TopoToolbox now on Mastodon

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Screenshot of TopoToolbox' Mastodon profile

Twitter has recently become a weird place (mis)managed by the world’s richest man. Whatever the future and developments of Twitter, I don’t think that I will be active their any longer. This is a hard step, as Twitter enabled me to connect to many other researchers around the world, and to follow what they are doing. Twitter has enabled also great collaborations, one of which eventually culminated in a Science publication on the Chamoli flood. Regardless, I will be silent on Twitter from now on (my profile will still exist, though).

Leaving Twitter, however, doesn’t mean that TopoToolbox will be gone from any social networks. Instead, I have moved to Mastodon and you will get news about TopoToolbox, but of course also other research (and some non-research related) stuff here:

https://mastodon.green/@topotoolbox

If you are already on Mastodon, you’ll find me under this username: @topotoolbox@mastodon.green

Perhaps, you’ll also join. If not, most of the relevant news on TopoToolbox will still be found on this blog, of course.

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TopoToolbox course at IIT Roorkee

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Photo from here: https://ir.iitr.ac.in/NSIH2022/index.php

As part of the Natural Hazard Symposium for the Indian Himalayas 2022 (NSIH 2022, 12-13 Oct 2022), I will give a 2 day (each 3 hours) course on TopoToolbox. If your are participating, you may want to download the data required to replicate the examples as well as to conduct a couple of exercises. The file is a zipped folder structure which follows the course structure and contains the data (~262 Mb).

Please download the data here. See you soon in Roorkee!

Update: You can now download the mlx-files (Matlab LiveScripts). Before you run the files, place the mlx-files in their appropriate places in the folder structure that you downloaded previously (see above). Moreover, the zip file contains pdfs.

Don’t smear knickpoints when smoothing river profiles

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Smoothing river profiles is often necessary to remove errors and artefacts that prevail along DEM-derived river elevations. However, some of the sharp knicks are real. For example, waterfalls or, more general, knickpoints produce distinct changes in river gradients, and you might not want to smear those features. This blog post describes how to keep these features in smoothed river profiles.

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The entire blog translated into Chinese

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Screenshot of the pdf.

Recently, Weiheng Shi translated the TopoToolbox cheatsheet into Chinese. I thought this was quite an impressive service to the Chinese terrain-analysis community. But now there is even more. Weiheng translated the entire blog which is now available as pdf with >270 pages here. In the next day, I will need to better link all this documentation that has now become available.

Thanks Weiheng! I really appreciate it a lot!

Stream burning – or how to convert a shapefile to a STREAMobj

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Frequently, readers of this blog ask how to convert a shapefile of rivers into a STREAMobj. In this post, I’ll show, how this can be done. But let me state right from the beginning on, however, that there is no such thing as converting a shapefile to a STREAMobj. This is because a STREAMobj is, and mostly must be, directly linked to and thus derived from a FLOWobj.

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TopoToolbox Cheat Sheet in Chinese (and more)

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I am very grateful to Weiheng Shi, who translated the Cheat Sheet into Chinese language. And that’s not all. Weiheng also translated the user guide which provides an introduction to objects in TopoToolbox, a guide towards calculating Ksn as well as a documentation on multiple flow directions. I believe that this is a great resource for students in China and I hope that it will make TopoToolbox much more accessible to many. By the way, Weiheng also translated the documentation of Chad Greene’s Climate Data Toolbox (github link) and the Chinese documentation can be found here.

再次感谢! 伟大的工作!

TopoToolbox Cheat Sheet

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Cheat sheets are documents that I mainly know from R and its packages. It’s a great resource to quickly get an overview on functions, their syntax, and their application. Inspired by these, I have now created a TopoToolbox cheat sheet (pdf version of the image above). I hope it is useful for beginners and more advanced users alike.

Hilltop curvature as tool for mapping erosion rates in soil-mantled landscapes

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This post is written by Will Struble who is PostDoc at the University of Arizona. Will works on a wide array of problems in geomorphology, tectonics, and surface processes. One of his tools is digital terrain analysis. Thanks for this post, Will!

Many geomorphic analyses focus on fluvial drainage networks. Indeed, metrics such as channel steepness (ksn), χ, and related measurements can provide great insight into how fluvial portions of landscapes respond to climate and tectonics. A significant proportion of the landscape, however, is not composed of fluvial channels. What are we missing? Hillslopes, of course!

Nicely rounded, not so much soil-covered hilltops in the Zin Valley Badlands, Israel (Photo: Wolfgang Schwanghart)
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Calculating the transverse topographic symmetry (T-)factor (2)

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In my previous post, I wrote about calculating the transverse topographic symmetry factor or, short, T-factor. I presented a computational approach to derive the centerline of a basin using (gray-weighted) distance transforms. And in fact, it worked out quite nicely for the Big Tujunga catchment, I think.

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Calculating the transverse topographic symmetry (T-)factor

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In response to a recent blog post about drainage basin asymmetry, blog reader Allan asked, how one could calculate the transverse topography symmetry factor or T-factor using TopoToolbox. To be honest, I had never heard before about the T-factor, but then I came across Heidi Daxberger’s paper (Daxberger et al. 2014) which contains following description.

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