 our first speaker will be Uwe Best, who's at the Delft Institute for Water Education, UNESCO IAHE in Delft. She works on and has been presenting at the CSD Mass Meeting before and works on mangroves and interactions with vegetation with tidal sedimentation, wave surges, et cetera. And so I'll stop sharing and we'll give Uwe the floor for this. We are seeing your screen, we're not. Yes, you're right. Yeah, so the bugs have been worked up. Okay, so thank you for the introduction. And I also wanna thank you for the opportunity of joining the session for today. Yes, so I also wanna thank you for allowing me the opportunity to join the session. And I've been seeing quite a lot of interesting presentations. So I'm very happy to hear about all of them. So hello, everyone. My name is Uwe Best and I'm a PhD fellow here at the IAHE Delft and TU Delft in the Netherlands. I've been working with Mick van der Weggen, Johan Rheins, Dana Rulfink, all from IAHE as well as Jasper Dijkstra from Del Taris. And so today I really wanted to discuss with all of you our approach taken in modeling the mangrove mudflat dynamics and more so the capacity for such systems to be able to adapt to sea level rise. So in 2009, the government of Guyana attained funds from the European Union and the IDB to evaluate the state of its city fences. And during this project, it was highlighted that the country's coastline had lost about 60,000 hectares, which is equivalent to about 600 square kilometers of mangrove coverage over the last third one years. And this was attributed to a combination of both natural and anthropogenic factors. But more so, it was attributed to the cyclic erosion and accretion patterns that are inherent to this particular system because of the longshore movement of the mudflat. And so in 2009, the mangrove restoration and management unit in collaboration with the ministry commenced among other measures, the restoration of several stretches of mangrove fringes along the coastline. And for today's talk, I will just focus on one of them, the Chateau Market mangrove. And this is along or this is located along the lower east coast of the South American or of the Guyana coastline. And here you can see an overview of what the area looked like in 2002, which was eight years prior to the restoration. And more so the development and natural expansion of the area over the last 19 years. So it has really been able to expand. And this is one of the successful cases of restoration within the country. And so last November, we collaborated with the government of Guyana to monitor the effectiveness of the mangrove fringe, wherein we traveled with instruments to capture the hydrodynamics and the sediment dynamics within the system. And a total of 10 transects were established. However, in the figure, you're seeing the main transect along which the instruments were then established or set up. And the instruments were then left there for about two months. And so we've been able to capture lots of interesting interesting information. And what we've also been able to do along the other transects or all of the transects is that we've been able to capture the vegetation property. So the density, the diameter, the heights, and these were all attained manually using 10 by 10 quadrants. And so from the data, I should also mention that we were able to capture batometrics of the extending six kilometers offshore. And so the system is really characterized by a combination of semi-dialtides ranging between one to two meters, swell and more so locally generated waves, as well as currents. And we found that along the mud flat, the wave heights kind of ranged between 0.5 to just about one meter. And most importantly, the mud flats were really showing capable of reducing or dampening the wave energy, in some cases by 50%. And within the mangrove, the wave heights were quite minimal. And we saw that they ranged between five to 50 centimeters. So they were quite small. Yes, so we were more interested in determining the extent and the presence of the infragravity waves along the South American coastline. And we really wanted to see if the infragravity waves were able to reach the intertidal zone and then to what extent they were then seen within the mangrove belt. And what we noticed was that there was a limited presence of the infragravity waves within the mangroves. They were more so seen along the mud flat. And you can see just from the figures that the infragravity waves were really, really quite small. And they were probably between 2.5 to five centimeters. And so we can definitely conclude that the infragravity waves are quite minimal, at least along the stretch of coastline. And so their impact on the sediment transport could also be quite limited. And so we then developed using the data, 2D high resolution depth average model using DAL3D flexible mesh. And this was coupled to the vegetation module in Python through BMI. And so we have a coupled model that is now able to stimulate the development and the interaction of the flow, the waves, the sediment transport, the temporal and spatial variation in the mangrove growth and also the biomass accumulation. And just to give you an appreciation, we're only using one open boundary through which we have the waves and the intertidal flow being imposed. And so now you have an appreciation for what happens with the development of the mangrove vegetation from its establishment. And once it's been able to establish, you have the interaction between the inundation and the computation stresses, which limits the establishment extent of the mangroves. And more so you have a system that is then able to develop to some sort of equilibrium. And this continues for just about 160 years. And so we have a system that if compared to the typical salt marsh, we notice that the mangrove development is much slower and equilibrium tends to extend to centuries. The spatial layout, the shore patterns were all achieved within 200 years and based on our quantitative validation, the results were satisfactory. And what we've seen also that is quite crucial is that the waves are definitely the main process, the main driver that brings the sediment into the intertidal area and then it's allowed to then be transported into the mangroves during high tide. And so for this system, we even looked at the biomass impact. So we can see that for systems with a below ground biomass attribution that exceeds two mm every year, they're generally able to keep up with the sea level rise as well as to just have a constant increase in the bed level. And so the last aspect of this that I really wanted to then share with you is the sea level rise. And so we decided to impose linearly increasing, decreasing rates as well as an exponential increase. And so for the linear approach, we can see that the rates ranged between one to 32 mm per year and that the mangroves were seen to be quite resilient against all rates except those exceeding 25 mm. And under the 25 mm per year, the mangrove started to drunk after 90 years when the water level exceeded 2.3 meters. And so it was also similar to the scenario-based approaches where we also noticed that once the water level exceeded two to 2.3 meters, the system was no longer able to adapt and respond. And so we saw two things, definitely the tipping points as well as the relationship between the sedimentation and the inundation net. And what we also found interesting was under the linear decreasing rates, there was a tipping point also noticed for rates less than 2 mm per year. And so we definitely see that there is a particular range in which the mangrove system is able to adapt, is able to develop. And so in conclusion, the main points is that we've been able to establish or develop a coupled 2D model that is able to represent the biogeomorphological development over 160 years and further to expand to see the impact of sea level rise. And of course the initial conditions for any model will then determine and play a significant role in the resilience of the overall system. And systems with a high carbon content are definitely able to withstand the increases in sea level rise. So I hope it hasn't been too much, but I hope you enjoyed the presentation. Thank you. This is amazing work, Uwe. I really enjoyed that you showed us a big update from a year ago or so and there's so much intricacy. We'll take one question and I think that is gonna be typical for most speakers that we can ask the questions in the chat. Maybe we can like ask the questions even while like the speaker, if you have like a really important question, like ask it while the speaker because then we can like field them fairly quickly. But I'll take one question and convey it to Uwe. Okay, and I'll stop sharing now. Thank you. I'm trying to... Greg is raising his hands. Do I see others? Appropriately. Greg, do you wanna ask your question? Yeah, thanks, Uwe. That was fantastic. I especially appreciated your visualizations as really gorgeous visualizations. I was curious about the kind of scalloped features that form in your simulations or I don't know what the word for it is, but these sort of alternate bays and promontories, can you tell us a little bit about those and why they form? Yes, so we've been trying to establish equilibrium, the symmetry with the waves with just tidal flow, you tend to not see the bays forming but the waves generally have such a large impact on the directional flow. And so you definitely see the bays formed. What we've also been trying to establish is to see better just having the... Either having just the short waves or just more interstices in the swan. So once we have the triads and the other elements being placed, you don't see the triad, the bays formation so much. But it's definitely something that we're playing around with to see how to better represent what's happening. But yes. Thank you. Interesting. Yeah. Thank you. Interesting. Yeah.