 I would like to take you again to Hamburg. I didn't know that my pre-speakers also showed so many examples from Hamburg. Yeah, my name is Kastri Stelzer from Bokman Consult and we are also located in Hamburg, so I know very well the area I'm talking about now. So, CIVAVA or City Water Watch was a project co-funded by the Ministry of Economy and Energy and we were three partners and one was the Hugen Institute, so the Institute in Hamburg responsible for the water quality for measuring and monitoring and providing data and BBA Moldenke, who is a company producing and constructing in situ measurements and we from Bokman Consult we were the remote sensing the satellite data guys looking into the water. So, we have a lot of water in Hamburg. There is the Altster, a very large lake in the center of the city and the Elbe River with a large harbor area and there are a lot of bathing water lakes in the surrounding and in the city. So, all this needs to be monitored and we all like water, it's good for the climate, it's good for our feeling and for recreation and also it is used for industry of course. And now what was also the intention of the authorities is to know more about the spatial distribution of the water quality because they always look at points and in situ measurements taken at a certain location but they are interested in the spatial distribution of of water quality and what is water quality I will come in in a second. So, the what we see from the satellite from the water is first the color and the color is is coarsed or the responsibility for the color is either there's sediment or sand or something like this in the water or there's there are phytoplankton so little algae in the water which produce chlorophyll and there's also humic substances which are very dark. So, all these substances they are responsible for the color of the water and this is changed so these substances in the water change the light and reflect it back to the satellite sensor and this is what we measure and this is where we get our information out looking at the absorption and scattering processes which happen in the water at these little constituents in the water and this tells us what is in there and what we understand of water quality is chlorophyll concentration so a proxy indicator for algae blooms suspended sediment concentration turbidity how clear is the water or how turbid is the water the second depth how deep you can look into it and a very important indicator cyanobacteria indicator because cyanobacteria it's blue algae also known as this can be toxic and then bathing water need to be closed because yeah it can it can be influence the health and it even can kill dogs so nobody wants to drink this water anymore and and the authorities are responsible to close those waters. So, when we deal with waters in cities we have a lot of surrounding we have a lot of okay this is not working a lot of boats on the water and we need to take care of all these subjects when we process our satellite data what you see here is the chlorophyll concentration overlaid in parts of the harbor in Hamburg and so it's important that we flag everything that is not valid not a valid water pixel to get really good results so that we only show what is what is reliable. Coming to the monitoring the monitoring is done by the authorities they are responsible to detect or to monitor the water and there are several permanent measurement stations there some stations they go from time to time but I would like to look at one of the permanent stations where the water is just flowing through they do their analysis and I can show this in the time series what you see here is one of the stations at the Elbe River the blue line is the permanent measurement station chlorophyll concentration and the red dots are the chlorophyll concentration derived from the satellite data in this case it's Sentinel-2 and what you see here is we have more measurements from in situ but this is not very often the case often they go there once a month or every two months and then we have much more information from the satellite data those images are used or those graphs are needed to convince users that we measure the same thing that we are not measuring the same thing but we get similar results that's the important point so that it is a technique that can be used and help them also to to monitor their waters and yeah producing these water quality products from satellite data is one thing and the other thing is to develop interfaces so that this information can go to the users and combine with their work they are doing with their in situ measurements so that this comes really into interaction into interaction and this is what I would like to scratch here so we start as a one satellite image we process it we need certain processing steps atmospheric correction water retrieval masking so this is all that that we know very well we produce this for for each available and suitable image so clouds are disturbing our images we we are reliant on on clear water clear sky conditions and we put all this in data cube to have a consistent temporal spatial data set and and this is then then then we need the interfaces to the users because usually they cannot work with with those data but then we also work on the interfaces either we provide them APIs they can program and access the data or we provide the data via data viewers or or in fact sheets explaining how their water look like with different graphs and maps this is where we individual from user to user we talk a lot with them how would you like to get the information we can provide you so that you can very easily integrate it into your daily work because this is often a big problem that earth observation data is not integrated in the authority test but this is getting more and more the case yeah just a small sketch into the viewer via we use and developed in order to show the data these are just RGB images it's a very nice clear sky RGB image and then there's the chlorophyll concentration divide only for the water bodies that that are shown and now we can see how nicely we have the spatial distribution of the parameters which cannot be sketched by only few measurement stations and as we have this data cube we also have time series what you see here several years and the chlorophyll concentration within one lake and if you squeeze this to one year only we see the seasonal trend of the chlorophyll concentration they are growing in spring time going down in summer a bit and then have a second bloom in autumn this is a very normal way how they how they grow so that the user has this viewer and can can look at his or her lake and investigate in detail another example how we try to get the data closer to the user is that to format it the way they are used to it for instance here this is an example of a harbor cruise they do this every two months and in each of these segments you'll see there they have one water sample which they analyze which is then representing all the all the area and if we come now with the satellite data we have similar information all over the water bodies and we can format it the same way they are used to it and provided via OGC services to their system so this is the Hamburg geo online portal where they store all their harbor cruises data and yeah if we provide them the data from the satellite data the same way they can simply integrate it and have a bit more and more often information on the clover concentration and what we are doing now so Chibawa was a project and at a certain point it entered into a service which is always a very nice thing if you can continue after a project with users that are interested what you see here is Eichbaumsee it's a lake southeast of Hamburg and it's very famous in Hamburg because it's closed since years due to Blau Algenblüten which Ciorna bacteria blooms and this year they wanted to open it again they said we want to open it and regularly monitor it but unfortunately at the bathing spot here already in June they were again they had to close it because Blau Algen was growing and they opened it again end of June but in end of August they had to close it again so and then as we were serving them with this satellite data this helped them also to assess where are the algae is it only at the bathing spot is it at the west end of the lake and yeah this is a indicator for Ciorno bacteria blooms which indicate if it's wet be careful please go out do a measurement and and look at the water so it's not that we say yeah it's more triggering than Tito measurements so that they know okay we have to go to our lakes we have to control and do our measurements and this is the time series of the Ciorno indicator and so we sent out automated alerts by email whenever this indicator is too high they get next day they get the message be careful we see a risk in your lake here and there and yeah this I would like to summarize so we have this complementary information in space and time from Earth observation about the water quality a good quality or a good validation is needed to convincing users that this is a technique they can use in addition of course the availability of suitable satellite data is key and we have to be honest the problem that if we have clouds during the summer we cannot see and detect the algae so it's always the user needs to be trained a bit that this can happen and if they do not get an alert this does not mean there is nothing but it means it might be also a cloud so that we cannot see everything and then the very important thing there need to be interfaces very individually to the users so that they do not have work to work with it aid data but they really can help them to work with it and combined monitoring concepts are tested more and more by the monitoring agencies which is a very nice evolution development so it's getting more and more used and and accepted thank you