Stream Design 101

Concrete channels, buried creeks, and straightened streams simplified urban development but decades later we see the side effects: faster water, steeper channels, collapsing streambanks, and pollution.  Manager of Stormwater Design Kristen Buccier and Project Manager Denis Zaharija explain the benefits of more recent, holistic stream design methods. 

A stream is a living system seeking stability. Denis and Kristen discuss hydrology and hydraulics, how a stream's bends (or "meanders") dissipate energy, and how riffles and pools create habitat for fish and aquatic bugs. We also learn how “flashy” stormwater volumes can overwhelm streams and how designers work to bring resiliency back to those impacted waterways.

Transcript

Cold Open And Stream Design

SPEAKER_01 0:00

Well, this should be a fun episode. We're gonna be talking about stream design. Why is that funny?

SPEAKER_03 0:04

I'm laughing at my own joke. Donna's jokes are very hit or miss for me.

SPEAKER_04 0:10

This is Kristen's feelings about this.

SPEAKER_01 0:12

You're just throwing things in a wall, saying what sticks and exactly.

SPEAKER_03 0:15

No, I mean I just serious I genuinely think she's she thinks she's really funny. I'm working on my stand-up routine.

SPEAKER_01 0:22

This is just a stepping stone to your comedy burger.

SPEAKER_04 0:24

Exactly.

SPEAKER_01 0:25

This is Clean Water Works.

SPEAKER_04 0:27

This is our podcast about clean water.

SPEAKER_01 0:30

It is. And we have some sewer district staff joining us today from the watersheds department. Kristen Bussier, who has been a guest on this podcast before, is the manager of stormwater design, and Dennis Saharia is a project manager. And we're going to be talking today about stream design.

SPEAKER_04 0:49

Design and engineering is really complicated, kind of no matter what you're designing and engineering. But I think stream design in particular is like a newer field of design and of engineering. And it's developed a lot. You maybe picture the concrete channels of California where they're just trying to rush the water out of a flood zone as quickly as possible. Or just really channelized streams. And nowadays the science has really developed a lot. And so we I wanted to bring in two of our experts to talk about how the sewer district designed streams.

SPEAKER_01 1:22

I bet some people didn't even know there was such a thing as stream

Why Streams Got Straightened

SPEAKER_01 1:25

design. Because streams exist already.

SPEAKER_04 1:28

So it's a fascinating thing.

SPEAKER_03 1:33

Is that weird?

SPEAKER_01 1:34

It is weird to me.

unknown 1:35

It is.

SPEAKER_03 1:36

I think what Mike was maybe getting at was why did we previously kind of manipulate streams, channels?

SPEAKER_01 1:43

Why did we create concrete walls?

SPEAKER_03 1:45

Yeah, concrete channels, or why did we put streams into pipes? And that was mainly for development. Stream channels were considered to be in the way, in the way of where we wanted to build a housing development, where we wanted to put in a commercial building development. And so the easiest thing to do, or what was thought was the easiest thing to do, was to put streams in the ground or straighten them out, move them away from where we want to develop so that we could get that building in, those houses in. And also, you know, streams were considered to potentially be dangerous. There's this really interesting advertisement from the 1930s that is kind of cool for stream geeks and well-known to stream geeks like Dennis and I, but it was from a chemical manufacturer, and their advertisement uh punchline was how dynamite streamlines streams. And so basically they were advertising for use of buying their product, a di a dynamite product, to basically blow up stream channels and um kind of get that sinuosity, and we'll talk about sinuosity a lot more, I'm sure. Get those meanders out of the stream and actually use that to straighten the stream channels. And actually, crooked streams, they they had another quote in there, were considered to be like a menace to life along the stream banks.

SPEAKER_00 3:08

Aaron Ross Powell Just for centuries, streams were at the whim of economic and political decisions and not treated as living beings. So I'm glad that we're starting to see them more as parts of the system.

SPEAKER_04 3:26

That's interesting that you said economic and political. I guess like I think a lot of times streams end up being like an actual territory boundary, too, right? Like the Ohio River is like a good example.

SPEAKER_00 3:38

And then it moves. Right. And then you have a weird boundary.

SPEAKER_04 3:41

You only own half of a river. Aaron Powell Can you give us some examples of ways that development impacts the streams that we can think of or that might be in people's neighborhoods

West Creek And Runaway Energy

SPEAKER_04 3:50

here?

SPEAKER_00 3:50

Yeah, so West Creek in the village of Brooklyn Heights. And it also flows through uh independence, Seven Hills, and Parma. But this particular project was at the lower end of West Creek in Brooklyn Heights, and it was channelized in the 70s and 80s to allow room for industrial development and also the highway. So the stream valley was filled in, the stream itself was shortened by about a mile. So you can imagine the instability that that created that was then solved with the heavy engineering solution of putting the creek in a concrete channel and uh really shoehorning this living system into a manufactured environment. You know, if you've seen a natural stream, you know it has a tendency to want to meander to try to manage the stream energy. So um it's gonna deepen itself in certain areas. We call that uh insizing, and then it's also gonna try to create its own appropriately sized stream channel and floodplain. Uh so it's gonna try to uh move to the left and right and up and down in order to try to create what it considers an appropriate geometry for itself.

SPEAKER_04 5:16

Aaron Powell Can you explain what you mean when you say the stream was shortened? I think that that's like a confusing concept for people that aren't in the field. Yeah.

SPEAKER_00 5:23

If you look at maps, um Cleveland Public Library has so many good old maps, and you can see how the streams flowed prior to major human population in this area, and they just encompassed huge valley sizes. Um it's just amazing to see how much room they took up, you know, in their flow paths, as well as the floodplains, just an incredible amount of wetlands were present, and you know, that makes it inconvenient for development.

SPEAKER_04 5:55

Aaron Powell And so then when they try to reduce the amount of room the stream is taking up, they take out all those bends, they take out all those meanders, and in summary, it it literally shortens the amount of stream between point A and point B. So it literally it lacks the amount of distance between those two points that it used to have.

SPEAKER_00 6:12

Aaron Powell So it used to go for a casual stroll between point A and point B and point A and point B straight track. And now it's a race. And if you think about the topography, now you've made it a lot steeper than what it was before. So now it's carrying a lot more energy with it. It ends up causing a lot more problems uh down the road, whether it's a residential subdivision or uh roadway. The West Creek example with shortening the stream length made the stream channel a lot steeper, resulting in a lot of erosion along Granger Road, along I-480, and also resulted in an engineering solution where they built this giant, I'll call it a concrete pool that's like 18 feet deep to just kind of accept all of that energy instead of having it distributed along the way. Right.

SPEAKER_04 7:13

It's kind of like for skiers out there. I'm not a skier, but it's sort of like if you're at the top of a hill and you're like slaloming down the hill back and forth side to side, you do that to dissipate energy. And it was it's the same thing with like a stream meander. If you were to just ski straight down the hill, you'd be picking up a lot more velocity, and the stream does the same way. So it does the same thing.

SPEAKER_03 7:32

Over time, we've also just seen increases in volume of stormwater runoff. So as you know, areas have been developed over the years, we're seeing those greater areas of imperviousness, which means more runoff is going to these streams and channels. So you know, maybe something that was built 75 years ago was sized appropriately at that time for the amount of flow that it would receive. Um, but you know, years later, with all of this additional development, it's just not adequate to handle those additional flows. Aaron Ross Powell Yeah.

SPEAKER_00 8:02

Before humans, when it would rain, that rainfall would get absorbed into the ground or by vegetation. But as we replace the soil and vegetation with roads, houses, driveways, all of that water is now almost immediately directed into the stream channel instead of being able to take its time to get absorbed and travel through the soil to the creek. So you're seeing a whole new range of flows that the stream never had experienced. You know, you can't bring the stream back to what it was uh in the 1700s just because of the significant impact of humans on the environment.

SPEAKER_04 8:53

And that impacts stream design. Like we can't design a stream to pretend like it's in a fully forested or a fully wetland ecosystem, because that's just not the case anymore.

SPEAKER_01 9:03

Aaron Ross Powell Given that these structures that they built to channelize streams started to fail, is this what led to a new

Impervious Surfaces Change Everything

SPEAKER_01 9:10

school of stream design, like a more natural approach?

SPEAKER_04 9:12

Aaron Powell That's a good question. Was it Captain Planet? Was this Captain Planet's idea?

SPEAKER_00 9:16

It was Luna Leopold's idea.

SPEAKER_04 9:18

Oh, okay. Well, tell us more about Luna Leopold.

SPEAKER_00 9:21

Aaron Powell Luna Leopold wrote Fluvial Processes in Geomorphology.

SPEAKER_02 9:26

Oh.

SPEAKER_00 9:27

And he was a scientist that like finally realized that geology, geography, and climate were also important for water management. He was the son of Aldo Leopold, who wrote a Sand County almanac. Again, a couple good books here mentioned. Right.

SPEAKER_01 9:47

These are uh giants in the stormwater field.

SPEAKER_04 9:50

Environmental field. Environmental field. Yeah. Okay. So streams are living systems. They're always changing. So what does that look like when we say like a stream is changing?

SPEAKER_03 9:59

So, you know, during a large storm event, you'll see those higher flows and higher velocities kind of moving more sediment downstream. It's pushing things around, it's moving rocks, it's moving cobbles downstream, it's potentially scouring out areas. So that's eroding away at the stream banks. The kind of velocities and the flows that we're seeing today are not natural, or those stream channels haven't experienced those before. So it's going to have a more detrimental impact. Like Dennis said, we're going to be eroding the bottom of the stream channel. We're going to be eroding those stream banks just because the stream can't handle it, or the stream channels no longer have access to their floodplain to be able to dissipate those flows.

SPEAKER_04 10:42

Do they ever get equilibrium then? Or does it just keep unraveling?

SPEAKER_00 10:48

It keeps unraveling until it hits a really hard layer where it can't erode at a rapid rate anymore. Often it hits bedrock, but then it'll go laterally. Right. It'll start to widen.

SPEAKER_04 11:02

Can we go through the key parts of a stream?

SPEAKER_00 11:05

There are parts of a stream?

SPEAKER_04 11:06

There are parts of a stream.

SPEAKER_00 11:07

The water part.

SPEAKER_04 11:08

Uh-huh.

SPEAKER_03 11:09

The water in a stream channel.

SPEAKER_00 11:11

Yes. The water can come from groundwater or precipitation as it runs off of the land or the impervious surface.

SPEAKER_03 11:22

That's a great intro because we usually talk about the hydrology and the hydraulics of a stream channel. So Dennis talked about the hydrology there, like where does the water come from? Or if you go back to your elementary years about the water cycle and that whole process. And then when you look at hydraulics, you're looking at how the water moves through the system or moves through that stream channel. So we mentioned a stream has water. That's the first key. It should generally.

SPEAKER_00 12:22

Also, a stream has a stream bed, which is the bottom of the stream, and then the stream banks, which are the sides. What's a riffle? A riffle is um when you're looking at a stream, it'll be the shallower section where the water is running a little bit faster than normal. And then that eventually transitions into like a pool, which is uh your deeper section. That's just how the stream um maintains its energy. Uh the riffles in

The Science Behind Natural Design

SPEAKER_00 12:55

a healthier, stable stream system are typically in the straighter sections. And then you'll notice the pools uh wherever the stream uh turns or meanders, and it'll be deepest along the edge. So I'm sure kayakers are familiar with uh seeing um how the current takes them through a riffle and a pool. The banks of a pool are typically along the outside edge of the stream, they're undercut, you know, and that provides uh, you know, both features provide different types of habitat for both insects and fish.

SPEAKER_04 13:33

Yeah, I think that's like another really cool thing about streams and their their own ecology is that fish and microinvertebrates have developed with these ecosystems. And so, you know, in the in the pools you may see more sunfish. If you're in a bigger stream, you may have your your bass, things like that. Um, but then in the riffles, you'll have your darters, things that like to really sit on the pebbles and stuff right in that shallow water where the water's breaking over them. And they're specifically designed to do that. Like if you look at a darter the way that their fins are, they're designed to sit on a bottom of a riffle like that. And it's really cool just to see how it's all come together. But it is a little scary to think that that's threatened by climate change and by our development when you have these species that were sort of evolved to be where they're supposed to be, you know.

SPEAKER_00 14:22

Yeah, especially with the increase in impervious areas, because not only do you end up having more flow, but um that's picking up a lot of human detritus, whether it's trash, whether it's uh uh stuff as your brakes wear down, tires, sediment, oil, uh everything that's on the surface. Oh my gosh. Yeah, salt is increases the chloride levels in the streams. All these pollutants end up entering the waterway, and a lot of times they'll impact the biological function of insects and fish. Uh, it can really impact the life in the stream, and sometimes it degrades it to a point where you only have species that are pollution tolerant.

SPEAKER_01 15:13

And uh the channelization that you talked about certainly doesn't provide as much habitat for the fish and bugs as well. So you were talking about the West Creek project. Was that to address the failing channel? And and what what does that project entail?

SPEAKER_00 15:28

Um so the West Creek project was about a mile-long stream stabilization project. It was one of those instances of uh, hey, there's a lot of erosion along the stream that's impacting buildings, roadways. And we're always in the business of trying to do the best we can with a site. Um again, you can't restore it to what it was in the 1700s before people were here. So uh you have a site and certain a lot of constraints, and you just try to make it as stable as you can. And making the stream stable also in turn makes the habitat better. So erosion was an initial driver, but uh with West Creek's project site proximity to the Cuyahoga River being about a mile upstream of the Cuyahoga River, there was a significant fish migration barrier because they did put in that concrete channel and the large drop-off. That was one of the deficiencies that was resolved as part of the project.

SPEAKER_01 16:38

And for people to picture that would be like a waterfall feature, right? And the fish couldn't make it up the other way.

SPEAKER_04 16:44

And there's also velocity barriers. Most of the time, the water, especially where that flume is, was just coming around that bend too quickly for regular fish to be able to push through. Maybe you'd have a couple strong ones, but for the most part, you can you can also have a velocity barrier.

SPEAKER_00 17:00

Since that project was done, our water quality industrial surveillance uh group does fish surveys, and they did notice um a number

Riffles Pools Habitat And Pollution

SPEAKER_00 17:10

of new fish species in this area compared to their prior surveys. So uh we just hope that trend uh continues. In the past, we had done little band-aid solutions which were pretty much putting rock along the stream bank here or there, but it didn't really address what the stream was trying to do. So, you know, there's areas of West Creek that were down to bedrock, and then there was areas that had a ton of sediment accumulated, big rock, cobbles, shopping carts littered throughout the stream. So you could just tell the stream energy was off through this whole section. So our designers looked at it and were like the only way to really make the stable was to raise the stream bed up in certain instances up to six feet high to try to both lower the slope through there and create a better connection to the floodplain to minimize the erosion. It was a lot of work to get rid of like a very small engineering feature, you know, that had been in place for decades but had failed. Yeah.

SPEAKER_04 18:30

Krisin, what is the purpose of the floodplain and is it part of the stream?

SPEAKER_03 18:35

Absolutely. So the purpose of the floodplain is to allow a stream channel during higher storm events to get up out of its banks, get onto these floodplain areas, dissipate some of its energy, drop out sediment, nutrients, and the floodplain will actually store some of that water. Once the storm subsides, that water will either infiltrate into the ground of the floodplain or it'll flow back into the stream channel. It's alleviating some of that initial energy that's going to go downstream, both in volume of water as well as in velocity. Usually we'll excavate an area out. The width of the floodplain will depend on what size the stream channel is, how much drainage area is coming into that stream channel. And depending on what techniques we're looking at or what we're trying to achieve on a specific project, we'll plant within the floodplain all native vegetation. Sometimes we'll do trees and shrubs. Other times we're doing a lot of floodplain tolerant seed mixes. The more vegetation we can get in there, the more it's going to help to slow down the water as it's moving through the floodplain. And then if we get vegetation in there, also those roots actually provide voids within the soil where more water can even infiltrate into those floodplain areas. So to me, floodplains and streams go hand in hand. Uh a stream is not a stream without a floodplain, in in my mind.

SPEAKER_04 20:08

Do you guys want to talk about Rosgen and how how that kind of factors into old school stream designs versus how it's done now mostly?

SPEAKER_01 20:16

Rosgen.

SPEAKER_04 20:17

Rosgen. Dave.

SPEAKER_03 20:18

His first name is Dave Rosgen. He's uh a hydrologist and he pioneered this stream classification technique. And he to this day continues to teach a lot of students and practitioners, engineers in the stream restoration field how to go about classifying streams. Uh actually, uh many of our project managers here in the Sturmwater Group have taken trainings directly with Dave Rasgin to understand this process and apply it to the way we do projects today.

SPEAKER_00 20:55

Again, like with West Creek, instead of applying spot fixes to eroding banks, the Rasgin method uses actual field measurements to figure out what a stream or river should look like. And it allows professionals to communicate it's important to have the same language amongst professionals when dealing with stream restoration design.

SPEAKER_03 21:23

I agree, Dennis, because there can be some subjectivity when it comes to stream restoration designs. There's can be some art components to it. And so having this base classification system kind of gets everybody on the same playing field when it comes to designing streams.

SPEAKER_04 21:41

And I think that also speaks to what we were saying before about it being such a new field. Like Dave Roskin's still teaching, right? And this is like the method that a lot of folks are using.

Floodplains Fish Passage And Stability

SPEAKER_00 21:50

Yeah. And using the data gathered during the classification, designers can then use formulas to try to restore. The stream to ideal width-to-depth ratio, sinuosity, which is the meanders, the spacing of the pools and riffles. He's a big proponent of natural channel design, which tries to mimic basically nature's ability to transport sediment and water efficiently.

SPEAKER_04 22:22

There's a lot of math. There's not it's not just like vibes, right? It's like there is math and like hard science around how to do these things.

SPEAKER_03 22:30

We utilize living plant materials a lot in our restorations, trees, shrubs, and live stakes, uh, which is uh a bioengineering technique that we use on many of our projects, and it's basically taking three to four foot-long dormant pieces of willows, sycamores, dogwoods, um, removing all of the uh branches on them and basically sticking them in the ground. When it's a done deal, it looks like you've just poked sticks in the ground. But these things are a really cost-effective way to get a lot of stabilization on the stream banks and on the floodplains, um, because species that are selected develop these very fibrous roots systems that actually get incorporated into the stabilization of the site. For us, plants are just as good of a tool to use as rock, or even more so, because they do get stronger over time, their roots develop even further, and they really integrate into the restoration of our projects. We use dead woody material. So we'll use bundles of dead wood to potentially use as like a stream stabilization technique, or we'll embed it into the toe of the stream channel, so that's where the bottom of the stream meets the stream bank. We'll use dead material within the stream channel itself as habitat. Uh, we've used dead trees as like log sills within a stream channel horizontally across the stream as a grade control instead of putting all rock into a stream channel.

SPEAKER_00 24:08

My favorite is root-wide. So you take the bottom of a felled tree roots intact, and you excavate a trench into a stream bank and you place it in that trench, the trunk side out into stream flow. I mean, the entire structure is kind of pinned in place with like a footer log and wood pins to make sure it stays there, but it serves to direct the stream flow kind of away from an eroding bank while also providing habitat. So a lot of these wood structures that we use mimic what would happen in a natural system over time, but by designing them and installing them, they're present on day one to function in a controlled manner.

SPEAKER_03 25:04

Yeah, and utilizing these woody structures on our projects are a great way to reuse some of the material from the project site. So to do some of our stream restoration projects, there may need to be some element of tree removal. So we are able to reuse some of that material on site and incorporate it into the stream design features. I guess one of the features that we didn't talk about was the live branch layering, similar to what I had said about the live stakes, but you kind of bundle maybe about a foot deep worth of these branches, these live stakes, and you can lay them across a rebuilt stream bank. Then you put like another soil lift on top. We call it fabric encapsulated soil lifts.

Rosgen Methods And Bioengineering Tools

SPEAKER_03 25:50

And in between those lifts of soil, you're putting these bundles of live branches. And so those roots are actually growing into the bank, and it's providing that additional stabilization. So we've done that on a couple of our project sites over in Pepper Pike along Pepperloose Creek. We did a project over along Shaker Boulevard, one along Lander Road that we utilized this fabric encapsulated soil lift with those branch layings in between, and it's been very successful.

SPEAKER_00 26:22

Part of the beauty of using these features is if they're installed correctly, you sometimes may not realize that they're even there because they're underwater or as vegetation matures, they just become part of the fabric of the stream channel.

SPEAKER_03 26:40

With our natural stream restoration projects or these natural designs, the goal is to not make it not even look like we've been there, like we've touched it. If we get enough vegetation in there and those roots are taking off, and we're continuing to maintain these sites, the goal is eventually this is back to a naturalized system that requires little maintenance on our part after those first few years.

SPEAKER_04 27:06

Going back to sizing the stream and looking at shear stress and velocity, can you talk a little bit about the role of modeling when it comes to stream design?

SPEAKER_03 27:15

Back when we started the stormwater program at the sewer district, we started working on these stormwater master plans for all of our various watersheds throughout the region, the Cuyahoga, the Rocky River, our Chagrin River tributaries, direct tributaries to Lake Erie as well. And part of that was coming up with these sort of master models of all of our watersheds. These are sophisticated computer programs that we can input the data, the width, the length, all of the data of the individual stream channels, the slope, putting it into these models so that we could predict how they'll react to future climate scenarios or future projects that we undertake. Those models are really living programs for us because we're constantly updating them. We've installed flow monitors throughout our system to be able to input this real-time hydrologic data into these models. And so when it gets to design, we've built these very sophisticated models and we're able to very accurately predict how the stream channel will react to a project, to putting in additional floodplain, how will it reduce flooding to neighborhoods and to roads? These models have really become a tool both in creating the design, but also seeing how the system reacts in the long run.

SPEAKER_04 28:50

Yeah, I think it's critical in how we go about our work. You know, there are all these different elements and there's different ways to do things, but when we look at alternatives, you know, do we have the stream going further north or further south, or how how wide can we make a meander? We're looking at that model and we're seeing where the shear stress is on those outside meander buns. Is it too high and is it gonna blow out that bank? Is it gonna cause erosion? So every time we tweak the shape of the stream or the depth of the stream, the slope of the stream, we're looking at that model to predict how it'll react during a one-year event or during a hundred-year event. We're looking at all of those things to make sure that the work product is stable at the end of the day.

SPEAKER_03 29:35

A good point, too, about the makeup of the design teams that we work with. You know, there's our modeling folks, so the HH uh hydrologic and hydraulic modelers, um, but they're working on the same team as the on-the-ground stream specialist, the ecologist, the hydrologists, the civil engineers. So we're bringing together all of these different disciplines within uh the design of a stream project and really trying to use all of that knowledge to create the

Modeling Tradeoffs And Public Expectations

SPEAKER_03 30:10

the best uh design that we can.

SPEAKER_00 30:12

Aaron Ross Powell You're trying to do the best with what the site gives you. Uh the reality is you'll have roads in the way, you'll have buried infrastructure, highways, um buildings, houses.

SPEAKER_04 30:26

Houses.

SPEAKER_00 30:27

We also don't have endless money to spend, endless budgets on projects. It's really balancing all of the constraints and trying to make the system healthier, uh aiming for as much of an ecological impact as possible. And sometimes you may impact a feature that folks are familiar with, but overall you're trying to leave the area in a much more stable condition and hopefully with more habitat than before, and just setting the stage for more of an ecological rebound.

SPEAKER_03 31:09

That was very nicely put, Dennis. These are incremental changes that we're making. The hope is with enough of these smaller projects, we can make that more cumulative, larger effect. You know, it took a long time to get us where we're at today in terms of development. So it's going to take time for us to piece and stitch these streams back together. You know, a lot of times we're working right in people's backyards. And they've seen a stream one way, maybe it's, you know, within a concrete channel or it's been straightened, and that's what they're used to seeing. And the concept of a stream restoration can be completely foreign to folks. And so a big part of our jobs in the design group and working, Donna, with with your group is getting out there and talking to individuals about what we're trying to do here, why it's important, not only from you know, the arresting of erosion and the flood risk reduction, but the ecological gains that we're getting from these restorations, you know, literally right in their backyards, and then just kind of seeing those finished projects and talking to people afterwards. And, you know, people are like, it's not what I expected, but it's pretty awesome because we didn't really know what to expect.

SPEAKER_01 32:37

Thank you both for joining us for Clean Waterworks. Kristen Bussier is the manager of stormwater design, and Dennis Sahari is the project manager within our watershed programs department. Thank you.

SPEAKER_03 32:48

Thanks for having us. Thank you.