 Hello, this is Hans van de Kwas, Senior Lecturer at IHE Delft Institute for Water Education. Someone asked me how to create tapered rivers in QGIS. There have been some nice tutorials about that, like this one from Anita Grazer, and this one from Rodriguez Lombardo. And I'll put the links in the description, but in this video I'm going to show you how it works. And I'll start with this dataset from the root catchment that in a previous video I have downloaded from OpenStreetMap, and I've dissolved all the rivers. So this is one feature, because I can then use this lines ranking plugin to create features of each tributary. That's the first step I'm going to do. I'm going to zoom in a bit, and I can point to the outlet, so it will create different tributaries, zoom to the layer back, and let's look at the result by putting the labels there, use the rank, so here we see the different ranks of the streams. And now to get these tapered rivers, we need to have them as a feature for the different lengths of continuous streams. I'm going to do that manually, so I'm going to total editing mode, go to the attribute table. So I'm going to add a field to assign unique numbers to each part of the stream that I want to have tapered over its full length, and I'm going to call this one, let's call it ID, the whole number, and only one number needed in this dataset. I'm going to select the longest stream here, so when I make this one feature, then the line will be tapered over its full length, and I'm going to do the same with the other streams, so that's the purpose of this part. So here I can change the value for the selected lines, and I'm going to call this one line number one, and I'm also going to change here the label, so I can see what I'm doing. Then I go to number two, let's take this one, the control button, I select river, number two, save it, and now I'm going to dissolve these lines, it's all these features that are part of one tributary, they will be then one feature, and that's what we need, so I'm going to choose here the dissolve fields, and I choose there the unique numbers, the IDs that we gave, and the next step is to assign the size that we want to use for the tapered stream, so we make sure that the biggest one is the largest, and then the smaller one a bit less, etc. So I'm going to edit, and I add a new field, double editing on, and I call it size, again a whole number, so I'm going to give length, I'm going to sort it on the length, I can give the size, and now we can use it for the styling, I'm going to choose here simple line but change that to the geometry generator, and it needs to be a line to generate it from the geometry, and then it will be segments to line, lines, there we go, so now all the segments are lines, and then we can style it, and I'm going to use a color blue, and I change this to meters at scale, and I'm going to edit, and I'm going to use the size here, we do size times geometry part number, divided over geometry part count, times the log of the length times 3, and the 3 is just a scaling factor that you can increase if you want it larger, and now you see it's drawing, we can play with the values to make it a bit more prominent, I'm going to use here a big value that looks great, I'm going to remove the labels, and I'm going to combine it with elevation to see the final result, and that's the result, hope you enjoyed the video