Stanford [00:00:13]: Several years ago, a senior technical director at the Corps of Engineers told me that he only trusted two people in the world to develop a sediment transport model. And one of them is today's guest, Doctor Ron Copeland. And while I like to think that the set of competent sediment modelers in the world is maybe greater than two. Ron has been on a very short list of the best mobile bed morphodynamic modelers in the world for decades. But one of the reasons I wanted to talk to Ron early in this season is that he's more than a modeler. Even though he found the time to develop world class skill. In the difficult and detailed discipline of sediment modeling. And has contributed to algorithms that many models use. His insight and expertise sample a much broader swath of sediment transport and river mechanics. He wrote some of the course earliest technical guidance on river restoration and channel design. And he spent so much time immersed in the Mississippi sediment data. That I'd put his intuition up against anyone else's numerical or physical model. Ron's worked for the Corps of Engineers for over five decades. Yeah, that's right. 52 years at the La district in the course coastal and hydraulics lab in Vicksburg, Mississippi. And he worked ten years as a principal engineer at Mobile boundary Hydraulics. Which was the premier 1D sediment modeling shop in that era. In 2020, he won the American Society of Civil Engineers Hans Albert Einstein Award. Which recognizes lifetime contributions in sediment engineering. He's been one of the corps senior sediment specialists for decades. And I just wanted to take a shot at capturing a little bit of that insight before he retires for real. I'm Stanford Gibson, the sediment transport specialist at HEC. And this is the RSM River Mechanics podcast with Doctor Ron Copeland. Ron Copeland, welcome to the podcast, boy. Ron [00:01:59]: Thank you. Thank you. Stanford [00:02:00]: So how did you get involved in river restoration design? Ron [00:02:03]: Well, I was part of the Channel stabilization committee. And we were reviewing engineering manual 1418. And I was pretty critical of the empirical methodology that was advocated in that em. And so I complained quite a bit at that meeting. And the next thing I knew I was in charge of the research program. Stanford [00:02:25]: That's how that works. Ron [00:02:27]: Come up with a better general restoration. Stanford [00:02:30]: Can you give me like a date timeframe? Like what time was this? Like just decade. Ron [00:02:35]: I guess it was probably in the nineties. Stanford [00:02:39]: In the nineties. Ron [00:02:39]: Early nineties. Stanford [00:02:40]: I think it's important for like younger people who might be listening to this to realize like, river restoration is a hundreds of million dollars a year industry now. Like, it is a. It is a legit industry. But back then it was the wild west. People would, like, send a bulldozer out to a river to make a straight river wiggly. That's like the level of analysis that's being done. Ron [00:03:00]: That's true. And there was a lot of disasters as a result. Stanford [00:03:04]: Yeah. So you revisited this manual and you developed a guidance about restoration design. So what are the steps involved in restoring a channel? Ron [00:03:15]: The first thing that is important is to get together a team of people, because there's so many different things involved with channel restoration. It's not just hydraulics and it's not just trout fish, and there's a lot of different things. So you need an engineer, you need a geomorphologist, and you need a biologist. And of course, it all depends on what your objectives are, which is the next really important step is to identify what the objectives of your project is. You know, is it aesthetics? A lot of times it's just want to make it pretty. Stanford [00:03:50]: Yeah. Ron [00:03:50]: And that's. That's a legitimate reason. You know, like in some places, San Luis Obispo, for instance, they took the stream and they made it real pretty, just so that it would improve the commercial zone or area that it was in. So aesthetics could be. It could be recreation, it could be fish, it could be flood control, it could be just, hey, this stream is eroding away. We got to do something about it. So the first thing is to identify specifically what the objectives, and not just a lot of times the objective is, well, let's fix it. And that's not a good objective. Stanford [00:04:25]: Do you feel like sometimes different stakeholders have different objectives? Ron [00:04:28]: Well, certainly. And it's important to get them together and specifically lay out what the objectives are, because sometimes one objective might be counter to another objective. So you have to recognize that and settle on what it is you're trying to accomplish. So that's really important. I think that's really important in what you're trying to do. So once you set the objectives, then you need to go out and do a geomorphic assessment and see, well, what is it that is causing this problem? Whatever it is, instability, deterioration, maybe it's just full of trash and it's just not a good, pleasant environment. Stanford [00:05:08]: The shopping cart index is something I used to go on buffalo or. Ron [00:05:13]: And in some places it's needles and other things. So you have to figure out what it is that's causing the problem. This involves collecting data and historical data and doing geomorphic kind of assessment stages and things like that. And then the next thing is to do the hydrology figure out what the discharge is. And typically, with channel restoration, we design a channel forming to a specific channel forming discharge. And that's the first step, I think, in cybere the channel and figuring out what it is you want to do, but you need to do that. But you also need a flow duration curve and a frequency curve, because you need to know over the long term, how will the stream respond to different discharges in different conditions. Stanford [00:06:01]: So can I stop you there? So those are a couple terms that we use, but maybe younger engineers might not. I realize this is a loaded question. Can you tell me what the channel forming discharge is? Ron [00:06:12]: I use the term channel forming discharge because that's a process based term. Yeah, but it's a discharge that if you kept that discharge going for a long period of time, constant, steady state, it would actually form a certain channel shape. Stanford [00:06:26]: So it's a conceptual flow that could reproduce the same channel as the whole time series. Ron [00:06:34]: That's correct. And then we usually. There's several different ways to calculate or determine that. One is bank full discharge. One is the effective discharge, which is the discharge that carries the most sediment. Sometimes people like to use the frequency of the two year flood, the two year frequency event. So there's different ways to come up with that channel forming discharge. And they have various variable degrees of success. Stanford [00:07:00]: Yeah. John, Shelley and I, we have a little video series on this that maybe I might link to in the notes of this. Ron [00:07:06]: Okay, good. Stanford [00:07:06]: Then you used another term, the flow duration. Can you just describe what that is? Ron [00:07:12]: That's a curve that says, how often does this discharge, how often is it exceeded during a year or actually during a long period of time? What's the average exceedance frequency of a specific discharge? And so flood discharge is not exceeded very often, but it's a little bit different than a frequency curve. And a frequency curve just looks at the peaks, but the flow duration looks at the long term. In some ephemeral streams, you could well have zero flow most of the time. Stanford [00:07:44]: That's a little bit different for our agency because we're often just looking at those annual peaks. But for restoration, we care about all the flows. Ron [00:07:51]: That's right. Stanford [00:07:51]: So you take all the flows and you line them up like elementary school style, from shortest to tallest, and that's your flow duration curve. Okay, so so far, you've built the team, you've identified the objectives. You're doing your geomorphic assessment and identifying the problem. And now you're sizing the channel with the channel forming discharge and the flow duration. Ron [00:08:11]: Right. Usually you size the channel with the channel forming discharge first time through. Stanford [00:08:16]: Yeah. Ron [00:08:17]: So then it comes, then you have to decide, well, is this gonna be a threshold channel or is this gonna be a channel that actually has movement? Stanford [00:08:24]: Okay, I'm gonna need you to define those as well. What's a threshold channel? Ron [00:08:27]: Threshold channel is one where it doesn't. Stanford [00:08:29]: Move until it does. Ron [00:08:32]: Until it does. Stanford [00:08:32]: Right. And that's the threshold. Ron [00:08:33]: Then it's an alluvial channel. Stanford [00:08:35]: And so the threshold is usually like a critical shear stress or a critical stream power or something like that. Ron [00:08:41]: Something like that. Stanford [00:08:42]: Whereas what was the other one? Ron [00:08:44]: Alluvial. Stanford [00:08:45]: Alluvial. And that's like a moving bed a bit. Generally more of a sand bed where things are moving all the time, even if it's not a lot. Ron [00:08:53]: Right. Yeah. And an alluvial channel, like you said, that's a good point, that sometimes it's not really moving at all, but it moves, say like a channel forming discharge, it'll be moving. Stanford [00:09:05]: Yeah. Right. Ron [00:09:06]: So, and gravel bed streams, obviously, they move too. It's certain discharges eventually. Stanford [00:09:13]: So when you'd say threshold channel, a lot of times we're talking about gravel or cobblestone. Ron [00:09:18]: That's exactly right. We're talking about a stream where it doesn't, the bed is not much of a factor in terms of stability. Stanford [00:09:24]: The majority of the time it's not moving. But then I, you know, during these events, we get bed movement. Ron [00:09:29]: Right. Stanford [00:09:29]: Okay. So then what's next? Ron [00:09:31]: So one of the big differences in what we recommend in the manuals now is to do a stability analysis and make sure that the channel can carry the sediment that is supplied from upstream. And so you don't want to have a channel that's degrading or aggrading. Stanford [00:09:51]: Right. Ron [00:09:51]: So that's kind of, that's one of the things that you do in the analysis to size the channel. And then of course you have to be careful of bank erosion and things like that. Do you need to protect the banks? And if so, you use rip wrap or root was or some sort of a bank protection method. So you have to. That's what you do. So you determine the details of the channel. And then finally you use the flow duration curve and do a set of impact assessment and see what happens with the range, the full range of discharges that the stream will be subject to. And then another thing that should be on the list is monitoring, and that is after it's constructed in the plan itself, there should be a plan to go out and check to see what's happened. Stanford [00:10:36]: And what percentage of the time is that actually done? Ron [00:10:38]: It's not done usually like one. And that's very unfortunate because first of all, you can learn from your mistakes. And second of all, you can also learn from your successes. Stanford [00:10:48]: That's right. And I do feel like. I feel like no one wants to monitor because no one wants to be proven immediately wrong. Ron [00:10:57]: That could be. It could be that. And it's just the budget, the way the budget works out, you have a two year budget, you have a budget and you build a project and then there's no budget for monitoring. So that's unfortunate. Stanford [00:11:08]: One of the things that this hallway, we're at ChL, the coastal and hydraulics lab down in Mississippi, and one of the things this hallway has been doing is actually going back and looking at a lot of these projects and trying to do like ten year later monitoring to see what's done very good. Ron [00:11:23]: That's important. One of the things in my career is I never get called in until there's a disaster. So everything I see in my experience is that everything, nothing works because nobody ever calls us up to go look at a successful project. But I think you can certainly learn from successes too. Stanford [00:11:40]: That's right. Let me see if I can reproduce this. So you build a team, you define the objectives, which is an underrated step defining the objectives. If you don't do that, then you're not going to hit the objectives. Then you do your geomorphic assessment and you identify the problem. And then you size the channel with the channel forming discharge. You determine whether it's a threshold or alluvial channel because that's going to really determine what you want to do to restore it. You do your stability analysis looking at the sediment flux coming in and is your new channel going to be in equilibrium with that? You determine the banks if you're going to have impacts on the banks and if you need to protect them. And then you use your flow duration curve to look at how do the new flows translate into new stages and what are the impacts of those in the new channel. And then you monitor so that you and other generations can learn from your successes and failures. Ron [00:12:35]: Right? Stanford [00:12:36]: So you said that at the point in your career that you've been at for a while, you are the, the modeling subject matter expert in the core, but also, you know, the stable channel subject matter expert. You get called in when things get really bad. Could we learn from that? Can you tell us a story of something, of a project that failed because of things that we could learn from. Ron [00:12:59]: I won't talk about a core project because I'll talk about actually the core. At the time I was doing this work, we hadn't really been, didn't have both feet in on this channel restoration concept. So a lot of the work was done by others and then reviewed by the corps because the corps was the regulator, if you will. So I think one of the biggest issues with a lot of the early restoration work and again, a lot of these restoration projects worked pretty good. But I didn't call, get called in to see those. So I got called in to see the ones that weren't working. The biggest problem was that they weren't designed on this concept of we have to move the sediment that's coming in through the project, reach through the downstream end. A lot of times people have preconceived notions about what a channel should look like. Some people will say it's obvious that a channel should be meandering and it should have nice pools and riffles and that's the way the channel should look. And so a braided channel, for instance, is just not pretty. Stanford [00:14:15]: Yeah. Ron [00:14:16]: However, abraded channel is braided because there's a lot of sediment coming down from a stream. And so you have a braided channel and that's the natural condition of the stream. So if you try to turn a braided stream into a meandering stream, if you just think for about 5 seconds, you can say that's not going to work because there's too much sediment. Abraded stream moves sediment and a meandering stream doesn't move nearly as efficiently. So it's going to fill up. And that's essentially what happens in a lot of the projects that I reviewed. I went to an ase conference one time, Alaska, and somebody had a alluvial fan and they decided that what we needed on an alluvial fan was a meandering stream. So they built it with, they went out with their bulldozers and put it in a meandering stream and it worked pretty good the first year. So they wrote a paper and said, this is a great idea. I mean, you just shake your head and say, what are you thinking? Stanford [00:15:22]: Yeah, right. Ron [00:15:22]: It's a simple concept. What goes in must come out or you have a problem. Stanford [00:15:27]: That's right. So I remember the first time I went to a restoration conference. There was like a standard narrative to the presentations. It's like, okay, here's a before picture. Here's a picture of our bulldozers. Here's a picture of after and here's a picture of one year after where all the vegetation is back and ta da, it's a success. And I remember sitting in there thinking you can't claim any sort of success until you've. Till you've seen the full range of flows, because I don't know how your channel is going to respond, and not just locally, but how is your channel going to respond to the sediment flux that comes in? Ron [00:16:07]: Exactly. Stanford [00:16:08]: And so would you say that in general deposition or erosion has been the bigger problem in some of these restoration channels? Ron [00:16:16]: Yes, that's the case. Both. Stanford [00:16:20]: Both, yeah. Ron [00:16:23]: We spent the course, spent a lot of time in North Mississippi working on channels that were degrading, degraded. And how do you address that situation? I mean, it's not just North Mississippi, but all over the country you have degraded, especially with urbanization. You have a lot of problems with degrading channels. I think maybe that's not as difficult to figure out how to solve it. Stanford [00:16:46]: As the aggrading situation because the grading situation, you have a systemic watershed scale problem because the watershed is giving you too much sediment and you can't deal with it. You could armor locally to get away from erosion. Ron [00:17:01]: Right. Or I think another common solution is drop structures. Reduce the slope by drop structures. Stanford [00:17:08]: Drop structures. Ron [00:17:10]: Another way to do it would be to make it a meandering stream. And maybe that's where this idea of a meander extreme, such a good idea comes from. Stanford [00:17:17]: That's right. Ron [00:17:18]: That's one of the things. Decrease the slope. Stanford [00:17:20]: Right. Before you move on, can you just tell us what a drop structure is? Because this is something that the core does use a lot in restoration. Ron [00:17:27]: Right. A drop structure is just a structure that holds the bed and the water surface at a higher, you know, at a higher level. And then it reduces the energy as the water flows over the structure and into the stilling basin or whatever it is, that the energy dissipated whatever it is downstream that they use to dissipate the energy. But that's the way to eat energy. Stanford [00:17:47]: So instead of having a steep slope, you have a series of shallow slopes with some drops and that actually, that dissipates energy more efficiently and keeps the system from eroding. Ron [00:18:00]: That's correct, yes. That's been a solution or a method that has been going on for years. Soil conservation service has been over decades ago and came up with lots of design structures for that purpose. Stanford [00:18:14]: It sounds like what you're talking about isn't so much something local for the channel itself, but that the channel wasn't sized to the system. Ron [00:18:24]: That's correct. And that goes back to. One of the biggest issues of any kind of river engineering. Is you look at the whole system. And not just the local site. But the local sites is also an issue, too. It can be an issue. But it's important to identify. When we go back to the steps here. Is identifying what's causing the problem. You know, sometimes it's just a local. Or a poorly aligned channel. Or a weak material in the bank or something like that. That it's not an issue, but it's a local issue. Whereas when we talk about channel restoration. Usually we're talking. I'm talking about the system. Stanford [00:19:00]: Yeah. Ron [00:19:01]: And that's another problem we have with a lot of channel restoration projects. Is that they're very short reaches. And they try to fix a little reach. And they're not looking at the system. And it doesn't work. Stanford [00:19:12]: I would be remiss to not point out that this podcast is being funded by the regional sediment management program. And the premise of that program is that sediment problems and solutions need to be regional. That you very rarely can put a band aid on a single bend. Ron [00:19:28]: That's true. Stanford [00:19:29]: About a decade ago, I was talking to Peter Wilcock. Who, you know, but just for the listener's benefit. He's one of the most well known sediment academics in the field. And he said the biggest contribution that you made to restoration design. Was to bring slope into the calculation of channel shape. Now we have several algorithms in HTC Ras. The open channel model that I work on. That have your name on them. We have several Copeland methods. I think Peter was talking about. You have a stable channel design tool. That got used in Sam for years. I think this came out of the things we're talking about. Where you recognize that people are kind of missing. On sizing their channels to the regional context. Can you tell us a little bit about what we call the Copeland method in hydraulic design? Ron [00:20:18]: I like to call it the stable channel analytical method. I like to focus on the analytical part of it. One of the problems with that was, of course, the acronym for stable channel Analytical method is scam. Stanford [00:20:34]: I just wrote it down. Ron [00:20:35]: We didn't think that that was going to be a big seller, the scam method. So we hyphenated stable channel. So it became the SAM method. Stanford [00:20:48]: That's the source of the name of the SAM program. Ron [00:20:50]: That's the way I remember it. It so happened to. Stanford [00:20:53]: Because that program did a lot of things. Ron [00:20:54]: Yeah. Because this was like one of the first things that we did. And then other people had stories that we called it SAm because Sam was the man who funded, in charge of funding the whole research program. And it did grow. It grew with SAm, did a lot of other things besides this. Stanford [00:21:12]: But this was the start, this was kind of the start of the analytical method that you developed. Ron [00:21:16]: So this was sort of the answer to the empiricalism in that. EM 1418. Okay, so what is it? Well, again, the object here, the purpose was to design a channel that would move the sediment from upstream through those design reach to downstream. Stanford [00:21:35]: Okay. Ron [00:21:36]: So, and it had, it was supposed to be simple because a lot of the projects that, you know, the channel restoration projects were kind of small and didn't have a lot of budget. So we don't have time for a sediment study. So it had to be simple. So the idea was this was just like a normal depth approach. I mean, we're just looking at one cross section and getting an idea of the shape for the reach, the channel restoration reach that would be adequate to move the sediment through. And as you go on the design process, you add more features, you digest it and whatnot. But the idea was to just come up with a shape that would work. And so what we call the dependent variables were slope width and depth. Those were dependent. And then the independent variables was the sediment supply and the bed roughness, the bed gradation. And we said that the size slope would be independent. We would assign that to and we would assign the roughness. Stanford [00:22:37]: Let me see if I can reproduce this. It sounds like the sediment properties, the sediment flux coming in and the bed gradations, those are the things that you're going to stipulate in the model. That's right. And the model is going to use those to come up with slope depth with the sorts of things that you have control over with a bulldozer. Ron [00:23:02]: Right. Stanford [00:23:02]: Okay. Ron [00:23:03]: We like to focus on the terminology independent and dependent variables. And so the independent variables are what's coming in. You can't really do much about that. Stanford [00:23:13]: Right. They're independent. You don't control them. The watershed controls. Ron [00:23:17]: So we got three variables unknowns. So we need three equations. Stanford [00:23:21]: Yes. I'll just mention here that we have the Brownlee approach in ras. And I'm in the process of adding the Meyer Peter Mueller approach and in reproducing the work you did. I have never done so much calculus since undergrad like you. So this isn't a brute force numerical approach. This is analytical. This was very elegant. Ron [00:23:41]: Well, you know, I spent a lot of time with calculus and I said, this is really not anything I need. So it was finally good to use that stuff that I suffered through so moderately in college. So that's good. I'm glad you got to use it. Stanford [00:23:57]: I got to use it for the first time in a long time. Ron [00:24:00]: I think one of the things that when I was teaching stem classes, I always made the students solve the transport equation by hand. And it's very painful. Like Tafuletti was what I like to use. It's very painful, but it addresses all of the functions of center transport and so you learn something from it. And of course when I was teaching, they didn't know that it was all programmed, so they didn't have to do that. But it's important to understand the basics of some of these, these equations and some of these techniques. Stanford [00:24:33]: So this is where the podcast format breaks down a little bit because the output from this tool is so elegant. Basically what you end up with is you have a relationship. You don't just give it a slope and end up with a width, you end up with a relationship with slope on the x axis and width or depth on the y axis. And then you have the whole parameter space, and we affectionately call it the Nike swoosh because it's not a unidirectional relationship. A lot of times there's an optimal. And so in this width slope space you have this line, and then you can give this curve to planners and landscape architects and say, if you want this width, that's fine, but you have to have this slope. And it just becomes an incredibly helpful tool to just bring this curve to a meeting and say, you can do whatever you want, but this is what you can have, right? Ron [00:25:37]: Some people would advocate to use the minimum, not the minimum slope, but the minimum width. And they call that the extremal hypothesis. So that is one option to come up with a unique solution. But I didn't like that. I liked what you're talking about. So you have a range of solutions and then what you do is you have constraints that you've determined from your objectives. Stanford [00:26:05]: Objectives, yes. Ron [00:26:06]: And you say, well, I can only have certain depth because we have for flip control reasons. So then, you know, then you cut off a lot of the solutions on that curve you're talking about. Stanford [00:26:17]: That's right. Ron [00:26:18]: Or maybe you have a slope. I mean you can't, if the value slope is a certain value, you can't make it any less than that. Stanford [00:26:25]: I mean, any more than that. Ron [00:26:26]: Yeah, more than that. So that's another constraint you might have. But anyway, and you might have, you have constraints, so you can, you can limit the solutions that you have. You know, maybe you don't want. Maybe you have a fish criterion. Stanford [00:26:38]: Yeah. Ron [00:26:38]: And that will mean, well, I have to have a depth of at least this much. Stanford [00:26:41]: Right. Ron [00:26:41]: So, so, yeah, the constraints then come into play and to limit the solutions on that swish, that's. And I think the switch also tells you when you're on that curve, then you know, that means you're in, what comes in is going out. Stanford [00:26:57]: Right. Ron [00:26:57]: But if you go and you're above that curve, then you're going to get, you're likely to have deposition. And the further away from that curve you are, the more deposition you can expect. And also if it falls below that curve, you're going to get more likely to get erosion. So one of the things that you can do then is, you know, that curve you have is based on a specific discharge. And we talked about it being the channel forming discharge charge, but you can look then and do another curve for a flood event. Stanford [00:27:22]: So you and I are both numerical modelers. And so we generally think the solution to any problem is building numerical model. That's not true. We'll talk about that in a little bit. But what I found is that just, I just feel like every project should do this. It's not a big lift and it gives you an analytical space. And I was involved in a project recently where they had defined a width and I ran this method and there was no place where the width they had defined intersected with the curve. It was going to erode in all slope conditions. It took me a day because I already had the data worked up. I feel like this sort of analysis should be standard. Ron [00:28:01]: And that's exactly why we developed this method to be. It's quick and easy. It's a check. Stanford [00:28:07]: Yes. Ron [00:28:08]: Something to look at. The sedimentation issues that are so often ignored or were, maybe they're not so much nowadays, but at that time they certainly weren't ignored. Stanford [00:28:18]: So we'll put some links to some more information on that material because this is the sort of thing that it's nice to interact with some pictures. Ron [00:28:24]: Okay. Stanford [00:28:25]: Okay. So let's switch to another part of your career. How many sediment transport simulations do you think you've done in your career? Numerical model simulations of the Mississippi river. Ron [00:28:36]: Well, you're talking about when you do a numerical model study. I mean, you run thousands of hundreds of simulations or thousands. Stanford [00:28:44]: That's right. So how many all told? Ron [00:28:46]: Different projects. Probably maybe ten projects. Different projects looking at different issues on the river. But each one of those entails hundreds, hundreds of simulations. Stanford [00:28:56]: So you've run thousands of simulations. And incidentally, that's just good. That's also my experience is that if I'm doing a project, I'm going to run hundreds of simulations to kind of try to understand the system. Ron [00:29:09]: You've probably done less than me because I make more mistakes and have to run it more often because that's not right. Stanford [00:29:16]: You've been at it longer and six t runs faster than Raz. So I think you. Ron [00:29:22]: Okay, maybe I have. Stanford [00:29:22]: You got me back quite a bit. But. So this is kind of the way I like to think about it, is like every one of those simulations, it's a parallel reality. It's a wormhole into a different reality. And so you have explored thousands of parallel realities of how the Mississippi river responds to different scenarios. And so I guess what I want to ask you is, in that science fiction world where you've explored thousands of parallel realities of this particular river, what have you learned in these numerical decades? Ron [00:29:54]: Well, one thing is the Mississippi river specifically. It takes a long time to fully evaluate what any specific perturbation or change that you impose on the river for the river to respond. And so you have to do long term simulations. Stanford [00:30:16]: So what does that mean? I mean, what's long term? Are we talking like three years or decades? Ron [00:30:20]: We're talking 50 years, maybe even 100 years on the Mississippi, maybe on a stream that's not that long. Of course, you wouldn't need. Probably not so much. It changes very slowly. Changes very slowly. Stanford [00:30:36]: I feel like that is one of the differences between someone who comes over from hydraulic modeling or even hydrologic modeling that they're used to seeing the changes, the upstream perturbations change the model domain in days or weeks on the largest systems. But getting used to the fact that if we make a change, it could be decades before we see the result. I feel like that's a big paradigm shift for a modeler. Ron [00:31:05]: Yeah, I think you're right. And it's not just because you're running the same discharge for 50 years is because you might go 50 years before you have a big flood. Yes. And so, like Mississippi river, for instance, there was a long period of time after the sixties where nothing really happened and the channel filled up with sediment. And then we had a big flood in 73, washed it all out. And so there's a huge change in the river in 73, just not because of anything we did. But that was just the natural course of events. It took a long time before something would happen sometimes. Then they had another big flood two years later. And the changes were not nearly as significant. Because it's just the antecedent conditions change for sediment work. Especially if, I mean, you have to look at a long time period. Not just run the same discharge for 50 years, but to look at a long time period to see what to expect. Stanford [00:32:10]: So it's not just that it takes a sand grain much longer to travel from St. Louis to New Orleans than a drop of water. It's that your simulation has to integrate the full range of potential hydrologies and floods and droughts in order to kind of understand how the system's gonna respond. Ron [00:32:31]: Exactly. Stanford [00:32:32]: So based on this instight that we need to do these kind of long term large domain simulations in order to actually see what the effect's going to be. I suspect that that is one of the reasons why you're still a fan of 1d models. Ron [00:32:48]: Well, I think you have a lot of tools in your tool bag and you can't build a house with just a hammer. Stanford [00:32:55]: That's right. Ron [00:32:56]: You need a saw and the nails. You need a lot of different things. And so yes, I think the one dimensional model is very significant because it can look at these long term simulations very quickly and not real quickly. But you can look at long term simulations. Whereas maybe a two or three dimensional model, it captures more of the processes locally, but it's more difficult to do a long term simulation with those. Speaking of that, going back to the previous question I thought about. One of the first studies I did was on the San Lorenzo river in California. And that was basically 2 miles of a project as opposed to 1000 miles Mississippi. But that was the case where the corps had built a levied reach there to protect the city of Santa Cruz. And it came out of the mountains and it took 2 miles to get to the ocean. And so it was not a long study. Stanford [00:33:56]: Right. Ron [00:33:57]: I wanted to run the long term simulation to see what happened. So we did a real scientific experiment. We took all the years we had data and we put them in a paper bag and I shook them up. The original stochastic model and my technician took a year out. And so we came up with three different series of annual hydrographs. And we ran them. And I don't know if it was an accident or not, but we then plotted what is the volume of sediment that passes through this channel over that 50 year period. After 50 years we got the same answer. But in between it was way, way different. Stanford [00:34:35]: Oh wow. Ron [00:34:36]: So that supports the 50 year I never did it again because I had proved my hypothesis. Stanford [00:34:42]: Hypothesis, that's good. Well, we actually have done that. Now that we have, we have the HCC. Watt is a kind of stochastic driver for RaS. We will run like random 50 year simulations doing exactly what you're doing. Going to let the computer pull it out of the bag for us. And so we have looked at that and we've gotten very similar results. Often at the end of 50 or sometimes we'll do 300 years, it's the same. But how it gets there is very different. And that's a big deal. If you're building a billion dollar project, does the deposition happen in year one or year 50 for your cost benefit? Ron [00:35:20]: That's important. Another thing that was very interesting in that project was that at the downstream end, the river went through a constriction formed by a bunch of clay outcrops. And I looked at the model and it was getting this horrendous scour down there at the downstream end. And I said, well, that's not what they saw at all. So I told the city planner who we were doing the work for. I said, I think you should do some drilling there to see what's down there. I think there's cobbles down there. Stanford [00:35:44]: Oh, interesting. Ron [00:35:44]: And. Which is right at the beach. So he says, that's crazy. So anyway, he went out there and drilled and sure enough, there was cobbles down there. Somehow those cobbles had passed through that river, those 2 miles of river, and they deposited right there at the mouth of the river. And it was pretty deep by the time it got there. But those cobbles had moved through that sand bed stream and were down there at that constriction. And so the good thing about that was that after that, everything I said, you believed. So that project went real well. Stanford [00:36:18]: I've never heard that story. That's a fantastic story. I feel like a less experienced modeler might have seen that and just changed a parameter. The thing I love about that story is before you change the parameter, you wanted to see something real to justify changing that parameter. So what have you learned about sediment data in your years of modeling? Ron [00:36:44]: Let me start off with saying, just throw something up for it. Discussion. Stanford [00:36:48]: Yeah. Ron [00:36:49]: Instead of using, you know, a lot of times we use the measured data to calibrate our models. I think we should use our models to calibrate the data that if their. Stanford [00:36:58]: Data is any good, that's a hot take, as the kids would say. That is a controversial statement. But I don't entirely disagree. Ron [00:37:06]: My grandson would say, I'm coming in hot. Stanford [00:37:09]: Your uncle is coming in hot. Why do you need to defend it? Ron [00:37:13]: And the reason I say that about the data is Mississippi has lots and lots of data. And people have used that data. They write papers about it. And you can read them about how the Mississippi river doesn't have as much sand coming down it as it used to. And they go on from there. I've looked at a lot of the data that has been taken in the last few decades down there. And the decline in sediment transport actually in all cases is related to the equipment that is being used and the methodology that's being used. Rather than, I think, the true set of transport, for instance. Stanford [00:37:52]: Yeah, tell us more about that. Like help me understand that. Ron [00:37:55]: They use point samplers to collect sediment data. A point sampler is a fish type shaped metal device. Stanford [00:38:04]: It's a giant piece of metal that literally looks like a fish. Ron [00:38:07]: Yeah. And it weighs about 100. Well, the one they're using weighs about 100 pounds. Stanford [00:38:11]: Okay. Ron [00:38:11]: There's another one that's heavy fish. Like a mark 250. Stanford [00:38:13]: Yeah. Ron [00:38:14]: But the point samplers have a cable on them. They lower them down into the water to a specific. Usually. Usually they pick five verticals. And then they. They measure five different points along that vertical. Stanford [00:38:26]: And so it has a little like. Has a little nozzle. Ron [00:38:28]: It does. Stanford [00:38:28]: And when it gets down to a certain level, you kind of open the fish's mouth. Ron [00:38:31]: You open the fish's mouth and it swallows a certain amount of sediment. And it's what they call isokinetic. The velocity coming in the nozzle is supposed to be the same as the velocity. But anyway, these point samplers, that's how they operate. They'll take about. They'll take about what? I don't know, about 25 samples in during any measurement. Stanford [00:38:51]: Yeah. Ron [00:38:52]: Well, now they've decided that what we should do, instead of taking these point samplers, we should use a depth integrated sampler, which is the same shape of a thing. It's also isokinetic. But instead of having a point where you open the valve and you collect the sample at that point you have a specified transit rate. Where the sampler goes down, hits the bottom, comes back up. And so that's called depth integrated sample. You need a bigger sampler to do that and collect a bigger sample. Stanford [00:39:22]: Yeah. Because you're sampling for longer period of time. Ron [00:39:25]: So they have like three liters sample. They collect as opposed to a pint or a quartanous. So you can tell by the terminology there the units which one is more recent. So in Mississippi the G's is changing to using the depth integrated samplers at all the stations. And every single time they do that, you get left sediment transport recorded in the books. Stanford [00:39:54]: I think this is interesting because we tend to just take these numbers from the USGS website. And actually in the most recent version of Ras we've written a tool that will directly import these into Raz and they show up as points in a flow load curve. It feels like I would just load these in and then see that there's change over time. And what you're suggesting is that there are more than one reason that data change over time. Ron [00:40:22]: Exactly. And it's not just the point samplers. They used point samplers for years, but sometimes they took five samples, sometimes they took four in a vertical and that caused a change too. So it's not just the sampler itself, but it's the methodology that they use to come up with it. And unfortunately if you go to take a hydrology 101 class in undergraduate school, they tell you if you ever change your gauging site or you change any kind of sampling, then you should do a period of time where you could use both methods so you could coordinate. I mean that's basic, but we don't do it. Stanford [00:40:56]: We run into that in the reservoir surveys as well. They changed the method which they do reservoir surveys. And it gets better. But then it looks like your reservoir has scoured over one decade. And so you always, whenever you change any sort of measurement or sampling, you always need to do both for a. Ron [00:41:11]: While, I guess I would say. Don't necessarily believe everything you see or. Stanford [00:41:18]: Hear or everything you download. Ron [00:41:20]: Yeah. And that's part of the scientific method I think is question everything. Stanford [00:41:24]: Yeah. Ron [00:41:25]: And I think that's what you, especially in sediment work, you have to question. Don't believe everything you hear, don't believe everything I say or even stand, but question it. Stanford [00:41:36]: That's good. Ron [00:41:36]: Check it out. Stanford [00:41:37]: So we've been basically talking about flux gradations, the like suspended sediment load or bed material load. What about bed gradations? What have you learned about bed gradations in your years of trying to model rivers? Ron [00:41:49]: Bed gradation is extremely important because all of the sediment transport equations based on the bed gradation. Stanford [00:41:55]: That's right. That's right. And I probably should define that. This is if you were to go out and take a shovel of the material that's on the bed, that's the bed gradation. It's going to be coarser than what's transporting in the water column. Ron [00:42:07]: That's correct. You go back to Einstein and that's one of the, I think he was probably one of the first people to look at this and say, you know, we really gotta consider each size class and how it's transferred because the very fine sand moves much quicker, you know, more with the water and exponentially. Stanford [00:42:26]: So exponentially. It's not linear, right? Ron [00:42:28]: Yeah. It's not linear at all. And so, so it's important to look at the size class. But when you do that, then it becomes very important what your bit gradation is. Because if you put a whole bunch of very fine sand in your bed, wow, you're going to have a lot of sediment transport. And I think that's the reason why so many of the early transport equations based on D 50, because you erase that issue, that variability, because you don't really need to be that accurate with your bed gradation. Just get the medium size and you can probably come up with this transport equation. But if you try to do it by size class, the bed regression is much more important. If you go out to the river and you sample the bed, it's pretty simple. You would say. You just scoop up some of the material and they're okay. Except if you go out there and you go across the river and you take five different locations, you find out, hey, wait. There's a heck of a lot of difference between the great asians across the river. In fact, on the Mississippi, I found that you can have more variation going across the river than you can going, you know, 100 miles or 200 miles or even a thousand miles. Stanford [00:43:33]: That's outrageous. Ron [00:43:34]: It's outrageous. Yeah. So if you're going to do a one dimensional model where you get one gradation per one gradation, you know, it's a blessing and a curse, but you still have to use the whole full range radiations. But you could kind of come up with an average condition. And when you do a one dimensional model, you like to smooth things out, you know, and kind of get the average. And then you, you might run a channel forming discharge or a bank full discharge or some discharge for the same discharge for maybe 60 days or something like that to bring the model in. Stanford [00:44:09]: Balance, to initialize your model, to initialize the condition. Ron [00:44:13]: So you need, you need to do that if you're going to do a numerical model. If you've got a multidimensional model, you have a lot more problems. Stanford [00:44:20]: You do. They do the same thing. We put 2d sediment in raz so I'm learning about this. They do the same thing, but it's tough. Ron [00:44:25]: It's tough. And then you get to the next problem. If you have a non equilibrium stream, that bed gradation is going to change significantly with discharge, even with time. So then you have another layer of issues. Stanford [00:44:40]: One of the things that surprises me is a lot of times when I review sediment transport studies, I'll see five bed gradations or something like that. And when I see your studies, it's one or two orders of magnitude more. And I actually bought a bed gradation equipment for my garage because I just find that my clients don't generally want to fund the gradations that I want, but I want dozens to hundreds because of that variability. If you get five, you could get lucky or you could get unlucky. How many bed gradations do you like to specify on the order of magnitude? Ron [00:45:18]: You talk about average longitudinally? Stanford [00:45:21]: Yeah. How many samples would you like to see if you were like at a cross section or in a reach or, you know, maybe per mile or something like that? Ron [00:45:31]: I like to take, go laterally across the stream and take three or four. Stanford [00:45:34]: Or five multiple cross sections at each cross section. Ron [00:45:38]: Right. And then I like to focus on the crossings because it's, hopefully it will be average at the crossing. Of course, if you're doing a multidimensional model, when you've got all kinds of different shapes, then you have to take a whole lot more because you have to identify what the gradation is on the bar and in the bend around the curve and in front of the structure and all these different things. So you have to take a whole lot more. If you're doing a multidimensional model, that's. Stanford [00:46:03]: An unbelievably important point, is that the model is going to be more forgiving in the pools. But getting this right at the crossings, which is what we, on big rivers, we call the runs or the flatter portions of the river. In smaller rivers, the runs or even riffles, getting the gradation right at the hydraulic controls really is going to be more important. Ron [00:46:25]: I try to be precise here. Hydraulic control, I would say the crossings, yes, because they're average, but a lot of times, like a bridge would be a control and then you would have be uncharacteristic. So usually you want a gradation that is representative of reach as opposed to a point. Stanford [00:46:46]: Yes, that's good. Ron [00:46:47]: So that's important. But I think what you were saying when you said control, you meant crossing. Stanford [00:46:54]: Yeah. Right. I guess natural river hydraulic control is what I'm thinking. Ron [00:46:59]: Now, there are people that you and I know well who would say you should take the bed gradation on a point bar. So I would say that not necessarily is the crossing the best place, but probably a point bar. The reason I say a point bar has advantages, because low flow, you can get. Stanford [00:47:24]: It's accessible. You can get there with a shovel or a camera. Ron [00:47:26]: You don't have to have a pipe. Stanford [00:47:28]: That's right. Ron [00:47:28]: Or a B 54. Stanford [00:47:30]: Or a boat. Ron [00:47:31]: Or a boat. Stanford [00:47:31]: Yeah. Ron [00:47:32]: So there's that. But a point bar has a wide variety of samples. Characteristics of point bar. Stanford [00:47:38]: That's right. Ron [00:47:39]: Much finer toward the bank, and it's much coarser toward the river. I think it's downstream is coarser. But anyway, it varies longitudinally across the bar and also laterally. So it's not a good place to get an average bed gradation. Stanford [00:47:52]: Right. If you're trying to run a model with gradations from a point bar, then that's a much more uncertain parameter that you might have to adjust more. Ron [00:48:00]: Right. And the point bar, just to argue the opposite, the point bar represents the material that's moving. Stanford [00:48:07]: That's more. Ron [00:48:07]: So maybe that is a good. Stanford [00:48:09]: Yeah. All right, so is the Mississippi river on a decadal scale, is it eroding? Is it depositing? What is this river doing? Ron [00:48:22]: I think that the cut off program in the twenties and through the forties was probably the most significant perturbation in the river. Stanford [00:48:33]: So the cutoff, like, how did they do that? What's the cutoff? Ron [00:48:36]: The natural plan form for the Mississippi river was a meandering river. It was a meandering. Stanford [00:48:42]: And so has these big loops. Ron [00:48:43]: Yeah, it had the big loops. And the natural process is that eventually meanders migrate downstream. Eventually they run up against some kind of a hard point. Then the loops come together and they cut off. They shorten the river. And at the same time, other meanders are developing and then are lightning the river. So, basically, over time, the river stays. Stanford [00:49:06]: The same because some parts of it are getting shorter and some parts of it are getting longer. Ron [00:49:11]: So it makes a lot of sense. If you're worried about navigation or flood control, hey, let's cut these things off artificially. Speed this process on and rip wrap the bank and make the river shorter. Stanford [00:49:24]: One of these processes, we're going to accelerate the shortening process. Ron [00:49:27]: That's right. We're going to accelerate the shortening process and rip wrap the bank so that it doesn't move. So we're going to improve the river. As Fergie said, who was the chief of engineers, some general told him to go fix it, and so he did. And so anyway, so the cork cut off and shortened the river by about 500 miles. Well, the immediate reaction, I think probably the most significant, was that Arkansas City, which is north of Vicksburg, it degraded tremendously. That was the initial response, and it degraded upstream, and then that material deposited downstream. Well, over the years, that degradation has moved upstream and it continues to move upstream. So now, in the Memphis district, above Helena, it's degrading, it continues to degrade, and below Helena, it's aggrading till you get to about red river landing, and then it's kind of stable. Stanford [00:50:33]: Can we just think through this process a little bit? We've made the river shorter, but we haven't actually changed the elevation of these major landmarks, St. Louis or Helen R. And so by making the river shorter, but keeping the elevations the same, we've increased the slope. Ron [00:50:50]: We've increased the slope, and the elevations are changing, too. I mean, the bending. Stanford [00:50:53]: Well, that's true. Ron [00:50:56]: Are eroding. Stanford [00:50:57]: At the moment we cut it off, the elevations were the same and the distance was smaller, and so we increased the slope. And so the river's going to respond by decreasing the elevations upstream, and that creates more sediment than the downstream is used to, and so we get some erosion upstream. But that was a long time ago. Ron [00:51:16]: Yeah, that was. What was that in the 40? I think they were about finished in about forties. Stanford [00:51:22]: So we're talking 80 years. But this is still an active process. Ron [00:51:25]: It's still an active process. And we did simulations 100 years into the future, and it was continuing 100. Stanford [00:51:31]: Years into the future, and so we're talking about almost 200 years from this. Ron [00:51:37]: And I don't know that. Yeah, I don't know if it ever will reach. I don't think there's such a thing as an equilibrium in a natural river, so it's responding to those changes. Stanford [00:51:49]: But when you started out this conversation saying rivers take a while to respond morphologically, granted, this is one of the biggest rivers in the world, but you had this in mind. Ron [00:51:59]: Yes. Yeah. I tell you the truth, I was very surprised. Stanford [00:52:03]: Yeah. Ron [00:52:03]: Because my geomorphic friends have been saying for years that this was the case. Stanford [00:52:10]: Oh, interesting. Ron [00:52:11]: And I said, I don't believe that, but I do now. I didn't have it because that's what the computer model says. Yeah. Stanford [00:52:17]: Right. So one of the objectives of this podcast is to try to, you know, you are a rehired annuitant. And a lot of the younger engineers or mid career engineers in this hallway have had a chance to interact with you and get some mentoring and learn from your years of experience. And theyre super lucky. So one of the goals of the podcast is just to maybe get some other people a little bit of access to that. And so I just want to wrap up here with a few just kind of mentoring questions. And one is just kind of selfishly, id like to ask, what do you think are some of the most important practices of a good segment modeler? Ron [00:52:56]: I think I already said this once. Don't believe everything you hear. And you'll go in with a skepticism that maybe that data is not right. It's difficult to know what really is going on. And just because you have papers written that say the streams are grading or it's degrading or whatever, dig deeper and find out historically what's really happened, what has really gone on there. Do investigations. I think another thing that I think I'm fortunate in my career, when I got started, we didn't have computers. And so you couldn't do as much. But you had to understand the sediment processes more. And you had to understand what the equations were doing and how accurate they were. And you actually did these things by hand. So you went through the processes and said, okay, this is what's happening here. And this is the sensitivity of this parameter or that parameter. So I think that helps you a lot. I don't know what the solution to that is. Maybe if you do a lot of computer simulations and variables, you get a feel for what the significance is. I was just talking to a fellow down the hall this morning about a channel that he was designing. And he was talking about the significance of the n value and how people are making different assumptions of what the n value is. Stanford [00:54:29]: That's the meanings and the roughness of the channel. Yeah. Ron [00:54:33]: And it made a difference between what the flow regime was. It was shifting from critical to subcritical. And the engineers that were working on it were unsure as to what it should be. Or I should say they were sure of what it should be. But they had different. There were different opinions, different people were. Stanford [00:54:49]: Sure about different numbers. Ron [00:54:51]: And it makes a huge difference. And this was a channel of designs. They couldn't go out and measure what was actually in the field. This was a problem of figuring out what it would be after it was designed. So this is simple things like that, like what are the variable? How significant is it? It makes this tremendous significance. If you design a channel in near critical depth. You don't want to do that, right? Stanford [00:55:16]: Yes. I had an experience in grad school. I remember I gave this presentation, and it was very pretty. It was a GIS class, and so obviously there were lots of colors, and I thought it was super impressive. And the professor sat in the back of the room, and it's like, very nice presentation. What variables are your results sensitive to? And the question kind of blew my mind because I realized I should not show a pretty picture without understanding. If I change this number, the picture doesn't change. If I change this number just a little bit, everything changes. That's almost the point of modeling, and. Ron [00:55:55]: That'S something you can do nowadays with computer models that you couldn't do so much in the past. Stanford [00:56:01]: The other thing that's very interesting is you describe when you were doing these by hand, it was very obvious that I changed this number, and this number got bigger as the equation went on. It's less obvious. Now we can do more runs, but we should be maybe thinking about how we're using those runs to help us understand what the equations are doing under the hood. Ron [00:56:24]: We talked about bed gradation, and we talked about the hiding factor. Stanford [00:56:27]: Yeah. Ron [00:56:28]: Now, the height factor Einstein came up with is not very good, except for the particular stream that he worked on. Stanford [00:56:34]: Oh, interesting. Ron [00:56:34]: And then other people. There's a lot of people who come up with different hiding factors that you should be using. Stanford [00:56:40]: We have about eight of them in Raz right now. Ron [00:56:42]: Oh, you really do? I didn't realize. Stanford [00:56:43]: Yeah, we added them for two d, and then we connected them to 1d. There's about eight of them. Ron [00:56:47]: That's good. Stanford [00:56:47]: Yeah, but you're right. Which one of those you choose is a big deal. Ron [00:56:51]: Yeah. And so that's an issue, but that's good. I'm glad you've done that. Cause I don't think a lot of people don't even know what a hiding factor is. Stanford [00:57:00]: Well, why don't you tell us about it? Cause it's really cool. Ron [00:57:02]: We talked about the gradation and how different sizes move exponentially. Different is exponential. Stanford [00:57:08]: Right. So you have these big particles and these little particles, and little particles move not just more than the big particles, but a lot more than the big particles. Yeah. Ron [00:57:16]: Yeah. And so if you have a degradation process going on, then these finer particles are moved out, and so that the surface layer, where the sediment transport is determined, coarsens. And it's not like all of a sudden it's covered with cobbles or all of a sudden it's covered with gravel. It's a process that's going on. So maybe 40% of the bed is covered with coarser material. So you have a hiding factor then, that reduces the transport of the finer. Stanford [00:57:51]: Particles, because they're like, the finer particles are like in the shadow of the big particles. Ron [00:57:56]: That's a good way to look at it. Stanford [00:57:57]: And so they don't experience the flow as much. So even though if they got up in the water column, they'd be more transportable, getting them into the water column is harder than it would have been. Ron [00:58:07]: Yeah, that's much better description of it. More succinct and quicker. Stanford [00:58:16]: You review a lot of models and you have a little bit of a reputation for being a thorough reviewer. Ron [00:58:22]: I reviewed one of your reports. Stanford [00:58:23]: You did review one of my reports. Ron [00:58:24]: I waited until I went a furlough before you answered the questions. Stanford [00:58:29]: That was not intentional. But I have to say that my model and my report got much better in the course of the review. What are some of the most common mistakes you see in segment models? Ron [00:58:41]: Actually, I don't review that. Many people have no reputation. I think one of the biggest problems is that we just talked about that. A lot of times, modelers don't pay attention to the process, pay more attention to what the computer model says, and they don't look back and say, does this make any sense? Stanford [00:59:09]: Right. Ron [00:59:10]: I think that's probably the main issue. Stanford [00:59:13]: Is that you'll see a result and the result is counterintuitive. Maybe, but it's the numbers that the model spit out. And there isn't a process story that tells you why this is true. They just kind of trusted the model. Ron [00:59:31]: Right. I think that's. That's probably the biggest mistake. Sometimes people just make mistakes. Stanford [00:59:38]: Errors, straight up errors. Ron [00:59:39]: Not really calibrating to real data or to more than one thing. Stanford [00:59:45]: Right. Ron [00:59:46]: First is you might try to calibrate to stage data. That's always good in a numerical model. We can do that because we have historical data. We can go back and see what the roughness is and things like that. That's important. And things like the downstream water service elevation. Does it account for tides or not? I don't think you need to account for tides and long term studies, but there's other things. Subsidence, volume calculations. We know that this, historically, this area is an area of scour. Am I reproducing that? Yeah, that kind of thing. Stanford [01:00:25]: So what I hear you saying is we don't connect it to the real world either. Anecdotally or real world data enough. And this is the most memorable of your comments on my report. I'm a big calibration guy. Like, I bang the calibration gong if you don't calibrate your model. It's not a model. Yeah, I'm in the Tony Thomas tradition there. And so when I submitted that report, we calibrated to bed change, and we calibrated to stage. And one of your comments was, yeah, but why didn't you calibrate to concentration? And we kind of looked at each other as, like, why didn't we calibrate to concentration? Concentration was there, and we went in, and it actually changed our model substantially. And so comparing your model to whatever points in reality, is that what I'm hearing you say? Ron [01:01:11]: Yes. Yeah. I think that one of the big problems that we have in our study process is that we don't have a team type approach a lot of times, and we don't have a lot of collaboration that occurs during the course of the study, and then we send it off to a reviewer at the end. And I always wish that reviewer made those comments earlier. Stanford [01:01:38]: 100%. Right. Ron [01:01:39]: And that's the problem. We have a review process now, and I'm in, and it's. The comments are very good, but it's too late to do anything. The money is spent, the project's over, and I'm getting some really good ideas. And I had this project I'm working on now. I had good collaboration. We had scheduled meetings where we presented our results to a big team, so there was collaboration. But I think a lot of times when you have those meetings, people are interested in what their part of the study was more than what your part of the study is. So you don't get the collaboration you really need, you don't get the critical review or critique that you need. And the reviewer, who's usually separated from the process, focuses on what you just said and says, oh, well, no, you didn't do that. Right. Stanford [01:02:31]: Right. Ron [01:02:32]: And the comments that I are frequently very, very good comments, but they would have been. I sure wish I had them ahead of time. And so I don't know what the solution to that is, because I think we do have a lot of collaboration. As the process goes on, the review. Stanford [01:02:46]: Often turns out to be the one time you get subject matter, expert feedback on your model or your report. But it happens, after all, when you're already at the end of your timeline and budget, and it would have been a lot more helpful at the 30% mark. Ron [01:03:01]: Right. I think the primary reviewer to be involved earlier on in the process. Like you said, 30%, you know, 70%. Or maybe I'll give the reviewer a call and say, hey, what do you think about this? And he'll say, no, no. Stanford [01:03:17]: Yeah. Ron [01:03:17]: Oh, yeah. That's a really good idea. Stanford [01:03:24]: So one of the things that happens. When you get a couple of sediment modelers talking. Is that some of the topics can get a little technical. I couldn't help asking Ron about his sediment transport function. His bedmail mixing algorithm. And we actually got into more technical detail. About his channel design process. You may have noticed those were not in the podcast. And that's because that content really works better as video. So we've created several video shorts. Featuring those more technical conversations. And including the equations and visuals that those conversations really need. You can find that bonus material on the webpage. Linked in the episode description. Or on the video tab of the RSM website. I really appreciate Ron taking the time to talk. This is exactly the kind of conversation I imagined. When we set out to do this next episode. We're talking to doctor Joanna Curran. Who sometimes uses the name Crow Curran in the literature. And you might recognize from the Wilcock and Crow sediment transport equation. Joanna talked to us about the development of that equation. Plus her research on step pool systems. And something called sediment memory. Which is kind of mind blowing and worth the price of admission in its own right. I learned a lot, and I think you will too. This podcast was funded by the regional sediment Management program of the Corps of Engineers. And is led by Doctor Katie Boucher. And is part of their tech transfer initiative portfolio, RSMU. We also received funding from the Corps Flood and Coastal Storm Damage Reduction R and D program. Led by Doctor Brandon Boyd and the HH and CSeT program. These are informal conversations and the views expressed do not necessarily reflect the position of the US Army Corps of Engineers, their partners, or the offices or centers of the guests or hosts. Mike Loretto edited this episode and wrote the music for this season. Thanks for tuning in.