I lead the product on the Microsoft side called Azure Cosmos Database, it's a NoSQL database. But today I am here to talk about one of the companies that we acquired a couple of years ago. It's a startup specifically called the Citus database if you have heard of it and we continue to keep it open source and most of our team is supporting the Citus core engine. It is platform agnostic meaning you can run it in bare metal, you can run it in multiple clouds. Just to kind of clarify the synergy of why Microsoft, like Microsoft or my team acquired Citus is to also have the ability to provide the distributed Postgres as a hyperscale service say as first party in Microsoft. But for today's session we will be talking 100% about the technology piece of the thing which is essentially how interesting it is to distribute PG SQL using the Citus engine. With that I wanted to kind of just start off with a quick overview for the, how many of you have heard of Citus here, okay not bad quite a bit, thank you so much. Essentially I think I have spoken or I have worked with the co-founders and the founders of the Citus engine when it became for example part of the Microsoft family but also very passionate group of founders who want to and who are committed to keep this open source and it will continue to be so. There were couple of caveats of how one, what problems Citus was trying to solve and also why for example choosing Postgres as the base to start a distributed, sharded like a distributed SQL engine for extremely real time analytics and fast query pushdowns and enabling at scale scenarios, right. So firstly wanted to kind of call out that the Citus is more like an extension over PG so essentially we will see that any time there is a new upgrade on PG the next day Citus will be supporting the latest version of PG so that is the promise that we provide on the release pages and this will be fully open source and provides you multiple self managed environment setup for PG. Also just if you are curious this logo that the Citus team came up with is to kind of say here will start with Postgres the elephant out there but will bring some magic into the elephant like a unicorn so it is like trying to bring a sharding in terms of various kinds of tables on it. Also wanted to kind of call out where we are and these links and all of them will be provided. We do have for example if I quickly try to take you to two links as we speak and those are your landing links for this conversation today's Citusdata.com and the other one is where the releases are deployed and we will see the latest one is 11.2 and every few months you would say that it is a standard stream of releases and we can see that there and similarly the Citusdata page on getting started the main value prop of distribution and scale, parallelized performance using Postgres as the base storage engine in terms of the way it is used open source and fully managed database service that can be deployed individually and simplified architectures so just wanted to call out on that before we proceed. Setting context here when we look at modern database platform like to think of it as explosion expansion on three pivots one is the data structure itself we started off like decades ago as structured databases and from structured databases and the last 10 to 20 years no SQL databases have come up big time and then the no SQL databases providing geo distribution scale and shard but then query performances are still the best when you say in relational data stores. So how can I get more asset compliance in no SQL base where we transition to what we call as new SQL data stores but then if you look at SQL world of things they have also improved they are also supporting stores like json b and various other kinds of data structures but also enabling query pushdowns and sharding and that is what they call as d SQL or distributed SQL so it is emerging of d SQL and new SQL world and that is where for example Citus engine is providing strong query language in terms of relational database of Postgres but also being able to provide that kind of shard right. So that is the variety of data the other thing is volume of data data is very cheap to store and the compute of the data is what is more expensive but the data itself GBs to TBs to in fact petabytes of data is something that Citus we have wanted to customers and Citus who are using that so it is really the volume of data that is expanding and the velocity at which they are working as well. So starting from batch operations to transactional workloads to real time analytic workloads there is no all of these need data to be accessed in specific formats right. So multiple questions that we asked when and on by the way I am speaking on behalf of the Citus founding team the ones who have been contributing to the source code etc. I joined late personally into the bandwagon so I would like to be more like a messaging folk to that but then the key detail on which is how can I solve problems of scaling out of data performing various kinds of queries on data could be transactional queries could be real time analytic queries could be you know batch queries essentially systems have become what we call as headstab systems hybrid transactional antiprocessing systems and how can you know today's workloads bet on that and the data structure on how you are trying to store the data while these are being said now on which Citus has been built in terms of core benefits of Postgres SQL. So in terms of the you know the extensions has been something that probably is being the singular most important thing by Postgres has been adopted so widely by the community as opposed to forking and setting up your new data store how can I build on and then build extensions on it is something that is being valuable data structure such as JSON B as I said has been pivotal in terms of being able to query and also being able to distribute so a geospatial data so all of those are the tenants rich indexing of course the query and query push down these have been the search index extensions have been the pivotal of PG while we look for example in terms of scale out terms of global reach security components HA that has been built in there is options to have high availability and replicas out running queries and running queries that can be more intelligent integrated etc so those are certain things right. So the other thing is when we look at Citus extension for Postgres code benefits we are looking at four main pieces one is scale out horizontally as we said simplified infrastructure where you can decide the number of nodes we want and then how the system sets up performance and then like literally one day in terms of catch up in terms of the existing PG version support as well. What are probably the key differentiators when it comes to Citus? So today on Citus you can start with a single node for example and in place without downtime you can scale out to multiple nodes so that is an interesting thing and when we say as a single node there are two three interesting constructs in fact just two simple constructs on Citus one is called the coordinator node but today at least everything is piped through a coordinator single point of failure if you have a single coordinator node so to speak but from the coordinator which has the metadata store you have multiple worker nodes where you can decide how your data needs to be sharded and then the worker nodes actually contain the data. So if you have a single node then the coordinator and the worker and all the shards essentially sit on a single node and then you can have scaled out to multiple nodes what we call as shards splits and non-blocking shards splits meaning the incoming queries can be allowed to without blocking any active workload from coming and if the back end shards can be the worker nodes can be split out as well so that is something that in terms of online scaling and the other thing is called online rebalancer these are issues that people see we see a lot for example in the NoSQL world that I am more familiar with for example where you know just the laws of the physics and how your data has to be stored partitioning in a geo distributed space is completely given so your data is sharded now once your data is sharded and you shard based on a particular shard key and the shard key could be a single property or a single value could be a compound key could be a nested key could be a hierarchical partition key where you have one shard key and then multiple other shards as sub partitioning so you have this option all of those are things that you probably familiar or it is there in other services in today out there but what is interesting is this how in an active production workload can you avoid hot partitions or can you avoid shards some of them which are hot while others are very cold and for example you do not have a for example including Citrus and in other databases as well actively you do not have a hot and a cold tier in terms of storage or data and for you to run a query saying run this as a hot query run this as a slow query which means the query can go to a more cheaper storage or the query has to go to an in memory storage like in terms of the query pattern that is not very common if you kind of thing. The other option is actively real time assuming that I have all my data that I need can I rebalance can I remove components from one shard includes data movement and move it to another shard so inside this shard rebalance and distributes shards the old and new shards so the worker shards are balanced and the best part of it is it gives you granular control as you as a DBA or a developer can actually say in fact you can say I wanted to move from this particular shard to another shard one example of that is this tenant isolation so for example there are commands like you can say isolate the tenant to a new shard and you provide that table name and the tenant ID in this case a new tenant has come out in shard four and we want to say that here I want to separate it into an entire new worker node and then have this single tenant into that. So the difference is and in fact if I coming from my NoSQL hat if I look at that there are systems where in this happens automatically while it happens automatically could be a extremely cool engineering problem for us say I talk from Microsoft for example for us to solve to say in a multi-tenanted system how we can do that we actually see a lot of customers saying that hey we want we know our workload the most and so we want to be able to say which is that large tenant that needs to be isolated so systems like site is actually provides the granular control and that is something that is very much valuable. The other thing when I say key differentiator it is like the next availability of the open source PG version that is available will be available on Citus right there. So next we talk about the high level architecture of how the Citus extension works. So essentially a PG client would hit the coordinator node the coordinator does not contain the actual data it contains mostly metadata and also there are something called local tables that you can say it can reside only in the coordinator so it contains fair amount less amount of data but mostly the routing patterns to say which worker nodes have which shard and so it can you know route the request and aggregate the request part to create parallelization so that is the coordinator and then you have multiple worker nodes depending on again the user's choice to say I want to have two three I can even do a four core machine and scale it to six eight core in place or I could be able to you know fork it out and say I want X number of worker nodes. So next when we talk about the coordinator nodes I said it contains node with metadata information typically used for routing so in this case in this sample you kind of see that there are multiple worker nodes four of them here and each of the worker nodes can have X number of shards right they could have various number of shards. Now the interesting question is how is the shard decided and in case of PG for example say a PG a database has some 50 tables. Now all of these 50 tables need not sit in all the shards for example so there is the way we define it for example I would want to just go through a small example here like how do we take an example for example and having sales transaction here so a local table when I say create a table local table is created which has sales transaction ID the customer ID date and amount just an example that we are just sharing and then when we say create a distributed table and then I am giving it the customer ID as the shard key and then I am saying I want this as a sales transaction table so create a shard on this customer ID so you will see that all customer IDs 111 will be considered as one shard customer ID is 112 so all the sales transactions for one particular customer will be stored as a single shard. Now what is interesting is the three kinds of tables I will come back to this but I want to just talk about this so if we understand the architecture there are three kinds of tables this table that we saw here this the sales transaction is what we call as a distributed table that means this table exists in every worker or the subset of worker it is sharded table that is a distributed table and for the distributed table you need to have a shard key on which it distributes typically if you make a query based on the shard key then your query will go only to those worker nodes which have that shard data. For example there are multiple tables but all of those tables have that shard key as the primary key then your query is the most efficient because it is just going to go to those shards in that particular a single worker node or maybe couple of worker nodes to get the data and all the multiple tables which are sitting on the shard key for the respective key ranges will also be co-located with each other so that is your distributed table reference table is a table where you feel that I do not have a exact partition key or a primary key on which I can actually map two or more tables so I want the table to be there in every single worker node so situations where I know that I need the table to be again like a copy of the whole table to be stored I store it as a reference table and for it and the local table is typically the ones that stored in the co-ordinator node for a specific kind of you know joints that you want to do you have some sort of a you know you have a product catalog and you say I have these five items that are always going to be there or you know I want to merge it for a particular campaign and the campaign will go I can store it as a local table merge it and once the campaign is I can drop that local table so that is the high level there and the other thing is how are queries routed so that is what I was trying to just say that a high level when you write any query on the Citus engine essentially so query is typically what we say is we would say we want the query we want the query based on the shard key the query will go to the co-ordinator of the node and then it will be routed for example in this particular case will be routed to that particular shard which has that data now if the query has joints or query has multiple tables and there are two scenarios that can happen one scenario is the shard key is the same shard key in those multiple tables then actually the way the system is sharded is such that only those respective co-located data ranges is actually showed which means you will have lesser number of queries to be made on the worker node two is the option to use reference table or local table so that is one three otherwise the query will actually run to specific worker nodes that have and that is kind of the more worst case scenario or the situation where performance wise it is probably not the case the couple of other use cases in terms of what we wanted to cover in this session one was just highlighted four main use cases real-time data analytics mainly because we say real-time analytics means that you want a better kind of query query which includes some smaller aggregations query includes some real-time data and stronger query pushdowns so it helps to have Postgres engine for that and we see site is better there enabling htap where the same engine can be used both for OLTP and OLAP workloads IoT based elementary systems because of the real-time nature and a lot of so situations which have lot of concurrent needs tend to be better off in this site is because they parallelize workloads better and then definitely huge huge customer base and adoption and seeing in the multi-connected SAS workloads here so when we look at real-time or time series operational analytics in terms of reporting here is so the diagram which is there which is put in a lot of the customers that I have seen which includes a lot of Microsoft based workloads such as you will see data breaks hosted on Azure data break this could be any kind of web app service could be any push notification service like APNS, GPNS, in our case NPNS which is Microsoft push notification server any eventing systems so on and so forth but essentially as you see there is there are two three things that is interesting the site is engine enables what we call as spread out, shard out etc and hence we use the word hyperscale but in the true sense when I say hyperscale you probably want some cloud vendor to maintain that hyperscale for you but there are people who actually take the open source site is to be able to set higher hyperscale clusters also so that is very much possible freshness of data availability durability concurrency all of those are obviously the most important. Choosing the shard key is probably the most important decision in just as we do that in any no-sequel components inside this as well so that is important then scaling multi-tenanted SaaS applications as we spoke about and there are some interesting pitfalls IOT as well just go over that purely IOT workloads and considerations high transactional and critical workload considerations so those are the big things that we want to talk and just to close off today's session in the interest of time is some of our large customers for example open source site is have about petabytes of data sitting through situations where suddenly when we have huge number of workloads like concurrent users 60,000 to 100,000 users something that site is scales there is a site is con which is coming up this week actually April 18th and 19th I wanted to close today's session by saying that these are this is purely based on our open source site this engine and our contributors who are founding that pretty interesting sessions available there things around efficiencies of shard rebalances other extensions on PG high availability being baked and so on so with that thank you. Do we have questions for Sharnia Sharnia so the data model itself needs to be changed from an existing Postgres database to be adopted into hyperscale It's a very valid question Do you see any intelligent solutions being built at Citus which helps in bridging this gap schema migration is not expensive affair or it's not something that is needed 100% when we say moving from relational to no sequel there is an entire data modeling exercise that's needed whereas existing PG to PG Citus there are two kinds of activities needed one is based on what is the main query patterns and whether I have a right shard key on those query patterns and two is how is my data exploding or expanding how what is my elasticity needs and so based on those two there seems to be some tweaks but essentially if you have for example 20 tables on Postgres you have the same you have so the overall all extensions will be equally supported similar foreign key primary keys can be construed so I would say that is that's there but we don't have a ready made tool if that's your answer we have to work on building something the shard rebalancing is that part of Citus or is that part of the cloud service it's part of Citus the latest 11.2 provides shard rebalancing I have two questions the first one is just now it says it has parallel processing so does it mean that if I run a query across multiple shards so it will do an MPP on all the shards so if you do a query on multiple shards it will spin off separate threads and it will run the threads on each of the shards it will reply the coordinator will aggregate back in Respawn the upcoming version on Citus is going to parallelize the coordinator that is not yet available but that's coming up so we are really out of time we need to have our next speaker thank you so much but I'm going to be there here


Good morning and good afternoon, everyone. I'm Abram Abhishek from the Water Channel. I would like to welcome you on behalf of the Water Channel as well as IIT Delft. I would like to acknowledge Maria Laura Sorrentino, who's in the room, who's the driving force behind the series of webinars. And I think it would not be an exaggeration to say that in the past couple of years, we have seen some really unprecedented things. We've had the COVID-19 pandemic sure. But we have also seen a surge of sorts in the frequency and intensity of floods, cyclones, forest fires, and these are what we would call natural disasters because they come from nature. And so the solutions for dealing with them or the strategies for dealing with them or the strategies for limiting diverse effects should be nature-based as well. I think that's a fair position to take. So this is the context, the argument, the pretext for our discussions today. We are most fortunate to have here with us Zoran Virginovic from IIT Delft, who has several decades of experience in the areas of risk assessment, climate change adaptation, and hydroinformatics. And he's associate professor at IIT Delft and holds honorary and adjunct professor positions at several prestigious universities around the world. And Zoran was also one of the driving forces behind the European Commission-funded ReConnect project, which dealt in large-scale nature-based solutions. And I suppose a large part of what we hear from him today will be from that project. So thanks for joining us, Zoran. We really appreciate your time. And before handing over the proceedings to you, I would just like to encourage all the participants to please post your questions and comments in the chat box. We will keep collecting them throughout the presentation and we will discuss them. We'll try to discuss each one of them after Zoran has completed his presentation. So Zoran, it's over to you. I stopped sharing here so you can start sharing your presentation. Thank you very much, Abraham. Thank you for very good introduction. Also, I'd like to thank you to Maria Laura Sventino for inviting me to give this presentation today to participate in this series of seminars. As Abraham mentioned, we are observing all kinds of climate extremes nowadays from too dry to too wet. There are different ways to respond to such things. So one of them is through nature-based solutions. I would like to welcome everyone, particularly those colleagues who are joining in very early hours and also those who are joining late hours. I think we have kind of looked for time in between, so we hope that you'll be able to get what you want out of this. My intention is to give you kind of an overview from two projects, European Commission funded projects. This is Pearl Project, which completed a couple of months before the ReConnect project started. So that's why my subtitle is from Pearl to ReConnect and I hope you will enjoy this presentation. So as I mentioned just now, we can observe almost daily that we in one part we have the too dry periods and the other parts we have the too wet periods. Just maybe these kind of shifts or kind of extremes were observed on a more kind of rare scale. Whereas nowadays we can see these things almost daily happening in some countries, some places around the world. I know for example in Australia, within one season they can get shifts from a too dry to too wet and back to too dry and so on. So that poses extreme challenge for managing water systems because the systems are designed for one series of for example rainfall events that maybe are no longer appropriate or relevant given the trends of climate change. So there are different ways how to respond to that and I will give you my view on this. Just before I start, I'd like to show you some of these University of Louis and that database records would show that the we have this pot shows three kinds of disasters or kind of events that led to disasters. We have biological geological and we have hydro meteorological of course the I don't have the data that we show for example the latest pandemic but on the whole, if you look at the trends, the hydro meteorological disasters are really taking the the steepest drives. And what is what is a little bit puzzling here is that our technological advancements have really progressed enormously. We have, we can see technology and the, the way how we deal with water problems and in general, for example, communication technologies. And many other technology, maybe some construction practices and technologies that we use for construction of water systems have really, really advanced in almost the or the last 50 or 100 years of course but if you look at the disaster events and hydro meteorological, which are predominantly floods. These are still on the rise. So obviously there is some disconnected despite our technological advancements we are still unable to reverse the trend. So this is the trend that we are observing nowadays. And just to give some illustrations in 2013 there was a super typhoon Haiyan or Yolanda in Philippines. I at that time I was in Manila and I was working for ADP on some projects. And I remember when this happened it was a really mega mega event. It took so many lives, and it's brought so much of material damage. So the Tacloban is the area that was hit the most back then, and it also caused a large number of people to be displaced so this this is really. This was an extreme event in terms of the hydro meteorological parameters, which obviously has caused the extreme impact. And if we go to, I'll just run through some of these events that took place on 6 September 2017. If you remember there was a hurricane Irma that took place in the Caribbean. It really went the eye of this big storm and the big system that went through the Caribbean. It went through the island of St. Martin, which is some of you may know it's shared between the French and the Dutch administrations. It really brought enormous impacts to that island to the infrastructure to the houses, a lot of houses have got demolished completely. And a lot of them lost their roofs. After that, and then in the Yolanda typhoon, which is the system called hurricane India in the Caribbean. In, up until 2013, it was regarded the most intense tropical storm that grew into the into the typhoon. So, after that, the Irma. But then after that there was hurricane Dorian, which for which some people believe that this is even new, even even more recent, another record. So these things are happening. As we can see, this was in 2019 constantly. On the other hand, we can recall for example in 2014, there was a bad storm in Southeast Europe and Vulcans, which brought also unprecedented damage to the livelihoods to the infrastructure. And this really came from the rainfall. The storm related rainfall that which lasted for a while, very intense, and then caused a lot of rivers to burst the dykes and to cause some flooding. So again, in the in this part of the world, this was unprecedented demands that took place in 2014. Some damage was in Europe, 3.5 billion euros, some estimate, and the casualties in Europe, several dozens. So, in 2011, I also was, I was in Thailand back then. And, and it was the event that took place over a period of few months. There were few storms that coincided and and crocos the wide scale flooding which is nowadays referred to as great Thailand floods. So that was in 2011. Also enormous damage material and also the in terms of the human losses. So these examples that I just brought and we can find many, many more of these examples. I'm just starting off by, by, by, I want to my point here is that these are the examples of extreme events in hydro meteorological terms, which obviously have caused the extreme impacts. But it is not always the case that extreme events can cause large or significant or extreme impacts. It can be also the small events can cause extreme impacts. And there are many studies that prove that how does that happen. It happens through the cascading effects that you may have a particular event that can cause a physical impact, which can then lead to a certain disruption in the society, maybe it causes damages of the houses people need to relocate it. But then, but then you may also have the water that stays on the ground like it happened in, for example, in Thailand, the water staying on the ground for maybe two to three months in some parts even and that may cause disruptions or outages for the power supply. When the power supply is disrupted, then you may get some other chain reaction problems, maybe certain technologies and systems will be disrupted and then there will be some environmental pollution. And then also it can be some public health issues because obviously the storm water that gets mixed with a with a sewage, and then the two day together can flood the streets and people and get they get in touch they can they can, it can cause public health outbreaks. And then we can then we can track this progress of this impacts further social scientists, often referred to these kind of events that they cause quite significant social tensions people get relocated there is all kinds of issues due to that there is robberies that happen there all kinds of problems that we find. And the other day you also get some economic losses because there's a disruption to the operations, there's a loss of income, and that again has repercussions on livelihoods of people. So, sometimes even the small event, if it happens at the right time and the wrong place to create to create these problems may propagate through cascading effects and cause serious disruptions which eventually may lead into really extreme problems. And it is really our job to look at the these cascading effects and try to quantify how all this works. I can see that some colleagues are raising hands. I'm sorry but I don't think we can, we can have a lively chat here I would love to be able to do that but I think we're going to move on. I would just like to ask you to please put your questions and comments the points that you would like to to discuss in the chat box and after the presentation we'll have a dedicated Q&A session where we will discuss each one of them. So yeah please do that. Thank you very much. Excellent. Okay, thanks Abraham. Excellent. We should also not overlook the other spectrum of these extremes. These are also a couple of examples from Europe. You can see the 2003-2015 heat waves that took place throughout Europe have caused very, very significant damage and disruption and also the casualties. This is not to be overlooked. Now, when we look from the water management perspective, in the past we've used the philosophy of taking the water when it rains as soon as possible from point A to point B because obviously too much of water is causing flooding. Nowadays when we have such extreme periods that that is posing another question. Can we maybe retain that water and then treat it perhaps reuse it and the time of shortages and do something else with it. To be able to explore this kind of question and what are the possibilities we need to look into some other kind of measures, not the traditional ones, but really going into more towards some blue, green infrastructure and what we nowadays call as nature based solutions, but I will come back to that. Some more examples where the studies which show that the European, for example, critical infrastructure is really under big threat from heat waves, droughts, floods and so on. As you can see the baseline, which was a few years ago, then you have 1920s how it progressively goes the spectrum of this or the colors go towards red. And then if you go to that to 2050s, 2080s, then you can see really that the European critical infrastructure is great danger, because today it's not been designed for these extremes and be due to cascading effects it may cause a lot of problems to the population. So all of these is really requiring us to look at the how do we respond to these challenges to these extremes. A pathway, I would say this is my view again, and I'm here presenting some of the findings for the two European Commission projects which I'm leading the reconnect and I've also led the Pearl, where we were. Yeah, we've had a number of researchers looking at different types of issues concerning this particular challenges that I just brought up. Our view is that the pathway to resilience is to understanding hazards, and here I'm referring to hazards such as rainfall events, for example, and the change due to climate effects, then the coastal systems also understanding So it can be either that we're looking into the sources coming from the coasts from the rivers, or maybe from urban areas where the capacity of the drainage system cannot cope with the rainfall. So these are what we like to refer to as hazards and then further understanding of hazards is really, really, very important in order to build the resilience and when we talk about resilience we talk about the measures which can reduce vulnerabilities in areas where the critical infrastructure of course where where the people live but then also where the critical infrastructure is, and so on. Then another one is the minimizing exposure and by understanding hazards and working towards reduction of vulnerabilities and minimizing exposure which means we do not develop an urban plan where we are developing new areas and put the people right on the floodplain, because they're obviously asking for trouble we tried we need to expose, we reduce minimize exposure of population, as well as the critical infrastructure to those areas which are known to be prone to flooding for decades, if not centuries. And then another response below that is developing sustainable measures. I mentioned the two projects and I'm going to be showing some highlights from these two projects. The first one is the Pearl project and Pearl has dealt a lot with understanding of hazards reducing vulnerabilities minimizing exposure and to a certain extent it opened the question towards blue green infrastructure which is nowadays referred to as nature based solutions, and then the second project reconnect exclusively deals with the nature based solutions. So, Pearl preparing for extreme and rare events in coastal regions, this is the website which is still operational, and you may go there and find some information if you wish. Our very brief is run through this project and then come to reconnect. The research focus of Pearl was on hydro methodological events on a holistic view of risk. What is a holistic view of risk is really looking at the various processes that may take place in the social domain, technological domain and the nature related domain and how these interact. Example of that is that for example that the a particular event hydro methodological event that comes from the obviously the nature related processes sometimes can be human induced, but that event can cause a certain response by society and then that response by society will maybe demand a new process and then the new technologies that are developed will maybe drive the way how the society behaves because of the developments of this technology I mean classic example is the development of of our what used to be called mobile phones now their smartphones and how these things have have revolutionally changed our lives and how we live. So there is a constant interaction within the social domain technological domain and the natural processes and in the holistic view of risk we would like to capture all these three aspects as much as possible we can never be exhausted to capture everything but at least the key processes so this is what you addressed in the in the research in one of the research focuses of Pearl, and maybe the best I could, I could, I could point you to maybe one of the best examples on how you can capture different aspects of society technology and the nature for the disaster risk management in the form of modeling systems is the, is the PhD research of, of Yaret Abebe, who just graduated at the end of last year in December, and he got his cum laude and for which he's got also now the medal here in the Netherlands, because the committee who has looked into this kind of research would have thought that this is a great work and obviously he has done a great job by developing and combining different kinds of models there so Abebe is the, Yaret Abebe is the man, if you'd like to read his papers about this or his thesis, but then multiple hazards, the project looked into multiple hazards and especially those coinciding because you, if you have a river running through a city and then goes into the coastal system, it is always the interaction it is different water bodies causes the problem, and then traditionally we have organizations which are looking after these systems to be in operating in silence you have urban water or municipality or water utility who is looking only after the pipe network systems and you have maybe another utility which looks after the river, and then another one which is looking after the coastal, ports and coastal systems there. So now when it comes to a large scale flooding, then it's different to separate to differentiate who's, what is the exact cause for the problem, for the flooding so then you really maybe need to set up let's say a numerical model for all different water systems and model them jointly so that you can really understand what what is the problem so this is what we refer to the multiple hazards and particularly those coinciding, then multiple vulnerabilities. I would hear maybe point to the work of Naylor Medina Penner, who just graduated few months ago PhD again from TU Delft here, he worked with us in this project and he's also produced some very interesting aspects on how to look into the vulnerabilities and how to capture those that are related to the societies, and then of course it comes the combination of measures. Very briefly holistic view of risk we are looking at as I said social system or socio technical system that Professor Mike Abbott would say, and then, and then how the, the nature works upon the system. And as a result of that you may get risk that may go up or down depending how the society reacts in the in the form of responses and the measures. So, again, I would say Yaret's thesis would be very good lead for those colleagues who would be interested to learn more about that. It's not very abstract and conceptual but if you go into the into the publication of a better you will see that the way how we managed to put all of these different models to to operationalize or practicalize this conceptual, which may look similar to what you're seeing conceptual description multiple hazards I just said the coincidence between coastal river and urban floods. And then in the project we have looked we combine different kinds of models we have started off with the climate models we've used the atmospheric model from University of Cambridge. We've used the College London fluidity storm surge model and then we've also coupled the with various dhi models wave models one, and so on, in order to come up with the estimation of hazards. We did not manage to link all of these models at the time step, so that the time step this models can exchange the data and information but it's rather kind of in sequence running one, providing the boundary condition to the next model and through the chain of different models. So, this is just a snapshot of the of the University of Cambridge model that we've used in Pearl which which is one of the very sophisticated models that uses a flexible measures and it can capture different changes of the regime or the floor regime in the So that model has been used to model the atmospheric processes which creates forcing to the coastal systems and then the coastal systems and let's say pipe systems or maybe river systems interact. And then you have further propagation on what may become floods. In the pearl project we've also this is an example of that that of the model that was used to simulate the effects of the hurricane Irma. As you can see on the, the moving path shows the other pressure in the windfield of the system and below you can see the water levels in the particular region of St. Martin and the other one and then also we've looked into the basically triggering tsunamis because the working in the Caribbean along the Caribbean region and where the particularly with the same Martin is in the north for some matter not far is the Caribbean plate so the Caribbean plate can also cause disruption in the form of tsunami so we've also model the tsunamis that is then that's what you see in the screen on the left side that runs. We have in this project we have looked also in modeling very fine physics and in coupling the, not only the 2D models but also usually not only 1D and 2D model but also coupling these models with a three dimensional models to see if there is really that we are gaining something more with with modeling the very fine physics and using the third dimension, as opposed to using the standard, maybe 1D or 2D models. So now the one of the findings was that that depending of course on the on the local settings and configurations. Sometimes that advantage may not be significant. In some other cases that's advantage of using a 3D model maybe significant but on the other hand, that may be an issue with the computational time if, if we want to use this model for the real time operation and then we have looked also in the in the data conventional like the data, I would refer you to the PhD of our colleague mess look from Thailand, who has looked into the structure structure for motion technique that can be used to filter the lighter data typically we use the lighter data to set up two dimensional model, but then if the resolution is not good and if the depth. The model does not capture that the details such as fine openings that maybe the light that will not be able to detect, then you need to process your data by, by the use of some other techniques and what my soup has done is he has used the work with my suit is used the structure for motion technique and he has managed to get some very nice results and you can see the the difference between the lighter, the model to the model results using the conventional lighter on the left side and the 2D model results using the structure for motion technique filtered, which has actually filtered the lighter data and you can see how the pot map can be significantly different. So, then I will show you a little bit about the cascading effects where we have done that actually multiple hazards, this is the other work that we have done in poll we have done that for the case of Bangkok in the area, which is the quite busy and economically important part of Bangkok, but it is the area which floods very often. And, and what you see on this, this screen is the multiple hazard analysis in the sense that typically has obtained from the water depths velocities, and maybe durations of floods. What you see here is that we have also incorporated the E. coli concentration of bacteria pathogens in the, in the flood water. And then if you really combine this information you may come up with totally different hazard map, as opposed to the map that you may develop only by using one variable like a flood flood depth. So this is just to show to illustrate that the hazards, they have multiple dimension, and typically the data that you need to use to analyze the hazards is the water depths water velocities, the duration, and also maybe the concentration of particular pathogens. As part of that work, we have also looked into the quantitative microbial risk assessment, advanced that methodology by the use of numerical models, and, and looking into the flood water quality. And this is an example from the, from Denmark, grave, which you can see on the left side the calculated water depths and on the right side you can see the, which is basically a sewage dilution. And then you can from these different maps you can you can potentially look at the different measures that you can apply if you want if you're concerned on one hand with the flooding and on the other hand if you're concerned with the public health outbreaks. So, we move further, just couple of snapshots of the risk cascading it because I mentioned before that a small event can lead through the cascading effects for very large or substantial, if not even extreme impacts. We have also done analysis for the case of the secondary Bangkok so what you see on the left side is a DTM with the buildings, and on the right side to see the flood map for that area, using one of the events. The idea here is that when you have, let's say intermittent water supply in the city. And if there is a significant leakage that that may occur in the city like this case in Bangkok. Then maybe when you when you stop supply of the water, and then if there are some openings or cracks or whatever legal points where the leakage occurs. Now there is no pressure that there is no water that pushes the flow through the pipes, then the external forces coming from the rainfall. So, for example in the rainfall, like in Bangkok it's a combined sewer system so it's a rainwater mixed with the with the fecals with the wastewater may enter to your system, then when it gets into your water supply system then you have another problem, totally different then you may need to do a totally different kinds of measures, compared to the other flood related measures, but this is how the cascading effects can propagate. On the other hand, you may also have some electrical fitting that maybe is vulnerable sitting low on the ground. And then when it gets in context with the water it may cause outages or outbreaks with the with the problems with electricity. And then in places like in Bangkok where it's which is a 30 plus degrees. When when the food needs to be refrigerated then you can imagine how if there is a cut in power supply how this can go. And so on and so on you can try and then also there's a traffic disruption because you have high water levels. So the, we have done all of that. And I'm not going to go into details how we quantify these different impacts of the different risk cascading events that's published in the in one of the journal papers, our colleague Jeffrey Healy, in the MSC. He also managed to produce nice paper publication out of this, and it was published by the MDP in general for water. So it's a Jeffrey Healy methodological framework for analyzing cascading effects from flood events and the case of water in Bangkok for the vulnerability assessment. I mentioned that the we need to try to reduce vulnerabilities so that we can increase the resilience because resilience and vulnerability are kind of two faces on the same coin. If you increase the resilience you will reduce vulnerability and the other way around in the in the area in the domain of vulnerability assessment we can identify different aspects and they range from physical, which is a physical objects. Of course we can look into the social, which is the people who lives in the exposed areas is it's the area where you have several rest homes and the schools of obviously this the very vulnerable segment of our population, or maybe people who don't have access to insurance. That's another aspect. So whatever the case is you may you may identify social systems, you can identify physical systems and physical infrastructure and material objects and everything else. You can identify cultural objects, which may have a totally different value, like a heritage sites, spiritual and then so on religious. So that that's another aspect then you can have an economic sector, which obviously will has certain vulnerability or resilience to such events to restore their operation. And then you may have also institutional so all these different aspects you need to somehow combining to one big soup, which may be called vulnerability, and there are different ways to do that. I would like to refer you for those colleagues who might be interesting to see how did we address that in this in this easy funded project is to read some of the papers from our PhD graduate. And this is one of his papers that was published in the general system in MPI by MPI and it's assessing socio economic probability after a hurricane so he did this work for the case of St. Martin. Now talking about the flood risk and reducing flood risk, you can also when we start looking at the measures, we want to try to find the measures that that can be multifunction or multi beneficial in a sense that not only those measures that can that can minimize the flood, which is obviously very relevant I'm not trying to undermine that but it's also good if you can find a combination of measures that can also bring benefits to the some other types of hazards such as heat stress. So, we've looked into the flood risk and combining measures that can address flood risk and thermal comfort of heat stress. And we have done that again for the case of Bangkok because obviously they are the heat is one of the issue, but then flooding is another issue. In this work we have done the micro kind of modeling with fluid dynamics dynamics and other aspects we have also we've done measurements along the streets and look into this green green blue infrastructure compared. What is the temperature in these areas with the green and blue infrastructure such as nature resolutions are as opposed to those areas when they are not present. And then, and then we try to derive some kind of prospects for application these measures. If you would like to read that. Then, then I would refer you to the to another journal paper by our colleague Abdul Nassar Majidi who completely his MSC. And the paper that he has published out of that is the planning nature based solutions for urban flood reduction and thermal comfort enhancement so it's. He's looked into these different aspects and how he has even done these measurements in the field he has been going from street to street from different areas close to different parks and different water bodies measuring temperature in order to come up with some ideas on how to create nature based solutions that can be not only effective for flooding but also that can help the eternal conference in those areas so this is the the work of Abdul Nassar Majidi from Afghanistan, very good work and the work is published in the Now, I'm moving now towards the kind of the responses and nature based solutions. The traditional response to the, to the, to the storm water management to flood management in general is the great infrastructure, which is nothing other than this presentation is not to disregard or to to to undermine the value of great infrastructure but he's rather to say that we have to look at the combinations between the great infrastructure and something which is more towards the natural systems and nature based solutions. So the great infrastructure if you look at the pipe pipe has one kind of needs one discipline to be designed it's a hydraulic engineering you just design a pipe and look at the way you want to late and after the construction it's operated by a water utility. And you don't need other disciplines for that. And that's that maybe stride forward on the other hand, if you move from gray to green. And if you apply the concept of building with nature which incorporates the ecosystem services looking at the multiple benefits. And hence, and making it also more flexible and responsive to climate changes, then you need to really, you need to have a number of different disciplines. And these disciplines range from ecology biology, of course hydraulic engineering but also the economics, social science, and so on and so on because the number of stakeholders is enormously growing up. And that's the way designing gray systems towards the nature based solutions, very briefly sustainable solutions and evolution of terminology in 1970s low impact developments in US was a term introduced then in 1980s, best measure practices again in US, then in 1994 you have the water sensitive which is the Australian term for all these terms that you see here they're more or less depicting what nowadays passes under the name of nature based solutions. So you have in UK SADS sustainable urban drainage systems green infrastructure, nature based solutions term coined by the IUCN and adopted by the European Commission ecosystem based approaches eco DRL disaster risk reduction blue green infrastructure these are all terms that the interchange we use to describe the less nature based solutions you can find that in a paper that we published not too long ago by our MSc graduate but now PhD researcher within the reconnect a lot upon Rungpan from Thailand. And the title is a nature based solutions for hydro methodological risk reduction, a state of the art review of the research area. So there are different definitions of nature based solutions. This is one of them. The European Commission defines nature based solutions as actions inspired by supported by or copied from nature. So basically using natural processes trying to mimic how the, these processes operate, and they aim to address a variety of social environmental economic challenges. They define nature based solutions for different purposes such as urban regeneration and so on and so on, but also for water management and flood mitigation is a classic example. It is important to emphasize here that nature based solutions to heaven, a particular measure that can classifies nature based solution. As described by European Commission, it needs to fulfill multiple benefits so it's not, it should not only be efficient for the water management such as flood mitigation, for example, but also needs to bring benefits to the nature. So maybe enhance the biodiversity. And then on the other hand also needs to bring benefits to the social to the society in the communities. So only then if you can, if you if you provide this multiple benefits then you may. consider that that you're dealing with the nature based solution. And there are a number of SDGs that nowadays you can find that the nature based solutions contribute towards. As I mentioned, you really need for successful implemented design and implementation of nature based solution we need a really, really effective work between different disciplines, if not trust disciplinary way of working. As I mentioned people from different sectors from different disciplines, particularly because when it comes to design design is not only from the hydraulic perspective water management but also from the landscape architecture perspective because we're dealing with the systems on the ground, we are not dealing with the systems below ground such as putting the pipe under the ground we may not need any inputs from a landscape architect but here we are talking if you if you take for example a big pond. And then you need to do that that maybe serves as in dry times for another purpose and during the wet times. It will serve for flooding. You obviously need a landscape architect to help you with successful design. Nature based solutions are typically divided into two classes. One is the small scale in the other is a large scale, small scale or local or urban scale examples are green roofs swales porous payments. And so on and so on because these are really the measures applied at a small spatial scale. They can be applied numerously in many locations which collectively can create a large scale impact effect but they're typically installed on small in small areas. As opposed to that we may have the large scale nature based solutions, which are rural natural or watershed scale. These are the example of these systems are the afforestation or reforestation maybe large ponds or large, maybe type of measures that you can do along the rivers, maybe bringing the naturalizing the rivers in the sense of opening and bringing more space for the rivers when when they expand so that they can flood and receive back, maybe wetlands and so on and so on. So these are some of the examples of a small scale this is the the nature based solutions green roof maybe vertical garden. The effect of green roofs vertical gardens is to is the flow attenuation so when it's when the rain falls and then when it gets into your before it gets into your system. It will be attenuated the people will drop and we delayed which helps the system. So this is, this is to say that when you have a combined system. I mean a hybrid system between the nature based solutions and great infrastructure. You may help a lot the function of your great infrastructure by having this kind of installations like green roofs or rain gardens or vertical gardens where you can really attenuate the flows so that you can so that your great infrastructure system can operate more effectively. This example of the rain gardens in US which apparently are also good for the bonding of the society of the communities this is a I like to show this nice, nice project design the big you project in the lower Manhattan. So this is the using the nature based solutions of different kinds and planting different kinds of tree that has really special effects towards the coastal system and storm surges and waves that may impact this part of Manhattan. This is an example how the that that same area can be designed during the dry days so that the area is used multifunctionally so you can use it for different purpose and then when it rains, then you still have points that people can go from A to B without being significantly affected and when it dries out you are back to your other purpose. So this is that then you may find another interesting system which I also like to show which is in Thailand. In Bangkok Chulalongkorn Park, which used to be a big area which has not really had much purpose but then they turned it what they like to say the largest green roof in the world, but it's not only the green roof there it's also there are other smaller scale areas which are the areas measures which are fitted into this area which collectively try to mitigate the stormwater runoff and and deal with flooding. There is, there is also something that we have done the work in in Thailand, in the Ayutthaya. And I'm not going to go through that. Another example I'd like to show is in Korea. It's a very good example I was there just before the outbreak of Corona in 2019. This is the river, this is the river of the water cost in 1970s, which was really box calvated underneath this this road. Then in the beginning of 2000 they started to break this road to remove this, I would say not very nice appearance, and they, this is how now, how this area looks nowadays. So this water cost has been opened. It has much more capacity in during the time of floods. And also it has a very, very significant value for the local population they say when the people who go there during the hot periods they say that this is cooler for maybe four or five degrees compared to some other areas. So we'll have to go there. So this on the left side is how this this area looked like in 1970s, during the construction in the middle and nowadays, even the real estate and property values have gone considerably high in this area, due to this revamping and sort of improving. So this is another example of a nature based solution that can be how it can be done. And I will maybe show one more example. This is an example I received from our colleagues from Rambo. And colleagues, it's the Bisham Park in Singapore. I don't know if there is anybody here from from Singapore joining on this call. So this is this is the area where the Bisham Park is located with a red circle in 2008 for example this is how it looked like. And the Kaling River was passing through some lined channel, which was not as nice as you will see in a moment how they turned this area into any was not even effective in terms of the flood management. So now in 2012 what I've done they've reshaped the entire area with a lot of hydraulic modeling but also landscape architecture design options and this is how it looks nowadays so the water does not run through through that line channel but instead it goes meanders and then there is a large area that allows flooding on the left side here you see example how this area may look like on a dry day. And on the right side you will see the same area how it looks on the wet day so when the when the high flows are so again people can go across from this from one area to another and it's a very very appealing to the community today it is not only for flood protection but that's also is a site for innovation development that do a lot of research there will apply treatment. As I said research education and urban agent by the way so it's also landscape design it's a really wonderful example of how the nature based solution can be designed very effectively. And it's I'm finishing now the the you will now find there are many investments in research projects related to nature based solutions and a lot of funding has been put into that you can find the projects of different kinds, maybe in China it's this is referred to a sponge city program and so on and so on I will I will quickly mention we have managed to obtain the reconnect project which stands for regenerating ecosystems financial based solutions for hydro methodological risk reduction. It is the project which is worth about 40 million euros in terms of the, the, the, the value of works, looking at the construction and the contribution from the commission is in the order 40 million 35 plus partners we have a number of demonstration cases. This is the map that shows where we are demonstrating different kinds of nature based solutions and what we are doing there. In some places we are constructing them and then monitoring in some places they have been constructed so they're just monitoring. So we are populating the evidence based on how these systems operate. And we are really trying to be critical, not only to preach and look how good they are but also to look at their drawbacks and try to improve design and everything else. We are looking at the benefits and core benefits. Really, for this measures and we are looking at this an example in the, in Denmark, you can see the large area, which has been designated to be to act as a pond during the wet periods and drive periods it is a dry area. It protects for example urban area on the right side. This may look like a very, very good design from the flood management perspective, but this, this same design has some other issues and the issues are more ecological. The fish that go through this watercourse trout, they, they often get lost during these kind of events when you have flooding, and then the fish comes out and start swimming there and when they say it dries out you have a high fish mortality. So from the flood or hydraulic engineering perspective it is a very good design because you don't get flooding of the nearby urban area, but ecologically and looking at the ecosystem perspective. This is not very good and this and what we are trying to do in this project is maybe to think about some options how this can be proved. And we're looking at the biodiversity enhancement with these measures and also social well being we have also the colleagues from the medical school of University of Exeter, who are looking at the how these measures can have positive impacts on psychological aspects of humans. So, if you go to the website of reconnect you'll find the demonstrators type a which are those that we are constructing during the lifetime of the project and then demonstrate this type be which have already been constructed. And we also have collaborative cases all around the world, which are looking into this demonstration cases a and b in order so that we can replicate and upscale these measures into the collaborative cases. We mentioned there that we are not only looking at the bright side of these measures but we're also looking critically to evaluate how they function and what could be the challenges. A paradigm case in this in this project is the Dutch case demo case room for the river program, which took place for about over about 15 years it costed 2.5 billion euros at 39 different locations various projects have been done in the Netherlands. In this project it considered the number of different measures, such as a river restoration measures and other types of interventions in the order of maybe one to 200 different measures they've they've looked at and applied. This is an example from the city of my making when you have a parallel channel running to the main river channel. This is on the dry day when it get flooding this is this is how it looks like, but with no damages to the population to the housing to any of the infrastructure this is an example of the nature based solutions, a large scale application that you can do along the rivers. And this is some photos recently that I took when we when there was about two months ago there was some flooding that occurred in Germany, Belgium and the Netherlands and I would I would like to say that due to these measures that we implemented within the rule for the program, which is the nature based solutions measures, the Netherlands had the least impacts, and the Netherlands is downstream from these countries with the high flows come all the way from Switzerland and Germany encounter the Netherlands. And also for the river moves comes from Belgium, the minimum impacts have happened in the Netherlands and you would expect because of being downstream. But not it's really due to these interventions. And these are some of the pictures, and I'm not going to I'm not wrapping up this project if you'd like to go and see what we've done in this project you're more than welcome. Reconnect dot EU is the website. We looked into different indicators how do you measure if efficacy of your nature based solutions indicators in the water domain nature people. We are developing methodologies how to evaluate how to address these indicators for the water nature people. We have got a number of study paper publications you may you may want to go there and download. We also tried to have some reports soon that will be available not yet but sooner be there and then we also looking at the at the platform, and I'll show you, we are we are we have a real time monitoring platform, which is not publicly available at the moment but very soon it will be available where you can go there and and you'll be able to see different sites that we are monitoring you can see this example of dashboards for monitoring of nature based solutions you'll be able to go and let that say to the Netherlands or to Germany or to France or to Italy, for example and where we have these nature based solution sites, and then you can see rainfall flows, maybe cameras streaming the pictures 24 seven. And also some analytical tools that we plan to install, which will help us to critically evaluate how these measures work. And then last words, we, we are working on the upscaling this measures we work with a number of collaborating cases in around the world. And as you can see from the, from the website if you go there, we are really looking at the how to address the barriers, because there are these measures maybe very appealing but to us as a water researchers but if you go to the municipalities and local water operators you may find that they are actually still preferring the traditional gray infrastructure and there's still a lot of work to be done to overcome the barriers which maybe not only kind of address to the raising and bringing the evidence base, but also to some policy adjustments, governance issues financial economic because these measures, it was nice that Netherlands spent 2.5 billion euros but not every country can afford to spend this kind of money. So that means that we need to look also for the financing and business models, which can potentially attract public private partnership combinations, when maybe private developers can be also incentivized to work towards these measures. And so that they can they can create a revenues we're looking at this aspects very effectively in this project and then you will also if you stay tuned and follow our website you'll be able to to get some results. So, the last slide, I mentioned a pathway to resilience to disaster and climate resilience is through understanding hazards, reducing vulnerabilities minimizing exposure and I refer you to the pearl project. And on the other hand, developing sustainable measures such as nature based solutions and I would also like to refer you to the reconnect website. This is the page. And I would like to give the, this is my last slide credits to the Pearl project partners and associated researchers. We had a 24 partners in Pearl and also for the reconnect colleagues we have in the order of 3435 partners in this project. So thank you very much for your attention I'll be happy to to try to address some of the questions that you may have. I may have taken a bit more time around. I'm sorry for that, but but I hope we can manage some questions. Yes, definitely Zoran it's all, it's all contingent on how much time you have here after. So thanks a lot for the presentation which was at once for the informative and especially because it had so many examples that you used to, you know, sort of illustrate the, the theory behind the NBS that you laid out in the initial part will move quickly to the questions to make sure that you can address as many of I have, I certainly have time for 2025 minutes. So if you're asking me do I you said that depending on my availability. Yeah, I talk for 2025 minutes, I will be happy after that I have something else but 25 minutes no problem. And that's it. So let's quickly move to the questions I will unshare your screen so I can share the list of questions that we have been building up from our side. Yes. So these are the questions I'll read them out and then you can, you can perhaps address them. First question we have is from Henrique Clouting who asks how can these models and data support integrated city development concepts and create capacity of city planners in implementing NBS. How can these models, they can be very effectively used. And what they what what is required is a close cooperation between different departments you have a water management department you may have a special planners you may have the other important environmental protection agency perhaps or somebody else. They are very effective and and from our our dealings by setting up these models running different scenarios, obtaining different results. What is possible to be done is then is to bring these different stakeholders around the table and show them the impacts of how things can be done if they are doing if they're working silos as opposed if they're working jointly and you can use the models to effectively demonstrate that. And what we found, for example, in case of Pearl but also is in some other cases is that these models can brought people have made people to realize that without close cooperation we cannot develop sustainable measures of measures. So I would say this measure this models and the results can be used to effectively communicate the impacts of working in silos, as opposed to working jointly. And then this may open up more closer cooperation discussion between different stakeholders, which is our experience. So, so, so this is one example. Yeah. The, the next comment is from Abel Imardaj, who says thanks Zoran for a great summary of nbs for resilience and managing disasters with the Bangkok study look at cross contamination from sewers. Also are there any examples of nbs for bushfire risk and landslips landslides yeah in terms of the Bangkok yeah well we've been looking at the water quality the flood water quality and the mixing with sewers and looking at the pathogens we've had students taking the samples from the manholes and addressing that very closely there is we are preparing one publication now we've had a stream of students looking at these issues so that's been looked at unfortunately we don't have publication yet but we're working on one now. And the other question about the bushfire risk and landslides landslips I would say landslides the we don't have really for the bushfire risk but we have for landslides for the landslides we have the our key case in reconnect is the Portofino area in Italy. So, we do have, we do have one, one general publication which is now being produced and which will show what kind of vegetative measures and cascades that can be applied to mitigate the landslides. So, so yes we are addressing not only the other, the rainfall induced flooding but also the landslides as another type of hazards, and it is our Portofino case in Italy because we have steep slopes there. Yes. We have a comment from someone who's anonymous so many tools examples and institutions but what are the best examples that prevent disasters, including both climate induced and man made in developing countries it will be worth to learn and build on that for a country like Nepal. Well, you can find different examples it is really not here to, of course, you may find different challenges when you deal with the countries which have a less economic development and less potential for investments of course. But there are good examples. I would not pinpoint one or two now but there are good examples and certainly we can learn what the examples that I brought, maybe I'm not necessarily falling to that category, very developing countries. But there are the lessons learned here that we have, we are deriving from, from these cases can be used to bridge some of the problems and be more effective in the developing countries. Very cool applicable. Yeah. The next one from AK and Ibrahim is, there are a few events such as lowering groundwater levels that could be that could have happened because of both human actions and climate change how can you differentiate the impacts of human of man made disasters and climate change in those cases. Well, the typical example of man made men in Jews disaster would be that the you have, and you can see it, not only developing countries you can see it very much in developed countries and I would not also like to pinpoint but there are many places it's basically common case where the around the world irrespective to the developing developed countries is that the other planning people the spatial planners, they often go by by certain needs to develop economically develop certain parts of the area of urban of the city, and they start developing housing on a floodplain. And this is a human influence the disaster basically because if you if you put a housing on a particular area which is always known to be flooded. Now you put that the solution of the flooding to the flood engineers. I don't think that there's a magic that they can do to mitigate that they can they may reduce the limit with the various measures but you will not be able to make it flat proof area. So the example of, of how. So you have a nature related processes, which is, we know what they are, but on the other hand you have a human related process, and I would see here really pinpoint the the spatial planning, where do you develop area. The question of where to expand the city and to which extent needs to be done with a with a storm water managers with a with a flood managers who need to have a big saying that because if the spatial planners just go ahead on their own planning on the basis of the GDP or whatever economic growth that they would like to enhance or improving the city without consideration of this, or these other aspects then of course we ask it for a trouble. So the main thing is, I know for my projects working in, like, for example, send Martin if you if you build a house or block of houses right on the shoreline which is very nice to oversee the sea, and then start your morning by having a coffee by the then when you get these hurricanes, for example, like like Hurricane Irma that happened then you are, then you need to really bear for the, for the impact because, again, planning regulations, we need to have more strict planning regulations everywhere, and look, and the details of this plan is reporting regulations need to be made on the basis of these kind of studies like I've shown now in Pearl and also reconnect and then if you say this is really high risk zone then you really need to provide the regulations that people, for example, need to build with certain materials housing and roofs with certain materials, not with any materials like I said Martin and that was a major problem the building regulations. Actually they are the building relations that exist but enforcing that people comply in those mechanisms, these mechanisms to enforce that are not very, very good so therefore you have people building with the soft and very weak materials and then of course we have these events, there are major problems, but yeah it's a planning and also regulations, building regulations are the key aspects that we need to influence with our work, yes. Yes, certainly happens all the time in South Asia, which is the part of the world that I come from that there are regulations but they're not in post prime real estate is developing floodplains and then people are surprised when they get flooded. Sayed Rasekhuddin asked, when you were presenting the slides related to the leader analysis, is there possibility for PhD to conduct this kind of research, I'd like to respond to that. There is always a possibility for PhD research, I referred you to read a thesis and publications by Borovit Mesuk who has, and also another one before that it's the Fikri is our colleague who from Malaysia from Kuala Lumpur. Yeah, so these two thesis would be examples but then now is there a new PhD of course, if you would have funding to do that, we will certainly I would be very happy to lead this research further at the moment I do not have funding in the Connect project I have funding for I've had funding for three PhD studies and all three have been occupied, so we have researchers in the places. So, so as far as I cheese concern that my team is concerned we don't have the money there but we can look for another fund and like the technologies and processing like the data for flood management is a very hot topic. There is plenty of possibilities for the to define a new research topic. Yeah. The next question is from Dr the nature Prasad saying who says the entire globe has realized the importance of NBS to various issues related to water sector after after the covert 19 pandemic, but we are not able to popularize especially developing countries what are the reasons for this and how best we can address this issue. Yes. The issue is not really. Okay, I understand in the developing countries but but also, I would say worldwide, not only limiting to developing countries. No matter how much we as water professionals realize that nature solutions are the way to go, because you can get multiple benefits they're also good for climate change and climate mitigation as well if you talk about our forestation as a CO2 dealing with CO2 missions and all of that. So, they're not only good for climate adaptation, but also for mitigation, but that it comes the the traditional mindset. People are much more, I'd say, much more much easier convinced to live to live they feel kind of they're more safe in the areas where there is a let's say a dyke. Yeah, the traditional grave, for example, a dyke. So they be, they'll be more protected as opposed to if they live next to a wetland if you tell them no no no we can create the wetland because the wetland can do this and that and that but also can be efficient in a flood protection. So, so, so people still believe that the great infrastructure is more safe. So what we need to do, we need to do a lot of raising awareness amongst the population and very much amongst the water professionals. And to do that, we need to build the evidence base. So, so how do we raise the awareness we go with the results like what we're doing we reconnect we have the, the open layer laboratories if you wish, in a sense that that we have these sites which are functioning we're monitoring how effective we're trying to quantify their benefits and core benefits. And then once when we collect the jigsaw puzzle, then we can have some hard evidence to show because the best way to change people's mindset is by by showing the hard evidence. How these measures can be beneficial how can they eliminate or minimize the risk for flooding how can they bring the benefits in terms of enhancement by diversity enhancement, or maybe social values. So, so it is we're still not yet there that everyone realizes the various of these measures, and there's still a lot more work that we need to do in order that we can educate or raise the awareness. And I would say even some conventional water managers, traditional water managers in the mindset of those, but also the population. So, yes. The next one is from Hildi Nakoda from Philippines, would fisheries resilience be included in the framework hence also of critical coastal and marine ecosystems. Yes. Yeah, well, these are all aspects that we need to build the resilience to. So, not only fisheries, but also agriculture. Yeah, it's, I mean you're referring here to the coastal systems but marine ecosystems, we are also looking into the various coastal measures, I mean of course the, there are numerous examples like beach nourishment using some sand engines or maybe simple things like planting the mangroves to sort of absorb the wave impacts. And also that there are other aspects but fisheries resilience and building the resilience of the whole coastal or near to coast systems is definitely in the framework. Yeah. The next question is a query if there are any studies related to NBS that are being done in the Sundar runs area, which is shared between India and Bangladesh, the mangrove spot. I unfortunately I'm not aware of any study being done there but I would be happy to be involved if there is any opportunity that maybe someone wants to do the study and then you know just from the perspective of sharing our experiences and trying to upscale our findings and sort of support the study such as this one but I'm not aware of. And RK has another question which is how can these models and data support integrated city development concepts and create capacity of city planners and in implementing NBS. I think you demonstrated this in some of your slides. Yeah. And Rahim asks says that it seems that NBS need changes in the role of different agencies doing development works it's a very difficult task. Could you mention some examples where such changes or coordination were done successfully. Well, there are the right example so that it is not an easy one solution fits all. It all starts from the realization that we are dealing with with the natural systems social material systems, which is all interrelated. So therefore the agencies for creating silos need to also start to interrelate when it comes to their decision make. And I would say what being based in the Netherlands here working as I can, I can say that he the Dutch have done reasonably good job there in terms of the linking different agencies and also using different governments models so that they can integrate different aspects of water systems into one so that when you make, when you make decisions, you are more efficient in doing so rather than having piece meal decisions and hoping that everything will fit and improve it's rather to have this kind of umbrella organization like here is the right spot to start and then you can hear what's up and also here. So that's one example then then of course you can find that in other countries but it is very important this is very, very good question in a sense that that we may need to to make to make to implement nature based solutions if you're talking about nature based solutions, which require multiple agencies, we need to start with open dialogue, and perhaps some governance rich adjustments in when it comes to the water nature systems. That is a long process is not a quick, but it can be by using our models, we can be able in some cases to show that the value of working together. And, and these models showing the results from some scenarios can be very effective and actually open the dialogue. So you start opening, because traditionally we are put into the boxes it's like, also in the traditional educational system you will study only for microbiology or study only for hydraulic engineering study only for some other thing. So we are not, we are not trained to look big, but the problems are never coming in one discipline they are they are interrelated so therefore we have to try to start to break these boxes and bring this broader views. But that that is education is classic example but also in the way how we run our governance of water systems and water infrastructure. So it is not a quick solution but it's a rather process that we need to want to but I don't see other way, how we can go. Yes. Second last question is from Diego parades, who, whose question is about the limitation to apply nbs approaches and cities with a steepness with steep topography, as in keto Ecuador, which is a highland city. Also he points out that it is important to calibrate and validate the hydrodynamic model before implementation of nbs in the model. We've had a student from keto from Ecuador, we who has looked into some flood modeling back he had a model that that definitely you can use steep slopes, topography steep slopes in your models. If you're, it's not only in keto that you have these issues you have many parts of I know I worked on a project where we looked into the some parts of Bella horizontal horizontal in Brazil with steep slopes. Of course, you need to manage the kind of the flash floods that you get in local areas, you can, you build a model you, you can assess different measures, the target flash flood, and these kinds of physics. And yes, my, if there is no limitation to apply nbs in the steep slopes actually by an example of nbs is, is, is can be a series of ponds, this detention or retention ponds and we all know that mitigation of flash floods, which are result from steep slopes. The ponds a very effective way of dealing with such floods, rather than using some open channels only or pipes but then within the open channels, you can also put some cascades. You can you can you can do various things and you can line them, maybe with some natural materials so that you even slow down this runoff. You can do various things, nature, kind of inspired, but then your your second part is very important to calibrate and validate a model before input, definitely any model. If it's not, or every model which is not calibrated and validated is no better than just a guess, you know you may have intuition if something you work or not. And if the model is not calibrated may not be much better than your intuition, but, but when you set up a hydrodynamic model then you will of course need to calibrate it on some events or maybe series of events, but then you need to validate it. And then once when you gain the confidence in that model then you can use it reliably to plan nbs otherwise, of course, like with any model. So you need to really to improve that in the way to do that is to progress. Yes, right. And the next question is from Gopal Kumar are who asked what are the methods in addition to cost benefit analysis to evaluate the effectiveness of a nature based solution in terms of its sustainability. When you when you talk about, I mean, depends how we define sustainability sustainability. Yeah, it's, we can define it in a way that particularly comes to nature based solutions because they, I mentioned before, those measures that benefit not only water management but nature like biodiversity and also the social systems they can quantify they didn't qualify to be called nature based solutions so we talk about sustainability you talk about sustainability in all these three areas. Without so so we need to create such measures that that can that can be that can create longevity of so they can last for long without diminishing prospects for the future development. It's a very nicely said but very difficult to do, of course, and the methods that you can use to evaluate the effectiveness of such measures. First of all, we have methods to evaluate the effectiveness effectiveness through models, and running relations and doing the analysis, looking to different indicators related to water nature people. Then, then through various stakeholder driven discussions and interactions we can, we can come up with something what we believe for what the community believes is sustainable. And then you can have that to implement, but that's pre implementation but then once you implement these measures, then you really have to monitor effectiveness and this is what we are doing in reconnect for for demonstrate this type B is the what we really achieved what we plan to achieve so so to do that. To say they're effective you need to do some baseline monitoring before construction before implementation, and then once you implement this measure then you have to monitor how they operate in terms of water. Water indicators, nature indicators, social indicators, over time, and then against the baseline that you may have then you may say okay it's going up or down here we are really achieving a lot maybe here we are even even causing some other disruption, like I showed before in the case with this fish mortality that we have. So, so yeah, so what these are the methods of course you have cost benefit analysis but the problem with cost benefit analysis that the if you want to monetize all your benefits. You will very quickly run into challenges because you can you can monetize. If you're talking about the flood related impacts so so before NBS and after NBS, before NBS maybe the city will be impacted by so much and then we have so much of material damage with NBS you may reduce the damage to so much so so that that's the positive expression, but then when it comes to the natural systems. How do you do the cost benefit analysis of, let's say you enhance the biodiversity by adding five new species in the area. Can you turn that into my terms. It's very difficult. I hope if you say that you are now my the pond like I showed Bishop Park in Singapore which is very nice example. People like it very much. It's a very pleasant. It may mean world to some people to go around to walk the dog to sit in the nature to sort of rather than how it looked before, but how do you express that in money terms. So the cost benefit analysis of something which which is a statical, and even maybe a kind of effective for the psychological well being of people. So, the methods some some method that there is this traditional cost benefit analysis and there are a lot of things that you can express in money terms, but there are a lot of things that you cannot express in money terms and this is one of the great challenges. How do we bring this monetized benefits and non monetized benefits into one framework. This is a million dollar question, you know, some people would say how do you do this. Yeah, yeah, certainly. Thanks for that Zoran and I'm afraid we'll have we'll have to close the webinar now because we have gone well over time. So with that we really have come to the end of the proceedings and thanks again Zoran for your presentation and for your patient answering of the questions for staying beyond the schedule time. And thanks to you all all the participants for for turning up in such good numbers and for your questions and comments. Recording of the session will be available by tomorrow on the water channel and on the website and YouTube channel the links to which I have posted in the chat. Thank you again and see you at the next webinar which will be in November. And I would like to thank you, Abraham for moderating these events and of course, my thanks to Mariela for arranging follow that and of course, big thanks to everyone who found the time, which was maybe not very convenient to get up very early like some of the colleagues from Brazil, maybe for some colleagues very late so I really appreciate your attention and and I hope that that that you have maybe heard something new that you didn't know and I'll be very happy to to maybe address some of the questions via email or some other forums and very happy to perhaps be engaged in some joint work joint projects which could be PhD or anything else. So all the best, and we will now close the session.


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