Complete Updated Workflow Stream and Catchment Delineation in QGIS

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This video shows how to derive streams and catchments from SRTM DEM tiles from scratch in QGIS 3.16 LTR. The workflow uses different plugins: QuickMapServices, SRTM-Downloader, PCRaster Tools and GRASS tools.
A complete tutorial can be found at GIS OpenCourseWare: courses.gisopencourseware.org...
Note that the procedure uses the PCRaster Tools plugin. You need to install PCRaster prior to using the plugin. Here's the link to the documentation: jvdkwast.github.io/qgis-proce...
0:00 Introduction
0:20 Define study area extent
3:04 Download SRTM tiles
4:30 Mosaic SRTM tiles
5:24 Reproject and subset DEM
7:04 Style the DEM
8:37 Convert DEM to PCRaster format
9:26 Fill sinks and calculate flow direction
10:40 Style flow direction with directional ramp
15:50 Calculate Strahler orders
16:50 Calibrate Strahler orders
19:29 Derive channel network
23:25 Style channels with Strahler orders
25:52 Smooth channel network
27:13 Define outlet of catchment
29:02 Derive catchment of outlet
29:37 Polygonize catchment
31:00 Style catchment boundary polygon with inverted polygon shapeburst fill
33:10 Clip channels with catchment boundary
33:54 Store results and project in a GeoPackage
#QGIS #QGISHydro #GISOCW

Опубликовано:

1 авг 2024

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Комментарии : 141

@Phil-wi1zp Год назад

Great video! I was really frustrated that the SAGA Upslope Area tool doesn't work, this does the job equally well. Thanks!

@borislavagacheva6751 Год назад

Thank you so much! I would have given up on calculating the Strahler order very early on if i hadn't found this tutorial!!

@cevuardriddick3305 11 месяцев назад

Thank you 🙏 very much Mr. Hans for your tutorial. Help me a lots 🙏👏🏿 Merci infiniment 🇻🇺🇻🇺

@thangamraja8349 2 года назад

Very informative and useful. Thank you for sharing

@RegenerativeTV 2 года назад

Great tutorial! really appreciate it. Best wishes

@francktheeten8748 2 года назад

Very interesting thank you and felicitation for this nice tool !

@FormikFilms 2 года назад

Hi, is there anyone else with the issue that the new layer of 'Convert to PCRaster Format' is shifted to the north by about a kilometer, when running this command? I double-checked that all of my layers are in the 32232 CRS (I am working on the Ahr catchment)

@datamongerbonny Год назад

I think I may have upgraded to MacOs Ventura too soon as none of the conda installations are working--qgis 3.22 won’t load from Terminal. Anyone else find a work around?

@rhernan7 Год назад

Oh this is wonderful! Thank you for putting out such thorough content! I was wondering, and I’m not even sure this is the right question to ask, when should one prefer to use PCRaster over GRASS and vice versa?

@HansvanderKwast Год назад

It depends. Some things work better in GRASS other workflows are better in PCRaster. And you can also mix both in your workflow. Only take care of the encoding of the flow direction layer, which is different.

@rhernan7 Год назад

@@HansvanderKwast thank you!

@robsonpassos280 Год назад

Thank you very much for the video, PCRaster tools work perfectly for me. Just out of curiosity, is there any tool in PCRaster to calculate the horizontal and vertical distance from water courses?

@HansvanderKwast Год назад

Horizontal distance to the river can be calculated with the following tools: ldddist: distance over the flow direction spread: euclidian distance Vertical distance can be calculated using the methods in this video (Height Above Nearest Drainage): ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CtBiwxiv-Fg.html

@IATEBISCUITS 6 месяцев назад

Hi Hans, great video. instead of strahler order i used flow accumulation to derive the channel network. Is there a way to automatically search and define multiple outlet points of catchment when you are working with a large area?

@HansvanderKwast 6 месяцев назад

One way is to use the pit tool from the PCRaster tools plugin. See this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jSc3HDN6yEM.htmlsi=18XQHVyD7aiM_uFa. The pit tool will assign a unique integer to each pit, which you can use as an input in the catchment tool. If you want to have more control, you can use the Strahler orders and find the junctions. Then you can derive each subcatchment. This is explained here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5uGaLIlaFh8.htmlsi=Y2z2berpjYJVgucp. With the resource sharing plugin you can find tools to do this automatically (github.com/jvdkwast/qgisrepository).

@orkboy59 Год назад

I installed the PCRaster Library using anaconda following the instructions on your website. However, when I load the plugin, it says PCRaster is not available. Do I need to point the plugin to specific location?

@HansvanderKwast Год назад

You need to start QGIS from the anaconda environment where you also have PCRaster installed, then it should just work.

@rubenbloem4265 5 месяцев назад

Hi Hans, thank you for your helpful videos. I've been following your tutorials closely, particularly the warp reprojection process. However, I've encountered an issue when I reach the step where I need to export and save the raster layer. In the 'save raster layer as' editor, I notice that your default resolution values for the horizontal layer are approximately 20.7896 and 30.1119. Strangely, on my end, the resolution defaults to values significantly lower, often less than 0.1. I suspect this discrepancy might be causing errors in my workflow. Could you offer any insight into why my map layer resolution defaults to such low values? I wonder if there's a crucial step or setting that I might be missing. Your guidance would be greatly appreciated. Thank you.

@HansvanderKwast 5 месяцев назад

I assume you're using SRTM. If the target resolution is EPSG 4326, the resolution is a small number, because this is a GCS. You need to reproject the DEM to a CRS with units in meters. Then X, Y and Z are in the same units and the algorithms give correct results. See ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ZLUjSEK-nbg.html

@rubenbloem4265 5 месяцев назад

Thanx Hans@@HansvanderKwast

@camelapedernal3369 2 года назад

Hello Mr. Hans, if I would like to derive sub-catchments from other outlets, is it necessary for me to copy the coordinates of that outlet as well? If so, what will be the number after the comma in the new set of coordinates? Thank you in advance

@HansvanderKwast 2 года назад

Yes, you can past those coordinates in the text file. Add a unique number for each subcatchment. The result will then have that value for all the cells of that subcatchment. So the text file format is: x-coordinate,y-coordinate,id_number

@camelapedernal3369 2 года назад

@@HansvanderKwast Thank you very much for your response Sir.

@jqplebian 2 года назад

Hello Hans. First off thank you for all your videos, they have been quite helpful. I have pcraster properly installed and have followed your instructions, but when I run 'lddcreate' my system does not seem to get anywhere. I let it run last night for about 10 hours and when I got up it was still running. My windows resource monitor shows qgis-bin.exe is using a good chunk of memory but the disk is sitting idle. The CPU status monitor for qgis-bin.exe is stuck at 'not responding'. I am at a loss here. I know when you talk about lddcreate in this video you say we the users have to be patient, but is 10-12 hours realistic? The DEM is not all that large, about 1.4GB. If you have any advice I would really appreciate it. Thanks!

@HansvanderKwast 2 года назад

I think 1.4 GB is big and will take some time. But maybe what you experience is too much. Are you sure that your CRS is not in GCS (not EPSG:4326 in lat/lon coordinates), but with meters for x and y?

@jqplebian 2 года назад

@@HansvanderKwast Hello again Hans. I have reinstalled QGIS, reinstalled pcraster according to another of your videos, and run the lddcreate process again. I end up in the same situation, an idle CPU, etc. I have checked my CRS, it is NAD83(CSRS) and its information states that its units are meters. I don't think it's in lat/lon. Any advice you might have would be greatly appreciated.

@Daldek007 6 месяцев назад

Hi, Hans! Thanks for the great series of vidos on hydrology in QGIS, I find it very useful! Unfortunalte, I encountered an error trying to define an outlet point from a catchment. When running "Column file to PCRaster Map" I got an empty raster file. Well, on my disk it takes up some space, but it does not contain any numerical values. Would the seolution be to use point layer instead of txt file and rasterize it? I work with QGIS 3.28 (LTR).

@HansvanderKwast 6 месяцев назад

Your outlet raster is probably correct. There can be 2 issues. 1. With some QGIS versions the paleted/unique values renderer doesn't see the pixel value. If you use singleband pseudocolor you'll see it. You can also check the layer properties and see if min/max/mean are 1. If that doesn't work, your raster probably only has nodata, because the project map canvas from which you've sampled the coordinate was in a different projection than your flow direction raster.

@anggitaaulianie8872 6 месяцев назад

@@HansvanderKwast I use the same projection but still got an empty raster. how can I fix it?

@HansvanderKwast 6 месяцев назад

@@anggitaaulianie8872 Did you check the statistics in the Layer Properties as I suggested? Please confirm.

@Emmypeace04 Месяц назад

@@HansvanderKwast Hi Hans! I am experiencing exactly the same problem. I have checked that I am sampling the coordinates from the recalculated flow direction map. In the paletted/unique value I see nothing, and when I click on classify nothing changes. In the singleband pseudocolor I also see nothing. . Min is 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368, and max is a similar value... Any tips? Thanks a lot :)

@mehdiben4186 Год назад

Thanks a lot Hans for these videos and also for PCraster tools , every thing is working just fine like your tutorial , but i have an issue when i m on the part of Defining outlet of catchement , when i run the COLUMN FILE TO PCRASTER MAP the execution fail , it says it s an Assertion Error and i m pretty much sure i followed the exact same pats that you did on the vid ,pls sir do y have any suggestions to this issue . THANKS

@HansvanderKwast Год назад

Check if the on-the-fly coordinate system is the same as your flow direction layer. Another reason can be the file and folder name. Don't save it as a temporary file and save it in a local folder without strange characters.

@mehdiben4186 Год назад

@@HansvanderKwastthanks for replying sir , i ll check the OTF

@mujtabaandrabi5410 2 года назад

Hello sir, every time I try to execute ‘lldcreate’ program for flow accumulation,It shows *PCRaster* library is not available. can you help me here . Thanks 🙏

@HansvanderKwast 2 года назад

The PCRaster Tools plugin is a Processing Provider plugin. That means that you also need to install PCRaster. Here's the documentation that explains how to correctly install what's needed: jvdkwast.github.io/qgis-processing-pcraster/

@adamuel-oji3510 Год назад

Hello Hans Please sir what's is the solution to this error using fill in SAGA : SAGA 7.2.8 is not a support for windows?

@HansvanderKwast Год назад

This video is about the PCRaster Tools plugin. If you want to use SAGA, check these videos for explanations on the issue and work arounds: ru-vid.com/group/PLeuKJkIxCDj3YOheTt9qQps7HA3fE38eG

@diepnguyenngoc1944 Год назад

Hello, a problem occured when I run Lddcreate. The algorithm started but didn't manage to finish. My QGIS didn't respond anymore. Problem occured again when I reopened QGIS. I'm using QGIS 3.22 LTR. Is it the reason why ?

@HansvanderKwast Год назад

Probably your raster is very large. It is still calculating, but I can't show a progress bar. So give it more time when it doesn't respond.

@diepnguyenngoc1944 Год назад

@@HansvanderKwast Thank you! I will let it time. It is true that my raster is a bit large, about 3Gb.

@meiqiliu4537 Год назад

Thank you friend for posting the same problem. And thanks to Hans for this nice video and detailed reply!!

@ismailfaki9759 Год назад

Hi Hans, thank you for video. PCRaster not installed :-(. I can't continue. What can I do?

@HansvanderKwast Год назад

The PCRaster Tools plugin is a Processing Provider plugin. This means that you have to install both the plugin and the software to which it has to connect. You can find installation instructions in the plugin documentation: jvdkwast.github.io/qgis-processing-pcraster/

@rajatrana9539 Год назад

@@HansvanderKwast still does not work in qgis 3.28 version

@maiyourathaankarunanandara3382 2 года назад

Hello Hans, I am an water engineer and I wanted to thank you for your contributions, which is really helping me to improve and experience the new tools and methods in hydrology. I have couple of questions regarding catchment delineation. 1. What method does LDDCreate tool in PCRaster use to calculate the flow direction in not modified DGM, for example D8, Multiple Flow Direction (MFD) or D-Infinity (DINF) methods 2. I wanted to calculate the flow direction (Fließweganalyse) of my hilly catchment area and in my DEM the tunnels and bridge openings underneath the railway (Zug und Straßenbhanunterführung) are filled (These are not located on the river way). In this case do I have to burn the DEM first then do the fill sinks and the rest will be followed by in this tutorial? because in reality through this openings rain water is flowing downstream and merging to the river network. 3. How do i use the flow accumulation method to show the flow path of my catchment area (Not only main river but also foreland waterways)?

@HansvanderKwast 2 года назад

Thanks for using the videos. Here are my answers to your questions: 1. Lddcreate uses the D8 method. More info about the precise algorithm can be found here: pcraster.geo.uu.nl/pcraster/4.3.2/documentation/pcraster_manual/sphinx/op_lddcreate.html 2. It depends a bit on your purpose. If it is to delineate the catchment, burning the real depressions is not always needed. The filling algorithm (included in lddcreate) will remove the depressions and the purpose is to route all water to an outlet. In the lddcreate settings you can control the filling algorithm. Check the link above. If that isn't sufficient you can burn the depressions. There are some tools in the Resource Sharing repository of PCRaster that you can use for this, also see other videos on my channel. 3. You can use the accuflux tool to calculate flow accumulation through all cells. pcraster.geo.uu.nl/pcraster/4.3.2/documentation/pcraster_manual/sphinx/op_accuflux.html

@maiyourathaankarunanandara3382 2 года назад

@@HansvanderKwast Thank you very much for the quick response. I will work on the answer 2, definitely i will have more questions and hopefully i may contact you again. Regarding question No.3, in order to use accuflux i have to create a material raster, how do i generate it ? because i remember in ArcGIS you only need the flow direction raster to generate flow accumulation.

@HansvanderKwast 2 года назад

@@maiyourathaankarunanandara3382 I made a new video about calculating the flow accumulation: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-N_3wie5Srv4.html

@gemmam9892 2 года назад

Hi Hans! I've followed the video up to polygonize catchment. My catchment has a hole in it that's unexpected and cuts out part of the river. Why would this occur and how can I keep this hole in the catchment vector without removing it as instructed in the video?

@HansvanderKwast 2 года назад

In my example the hole occurs because there's a very deep open pit mine. The fill sinks algorithm of lddcreate doesn't fill it but creates a separate subcatchment within the catchment. Depends on your knowledge of the area if you want to remove or keep it. In my case there are no rivers crossing the mine, so safe to remove the hole for getting the boundary of the entire catchment.

@gemmam9892 2 года назад

@@HansvanderKwast I want to keep the hole, but as I change the symbology, the hole keeps the fill colour. How do I merge the hole into the catchment?

@HansvanderKwast 2 года назад

@@gemmam9892 I'm not completely sure what you need. If you have a hole you can remove it using remove ring from the Advanced digitizing toolbar. Just click on the hole and it's gone. If you want to keep the hole do nothing, but take care with styling using the Inverted polygons fill.

@gemmam9892 2 года назад

@@HansvanderKwast I want to keep the area in the hole and merge it with the catchment polygon. I have done this by using 'Dissolve' in Vector Geoprocessing Tools.

@szzor7651 2 года назад

Hello Hans, thank you for the tutorial, this is exactly what I need for my studies, but I have a question. I am stuck at the pcr "Fill sinks and calculate flow direction" point. My QGIS tells me that the "PCRaster is not installed - algorithms will not be available". If I try to run the algorithm, it aborts immediatley saying "PCRaster library is not available". Do you know what the cause may be? Thanks in advance!

@HansvanderKwast 2 года назад

You need to install PCRaster (it's a processing provider plugin) following instructions in the documentation (homepage link in plugins manager) or use the instruction videos on my RU-vid channel.

@szzor7651 2 года назад

@@HansvanderKwast The Convertion worked but the "fill sinks" didnt. I installed PCRaster with OSGeo4W as described in your tutorial. When I open QGIS I still get the same result as in my comment. :/

@HansvanderKwast 2 года назад

@@szzor7651 The conversion uses GDAL, not PCRaster. It means that you have installed PCRaster in another version of QGIS maybe. Before you start QGIS from the Start menu, click right, open location and run setup from there. Install PCRaster and run the corresponding QGIS version. Alternatively use the SAGA or GRASS approaches from other videos or install QGIS and PCRaster in Conda.

@szzor7651 2 года назад

@@HansvanderKwast Thank you for your answers! I still don't quite get it, sorry :D I right-click the QGIS Application and run it from there? It's still the same. I also watched your GRASS and SAGA videos. Very good content, thank you for that. In your videos, you use rather big areas like the Rur channel, but in my studies, I only need to analyze a rather small area around the Möhne See/Möhne Lake. There are mostly 2 outcomes when I run the algorithms (fill sinks (wang lui) or watershed basin etc.) 1. it doesn't work at all or 2. it works, but the watershed basins are completely wrong. At some points they are right, but it seems so out of place. I also posted on stackexchange. Here is the link: gis.stackexchange.com/questions/414794/watershed-basin-not-working-using-qgis I hope that my studies work with the PCRaster Tools as GRASS and SAGA don't work :/ Strahler Order is also very messy and not right at all. I tried so many different approaches but it doesn't seem to work at all.

@szzor7651 2 года назад

@@HansvanderKwast Thank you for your comment on StackExchange. You are absolutely right about your assumptions. It would be great if you could check my comment there. :) Kind regards!

@tamtamzhavanadze2187 2 года назад

Hello. I have a problem after converting DEM to PCRaster format. How many times I try I am given the shrank dem layer of the raster that I have inputted in PCRaster format. I choose the Scalar data type for this process. Thank you in advance

@HansvanderKwast 2 года назад

Do you mean that the result raster after conversion to PCRaster format is not the same size as the input raster? Is your input a GeoTiff? If you load the result layer from disk, is it then loaded correctly? The tool uses gdal translate.

@tamtamzhavanadze2187 2 года назад

@@HansvanderKwast Exactly, I meant that and input is a GeoTiff. I have just tried loading the result layer from the disk and it is the same. I do not know why but I think it shrank after that process. Thank you

@HansvanderKwast 2 года назад

It could be something with the projection? You can check in the Layer properties if the rows/columns are different or not.

@tamtamzhavanadze2187 2 года назад

@@HansvanderKwast I will check. thanks 👍🙏

@berkayvaiz4525 2 года назад

Hello Hans, I have followed your previous tutorial of deriving with saga. I am working on a Coastal Catchment and my DEM has the sea. When I use strahler order with saga I get streams where sea is supposed to be. Might be a beginner mistake, This is my first time with QGIS so ı am inexperienced.

@HansvanderKwast 2 года назад

You need to mask the sea so all pixels in the sea are nodata. Otherwise it will be considered in the calculations, which is normally not what you want.

@berkayvaiz4525 2 года назад

@@HansvanderKwast thank you! :)

@berkayvaiz4525 2 года назад

Dear Hans, I have solved the first issue but now I 'm having trouble with outlet definition, ı have tried saga upslope area but it didnt work and the pcraster method u show in this video also didn' t work. When ı created the filled DEM from clipped DEM using the step in this tutorial I didn't get the same result as SAGA Fill step from your video 4 years ago. So there is a very small bit with no data maybe that could be the reason? Finally, GRASS worked but outlet didnt show on the map.

@HansvanderKwast 2 года назад

The outlet should be taken exactly at a DEM pixel where there is data and where there is the channel. Otherwise it doesn't work.

@jakemercado2134 Год назад

Hello. Everytime i run the process it says value scale cannot be determined specify PCSRASTER_VALUESCALE

@HansvanderKwast Год назад

Use the PCRaster output format only when you use the tools from the PCRaster Tools plugin. In all other cases use GeoTIFF. PCRaster needs the data type to be defined, but with QGIS tools you can't, so GDAL gives this error.

@kyosuke.t120 2 года назад

I can generate the Layer "Channels" with the Channel Network and Drainage Basins Tool BUT without any information.... Not one pixel on the screen or any information in the attributtable for Channels.... how is that possible? Really need help.... :(

@HansvanderKwast 2 года назад

Can you try it again and check if you have checked the box to use the raster values as categories?

@kyosuke.t120 2 года назад

@@HansvanderKwast I'm not so sure what you mean by that. I have to admit that I'm pretty unexperienced with QGIS and I work with your tutorials just on another example in Germany. Is there any chance to give you my dataset so you can take a look at it? I really would appreciate it!

@HansvanderKwast 2 года назад

The tutorials at gisopencourseware.org have data that you can use. Also detailed steps are there.

@kyosuke.t120 2 года назад

@@HansvanderKwast I will give it a try. Thank you so much sir.

@aarizahmed2422 2 года назад

Very Informative tutorial. I am facing an issue that my outlet point is not converting into the raster format.

@HansvanderKwast 2 года назад

Maye the copied coordinates are not in the same projection as the flow direction raster?

@winsanguenza2419 2 года назад

@@HansvanderKwast Thanks for this tutorial professor. I am also having the same problem. I also have counterchecked the projections of both the flow direction raster and the copied coordinate, and they are both the same. I would really appreciate your answer.

@HansvanderKwast 2 года назад

@@winsanguenza2419 When my students have this error, it's caused by spaces, points, minus, etc. in folder and/or file names. It's good practice to avoid spaces in file/folder names. See ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kggwFZHXCl4.html

@Oldmoney.777 8 месяцев назад

Which qgis version are you working with ?

@HansvanderKwast 8 месяцев назад

This should work with all QGIS 3.x versions. I always use the latest LTR version for operational use.

@Oldmoney.777 8 месяцев назад

@@HansvanderKwast Thanks for your response. I have seen in your video you have used the QGIS version with Grass how can I install that type of qgis ?

@HansvanderKwast 8 месяцев назад

@@Oldmoney.777 You can add grass to your QGIS installation with the OSGeo4W installer. See for example ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pja_EX0tVZA.htmlsi=w5mzRAbX-mL-zEqp

@shaynehildebrand5324 2 года назад

no matter what I do I am stuck at column file to PCRaster with an AssertionError.

@HansvanderKwast 2 года назад

Send your files by e-mail and I'll check.

@nagalapallisatish4942 2 года назад

till @ 20:18 I successfully executed but at comparison operators option @20:18 my q gis getting close automatically

@HansvanderKwast 2 года назад

Probably wrong raster formats or issues with file names. You can use the raster calculator as an alternative.

@danielcoetzee9139 Год назад

Hi Hans, great tutorial. Unfortunately when i apply the steps to get the channels form the ordinal map, the channels do not pop up. I notice that my ordinal map and channel map come up with a band color scheme and not pixel color scheme. Please assist

@HansvanderKwast Год назад

Hi Daniel. I'm not sure what went wrong. Please check this playlist with more detailed videos for each step: ru-vid.com/group/PLeuKJkIxCDj05rwD3Fun7v7rpVRg7c_kE

@danielcoetzee9139 Год назад

@@HansvanderKwast Thank you for your speedy reply. i saw that it was just a styling issue and i was able to proceed further. I am now facing a similar issue, however, as my outlet point appears on the map, but it doesnt show up if i try to define it as a palleted or unique value. In the color band it is exactly one pixel, but it does not appear when i try to classify unique values. Please assist

@HansvanderKwast Год назад

That's a bug in recent versions. Simply style it with singleband pseudocolor to see it.

@butifarras Год назад

@@HansvanderKwast Hello Hans, I have a similar issue, I followed the tutorial no problems until when you use Column file of PCRaster Map command, it executes fine but I don't see anything in the output. E.g. if I select palleted style and click classify, nothing happens. Appreciate your answer.

@HansvanderKwast Год назад

That's a bug in recent versions. Use singleband pseudocolor and you'll probably see the pixel appearing.

@kashishshah2442 7 месяцев назад

Hi what to do if assertion error comes while doing the if Then step?

@HansvanderKwast 6 месяцев назад

Hard to tell without any context. Please check also this video to make sure you do the steps correctly: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-aXxHjUcvm88.htmlsi=FPTlMtbI3jRxmQJ6

@kashishshah2442 6 месяцев назад

@@HansvanderKwast ok thanks!

@szzor7651 2 года назад

Hello Hans, how do i go about subsctracting a lake from the dem? I got "waterbodies" as a raster layer in my QGIS Thanks in advance! :)

@ramyasreetelakarapu5382 Год назад

hello.. when i run idcreate i got traceback error.. could you please help me to solve this problem

@HansvanderKwast Год назад

Please copy the error here.

@erwinstubner2426 Год назад

@@HansvanderKwast i have the same problem :/ error: Traceback (most recent call last): File "C:\Users/erwin/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\pcraster_tools\processing\algorithms\pcraster_lddcreate_algorithm.py", line 169, in processAlgorithm report(LDD, outputFilePath) RuntimeError: Data source D:/Erwin Stübner_FLUVALPS_2022/Bachelorarbeit/einzugsgebiet/flowdirection.map(raster): cannot be created Execution failed after 33.36 Sekunden

@HansvanderKwast Год назад

Check if your input is the DEM in PCRaster scalar format. Also try to use folder names without spaces and accents.

@erwinstubner2426 Год назад

@@HansvanderKwast i got everything working now up until the point of using "Column file to PCRaster Map" tool. I tried several times now using coordinates ON and OFF the channelsthin layer to produce the new File but it turns out empty every time. Not sure how to proceed. Thanks for answering so fast by the way. :) Greetings E

@ludwigk2986 2 года назад

Hello Hans, thanks for your great QGis-engagement! I followed the instructions up to 28:34, but "Column File to PCRaster Map" throws an "assertion error", like others reported. The reason is the system-call of col2map.exe in col2map.py lines 105...130, which fails, if there are blanks in the paths. Workaround: Adding quotation-marks to these calls: before: cmd = "col2map -B {} {} --clone {}".format(table, dst_filename, clone) after: cmd = "col2map -B \"{}\" \"{}\" --clone \"{}\"".format(table, dst_filename, clone) And dont't forget to save, close and reopen the project to read the modified scripts...

@HansvanderKwast 2 года назад

Thanks. It was on my todo list. I'll update col2map soon.

@gemmam9892 2 года назад

@@HansvanderKwast Hi there. Thank you for the fantastic tutorial! I am getting the same "assertation error" and do not understand the workaround. Can you help?

@HansvanderKwast 2 года назад

@@gemmam9892 This is caused by file paths with a space. You can wait for an update of the plugin that will be released very soon. It is already in GitHub. If you know how to install a plugin from zip you can already try.

@gemmam9892 2 года назад

@@HansvanderKwast Thank you. Do you have a link to the zip file on GitHub?

@HansvanderKwast 2 года назад

@@gemmam9892 This is the link to the repository: github.com/jvdkwast/qgis-processing-pcraster. There you can click on Code and download the ZIP file. Note that you need to unzip on your computer and ZIP again the folder pcraster_tools. That's the file you can use in the plugin manager.

@mmbodnar 2 года назад

It seems the Col2map algorithm is generating an "Assertion Error" now when I try to convert the outlet(s) csv to pcRaster map. It was working 2 weeks ago... Not sure if this is a bug or something on my system. CRS's are identical and there are no spaces or odd characters in the file name or file path. is anyone else getting this error? Traceback (most recent call last): File "C:\Users/xxxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\Bodnar/python/plugins\pcraster_tools\processing\algorithms\col2map.py", line 119, in processAlgorithm self.set_output_crs(output_file=dst_filename, crs=input_mask.crs(), feedback=feedback, context=context) File "C:\Users/xxxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\Bodnar/python/plugins\pcraster_tools\processing\algorithm.py", line 69, in set_output_crs return PCRasterAlgorithm.set_output_crs_wkt(output_file, crs_wkt, context, feedback) File "C:\Users/xxxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\Bodnar/python/plugins\pcraster_tools\processing\algorithm.py", line 80, in set_output_crs_wkt assert ds AssertionError Execution failed after 0.28 seconds

@HansvanderKwast 2 года назад

I've only seen the error with spaces in the path. If you're sure that's not the issue, please post an issue on the GitHub repository of the plugin so I can check what goes wrong.

@mendacem4950 2 года назад

Having the exact same problem, checked all the files and file path names, there are no spaces nor odd characters. If you do find a solution please post it here as well.

@HansvanderKwast 2 года назад

You can try if it works with the command from the OSGeo4W shell. Try: col2map -N yourtable.csv outputmap.map --clone yourmask.map Use -B for boolean, -N for nominal, -O for ordinal, -S for scalar, -D for directional, -L for LDD If it doesn't work you'll probably get a clear error message.

@mmbodnar 2 года назад

@@HansvanderKwast Thanks so much. I am trying to calculate catchments for 700 outlets but I am testing this first with only 2. When I run this from the OSGeo4w it indicates an error of 'ERROR: output map 'xxxxxx.map' can not be created. I think i may have reached the limits of the ID value, I was trying to keep the 4 digit ID from the sample locations so I can easily link the catchment with the original data. I am running the tests form the usb drive so perhaps there are file writing limitations. I can create a thread on the github if that is easier.

@HansvanderKwast 2 года назад

Yes please. Hope I can help.

@ilyessbenmessaoud9272 2 года назад

Processing algorithm… Algorithm 'lddcreate' starting… Input parameters: { 'INPUT' : 'INPUT4' : 9999999, 'INPUT5' : 9999999, 'OUTPUT' : ............................' } PCRaster library is not available

@HansvanderKwast 2 года назад

You need to first install PCRaster before using the plugin. Check videos on my RU-vid channel or read the plugin documentation for the steps.

@ilyessbenmessaoud9272 2 года назад

@@HansvanderKwast i instal it by conda but the Iddcreate didn't work

@debojyotibhattacherjee3674 2 года назад

Same with me.

@mohammadshaieqfrotan4329 Год назад

Hello Sir thanks for providing this video, I received this error severaltimes could you please tell me the reason QGIS version: 3.26.3-Buenos Aires QGIS code revision: 65e4edfdada Qt version: 5.15.3 Python version: 3.9.5 GDAL version: 3.5.1 GEOS version: 3.10.3-CAPI-1.16.1 PROJ version: Rel. 9.1.0, September 1st, 2022 PDAL version: 2.4.3 (git-version: 6311a6) PCRaster version: QGIS PCRaster Provider version 0.2.0 Algorithm started at: 2022-11-09T15:43:29 Algorithm 'lddcreate' starting… Input parameters: { 'INPUT' : 'E:/Publications/Kabul River Basin 2022/DEM DATA/Kabul River Basin 2022Nov/dem.map', 'INPUT0' : 0, 'INPUT1' : 0, 'INPUT2' : 9999999, 'INPUT3' : 9999999, 'INPUT4' : 9999999, 'INPUT5' : 9999999, 'OUTPUT' : 'E:/Publications/Kabul River Basin 2022/DEM DATA/Kabul River Basin 2022Nov/flodir.map' } PCRaster library is not available Execution failed after 0.13 seconds Loading resulting layers Algorithm 'lddcreate' finished

@HansvanderKwast Год назад

It means you have to install PCRaster. Now you have only installed the plugin. You can find instructions in the documentation: jvdkwast.github.io/qgis-processing-pcraster/