 All right. Well, thank you very much for coming and thank you to the organizers for giving me the opportunity to talk about my research. So I'm going to be talking about some work that I've been doing over the past decade or so. Here you see a few examples on the left. You see a flue of the entire environment slash continental shelf evolving under sea level cycles. In the center you see a barrier island migrating towards land under constant sea level rise. And on the right. That was on the center and then on the right. I'm still thinking about what they want on the right represent so if anyone has some ideas come to talk to me afterwards but so. So has every all these simulations have something in common is what we call a moving boundary approach and they combine an idealized geometry with sediment conservation or or mass balance. This is, of course, the product of a lot of effort from students listed here out. Talk about them through throughout the presentation as well as many collaborators. The plan for today's talk is to give you three examples of how we how this moving boundary frameworks can be used to address specific scientific questions. And over a wide range of temporal and spatial time skills, which I believe that is aligned with the theme of the annual meeting so I'm going to start with glacial cycles. And then in terms of the environments and conditions that shells over those time scales then by islands, by an evolution of a millennia, and then in timescales of years to centuries we have to take into account what human development and human activities. How do they affect the landscape evolution so let's start with part one. I'm going to frame this moving boundary framework around the question do the dynamics of the fluvial surface play a role in paleocellular reconstructions. So the first step is to idealize the geometry so we have a linear basement on top of which we have salmon and water that come down and deposit form in the cemetery prism. It's delimited by the Louisville bedrock transition in the upstream end and the short line in the downstream. So the trajectories of these key geomorphic boundaries are going to determine what the evolution of the cemetery prism is it's over time. Yes, right. So, and just for context, the most common approach to reconstruct C level is sequence stratigraphy which assumes that the fluvial surface or top set response instantaneously to see level changes so if there are a stratigraphic indicators in the app proportion of the fluvial surface. Those are going to be contemporaneous according to sequence stratigraphy to see level changes. So idealize geometry combined with a salmon transport formulation which we assume that is just a simple relationship between salmon flags and the local slope. And salmon conservation in one dimension, because we have just a profile. So what you get this. A closed set of equations. This is an example of a simulation takes less than a minute to run and what you are looking at here is the evolution of the same entire prism. The same into supplies again coming from the upstream end, the solution of the cemetery prism over time and the syllable cycles the syllable curve is shown here in the upper right. So the changing colors you can think about it as the age of the position. So there are two points I want to emphasize about this model simulation one is the changes in curvature and relief of the fluvial surface. So, during sea level rise you have a lot of accumulation of segments in the near short portion that flattens the profile and makes the profile convex. And then during sea level four what you have is a lot of a bypass that is the Delta front and shifts the profile from convex to come concave. And then the second point I want to highlight this is if you hopefully you can see that if you look at what is happening in the upstream location, and what is happening to the sea level variations, hopefully you can see that it's not in sync. There are lacks geologically long leave lacks in the upper portion of the fluvial surface. And that basically at odds with sequences strategy what I mentioned before. So, this is of course a theoretical result. We need to validate this and I will be interested to talk to any of you about how to validate it with the field, we fill data but we started with flume experiments from to learn university so you see here a plan view of the cemetery prism. There is an inlet in the upper left corner where the salmon and the water is coming in. And the syllable curve in this case is this panel panel be right so you have low amplitude cycle cycles and then high amplitude cycle cycles when analyze the entire thing that I'm going to talk about only the high amplitude section here in the interest of time. And as we did because is basically take the radial average because we are interested to know whether these near short location here in light gray, responsible instantaneously to see the variations or not. And the same question for the upper location in the upstream location right. And other processes like river of oceans or meandering of the river to the channel to to affect the patterns of erosion or the position we are interested in the elevation changes on average at these two locations. The near short and the upper location so here is the highlight right of this slide because here what you can see is the elevation residuals. And the thin black line is the syllable curve, and then you can see that the near short location in light gray is actually following quite nicely. The syllable variations, but the green line which is the upper location, the upstream location is actually completely out of sync. So you actually can have river incision you can have erosion in the upper portion of the fluvial surface doing the sea level rise phases. So even an experiment days two meters by two meters, you can actually see lax in the response of the upper portion of the surface, which basically supports the theoretical results and still that is out of work to do. Connecting the numeric the theoretical work and then America and the experiments but it's, we cannot take. We, I think that here the message is that we might want to be cautious when looking at stratigraphic indicators of the upper portion of the surface. It might not be contemporaneous with a single variations. Okay, so part two barrier evolution barrier self deposits by yourself deposits are often associated with sudden changes in external forcing like for example I said and changing the pulse in the rate of the silver and silver rise. And, and then was interested in this question so he did a lot of literature review looking at bar yourself deposits in different continental selves. And he found that there is actually a characteristic distance between this bar yourself deposits if you are in the English channel is in the order of two kilometers is you are in Florida is another of seven kilometers. So, these basically suggest that there might be something else going on apart from just pulses in the rate of silver rise and to address this question. So, again, used an existing buyer model that still get us explain actually really well before. And basically it's assuming a linear short phase is a personal barrier is characterized by the average height and the average width and the key geomorphic boundaries here in this case are the surface though the short line and the back barrier phase so we can express and I don't have the questions here I'm happy to talk about it there. The change in the location of the geomorphic boundaries is a function of the living processes, the rate of silver rise, the exchange of segments between the upper and the lower short phase and over was fluxes which basically bring sentence from the front of the barrier and the positive on top and the back. That's what allows the barrier to migrate towards land and keep pace with slow. So what Dan found is that with this model he could to first order explain not only the not only the characteristic space in between buyers of the postage but also some degree the volume of sediments in different locations around the world New Jersey, Florida, Long Island, English channels of Africa, Italy. So, and one of the things that he learned is that a key. One of the key controls is the, the slope of the shelf so if you have a miles shelf you're going to have a larger characteristic spacing and larger volumes of buyers of deposits and. With the same spirit and previous example, this is not really answering all the questions about this brand that is still out of the work to do but it's just that we might want to be careful. We're not associating all buyers of deposits with a change in external forcing. All right, so, and last part of my talk is associated with a changing scene with time scales from years to centuries so here. You can see in this picture and in your new in New Jersey, a seven meters tall to 21 feet high right. So it's a massive future right and this is going to play a role in the way that the barrier islands long beach island response over these timescales. So the question here is, whether we can actually separate the effect of human activities and from natural processes, and to do that what we do is look at long long beach island over the last couple hundred years. And using a couple numerical modeling and mapping effort right and during this time period long beach island has transitioned from an undeveloped barrier system barrier Mars lagoon system to completely develop fully developed right. And just to give you an idea of what an undeveloped island looks like here I include an example of see that island in 1984 here in red now is the shoreline at that point in time. In 2016, the barrier has rolled over itself a few times is migrating towards land at that rate of approximately 10 meters per year that is in contrast with what long beach island has done over the past few decades has been fixed in place and here is an example of beach knowledge man episode that's why the shoreline is protruding into the ocean. This much and this what looks a small nine this picture, these are the seven seven meter tall deans that you saw in the previous slide so these are actually very significant volumes of sand are added. So to address this question, we basically added a few key your morphic boundaries to the framework before we now have them Mars platforms in the back. So we have in addition to the ocean shoreline back barrier shoreline that we have also the Mars lagoon edges and the inland Mars edge as well. All right, so I don't include the questions here but it's the key message here is that the evolution of long beach island roughly can be separated in two phases. One phase phase one, during, in which you have all the key your morphic boundaries migrating towards land as you might expect from from a barrier Mars lagoon system and their seal of the rice. So you have the shoreline eroding 170 meters. The Mars back barrier Mars is actually spending into the lagoon thanks to the overwash fluxes also that provide mineral inputs to the Mars environment and the inland Mars is eroding on the lagoon side but is expanding also towards mainland. It's not containing more or less the the width of the Mars platform but this, this situation completely reverses in phase two, where you have the shoreline program into the ocean during this time period due to coastline in the and these are some practices are hard structures, and the Mars platforms are eroding on both sides of the lagoon and they not only don't expand towards mainland but they actually lose area due to development so. So hopefully this type of exercises can help us to also look at the scenarios in which we don't have these landscapes fixed in place but we actually have a mix of the relative effect of natural processes respect to human activities increases. So then we is good to have that benchmark, how were barriers behaving before they were fully developed right, so I provided three examples of that hopefully illustrate how moving is moving manner framework approach can be used to address. Questions of a wide range of temporal scales and another people and I want to make it is that they seem to be very targeted to address a very specific question but they are also not, they can be extended. They are versatile and portable so they can be extended to address other questions I include a couple of examples here. So this profile model that I showed before, you can connect it via a long shore and include inlets so that's basically what job did and and that's the simulation that here you see in the top in the bottom left right so you see this in plan view. The barrier islands migrating towards land with the inlets and with coupled by a long shore cement transport. In the case of the fluid attack. There's last continent itself environment we, we are extended to account for more complex cement transport formulations that include the threshold of motion, for example, and that allows us to account for the evolution also of the of the fluid attack environment and I was after looking for this is basically also to illustrate that the same numerical technique that we use here is called the enthalpy method. We can actually extend it to two dimensions very easily and but of course it's not physically meaningful at the moment because it doesn't have channels you would expect channels to in size at some point during this level cycles right and. But it also you know illustrates how we can couple with other models using the CSDMS platform. And with that, I'm going to stop it there. We have time for one or two questions. Yeah cool talk. You probably guess which part of the presentation I wanted to ask a question about the second part I was wondering when you see these barrier islands migrating. Over time, there's a little bit of platform remaining. What, what is that and how is it different from whatever is underneath it. There is a little bit of platform. Yeah it had like a slightly different color in the figure that you showed. In this slide and then model. Okay. Oh, yeah, that's a that's a very good question. So yeah there is an alternation between the position and ravine them surfaces, emotional surfaces. And I changed the color, because I'm assuming that the basement, on top of which the barrier is migrating is. It's basically rock and the body already is leaving sand sand behind see my it's the world land. So that's why you see this is like contrast between the dark brown and the more yellowish color. Yeah, thanks. Mr. any Nicole has a question from really cool talk. I'm wondering about when you went when you illustrated sort of that the deposits and locations were not necessarily in sync with sea level changes. When you go to 2D, I guess I would expect it to be more complex and you didn't really talk about that. I showed this little video but I guess, is there, it just looks very symmetric. Are you getting the same kind of dynamics that you're getting when you do the 1D profiles or is there something that's maybe missing from the 2D besides the channel you said, like, I don't know. That's a really good question and that gives me the opportunity to also mention that, even though we don't have channels, we can actually use numerical models, laboratory experiments also to you to validate this 2D version, at least under constant scenarios when you have mostly sheet flow. So, and actually I've been playing with that. So, it seems like we are not missing anything much apart from channels channels is really what would give you the asymmetry, I think. We can capture the angle opening angle from experiments with this with this modeling framework, even though it actually has only one parameter really to calibrate so we actually thinking that that this is at least so channels is the key point that we need to add but do we see also the river incision in the upper portion of the fluvial surface and there's variations and the answer is yes. And from the modeling point of view it's actually not surprising because it's after all diffusion. Right. So, but the magnitude is actually even larger in that to the model because you have the it widens. So, the reason why you have river incision in the upper portion is because you create accommodation in the near short portion. Now, if you have a wider fluvial surface in a 2D model, the space that you have to fill with semens from the upper upstream for the from the upper portion is larger right so you have even more erosion in order to be able to fill that space, and there is no releasing relief and curvature. So, hopefully I didn't. We need that middle video that cross section somehow from the right because it's really hard to. Yeah, I mean it must, if the middle video how you have the cross sections and the timing with sea level rise and fall. I'm trying to like envision that for the, the movie on the right and it must be so complicated. So, yeah. And we actually have it I probably should have had a bonus slide to include that sorry but it's okay. Great talk. Thank you. Thank you.