Episode 20: The Impact of Seasonal Vegetation on Coastal Dune Storm Recovery

Episode 20: The impact of seasonal vegetation on coastal dune storm recovery

Travel on a journey with Pete Tereszkiewicz, Ph.D. candidate at the University of South Carolina, as he battled COVID restrictions, nor’easters, and hurricane Ian to understand how wind, water, sediment interactions, and seasonal vegetation affect beach dune creation, deformation, and erosion.


Peter Tereszkiewicz is a PhD candidate at the University of South Carolina. His current research focuses on coastal dunes and understanding how seasonal vegetation such as dune grasses and sediment interactions affect dune growth and post-storm recovery.

Links to learn more about Peter

Article about Peter’s research

Peter on Research Gate



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Hello everybody, and welcome to We Measure the World, a podcast produced by scientists, for scientists.

Yeah, in the moments leading up to it, you know, walking out of the field site, there was so much wind blowing above that threshold of motion. You’re just watching sheets of the beach, deflate, right? Deflation is this process where we have the winnowing away of finer material. And that removal of mass causes the surface to as the name implies deflate, right lower down. But I’ve never seen it happen this rapidly in front of my very eyes. I mean, it is happening faster than I could possibly measure it with the modern tools that we have.

That’s a small taste of what we have in store for you today. We Measure the World explores interesting environmental research trends, how scientists are solving research issues, and what tools are helping them better understand measurements across the entire soil plant atmosphere continuum. Today’s guest is Pete Tereszkiewicz PhD candidate at the University of South Carolina. His current research focuses on coastal dunes and understanding how seasonal vegetation such as dune grasses, and sediment interactions affect dune growth and post Storm Recovery. So Pete, thanks so much for being here.

Yeah, thanks for having me.

Alright. So we’d like to start off with a little bit of background, so can you just let us know about your background, how you got into this field of doing research?

Yeah, I think a lot of people in the environmental sciences, you know, it’s sort of dumb luck that you have that one class that sort of clicks, you know, in undergrad and for me, it was coastal geomorphology. And I was fortunate to I took it at a time where I was also kind of getting into surfing. So the ability to do research, but also enjoy being in the same environment for recreation was very much there. And so, you know, I was hook line and sinker from semester one, and that led on to a undergraduate thesis that then pushed me into a master’s program, and then finally into the Ph. D program. Um, so it’s very organic growth. You know, I didn’t finish high school and was like I’m gonna go into doing research, you know, and get a PhD. And that that wasn’t the way it worked out. For me, it’s pretty much you know, by happenstance and being the right people at the right time. And the dune side of things is pretty much new, my undergrad and Master’s was more focused on engineered structures and how those modify shoreline change. And then I kind of wanted to make a small pivot and turn around the other direction. Look at the dunes for my PhD research, just to kind of balance out and I’m really glad I did.

Awesome. Yeah, I know, we’ve had quite a few guests who have talked about, like you said, just that, you know, happenstance, like they started in one side and kind of move to the other. Yeah, like you said, there’s a class or something like that. I don’t know if we’ve had any who have said, surfing has been their catalyst for moving into, into their research field. So that’s definitely a first tier. So just to start us off, and just for the late people in the audience, can you give us just kind of a quick intro into why why dunes are so important for us and for beach ecology environment?

Yeah, so if we think about the ecological services that the dune itself can provide, it’s very much, or it functions very similar to like a levee would, right. So they’re really good at being the first line of defense during storm events, and tend to take a lot of that initial surge and beating that storms can provide. And so if you look at that protective service that is available, you know, if you have a strong established Ford in front of your residence, you’re probably going to receive much or far lesser impacts from that storm than if you had say, no Dune, or a small dune or dunes are discontinuous, you know, and not pieced together very well. So the biggest benefit is definitely the protective surface it provides during storm events, and not even just storms, you know, it could just be a really high tide or just really big wave event, right, any of those the dunes gonna be able to stand in the way and help out with that erosion.

That was my next question here is can you tell us a little bit about wind and water and other forces that affect beach dune creation, deformation, erosion, all that kind of stuff?

So when we’re thinking about dunes and how they’re formed on there’s two real main forces at work, right, we have the the sheer velocity of the wind. So how fast the wind is blowing, how long the wind is blowing for at that speed. Then on the other hand, we have the resisting force of the sediment, you know, the sand will move whenever that resisting force is exceeded by the wind, when it’s actually able to physically pick up the particles and move them. When that happens is very site specific, you know, you’re dealing with different mineralogy’s, which is differences in density, grain shape comes into play, of course, size. And so all those sites specifics or nuances really make beaches behave individually when we think about resiliency and how they’re going to behave and that dune building process. You know, I love when sand starts moving on a beach, you know, so I can talk about this for hours.

Well, that’s, that’s fine. We got we got plenty of time and we’ll we’ll be covering a lot of this. So with that background, can you just introduce us into some of the projects you’re working on or your main project that you’re working on for a PhD research?

Yeah, so as you mentioned in the intro, you know, my work is dealing with understanding the role that vegetation density and seasonal changes in that, right as they move from winter into the spring and summer months, what that means for volumetric change within the dune. And when initially trying to tackle this question, you know, the first thing you do is you hit the books, you check out the literature, you see what’s been done, or what is being done in the field. And a lot of those existing methods, you know, being quadratic analysis, which we kind of borrowed from biology and ecology, you could do frontal area and optical porosity and which are photographing the vegetation and you know, trying to pull out, you know, how much area the wind is experiencing, or you could use most recently drone photogrammetry, right, and pulling out by flying drones, vegetation coverage from that perspective. But all of those existing methodologies are contingent on you going to the beach, which is fine. It’s a great method, it works. You know, it’s one way of answering the problem. But what I was really curious about is, what can we put out there in situ to monitor for these longer periods of time, you know, to be at one point over the vegetation in the dune and monitor that growth and that emergence during the spring and summer months? What does that look like? And then how does that maybe tie into the volumetric change signal that we’re seeing? And so yeah, that’s why I chose the METER NDVI-SRS sensors. And yeah, it’s been incredibly interesting to work with them out in that environment. There’s something else that question I didn’t answer.

Well, I have. No, I mean, I’m, I’m interested because you’re talking about volumetric change. And my first thought was, Is this something where it’s actually measuring that volumetric change? Or are there proxies for estimating that change?

Yeah, so the drone flights are definitely the main methodology that I’m using to calculate volumetric change. But you know, also, in the field of view of the sensors, I’ve installed erosion pins, which are just like tiny little sticks, you know, and you go out there, they’re very rudimentary, you measure them right in time one, and then the next visit, you measure them again, and you have some sort of indicator of how much change occurred got on. So that’s just in the field of view to have a sort of check resource. There were some issues with those just really noisy signals. And I think a lot of this just comes down to, you know, the flow and the eddies that are forming around the individual reads of the vegetation. And there’s something I didn’t I didn’t foresee being a problem, but it doesn’t make enough sense to where, you know, I can say, hang my hat on and say, Yeah, that’s exactly what’s going on in the dune, and I think it’s just this microscale process he’s coming through,

How do you deal with messy data in your specific research?

I think the way I’ve been trained by my my advisor, and I think it goes for a lot of scientists out there is, you know, we, we don’t really smooth the data too much. It’s just not, you know, what you get back from the natural environment like that, that is what you have. And, you know, if you’re dealing with something where you have all this wave data, and you want to pull out tides, and you downsample that’s one thing, but, you know, looking at a noisy environmental signal, you know, I think what we tend to fall back on is just how many standard deviations is it off by or what is the variance? And then does the variance of that particular signal outweigh? You know, sort of the resolution of the change that we might see? And if that’s the case, then it’s gotta go. Right. But you know, still learning, right? Every data sets unique and different, and poses different challenges.

As you’re out there. How long is your field season when you’re doing this research when you’re taking these measurements or going out to the dunes themselves?

Yeah, so I installed all my equipment out there, January 10, this past year, and they were out there up until hurricane Ian, but for the dissertation work on just because of the compressed timeline, I only present up until about August, that particular chapter, but you know, the full blown publication will have work all the way up until hurricane Ian happened and those instrument were pulled.

Right, right. And that’s definitely something interesting. I definitely want to touch on hurricane Ian, for those who are listening. We’re recording this in October of 2022. And hurricane Ian, which peaked at a category four hurricane was, yeah, pretty devastating. And it passed right by where Pete was doing his research. So we’ll get into that here in a little bit. I did want to come back, you’d mentioned using NDVI and PRI sensors. Can you just do a quick explainer about how those kinds of sensors work and what you do with them within your research?

Yeah, sure. So both the NDVI and PRI-SRS sensors are a combination of your hemispherical or upward facing sensor that gets the changes within the natural environment. If it’s cloudy one day and sunny the next right, you want to count for that, then you have a field stop sensor which is looking down on top your vegetation. So NDVI has been used widely in the remote sensing community, I would say I think since the 70s, for getting vegetation density, mid density changes, and can also be used for like Leaf Area Index and other indices like that. And then PRI has been recently shown to be a really good indicator of vegetation stress. And so when thinking about using these are my two main questions that you touched on the intro duction is how do seasonal changes in vegetation density, you know, affect volumetric change, that’s the NDVI sensor, then in turn being that these dunes are existing on this, really, I mean, just crazy interface between land and sea that’s exposed to, you know, frequent storm events, high tides, drought, other sorts of, you know, disturbances: you know, they get hit with a lot of stress. And I really was curious to see if a stressing phenomena occurred, what would that PRI signal look like? Right? Because the benefit of having the sensors out there is that I’m getting an hourly record of this change.

Right? Is that something where you where you need that kind of granularity? So you’re talking about hour per hour type of recordings? Would it be better to have something even quicker than that? Or what are the issues with that kind of granularity?

Yeah, I think a lot of this comes down to the scale I chose for my field study, and a lot of, you know, recorded hourly, because it’s easier to take in more data and then downsample versus, you know, obviously go the other way. And so by going hourly, what I’m able to do is I’m able to take a number of readings around noon, and then average those out. And that’s my one value for the day, a number of our datasets, at least the ones tied to vegetation growth, come down to a daily recording a daily value. And so because of that, yeah, only a day is what came out of it and the data. But yeah, that granularity was just decided on based on other instruments at play and trying to compare, you know, apples to apples, but in terms of if smaller resolution is needed, I wouldn’t think so. But I’m also not a ecologist or biologist, you know, I’m like, I’m borrowing some really cool toys, they have to try to get my question that within coastal geomorphology, right, I can’t fully answer that question.

Right. So how have the results looked so far with this project?

Yeah, the coolest thing that’s come out of it as an inflection point, right, actually being able to see that you know, and I’m sure your listeners that are either in the agricultural field or you know, in biology fields that use these sensors already. Yeah, I get an inflection point every spring like we know this exists, but Right, but as I mentioned earlier, right, we, in the coastal and Aeolian world, we didn’t have this sort of resolution in situ, looking at a plant to see that inflection point. So if my field visits were, before the inflection point, and then after, I just averaged that out, right? Why that the timing of that flexion point matters. And when I say inflection point here, I guess I should describe as I’ve been looking at the data a lot, please. But it’s around like March 22. There’s this explosion of growth almost going from, you know, straight line to logarithmically changing daily. And so why that really matters is the timing of that inflection point, when the plants start biting out or blooming out as we move into this warmer months. How does that relate to when the winds are blowing at a speed that they can move sediment? Right, and the occurrence of those two variables? Are they in tandem? Or are they not? Because I think, and I can’t fully answer his question yet, but I think that’s what really gets at why systems or some systems are resilient and recover much faster than others. You know, having worked on Pensacola Beach, as well as one South Carolina’s coastline, there’s a huge difference in how these systems recover, you know, Pensacola might take 10 years to recover to a certain state that it won’t take South Carolina a year, year and a half to and why is that? And that’s kind of a little bit more background into why I sort of chose this question for my dissertation work.

With all this going on, what are some of the other special challenges that you’re facing and doing this kind of research?

Yeah, I guess I’ll start back at the beginning. I was fortunate to be a Grant A. Harris fellow and 2020 which was awesome you know, that announcement came in right before the first major lockdown came and the big challenge here I was you know, scrambling to get the shipping address changed to my house you nervous about that equipment actually getting to me right because the supply chain was in upheaval. And so that definitely pose a bit of an issue. And then once I had that equipment delivered, you know where to test it out, like everyone else was growing potato plants in my backyard. So that’s what I tried the sensors out on you know, and learn really fast that if your canopy is producing all sorts of shadows in your field of view, the sensors really don’t like that. But you know, obviously that didn’t really matter for the dissertation work because the beach there is no tree canopy over the top of the sensor. So right, it wasn’t too much of an issue. But uh, yes, that was definitely one of the challenges. The next one is definitely choosing the location of the sensors. And I think a lot of field scientists out there can relate to this where you build these experiments for months and two years potentially. And then it’s you know, it’s it’s game time, right? You got everything ready to go, you hit the beach, you’re deploying things you go and smooth right? But before you can actually start that process of installation, you need to look at the landscape again and verify that we’re going to put them makes the most sense To answer your questions, for me unfortunately, as I mentioned, this is a system that’s typically disturbed by nor’easters, you know, high tides and storms. And so naturally when I went out there, like maybe a few days before I got hit with a nor’easter, and it just really decimated the site, because it wasn’t just any nor’easter it was, it was one that was a real jerk, and he sat offshore, and just pumped waves during multiple title cycles, right. So you have localized, you know, sea level rise from the high tide, right, and then you have waves coming in on top of that. And then next tidal cycle, same thing, next one. So it really did number and scarpt my dunes, which is where you’re removing volume from the front or the toe of the dune. It can result in what looks like a cliff. And so he has a lot of scarping across the site and removed a lot of sediment deposited what’s known as RAC, which is like the vegetative remnants of former dune grasses or more species, you know, and it gets sort of balled up and placed on top of the surface. And so that change the initial game plan strategy, right, that had built up over multiple years for this deployment. And so when thinking about sensors that are trying to measure, you know, vegetation growth and health, you know, I didn’t know if I was putting my sensors on top of vegetation that was so stressed, it wasn’t going to come back in the spring, or, you know, if it was a viable candidate. And so I kind of just rolled the dice on it made the best educated guess I could, you know, got some right got others, not as ideal. But you know, the way I look at is this was a pilot study, in a lot of ways of, you know, the sensors that have been traditionally used in agriculture haven’t fully been vetted in a sandy environment, you know, with grasses that aren’t necessarily planted a certain way, right. And so there’s a lot of curveballs that are going to be thrown at it. And that’s what led to a lot of bench testing before even deployed these things. There’s a whole multiple months of just tripping the system down to its core variables of grain size or moisture content, and what different elevations of the sensor overbear sand looks like, and is that signal trustable, or can I actually use this data, just looking at the clean no growth of vegetation kind of in the mix of that so.

Yeah, with all of that going on, I do want to come back to your COVID lab, you’d mentioned dealing with with COVID restrictions, and, you know, traveling and social distancing, and all those kinds of things, and trying to do things in your backyard. But you also created some indoor test beds as well. Can you tell us a little bit about trying to imitate dune conditions indoors?

Yeah. So for those bench tests, I ended up building a basically a sandbox, right? So like, really brought me back to childhood, obviously, I’m like playing his massive sandbox. But but that was mainly done in order to, like I said, stripped down the natural environment, like what about the beach is different from an agricultural field, you know? And number one, that thing that stood out was grain size, right? And then not just one type of grain size, but how does it sensor respond across multiple grain sizes from the very fine that builds up the dunes to very coarse and you know, chunky gravel? Right? How is how’s that signal coming back? Is it affected by this or not, and then with the Sandbox is also able to, you know, do different tests with moisture content. And so for that, I had my sandbox did the dry run, took a reading I think I used the I use the ZL2 for that, which is like little handheld Bluetooth data logger that you guys have, that way I can get quick, rapid readings. Because if you think about you adding moisture, you really can’t wait 20 minutes, because the sun is evaporating that off, right. So see, I added that will take a reading and then with a little pump like pesticide sprayer, add more moisture on top of it. And then the whole time taking gravimetric moisture scrape samples, which is essentially, just to have some, you know, bonafide metric of this is how much moisture was within that sandbox at that period of time. And that process took a number of iterations just because, you know, I thought I saturated the surface. And then when I got all the gravimetric moisture samples back, it ended up only being like, maybe like 5%, back at it, you know, so he really tried to get the pump sprayer go. And you know, it was really fun, fun period of time, you know, just really trying to throw the book at the sensors and just see at what point the reading has more noise than I feel, you know, trusted that can actually go in the field and perform. But yeah, everything came back from that less than 3% of the operational index range, which is I mean, pretty, pretty incredible. And the one that was like the highest was the most unrealistic in which you’re changing the sensor out and each data logger port, you know, and that wouldn’t happen, but maybe once while we just want to see in case for some reason there was a massive failure because of doing scarping and how to replace all the sensors, what error could that possibly introduce? And so really you’re looking at the on the order of less than 2% of you know, the whole index which is I mean I was surprised I just knew the different grain sizes we’re going to you know throw a wrench in the whole plan but now you know I mentioned indoor I did try to use them indoor but that did not work out too. Well was very noisy so I had to kind of move everything outside which, which was probably for the better, you know, got to hang out with the sensors and get some good vitamin D. And it’s a good excuse to be outside. Of course, it Jhula looks whenever we’re back on campus testing some stuff out, you know, and everyone’s walking, you know, on campus to and from class, and is this guy with the sandbox? You know, kind of reading a book? Well, it’s just looking at their sand, you know, these downward facing sensors, it just didn’t make any sense. No one asked questions, but you know, they’re probably thinking like, that is the weirdest thing.

So I mean, that seems like just an immensely time intensive process, manually spraying things, checking things over and over, you said there multiple iterations, like how long does this process take overall?

Man, just the experiments, I would say probably about three and a half to four months, especially the the moisture content, I would say took the longest just because, as I mentioned, that you don’t really know until you get the oven results back, right. So if you’re too low, or you know, maybe you missed this range in the middle, right. So in order to make a complete data set, it just took a lot of time, a lot of lab work, as well as field work in order to get that figured out. And that doesn’t include the time to build the sensor mounts, you know, different set of time involved, you know, but but like I tell people, it’s like, this is the science to get to the science. Yeah. Right. We’re only as good as the measurements we have. And if we don’t know what those measurements are, then, you know, the confidence isn’t quite where it could be, you know, if we just do all this background testing before,

yeah. Could you just Yeah, run us through? Like, what types of discoveries or trends you’d been seeing with with that data? Specifically? You talked about grain size and other things. But yeah, can you just give us a brief recap of of what you you found in doing those experiments?

Yeah, the synopsis of it all is that it was a really flat line, which is good, right? It’s a very, the sensors are incredibly stable, depending on if you are changing grain size, or moisture content, or the instrument height over bare sand. So yeah, it was a really boring result. But that’s okay. I’m okay with that with, you know, whenever you’re dealing with validation studies like that, right? Obviously, at that point in time, in my academic career, I was ramping up for comprehensive exams, and like, I had this fuel project ready to go and everything was coming together. And so initially, you know, you don’t you don’t think about the benefits of it, you’re like, this is very frustrating and inconvenient. You know, why now? Right. But but it really gave me a lot of time to slow things down. Think through the science. And I think it’s what led to like really strong experiments. Otherwise, I would have been compressed for time when I’ve done half these experiments, and then I would have always wondered, right, so me, I think the benefit there was knowing more time for experiments, but also more time to just read in general, I think that’s a big, a big part of you know, that that extra time that we kind of got,

I wanted to come back to talking about hurricane Ian, I wanted to just kind of get a ground level view about how you deal with in your research in your field of study. I mean, hurricanes are one of the central impacting forces in coastal geomorphology. And how do you work around or work with hurricanes, tropical storms, or other major weather events like that?

Sure. Yeah. I feel like in our field, it certainly is a factor. I wouldn’t say we can ever plan on them. But we better make sure we have a contingency plan. If they come on, I think it’s the best way to put it. Yeah, no. So for, for planning purposes. I know like whenever I first installed in December, I’m looking at the landscape I’m looking at where I’m at which I’m operating within a what’s known as a wash over plane. So this is where it’s a flat, sandy area where years ago, a storm came and blew through the dune system kind of spread this this sand apron, if you will, across the landscape. So there’s very little resistance there. And that’s why you know, high tides with flooded or strong nor’easter with flooded going into this project, I kind of knew I was like, if there is a storm, there’s a good chance it’s going to, you know, destroy the dune system that’s here, or the one that’s trying to recover and bounce back. And so, December through to June, I had a lot of time to think about, okay, what is my, you know, threshold for pulling instruments versus not? And what does that look like? You know, how many people do I need? How much heads up? Can I guess, be expecting, I gotta have a couple of days to make this decision? Or is it going to be a six hour decision I have to make then how does that change sort of like my plan of attack? And so yeah, I think a lot of it going in, it’s just that contingency plan of what needs to happen. But the frustrating thing with these storms is even when it looks like there’s a potential they might hit, that track shifts so much, and you’re only as good as the information you’re given. And you know, obviously, like NOAA and National Weather Service does a phenomenal job and they give us the best possible prediction they can provide. But there’s just so many variables at play, then the track can shift dramatically. And that’s what happened with the second landfall of VN. Yeah, one of my questions was like, Well, how do these students respond to vegetation stress, right. And so when I made the call to go out on the Thursday before the storm to pull down my met station because I had other instruments out there that were not mine, you know, and I’m trying to graduate. So if I destroyed my committee members net radiometer, it’s probably not going to over very well. So I wasn’t making an emergency visit for that. But you know that with the vegetation sensors, I really had to think about leaving or not, right, and, you know, I think a lot of field scientists do this mental calculus of is the data I’m going to get, or the potential potentially get worth more than the risk of losing the equipment. And so that really drives your decision to leave or pull it out. At the time of the storm was projected to hit South of Charleston, which knowing this coastline, it means that, you know, all we get is higher waves, some more wind, and you know, we still get the surge, but not nearly as bad as they would experience it in Charleston area. And so looking at being out there, the day before landfall was made, it was really impressive how much energy was already in that system. I mean, the winds are whipping already. And it was kind of neat, there’s like a cold front, I believe, of kind of pressing it offshore and squeezing some moisture out so that I feel like enhance some of the winds that we were experiencing up in that part. But uh, yeah, in the moments leading up to it, you know, walking out of the field site, there was so much wind blowing above that threshold of motion, you’re just watching sheets of the beach, deflate, right? Deflation is this process where we have the winnowing away of finer material. And that removal of mass causes the surface to the naming flies deflate, right, lower down. But I’ve never seen it happen this rapidly in front of my very eyes. I mean, it was happening faster than I could possibly measure it with the modern tools that we have, you know, it’s really incredible see, but in that process, looking at my instrument nodes, because I kind of haven’t set up where I have these three dunes are more or less coalescing varying degrees of vegetation coverage. And so I split up and I had two ZL6 Data Loggers, and one was kind of further back and one was closer, you know, towards the ocean, the one that’s closer towards the ocean, there was so much sediment, it actually buried all the vegetation that was within the field of view. So that had already occurred. And so for me looking at that as like, well look, thinking back to my research question, it’s like, why don’t even see the vegetation, you know, and so, in the data loggers about to get buried by sand, it’s like, I don’t think it’s a good idea to leave this one in place. But the other one is further back further away from the ocean storms gonna hit South Charleston, so there’s the chance to get starved. There’s a lot of mass ahead of that station. And so I feel pretty good about where it’s at. I reinforced it and I left it. 6pm That night, when I got home, the trek shifted, it was a number of miles. Yeah. And so the center of the I actually was half a mile away from my study site, which means that my dunes went through the northeastern corner of the eyewall, which is the strongest winds the most intense part of the storm, you know, because it’s centrifugal force. And so, yeah, yeah, that’s what it looked like when I got out there a couple days after it was basically all the sand was just stripped from the dunes and pushed back so that same Overwatch plane I mentioned earlier, a brand new formation of that occurred. The sensors are still out there, they’re buried, I have to find them but but it was one of the things as a gametime decision, you know, in my defense if it would have hit South and I’ve seen the move south to just as much and then you don’t get any data, right. So it was a risk and I took it didn’t didn’t go too well. But I didn’t lose everything. But the opportunity to see what that vegetation stress to tropical systems is was just too appealing to not try Right, right. So and that’s Oh, that’s ultimately what the PRI sensors were out there for anyway so they were doing their job you know, it’s just the storm at that magnitude. I mean incredible force of nature and that was the only the second for what is just a cat one I can’t imagine the cat four I think you know a lot of researchers in my field we do kind of chase after these storms whenever they’re kind of in our backyard just because there’s so much information we can learn from it. And so I’ve been on in several survey crews where we go up before and then after and you know calculate erosion and shoreline change but I think being at this site for like the eight months prior watching it grow watching establish you know, and the vegetation really come into its own and stop sand from moving and building up his dunes then coming back right after the storm and seeing it obliterated Yeah, that was powerful. I did not expect that.

Like you’re saying it’s kind of the flip side of the same coin of tornado storm chasers where you guys are just kind of standing in one spot but dealing with the same thing about how do we measure the impacts of these major weather events without yeah losing all our equipment or you know finding the right spot or to move them out of the right spot in order to figure out what we want to see what we really want to be able to record there. How long then does it take for a dune like that to recover from a major storm events such as you know, a major hurricane might be just a matter of months or is it years you know, can you give us a general ballpark timeline of those kinds of situations?

Oh, I wish I could. Yeah, it’s it’s incredibly site specific. But just to kind of clue you into some of the variables that we’re looking for, you know, what could make a stronger system is number one, you have to have some form of we call roughness. So roughness is just anything that could slow down, the wind decrease its momentum in which it can no longer carry the sediment, right and that, and that process of decreasing its momentum means that it’s no longer able to carry the sand particles, it falls out in terms of deposition. And that kind of jump starts the process. So that’s number one, something has stopped the wind when it is carrying sand. But even stepping back, though, you need sand, right, you need a sediment source. And so depending on the magnitude of your storm, that sand gets relocated, and it can go in one or two directions, one of which would be like in the case of my study site, it was blown back through to the backside of the barrier, the barrier island, if it gets pushed too far into the marsh and is now underneath the water level, then that sand is more or less lost, because I don’t care how hard that wind blows, it’s not going to pull it out of the water and back on the surface. Right. And then other direction in which the sand can go is offshore. These storms are of such high magnitude, you know that it’s pulling the sand and and sort of grinding it off the beach and can shove it far offshore toward the normal waves that typically act within a climate aren’t able to bring it back to the coasts. And typically you’ll see beaches will have like what we call like a winter and a summer profile where the wintertime it’s, you know, it’s a steeper Beach, because there’s more wave energy. And it’s pretty normal for those waves to just take that sand, move it offshore, and then it builds up the bars, which the surfers like, right serves much better as well as a cleaner. But then as we move into the summer months, there tend to be these lower waves, but they’re sort of like bringing these bars and bringing the sediment back to the surface. And so we get this more gradual profile that builds out wider, more room for people that want to come to the beach for tourism or, you know, Sunday, that sort of thing. And so this process normally happens, but hurricanes can be on such a high magnitude that they take the sand off the beach, but they move it beyond where it can be recovered in the summer months, you know, from this normal processes. And so whenever that happens, you know, then you need to call in some sort of human intervention, I guess needs to take place, right? Whether it be the Army Corps of Engineers or some other dredging operation, beach nourishment, something along those lines, a soft management practice kind of brings that sediment back. And I’ll say that roughness, you know, in my case, it’s vegetation. But you know, it could be a sand fence, it could be bundle, a hay, anything that can slow it down. roughness, we got sediment, ultimately winds, you know, the angle at which the wind is going to arrive to the coast that governs change and transport, because it’s all about boundary layer adjustment and how the wind is essentially getting used to the surface it’s moving across, which takes time, you know, and so yeah, having ample space for that boundary layer modification to occur. I think that’s the main ones. And of course, you got precipitation, which you know, turns transport on and off doing really is this sort of like analog result of transport and depositional processes, the interaction of when sands moving and when it stops, and then that ultimately is what a dune is.

So along with that, as a Dune is forming, or starting form. Can you explain the process of how grasses begin to take hold? And how long does that or how long can it take for you know, grasses to take hold within a dune and become embedded and flourish there?

Yeah, man this is, what a cool question. The reason why I say is because I think what I initially pitched to METER a few years ago, was only looking at those three dunes that are now destroyed. That was like the main focus. But when I pulled it to my study site back in January, this past year and installed everything, seeing how much RAC right remember, it’s the vegetative remnants kind of balled up on shore, was on the field site, we kind of pivoted a little bit and said, Well, let’s look at this too, because RAC isn’t just dead debris, it’s typically because it’s been scoured and mined from a dune, it tends to have vegetative remnants that are reproductive so either be rhizomes or seeds. And also to it’s unique because it’s also a roughness element, right, it’s able to extract the momentum from the wind and facilitate deposition, which is what a dune needs. And so I kind of pivoted a little bit and then also, you know, threw some erosion pins inside the rack and then photograph them did vegetative counts per rack piles, and I divided the study area where it looked like it was more influenced by Aeolian activity versus Inundation from tides. And I had a control set as well. And yeah, it really came out of this. It really highlighted the role that RAC has in that recovery that an initial disturbance event levels, the whole dune system, there’s nothing out there, but these lesser events are able to float in RAC and maybe it’s just a high tide deposit a RAC pile. Now you have roughness on the surface, as your winds start to blow your infilling this rock pile and then causing it to really jumpstart colonization and emergence within the system. And dune grass species are really interesting and that they like burial or a lot of them do not all of them, but a lot of them do. And so there’s a stimulus that happens of sand now bares a rock pile where the vegetative matter is, or reproductive components are, right, and then now you have a burial response, which then causes that plant to want to grow, you know, through the Rockpile through the sediment, and then that growth now causes it to have a bigger presence to the wind field, which facilitates further deposition. Right. And so this process continues over time until eventually you get to do not have it right, this form is able to modify the landscape and modify the flow, and in a lot of cases to its favor towards slowing down that when and aiding in that growth.

So are there other types of plants that can help in this beyond dune grasses?

Yeah, yeah, some of the work I’ve done recently has been looking at the role of driftwood kind of in the system, right? It’s something that’s not necessarily alive, like dune grasses, but its benefit in terms of nutrients is this long term source of nutrients, right, as it breaks down slower because of its size, and its mass, you know, but it kind of helps that system of establishment. And so I know it’s not really a plant per say, everything else that’s going to be on the surface is going to be some form of Dune grass. Okay, so she’s, like, bitter panicum, or American beach grass or sea oats. They’re all kind of within a similar class.

That was my question. So are there any issues with beach degradation, say outside beyond your region of research there?

Yeah, yeah, I think a lot of that kind of comes down to the underlying geology of the region. And what I mean by that, as your beach slope is much steeper on the West Coast, right there is on the east coast or the Gulf Coast. And because of that, if we think about things like sea level rise, or like localized sea level rise, because the storms, the same amount of change vertically means two different things, because of that difference in geometry when we think about slope. And so I think that’s why we see a little bit more erosion, maybe more visible, perhaps, you know, on the on the East Coast and Gulf Coast. But yeah, not saying that original thinker on the West Coast, it definitely does. It’s just it looks a little different because of that legacy geologic framework. And also in a number of places, you know, you have kind of negative sea level rise values, because of the isostatic rebounding rises, glaciers pushed back 1000s of years prior, you know, that land is still bouncing back up. And so

I have heard of, of beach grasses being imported elsewhere introduced other places to protect beach dunes and other places. Is there any risk of beach grasses becoming invasive species in these new areas?

Yeah, this is we’re seeing a lot of this on the West Coast right now, I haven’t done research into it myself. But I have several colleagues who do, I don’t remember if it was introduced by the Fish and Wildlife, or if by some management agency or not, or if it just naturally floated across, but European beach grass is really aggressive at growing tall and fast. And so they’re seeing over there is that yeah, it’s growing tall and fast, which means that it’s sort of cutting off the sediment supply to the native species behind those regions, and is becoming a real issue in terms of natural biodiversity. Right. And then in terms of other invasive species, there has been a lot of work done on it. What I don’t remember though, is if those were intentionally planted or not, I don’t know. But we will we also see though dunes is the sort of invasion of Centipede grass, right, as we have these homes and properties along the coasts, you know, obviously you want a centipede lawn yard. And so by planting that sometimes it also will crawl out onto the dune. And I don’t think it poses as much of an issue in terms of like out competing, just because dune grasses are incredibly resilient to salty air to long periods of drought. You know, it’s like full sun exposure. And so yeah, they kind of they can hold their own, I guess against that. And I did misspeak earlier, there are succulents or succulent type species that do pop up here on the East Coast, there’s gonna be sea rocket, but they’re kind of like one hit wonders, you know, they’ll pop up a little bit of roughness, you know, to the surface, and then they’re gone, you know, so they do exist, and they are, you know, very beneficial for initiating some of that initial deposition.

As we kind of wrap things up here, I’d love for you to just explain to our audience about how can your research help the world at large? Or what can we as a society learn from the result of what you’re finding out?

Yeah, I think I think a lot of where the benefit of my research as it stands right now is going to go is to offering this new methodology this new lens to see vegetation data through from the site in situ perspective, right, as I mentioned earlier, these inflection points. I really think there’s a lot of strength in understanding the timing of that Mergence with you know, local conditions of wind patterns, and you know, if it’s the rainy season or not, and how these different variables interact with one another in terms of being able to put a number of different study sites or different locations around the country, on the same playing field right the way in which we can discuss Do it down to these core variables and measure resiliency or get out, you know, what is it take this speech X number of years to recover, whereas this one can do it half the time, because ultimately that sort of information tells us which systems are efficient. And if we know where efficiency lies, and the natural world, then how do we take what mother’s already trying to do and help it out a little bit, if I know what the ideal case is, then I can make some really powerful coastal management decisions in order to help out and give it that critical piece that might otherwise be missing. Now, obviously, we can’t like, you know, make a ton of wind blow all the time, right there. There are limitations to it, but but I do hope that it will kind of shed some more light into those variable interactions that leads to resiliency,

along those same lines to is what can we as a public do to help preserve dunes and promote their recovery?

Well, definitely don’t walk on them. Okay, all right. It goes without saying, I mean, we’ve had sign campaigns for years now. And that has really helped very much. But, but yeah, definitely, because whenever you walk on the dunes, you know, it’s obviously going to, it really hurts the rhizomes that are underneath, and they’re pretty fragile on from that sort of repeated trampling, you know, I think a lot of its advocacy going to the beach, and just taking a second to notice the dunes, I feel like a lot of us get sucked into going to the beach, for the beach. And so once we get there, you know, we’re looking out towards the waves, but, you know, like, if you turn around and look, that’s the barrier that’s preventing your house from potentially flooding during the next major storm, you know, doing little things, like if you have beach RAC that washes up on your shore, you know, and maybe you’re a homeowner, or maybe you’re just visiting, but you can move that RAC into towards the dune line towards the toe of the dune. And then to help it build it out, make it thicker and wider, help improve your grade on its own. So there’s little things like that you can do but yeah, I think the biggest thing is just just take a second notice them, it’s amazing how little recognition they get. And I always whenever I teach Physical Geography on on the campus, you know, I always, whenever I get to my coastal geomorphology section, I show a photo of the beach, you know, and I have my class, okay, label everything you can see on a piece of paper in this photo, only about 30% of them, notice the dune and it’s just I think that’s a real kind of indicator to where we’re at as a society, you know,

final question, we always like to try to get any fun, exciting or crazy stories, anything else that you’d like to share along those lines?

I always say that if you’re a field researcher you kind of have this sort of soft spot for type two fun you know, type two funs where you know, nothing’s going to plan you know, you ran out of water or it’s harder than you’re expecting or you get caught in a sudden rainstorm you know, when I was going down to go collect that equipment in advance of the storm out there and the winds whipping and it’s also I’m taking all sorts of photos and videos just like really taken in the change occurring before my eyes bow when I finally got the first load of equipment completed and first load because it took me four days to set everything up and only had or the weather window kept getting shorter, but only had on the order about maybe like three hours to get it all down. So you know moving, pretty quick pace. But I underestimated how high the storm surge that was already coming in was going to offset the high tide prediction. And so by the time I carts loaded up with 1000s of dollars worth of equipment I looked down the coast and I realized that I’m not going to make it because Because literally the the beaches go you know, it’s covered up by water it’s not gone you know, it’s covered by water and Okay, well that’s fine. I’ll just you know, Hang Hang tight on top of the dune you know, because I know that my Overwatch plan is going to flood now when I couldn’t pass it was still an hour from high tide. So that’s when your gears start turning. You’re like oh, that’s probably not going to bode very well. No, I post up on a on top of a dune hopefully waiting out the storm surge and it’s like initial flooding event in advance of the storm. And then underneath my tarp and the winds whipping next to metal and all this equipment trying to stay dry. Yeah, check the radar just to see what’s going on. And yeah, it’s definitely the outer bands of Ian and I was like well, this is too close for comfort. Right? Yeah. But you know you’re questioning life decisions and all that all that stuff at that point in time. But uh, but yeah, I mean, I had to get that equipment. There’s no no way around it. So yeah, I’m waiting out there and checking the radar and waiting for the tide to go down and watching the whole system to fleet I would say it was definitely a intimate experience with how the air force plane was going to fare in that particular storm event but yeah, it’s definitely the closest I’ve ever been to a storm or I’ve never been out there before I literally got stranded and how to wait it out. But as already is only like six hours.

That’s all make good.

Yeah, I was fortunate though is that I think that like I said, I’m pretty sure that they said there’s a cold front that was butting up against Ian and in that process, it was squeezing out a lot of that moisture and so because of that, I wasn’t sitting underneath of what looks like a lot of rain on the radar, you know, outer bands of this massive system. So I’m very fortunate for that but it was just a matter of waiting for the water to go down, as well.

Well, any other final things you’d like to share with anybody any final statements or suggestions or plugs or anything like that?

No, no, I was just gonna say, um, if anyone listening wants to, you know, get a hold of me about research or anything along those lines, um, you can find my email address on the department websites, just [email protected]. And yeah, no, this has been great. Thanks again, for all that METER does. And I’ve been a fan of the podcast since it first dropped. So it’s been really cool to get the offer to be on here.

Thank you so much, Pete for taking time to share your research with us. As always, super fascinating. And if you in the audience have any questions about this topic or want to hear more, feel free to contact us at metergroup.com or reach out to us on Twitter @meter_env. And you can also view the full transcript from today in the podcast description. That’s all for now. Stay safe, and we’ll catch you next time on We Measure the World!

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