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Landlab codebase, wiki, and tests
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Extracting watershed, long river profiles, slope, steepness index, chi index from chosen rivers... using a DEM #1617

Open newdeskarl opened 1 year ago

newdeskarl commented 1 year ago

Hello,

I am new in Landlab and I would like to extract longitudinal river profiles and related parameters by using only a DEM file. In details:

1) I would like to use the DEM as an input so that the watersheds and the rivers can be mapped.

2) I would like that the rivers of interest can be used as profile lines. I would like to be able to identify, see and choose the rivers on which I need to work (not just the 3 greater ones).

3) As a profile line, I hope that the distance and the elevation points can be extracted along the line (the river).

4) As the distance and the elevation points are extracted, the longitudinal profiles of the rivers can be extracted (each river on a graph or each river network of a single watershed on a graph)

5) Finally, I would like to extract and plot important parameters like slope, chi index, steepness index, .... for tectonic analysis.

May someone help me with that?

All the best!

nicgaspar commented 1 year ago

Hi, and welcome to Landlab (as you said you are new)! Landlab is not designed to be a DEM analysis toolkit. It is a modeling toolkit. Although we have tools to do most of what you want to do (I'm not sure about choosing the profiles to plot though), you might want to use tools that are designed for GIS systems. Is there a reason you want to do this in Landlab?

Here is a jupyter notebook that does most of what you want to do from a raster evolved with Landlab. https://github.com/landlab/landscape_metrics_course/blob/main/stream_power_channels_notebook_part2.ipynb

See code blocks 8 - 12 for plotting routines, but these only work on the X biggest watersheds, as in you can't pick which watersheds you want to analyze. There may be a way to do that, but I don't know it.

newdeskarl commented 1 year ago

Hi, and welcome to Landlab (as you said you are new)! Landlab is not designed to be a DEM analysis toolkit. It is a modeling toolkit. Although we have tools to do most of what you want to do (I'm not sure about choosing the profiles to plot though), you might want to use tools that are designed for GIS systems. Is there a reason you want to do this in Landlab?

Here is a jupyter notebook that does most of what you want to do from a raster evolved with Landlab. https://github.com/landlab/landscape_metrics_course/blob/main/stream_power_channels_notebook_part2.ipynb

See code blocks 8 - 12 for plotting routines, but these only work on the X biggest watersheds, as in you can't pick which watersheds you want to analyze. There may be a way to do that, but I don't know it.

Hi nicgaspar,

Many thanks for your reply. In fact, the GIS tools like QGIS can extract the whatersheds and the profiles but I don't know whether they can extract the other parameters (slope, steepness or chi index). So, I was looking for a python tool that can do all. I came accross LSDTopoTools (https://lsdtopotools.github.io/) but I was not able to install it correctly - too complicated. If you know other solutions, I would be grateful to know about them.

I was happy to find Landlab. The installation is easy and there are many tutorials. With Landlab I thought I could make the DEM analysis that I want now and get into modeling over time. Thank you!