 Hello everyone. Can everybody hear me? I can. Okay. I see a few yeses. Good morning, good afternoon and good evening depending upon which part of the world you're joining us from. Welcome to this webinar co-organized by the Water Channel and IIT depth and being supported in this case by Delta RS. This is a holiday season in several parts of the world which also means this is the beach season in those parts of the world. And rightly so, you should go to the beach and you should enjoy. But as you lie on the beach sand, we would also like to ask you to think about the several other functions that the beach performs apart from providing you pleasure. This beach is the first line of defense for the community living next to it when there's a coastal storm. It is the ecosystem that supports so many coastal life forms, so many coastal plants and animals. And the sandy beaches, the beaches, the coasts, they also define the lifestyle, the lifestyles and cultures of coastal communities. Being so important as they are, sandy beaches need to be preserved and protected. And to preserve and protect them, they need to be understood well. We need to have a good understanding of the different sources that feed sand to the beaches and what helps and disrupts the supply of the sand to the coasts. How are human activities affecting this process and how has climate change affecting it, if at all? So we are lucky to have with us today Professor Dhanno Roolmi from IHE to discuss all of these questions that you might have. Who has 33 years of experience in coastal engineering and research? You have seen his detailed bio on the landing page from where you came to this webinar. So I will not dive into details about his work experience and it will be a very deep dive because his experience is really extensive and it takes a lot of time. But what we are definitely looking forward to is a presentation from Professor Roolmi that will help us improve our understanding of coastal dynamics, some of the threats that our coasts face today and what tools are out there to track these processes and tools that will help us develop and target appropriate responses. Especially we are looking forward to hearing about shorelines, which is a tool under development and which I was made to understand can be used not only by scientists but also by engaged citizens to see how human impact has altered coasts, to see it and to ascertain what can be different strategies to adapt to it or to fix it, mitigate it. Before I hand things over to Professor Roolmi, I would like to emphasize that this is an interactive webinar. We would like this to be a very interactive session. We encourage you to share your questions and comments, which you can do by typing into the stack box over here. We will address your questions and comments during the Q&A session, which will be about 30 to 35 minutes into the webinar. Without further ado, I would like to hand things over to Professor Roolmi. Please take it away. Welcome everybody. It's great to see so many people tuned in. Many friendly faces, I know, and a lot that I do not know. So let's go. I would like to acknowledge my co-authors of these studies, Bas Haasman from Dottares, Ahmed, my PhD student now before master's student, Joon Reims, her colleague, and Mohammed Ghani, who just finished his master's thesis, also on his development. First of all, a bit of motivation. I've been able to visit many places along the coast in the world that have this kind of problems. Here we have a traumatic situation in the lee of a port in Benin, in West Africa. You see houses and infrastructure falling into the sea. We have sometimes migrating tidal inlets, like here in Grand Laou, in Ivory Coast, where this spit used to be extended 400 meters to the east just a couple of years ago. They've almost completely abandoned this spit now. Here is near the Volta mouth, you see this road really being endangered. Now it's a big rock wall and it's protected, but there's no beach anymore. This used to be a very affluent area in Ivory Coast. You see the swimming pool there. It's not doing very well at the moment. Again, this is the result of a large port project for Abidjan that was carried out in the 50s and 60s and that has robbed this area of its sand. Even in very affluent, touristic areas like here in Playa do Carmen, in Yucatan, beautiful hotels where the lawns are manicured, but the beaches are taken away. People will tell me that it's the sea level rise, but it's very likely that this was something else entirely because sea level rise doesn't manifest itself at this kind of timescale. What Abidjan calls here, I'd like to mention a very important one and that is that it's surprising, maybe, but an incredible amount of sand and gravel is used for construction and it's taken away from areas that can really not afford this. On the top right you see a whole sand spit that was excavated for a port project in Ivory Coast. On the right bottom you see many of those kind of holes in countries like Ghana and one such hole can build you a house, so that is very nice of course, but then if you build a lot of such holes people think that the sea will fill it in again and that's true, but it will go at the cost of the erosion. And on the bottom left you see just one picture taken from a hotel room where you see four sand ships transporting sand in the Mekong Delta. And the Mekong Delta is heavily threatened by erosion and due to all kinds of upstream things, but at the same time 28 million cubic meters per year is dredged from there for construction purposes. So that is a very important factor. So the amount of all that mining is equal to all the sand that is brought to the coast by rivers, but also the sand that the rivers bring is reducing enormously. So in the Yangtze for instance there you see the blue line is the average flow which is pretty constant, but the sediment discharge in the red line is showing the enormous decline. And the Volca River for instance I was mentioning, they built the Okosombo Dam and it has reduced all the sand output to zero. He has just in Ivory Coast gone on an overview of some of the big interferences with the sand system, the dams that were built and the ports that block the longshore sediment transport. On top of that we have many cities that also have very severe subsidence. Cities and even countries. So some examples in Jakarta is a very well known way where it can go up to 10 to 20 centimeters per year in such a way that they are now seriously considering moving the whole capital to another place. But also in the Mekong Delta at many places there is very serious subsidence. Louisiana is a well known case where an enormous amount of land has been lost over the last century and also I've just returned from Bangladesh where this is also quite a serious problem. It's mostly due to groundwater extraction and anyway these effects really often trump the sea level rise. And this can have an important effect on shoreline erosion. So the first lesson is, so far the things you saw did not meet climate change. So we don't need climate change to mess up our coasts. But of course it helps because what we are facing now we were getting used to relatively modest increases of sea level like 50 centimeters by 2100. But now it's more and more likely that it is in the range of a meter and there's a recent data that suggests that the sliding of glaciers on Antarctica and Greenland may accelerate this sea level rise maybe by another meter in 2100. We're talking about two meters of sea level rise and we're really in big trouble. And apart from sea level rise there's other effects. We can have a change in the storm intensity and storm surges. Wave climate can change but definitely we will look at many impacts of climate change. There's an overview of the potential climate change effects on coast by my colleague Roy Framacina. And we'll see especially if we look at the lower three parts then we're looking at the more slow evolution of the coast that then threatens the safety. So the coastal erosion of course threatens the houses that are directly on the beach but it also reduces the safety of the hinterland. Because if you cut into the dune or a dike that is protecting your land then you get more overtopping and a higher probability that your defenses will fail. So the rest of the talk I will talk mostly about this long-term evolution how we can model this and how we can predict and make sure or counteract this erosion. So I'll focus on these effects. I'll have to see my motions now they're sliding. So maybe we can play this video. So this is Ria Formosa in Portugal in large and dynamic system. He has an animation from Google Earth Engine. Something I would really recommend you to have a look at for the time lapse videos on Google Earth Engine you can find it on Google. You see this incredible dynamic tidal inlet that is moving over hundreds or over kilometers and now and then is relocated. So how do we simulate such a complex system? Maybe we can go back to the presentation. So we see here we have this house on the bottom left. It is not there anymore. So the way we see now and then we have big erosion we also have human growth. So how do we model the future of a complex system like this? This area is tight dominated but the beaches are really wave dominated. It has migrating inlets and the whole system is about 100 kilometers in length. So you have a wide range of scales. We need some clever simplifications to simulate the behavior of such a system. Maybe we can show the animation. I just show the incredibly intricate tidal flows and they also of course have a big impact on how these tidal inlets behave. We would love to do their own term simulation with a complex model like this but it's simply at the moment it's not possible yet. So if we go back to the presentation. So if we go to much larger time and space scales and then resolving the surf zone is really a problem because if a system that's 100 kilometers long but you need to resolve the surf zone with a great size of 20 meters or so. And that's just not an option. So we need a coastline model a simplified model that can deal with this but the existing ones are not good enough. So too fast. Existing models such as Unibest LTCL by DelTars, LitPAC by DHI, Genesis by the Corps of Engineers and Cosmos Coast by the US Geological Survey they have very nice capabilities of explaining wave-driven longshore transport and how the coast reacts to that. But they are only capable of having relatively small changes relative to a reference coastline. So no fun processes like moving spits and islands and migrating inlets. So this is what we do once we're going back. So an example of what such models can do is a relatively simple case of a port blocking the longshore transport and how on the left side of the port you see how it is... the accretion is simulated and on the right hand side you see the erosion and you see different models that are all in some way or other that are able to represent this process. Here's a very recent model by Jean-Francois II and others in California. This is as far, I think, as you can take this coastline modeling in the classical sense including data assimilation and long-term predictions. A nice model. But still the coastline is moving on rails. It can only go back or forth. On the other hand there have been models by Andrew Ashton and others that were grid-based but still relatively simple, just driven by longshore transport based on very simple transport formulations. The model is able to simulate very interesting coastal instabilities like you see on the bottom right and you see in the middle at the bottom how that model is able to predict those kind of instabilities. But it was never meant to be an engineering model. So the standard models they have a lot of experience in engineering the coastal evolution model and similar models have much richer behavior but they are only used for schematic system studies. What we'd like to have is a model that combines those things. First of all, how does a standard coastline model work? You represent the coastline by a series of points. On the left there is a plan form image of the coastline. We have a reference line and then we have S along that reference line in the normal direction and these points, they can move the squares, they can move back and forth. The angle between those points is computed in the middle and there we compute the angle between the waves and the coast and then on the top right we see the launcher transport again in plan form and then below that we see that the profile is supposed to shift back and forth in a uniform way and then the sediment balance is solved and we get this kind of like in the bottom right and we see the coastal evolution as predicted and as observed and you see that we can do a reasonable job of representing that with the classical approach. Now, what is the difference with what we do now? If I can get there. Sometimes. The difference is we just left out the reference line. So we take the coastline as a stream of points but the coastal orientation is just determined by the two adjacent points as you see here and the cross shore, so the seaward or landward movement of the coast is determined by the transports that you see on either side of a coastline point and the normal direction that the coast is moving in is just determined by the direction given by the two adjacent cells and then we solve this relatively simple equation which is the launcher transport gradient we have a term related to relative sea level rise and we have a bunch of possible sources and sinks due to nourishment or sand mining or cross shore transport and we... So this is the same equation again so we have a profile slope that plays a role in relative sea level rise, etc. And if we write this in numerical terms and it's just a matter of some bookkeeping of the transports and the locations of the coastline points in absolute space. Now what is important? So we have a bunch of different transport formulas but they're still... I won't go into the details of those they're still very simple formulas but the last, the important thing there to show is that transport is a function of wave height and wave direction only and it's a maximum at around 45 degrees of relative wave direction. Now how do we represent the coastline? The other nice thing is that we can have an arbitrary number of coast sections including islands and we can just click those on a map or download them from Google Earth or from other sources and we can have a number of polylines that represent the coastline and we also have a bunch of structures that can either block the long shore transport or block the wave energy. Very shattering can take place because of other parts of the coast or because of structures as you see here. So we run along the coastline look at where the waves are coming from and if there's anything between us and the waves then the waves are shielded and so sediment transport goes to zero. This illustrates this so the shadow can be because of the structure or because of another part of the coast. And there's an important part here of the numerical scheme that is that a central scheme will turn unstable when the wave angle gets beyond 45 degrees and physical instability kicks in that will tend to create undulations or even spits and with an upwind scheme as devised by Andrew Ashton we can make sure that our numerical scheme can deal with this. And then we can do this kind of things where when you start with a certain corner in your coast and maybe we can play this video and then you see that this can develop a coast you may be able to see that there's all individual coastline points that are constantly being re-gritted and not only does the spit develop but it also shadows the coast on the right so that there's an erosion happening there. Okay, so let's get back to the presentation. It can also handle islands that can move and that can weld to the coast again if we can play this. So the island develops these spits they grow to the coast and then they can break up again. So this is just a matter of some geometric routines that are called every time step to check what is happening with the coast. Yes, can you go back? So we now have a very interesting project in Senegal, together with Del Pires where a small bridge was made to reduce lagoon water levels in 2003 and this bridge grew to five kilometers width. We can see it on Google Earth if we play the animation. So you see here it started four meters wide and now it's six kilometers and several villages were actually destroyed in this process because the coast behind the barrier was totally not prepared for being on an open coast suddenly. Yes? Let's go back. Now we are asked to predict what will happen how this happened and also what will happen in the future with this. So to support that proposal I made this little animation here very schematic and there you see that the split especially on the south had been diverted by the wave-driven currents and it is shedding these bars and this looks quite a bit like what we saw in the Google Earth movie even though this is just a schematic simulation at the moment we are trying to do this in a more serious way and actually do a quantitative comparison with what has been observed if we go back to the presentation. There we go. So here we have an animation on the left you see a model calibration and on the right you see the observed from satellite imagery you see the observed evolution. Can you see that animation? No, the next one, sorry. Yeah, so what you see here this split is extending to the south the blue line indicates the river keeping that mouth open otherwise it would immediately weld to the coast and you see that this indicates that at least a past situation of before the breach in 2003 we have been able to simulate that quite nicely with this model and at the moment I am struggling to get the situation right after the breach which is quite different again from what was happening in the past and this is what we are really trying to understand why did it behave so differently the next time. Okay, let's go back. Here is another famous example the sand engine or the sand motor that was built to nourish a large part of the Dutch coast while having an interesting coastal evolution and nature values. A lot of research has been done on this area and a lot of model simulations also have been carried out with very complicated models this is how the shoreline asks if we can represent this can we show the animation that's the next one, yeah going very well oh no, we missed the one in between I guess Sorry, I think I failed to upload that No, that's not a problem it doesn't matter just look through the presentation because I have the here you see how the model has done over the first five years of evolution of this system and you see that it is able to simulate this growing of the spit towards the coast and then closing it off and evolving further so let me quickly go so here is the model showing the same kind of undulations as in the original paper by Andrew Ashton so you see that out of small disturbances these shoreline instabilities grow and they grow into large flying spits and these are actually we can go back, thank you so these end up looking very much like the ones we see in nature another case which I which Ahmed did after implementing diffraction in the model is the case of El-Gamil in Egypt and we play that very interesting development and this whole scheme in the end being filled up with sand much as happened in reality yes, let's go back so if we have a lot of interesting topography in the large scale depth like a big canyon then the waves can refract and they can lead to variations in the shoreline I will have to go quickly so this is the case of Paul Bouret where you see this coast orientation looks very weird, you have to find a reason why this is and one of the things is this on the left you see this the dark blue is a very deep area called the troux en fond the hole without the bottom and on the right you see in the colors how the wave direction changes because of this canyon and so where it's yellow the waves turn to the east and where it's blue the waves turn to the west and because of this if you take that into account then with refraction on the top left you reproduce this kind of coastal orientation whereas on the bottom left if you do not take that into account the coast is just very straightened out and isn't represented well at all Mohammed Khomeim has just improved the modeling of groin bypassing in a very nice way on the top left you see what the original screen was doing with it and now on the bottom left you see how the coast is showing very organized way of sand bypassing and let's skip this animation I do want to have some time for discussion the conclusion is now that we have a fun new model and it's a prototype for the next generation coastline model for engineering purposes it's available in open source MATLAB code the address is shorelines.nl and it's great for explaining coastal processes and it's easy to add more processes we are still working on a number of things for instance the coupling with the dune foot was just created by Mohammed Khomeim as part of his master's thesis Ahmed is working in his PhD together with the University of Algarve in Favre on barrier overwashing and rollover we're working on tidal inlet migration Ahmed has implemented wave diffraction and is making that usable for any hard structures and we're looking at the large scale effects of wave refraction together with Bas Haasman and Kaspar Möder and myself and we're happy to be involved now in case studies in Portugal in Alaska with the support of the US Geological Survey in Senegal based on this Nordic fund project and the Netherlands so the conclusion is that we have this new approach the modeling is available at shorelines.nl and it can be done in an interactive mode as I will illustrate with this little video unfortunately I cannot do a live demonstration now because I'm not in control of this presentation let's say I don't have a laptop in front of me but this was what I was doing during a conference listening to the talk so in interactive mode you can just click a coastline like this and you click your right mouse and then you go to another coast section so I'm clicking an island here an island is defined if you close the polygon and then I can introduce some structure here there is just one groin and then I simply start up the model or it starts by itself when you're done and you see that in the simulation we see the groin blocking the sediment transport we see the island deforming and moving towards the coast we see a spit developing so there's a lot of interesting things that are happening and really a lot of kind of coastal situations you can just simply simulate so it's very nice for classroom explanations and for a little practical hands-on exercises so let's... can I go back to the presentation? so I'd like to end up with handing the session over to you and say what would you like to add what cases could you bring what could be the ambition of a model like this and how would you like to use it so I'd say open the floor for questions yes thank you so much Dhanu we have opened the floor for questions now but we have been receiving questions throughout your presentation and I'll bring them up one by one to start off a question from from Rick Avin which wave height would you recommend to use 0.78-H for example if you have a wave propagation using swan is this question clear? yes this depends on the sediment transport formula that you use but most of them are based on the HM-0 the spectral significant wave height and so that would then be what you use and then internally this can be converted into the wave height at breaking but usually in the simulations I showed so far we just use the offshore HM-0 wave height excuse me question from Maya Hussaini is this model useful when sea level decreases like Caspian sea? that's an interesting question so the way we can introduce both sea level rise or sea level decreasing is through the bin rule which is in fact saying that if you have a 1 meter of sea level rise you have 1 meter divided by the slope of the beach so for instance if the beach is 1 in 100 then 1 meter of sea level rise would lead to a retreat of 100 meters everywhere along the coast so it's like a constant source or sink term and retreat would be treated the same way as sea level rise and of course near tidal inlets the situation is a bit more complicated and you would have a source or sink due to the sediment that needs to go in or out of the tidal inlet to reach a new equilibrium okay the next question is from F. Sancho who asks has a comparison been made on the performance slash prediction of shorelines versus classical one line models for example on the simulation of the coastline evolution for the sand motor yes we well of course we did the usual pearl marcon's idea and the standard analytical tests but also the sand model I showed the simulation result Bas Hausmann has done extensive simulations of the sand model with Unibest CL and he got it quite right the only point is that you cannot do this spit development and merging with the coast so you have to somehow start after that has happened and also sometimes you get these instabilities at the coast that in our case we can accommodate but in the case of Unibest you have to suppress it by some numerical means okay question from Jean Lindsay who asks in what way does the shoreline model differ from other models such as DELF 3D and X-beach for example yes so DELF 3D and X-beach are two or three dimensional models so they actually resolve the whole two-dimensional wave and current and sediment transport pattern but they are enormously more computer intensive like the simulation of the sand model for five years takes 15 minutes and it would take like a month on a big cluster using DELF 3D and X-beach so that is really of course they are much richer in processes but not necessarily also at predicting spit growth and so on okay what are the lateral boundary conditions used for example in the Egypt example well there is a number of options you can just fix the coast or you can fix the coastline gradient or you can impose sediment transport rate I think in the Egypt case I think the lateral boundary is probably some distance away and probably just fixed okay question about shorelines I suppose can you upload an image on the background and then construct the shoreline notes by just clicking over the image shoreline well this is something I would love to do to make a really professional using interface for shoreliners what you can do this you can do in Google Earth and you can click the shoreline or you can import it from Google Earth engine and then you just have to manipulate the resulting coordinates to a UTM or local grid so this involves at the moment some handy work anyone a bit handy with MATLAB or used to modeling would be able to do it because in the end all you have to give it is two columns of X and Y coordinates and you separate the different coast sections and then the number and then that's how it can be imported but there is no professional user interface at the moment to do that but it's quite doable to make it I love it when people would make it or really asks then is no consideration for the cross shore profile rate no that is assumed to be constant in time so the shape of the cross shore profiles is assumed to be constant what of course does play a role is the active profile height so in that sense that the profile shape can play a role and that you can play a bit with that profile height for instance a creating profile would typically have a somewhat smaller profile height than an eroding one because the eroding one will definitely take the dune with it but yeah there are possibilities to include cross shore behavior as for instance is done in this cosmos model by the USGS where they take the seasonal variation of the beach profile into account so if your coast is like that which it isn't in Holland but if it is like that with a typical summer and winter profile then you can add a process for that based on the wave height Arash asks here is a question about what you showed in slide 34 how is the backside of the trench developing without current effects yeah that's very interesting so that simulation was done entirely without any current effects and also apparently was not needed to include let's say a migrating inlet in how it keeps the inlet open because already the waves had a very large tendency to make the inlet much wider and then the current did not did not do much so this is an interesting observation in the case where you have the narrow inlet migrating along the coast then this current effect is totally dominating the behavior if you wouldn't have it the whole thing would immediately merge with the coast behind it but in this situation and we're still trying to figure out exactly why the current apparently did not play a very big role Jean Lindsay asks if shorelines can be applied in tropical islands surrounded by fringing reaps yeah that's a very nice Jean to I think in your thinking of reaps for instance I think so of course in this case it is important to have a two dimensional wave model that will provide you the waves as broken and refracted by the reef as so shoreline as does not have that capability but we do have a possibility to couple with a swan or with an own two dimensional refraction model and then when you have the wave climate behind the reef then you can certainly look at how the coast behaves for instance if you have a seasonally varying wave climate then you often see that these sandy islands protected by coral reef how they move back and forth and can be rolled and accrete as a function of the seasons and I think that should be perfectly possible to simulate the next question is from what is the resolution of the wave climate you have been running in other words how long does it take to run one year of daily wave conditions yeah I think the typical it depends a lot on the spatial resolution the time step depends on the spatial resolution to the power two and so 100 meter resolution needs four times smaller time steps than a 200 meter resolution so if we run typically with 100 or 200 meter resolution then your time step is in the order of days to maybe weeks and so it's not a huge extra effort to run daily wave conditions our wave conditions would really slow the thing down but if you take let's say every day you take a good representative wave height and period for that day then that is perfectly doable and for instance Mohammed and Ahmed have been doing those kind of realistic simulations can we specify a given stretch of the coast as non-erosive like in a coastal revetment I hope I pronounced that right yeah yeah no certainly so you can just define a structure that so you just click another polyline or provide another polyline with all the hard points in the coast that will either block the wave propagation or it will block the long-shore transport and also yeah so what you will then get if you have a revetment well obviously the coast cannot evolve further than that but if there is let's say a sand wave coming there is a supply of sand that will be transported in front of that that structure so yeah I'm sure we can refine that process still by gradually making the long-shore transport a function of how far the beach is in front of your your revetment but even in the cool way it is implemented now it will work have we considered bypass effect before filling the fillet back to the groini the groini yes yeah actually this is what Mohamed Komeen's master thesis is about and at least one of the things he did is accurately implement both the partial bypassing and also partial transmission through the groini so in my first implementation here this was not considered but now he has done something really nice and so the groini is implemented much more accurately that code is not yet on the shorelines.nl website but we are in the process of merging everything and it will be there very soon have you checked the have you checked the sediment balance is it conservative if the situation is not too complex then the scheme itself is totally conservative if we have spits growing or islands moving then we need to do some smoothing and the smoothing introduces a mass conservation problem that is sort of inevitable but the trick is to have that smoothing as small as possible but if we can do without smoothing then the scheme is conservative Saber wants to know if the model considers the soil properties not at the moment you would have to include that in some way in your description of the long shore transport or in some sort of what is conceivable is to include like a cliff erosion term but then you would have to add that as a function to the model have you validated shorelines with measured data for instance against satellite images yes well the example where we looked at this san louis case was done against satellite images yes so that is it is certainly possible and what I would like to go to is that we can actually use a lot of coastline data from Google Earth and then use that to automatically set up a model section and do an automatic calibration and then use it to predict the future so we haven't made that operational yet but the satellite data as it is coming in now for instance to the Google Earth engine or the shoreline monitor of that is very useful data to set up and to calibrate a model can it be coupled to a model of a woolly in transport and again I'm not sure about the pronunciation but I suppose everybody else is so this wind driven transport and yes also Mohammed Konin just built in a large part of a model presented by Caroline Frydiction and Magnus Larson from Sweden so we now have a description of both the coastline let's say the zero water level line and there is an EOEM transport process that is in between you could also use the longshore transport derived from shoreline s to feed into a cross shore profile model that includes EOEM transport such as the one that I published this year together with Susanna Kostas so that is a cross shore model that includes EOEM transport gradient and that gradient could come from shoreline s I'll now read out the next question which is from Tu who says that she's looking for a model to predict shoreline changing in coastal Mekong Delta I see it work well on sandy coast I presume she means a model that she's using right now could I use your model to simulate shoreline changing in 5, 10 or 20 years in Mekong Delta the coast is almost muddy it can add sediment provided from the estuaries so yeah it's a he he's from former student I think we have been thinking about this on the large scale it should be possible to but we need to have a different formulation for the muddy sediment transport along the coast but it's definitely something we're very interested in developing also because we're involved in a large project in Bangladesh where the muddy transport from the Mekong to the other estuaries is one of the big issues and I've seen that in principle if you have a good idea of the long shore transport of the mud as we've seen with the French modelers who were involved in this project on the large scale erosion of the Mekong we see that if we take the gradients of that long shore mud transport it correlates quite well with the coastline evolution so I think there's scope for doing that okay the next question is from Jean again can the model cater to sandy beaches with vegetation that includes creepers and tall trees yes and also model inter-galactic travel I I do think of course we do a lot of modeling of vegetation effects in two-dimensional and three-dimensional models what I can see is that so how would shorelines see this if this vegetation reduces somehow the long shore transport so if we can find some sort of reduction factor because of vegetation then we could model that in a simple way but you would have to come up with a formulation for that I'm not aware of existing formulations for both long shore transport due to vegetation but maybe we could do some X-beach simulations with various degrees of vegetation and then define some sort of empirical formulation for it we are three minutes over our planned time but I see that the questions they are still coming in but unfortunately we'll have to stop here thank you so much Dano for your presentation and for your very patient and detailed answering of the questions and thanks everyone for joining in for listening to the presentation for your great questions and comments I'm not competent to provide a summary of this discussion this is not my field of expertise and a large part of the discussion was much too technical for me but what has caught my attention for me the takeaway from this session is something that perhaps we did not get to discuss that much in this session but for me the takeaway is the fact that it is fascinating that shorelines is being developed with an objective that engaged citizens would be able to access it also and the fact that this tool aspires to be open source the fact that this tool is going to be open source I suppose will sort of multiply its usefulness all the more because information will be crowdsourced and solutions will be crowdsourced and that will be good for coastal management I would like to thank again Dano and thank everybody else and like end with this small pre announcement that the next IIT seminar will be September and as to the exact date and the exact topic please keep checking the water channel and the IIT websites and the recording of this webinar will be available later today or tomorrow on the landing page for this webinar so the page from where you came here and I'll type it down also in the chat box channel.tv slash webinars and I can add something that if people have more questions they can of course they can just email me and I'll be happy to answer great, could you please type in your email ID Dano in the chat box or somebody that would be great there is now a message in front of my okay just a second, there it's coming if I'm able to yeah, click this yeah, so it's d.rooving at un- i-h-e.org at net-org one one g okay yeah, there we have it okay, so thanks Dano thanks everyone and we'll see you at the next webinar okay, thank you everyone for coming