 Hello, this is Hans van der Kwaas senior lecturer at IC Delft Institute for Water Education. In a previous video I have demonstrated how to style rivers using tapered lines. We have used the geometry generator for that. In QG's version 3.20 there is a new styling feature called interpolated lines. In this video we are going to use that new styling feature to create the tapered lines. We'll first apply it to the strahler orders and then we'll apply it to the cumulative length over the river. We'll use this channels layer that we have derived with Saga using the channel and drainage basins tool. And you see that it has a field with the strahler orders. In other videos you'll learn more about that. And previously we have styled those strahler orders using a graduated style. And now we're going to do that differently in an easier way. So I duplicate the layer and I'm going to work on this one and switch to single symbol. And then for the symbol line there's now a new feature interpolated line. I change the stroke width to varying width and I choose the order field for the start and the end value of the interpolation. I click the refresh button and it finds that the interpolation goes from a minimum of 1 and a maximum value of order 3. And then I can give the minimum a maximum width. I'll change the color to something bluish. And there's the result and it's of course very easy based on this new tool. And you can play with the min-max value to change the effect. And when we compare it with the original there's just little differences. To get real tapered lines it's better to use the length from the upstream to the downstream. We can add that using a plug-in, the waternet analyzer plug-in that was also explained in another video. I've installed the plug-in and I go to the processing toolbox. And there I find some tools from the waternet analyzer plug-in. And we use here tool number 3, calculate a long flow path. We use our rivers and the field that we want to accumulate is the length field. And then for the ID field we keep segment ID. For the from and to node we use node A and node B. And then we can define the accumulated output file which I keep here as a temporary layer. Close and let's style the result. At simple line I choose again interpolated line. I change it to varying width. Now for the start and the end value I use the calculated length field. I refresh the min-max and here we already see the effect. And I change here the min-max values and the color. And now we see that the line gets thicker further downstream. And we can play with the min-max values to make that more or less prominent as we like.