 Hello, this is Hans van der Kraas Senior Lecturer at IHG Delft Institute for Water Education. I received a question from a viewer on how to delineate the catchment of a location for which he has the coordinates of a measurement, a discharge measurement. In other videos I've covered how to delineate the catchment of an outlet. In this video I'll show you two methods, how to define the outlet based on coordinates, and then to derive the catchment belonging to the coordinate. Here I've loaded a DEM. It is already projected, so make sure you're not using a geographic coordinate system, otherwise you can't proceed. You first have to reproject the DEM. And then the first step is to fill the sinks. We use here the Wang and Liu algorithm from Saga, and we keep the settings at default and we're only interested in the filled DEM, so we give that output file name, and we uncheck the boxes of the others. And what it will do is get rid of all the artificial depressions, also the real depressions, that get the water stuck, and make sure that all the water will flow to an outlet. Now we can remove the original DEM here, not to get confused later. And I'm going to show you two methods to add coordinates. To simulate that, I'll capture them first from OpenStreetMap. And here I assume that we are doing fieldwork and that we have a discharge measurement here at the outlet of the roar. And when I click right, I can copy the coordinates, and I use here the latitude-longitude coordinate, because that was the question I was asked if I have latitude-longitude coordinates. How do I add it? And I paste it here in Notepad and I add the ID number and I give it a header. That's the longitude, the first column, then the latitude, and then the ID number, and then I save it. And this is a classic, always change to all files, so you can give it your own file extension. And I'll call it pourpoint.csv. Save it and close Notepad. Then I go to the Data Source Manager and there you have the delimited text tool. And here I can select the file to CSV. And here make sure that you have checked that it is comma-separated, well, we made it ourselves, so in our case that's true. Check here if your decimal separator is not a comma. And it automatically finds the longitude and latitude coordinates and make sure you choose the correct projection, which is the PSG4226. And now we add it, but it's still in the projection, latitude, longitude, and we need to have it in the projection of our project, so I'm going to export it here to a geopackage, and I call it pourpoint, and I use the projection of the project, which is a UTM projection. I can remove the other layer to avoid confusion. Those methods, one, you have a CSV file, you can import it. The second method is that you have coordinate and you want to create a point on the map. So I create a new scratch layer here, location, geometry type point, EPSG4226, because I want to enter latitude, longitude coordinates, and an ID. Click OK. Now there's an empty layer, which is in editing mode, and it's a scratch layer that is just temporary. I'm going to install a plugin, and the plugin is called latlongtools. And here I get some extra buttons, and if I click this one, I can digitize from a latlong coordinate. I still have it in memory, so I just copy it here, comma separated. And you can choose here the order, latlong, lonlat, in our case it's lonlat. I add the feature it asks to fill in the attribute, and then it simply adds it to the map, so we're off the editing to save it, and it's exactly the same point as we had from the CSV file. And then you should also export it, save the features, and have it in the correct coordinates, but we'll proceed with the other one. Now this point does not necessarily match with the streams in the failed DEM. Therefore we need to derive the channels, and we use the channel network and drainage basins tool. You can use a threshold for the stralla order, the higher, the bigger the rivers, I put it here on 8, and then I can save it to a new file, save it to channels, and then uncheck all the other outputs that I don't need. Now we need the point to snap to the line, and we use the snap geometries to layer 2, where our input layer is this port point, and the reference layer to which it has to snap is channels, and I can change the tolerance, and you just need to estimate it a bit. Here I'll say 2 kilometers, and then there are all kinds of settings on the behavior, and you can also play with that, we'll just see what the effect is of using the first one, and let's save this one to our geopackage, and I'll call it snapped port point, and now we see that the point has moved to the line, and if you modify the behavior settings then it might end up at a closer spot on the line. Now we can delineate the catchment using the upslope tool, and it needs to coordinate, so we need to first add the xy field, so we have our snapped port point, and we use the projection of the project, because those coordinates match with the dm, we choose the geopackage, and I give it the layer name, snap to port point xy, and I run it, and now it should be added to the attribute table, and there we have the x and y coordinate in the UTM system, I can dock the attribute table, so I can easily copy it to the upslope area tool, just to ctrl c, ctrl v, here again ctrl c, ctrl v, choose the dm, choose the method, here I just use the d8 method, and then save the new file, close the dialog, and if I zoom to the layer I see the delineated catchment, and we can export that as a polygon, so I polygonize the raster, we can change it to 8-connectness, which will also take the connections in the diagonal into account, but I keep it here at the 4-connectness, and then we save it, and let's call it catchpoly, and here we have the result, but it has the catchment, and it has the boundary polygon, and we only want the catchment, so I go to the attribute table, dock it, and then let's see which one is the catchment, and that is number 3, so I invert the selection, and I toggle editing, click the trash bin to delete it, and then I save the result, and then we have the catchment boundary, and that's the result, so you've seen two methods to delineate the catchment of coordinates that you know.