank structures, stabilizers, etc. can be considered.




Posted on: 3/20 13:18

Edited by vern on 2014/3/20 13:38:28


Re: Bear Cr Jumps Into Road During Flood

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I'm not talking about building an Egyptian pyramid, but look around, especially with the aerial mapping; all the examples are really all around us.

And try to remind people you love: Trees are not round balls of green on a stick. They grow toward the sun. They cannot do otherwise.

Posted on: 3/20 13:36


Re: Bear Cr Jumps Into Road During Flood

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Vern: I gather you have not yet had a chance to read the Big Bear Creek post-restoration studies. I hope you get a cance to do so because the project is a good illustration of a Rosgen-style restoration project. I think it's fair to say that Dave Rosgen's purpose was to create a restoration system that attempts to balance stream flows and sediment movement during both high and low flows.

I'm not the sharpest hook in the box and I'm still trying to decide whether or not you favor the Rosgen system.

Posted on: 3/20 14:00


Re: Bear Cr Jumps Into Road During Flood

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I was not ever able to attend any of his courses. The cost was prohibitive for me individually and I couldn't get sponsorship. However, when his designs and work on Western streams first appear on the scene I looked at the images and designs and commented to one (I worked closely with) who had attended that it more or less seemed to me that what he had was more or less a variation of a "V" weir (flipped), with a center rock in the middle flow.

I could see what he was doing, keeping the concentration of flow into the center of the streambed to scour and maintain the integrity.

However, he's been criticized for some of the failed practices over the years and I think it's a bit unfair because of the locations and the volumes of flow. Too much. For what they are, they are really good. They are not a cure-all.

I go by this motto = one-size fits all when there's only one to fit.

That structure and design is excellent for use in an appropriate place in the overall length of a stream slope, but each practice has its place.

Posted on: 3/20 15:54


Re: Bear Cr Jumps Into Road During Flood

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Got distracted. It's high school musical night. I'm probably not alone.

But the gist of it is that unless you are trying to create a truly artificial situation - you got to get out and investigate. The survey rods and slopes and historic flow records are necessary, but not the end of it, only the beginning. Each stream is different because each place on this planet is different and each section of flow is slightly different.

Rough it out with engineering, but finesse it in the field.

That doesn't go over so well with some of the office bureaucrats. Some of them don't understand that life and reality is dynamic.

One guy who was strictly tied to desk calculations and reports didn't even understand that the length of a stream changes over time.

But they do. It can be XX number of units length for 20 years and then average XX+126 number of units length the next 20. It all depends on hydrologic cycles, solar cycles, human activities, forest maturation stages, etc.

Later. Got to catch a show.


Posted on: 3/20 18:30


Re: Bear Cr Jumps Into Road During Flood

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Quote:

vern wrote:
Got distracted. It's high school musical night. I'm probably not alone.

But the gist of it is that unless you are trying to create a truly artificial situation - you got to get out and investigate. The survey rods and slopes and historic flow records are necessary, but not the end of it, only the beginning. Each stream is different because each place on this planet is different and each section of flow is slightly different.

Rough it out with engineering, but finesse it in the field.

That doesn't go over so well with some of the office bureaucrats. Some of them don't understand that life and reality is dynamic.

One guy who was strictly tied to desk calculations and reports didn't even understand that the length of a stream changes over time.

But they do. It can be XX number of units length for 20 years and then average XX+126 number of units length the next 20. It all depends on hydrologic cycles, solar cycles, human activities, forest maturation stages, etc.

Later. Got to catch a show.


My view is that too much has been constructed in floodplains, and that floodplains have never been considered as a part of the whole system. In fact floodplains have pretty much been ignored. A flood plain should be viewed as a part of the stream as a whole and be left undeveloped. Of course it's hard to go back, but the flood insurance laws in this country have been totally misused as a development opportunity by developers and the real estate people.
This puts development in the way of a floodplain and prevents a floodplain from doing what nature intends, diverting the flood of a stream when it is out of its banks, and slowing the force of a flood.
Rosgen is wrong in trying to channel flows.

Posted on: 3/23 9:02



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