Calculate percentage of land use per subcatchment in QGIS 3

This video shows how to derive the percentage of land use/land cover within the polygons of a layer with subcatchments. The example uses open data from CORINE 2018. QGIS 3 functions for vector analysis are used such as dissolve and intersect.
This video is based on Chapter 6 of the book "QGIS for Hydrological Applications - Recipes for Catchment Hydrology and Water Management" by Kurt Menke and Hans van der Kwast. More information about can be found at the website of Locate Press: www.locatepress.com/hyd
This video is part of IHE Delft OpenCourseWare. More free materials can be found at www.gisopencourseware.org
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[@lesliethilow3011]

You have a great 👍 teaching style Hans! Thanks so much for taking us through these processes. It’s nice to hear you explain things so clearly and succinctly.

[@archidmdemdoum3008]

Thanks a lot, no words can describe how thankful I am right now, keep it up bro.

[@fredsmithers6529]

Thanks so much for this great tutorial Hans you legend!!! This has helped me with my dissertation heaps (I'm currently studying land use in train station catchments in Auckland, NZ). If i ever make it back to NL, i'm coming to buy you a beer!!

[@sanderamamama]

Thanks a ton, precisely what I needed!

[@KEcAzZ1]

Brilliant! Just what I was looking for. Thanks!

[@evitaooo7]

Thank you very much! Very well explained!

[@ewighol]

That's awesome, thank you so much ! It works perfectly, and the video is so clear..!

[@OrGaAn]

Thank you loads, this has been really really helpful :)

[@sristikaadhikari2256]

Thank you very much. It is helpful.

[@sharonguba949]

Thank you very much Hans

[@OliiwiaB]

Thank you for this tutorial!! It saved me

[@arminwahl3110]

Super Nice! This helps a lot!

[@HanyingWei]

very helpful! thanks for the sharing!

[@giacomoarlotti7075]

I love you man, thanks a lot!!!

[@DrAgOnKrIeGeR]

awsome! thank you very much good sir!

[@AbdullahSalimalig]

Your way of explaining is really amazing. Keep doing the good work.

[@azar_asar2909]

Thank you

[@gemmam9892]

Fantastic video! How does one colour each catchment according to percentage of a certain land use type?

[@martinallart5828]

Thank you very much Hans for your video, very useful. Quick question, is that possible to first deal with the intersection and then with the dissolved. I have geometry bugs and I thought it might help.

[@HansvanderKwast]

That depends on the work flow. But maybe you can try first Fix geometries tool from the Processing Toolbox.

[@canha1984]

Great Video. Very clearly explained. Can this method be applied to calculate the area percentage in raster layers? I'm interested in calculating the proportion of NDVI classes in certain cultivation plots, using data from sentinel-2. Thanks!

[@HansvanderKwast]

Thanks. In QGIS it is not possible (as far as I know) to use a discrete raster (in your case a raster with cultivation plots) to extract the zonal statistics from another raster (NDVI in your case). You should then first vectorize (polygonize) the discrete raster and use that in zonal statistics or in the way I used it in the video.

[@felipemnzs1]

Thank you !!! :) :)

[@berenicerobaglia2449]

Hi, thank you for the video! How did you select in the first place only the country you were interested about? I have very heavy files from Copernicus database with every EU countries and only codes in the attribute table...

[@HansvanderKwast]

As far as I know you can only download the full dataset from Copernicus. You can clip it to your country if you have a polygon with the boundary.

[@amanjain6680]

Thank you. Quick question everyone reading this. If my catchment is small ( 10 ha or less), then using 100m res data isnt going to benefit me. If I classify sentinel-2 imagery ( k-means), how do I validate that? Or should I use any other approach?

[@laurasaggiomo4314]

Dear Dr van der Kwast, thank you for this extremely useful video. Unfortunately, following your steps, during the dissolving process (and I am quite sure it will happen also during the intersecting one) I got the warning for some non-valid geometries. Would you be so kind as to tell me if it is still okay, or suggesting me some solutions (maybe some tutorial of yours, or some manual)? Thank you Laura

[@HansvanderKwast]

You can use the fix geometries tool from the processing toolbox to fix those layers.

[@omerl.2539]

Can we calculate the land use rate around 5 square km of an area we want?

[@CLARISSEXOXO]

Dankjewel!

[@MovIEsL0veR]

Great video! I successfully made the table you show in the end. But some polygons have multiple percentages per land use. Is there a way to let QGIS combine those results from the same class? I could do it myself in excel but would be quicker if QGIS could do this.

[@HansvanderKwast]

Dear Lola, I also saw your previous question. If you have raster data and polygons you can better use zonal statistics (it's in the processing toolbox). If you polygonize rasters like you probably did, you'll introduce some challenges. docs.qgis.org/3.10/en/docs/user_manual/processing_algs/qgis/rasteranalysis.html#qgiszonalstatistics

[@khawlaalbedwawi5819]

can you help and record a video of how to calculate the areas of land uses (agriculture/roads/buildings) effected by different sea level rise scenarios? please i need urgently

[@gis1875]

tnx man ;)

[@anjanaadevi775]

Thanks for this! I'm using this video to calculate percentage of land usage falling within 10-minute-buffers of individual MRT stations. Since the catchment areas (buffers of adjacent MRT stations) are overlapping, it's tricky. Do you know how I can work around that?

[@HansvanderKwast]

Tricky, because if your buffer polygons overlap your areas get double counted. Try to see how you can conceptually solve that for your case.

[@peytonpriestman1846]

I'm trying to do something similar at the moment, and really struggling! Did you figure anything out?

[@Rapsaj]

12:48 would it be ok to use the “fix geometries” processing tool instead of the negative buffer or would it mess up other calculations

[@HansvanderKwast]

Fix geometries is the best way. Didn't exist in earlier versions. Also check QGISHydro Webinar 6 video.

[@deemahsukkar3373]

Hello, thank you very much for this video, it helped me a lot in my thesis. however, in the dissolve step, the area do not sum up after aggregating the data in terms of level value. i really would appreciate your help on this. thanks in advance :)

[@HansvanderKwast]

After dissolving, you need to calculate the areas of the new polygons with $area. The existing values in the atribute table do not automatically update after dissolving.

[@raidanmaqtan2652]

thanks a lot for this very helpful explanation, please, could we download the land cover vector file by this method for Malaysia ?

[@HansvanderKwast]

Thanks. This is open data from the European Union. For Malaysia you need to check if your government provides open data. Here's a webinar that I gave on this topic: www.thewaterchannel.tv/webinars/501-webinar-open-source-software-and-open-data-for-integrated-water-resources-management

[@raidanmaqtan2652]

@@HansvanderKwast Thank you very much

[@edr424]

is this same to land use mix?

[@rizriyandini5733]

Thank you for your video

[@gerryroberts458]

Great job Professor. What about soil data and land uses for other countries outside Europe? Let's say Oman?

[@HansvanderKwast]

In general one should check first with the national mapping agencies and research institutions to get the local data if available and accessible (the latter is often the problem). There are global data sets, but often coarse. Finally for land cover, you can do a remote sensing classification if data is not availabe.

[@gerryroberts458]

@@HansvanderKwast Thanks a lot for your response.

[@bloodymary8707]

if I have raster data and not vector can I calculate the area?

[@HansvanderKwast]

You can use raster zonal statistics: kzbin.info/www/bejne/qXnJiaaVmZ2JgrMsi=mCSFBVmHSSBzLwjo or use area calculations with the PCRaster Tools plugin: kzbin.info/www/bejne/iJ6kfmaKh7Ksjqssi=ggkoT809SmA04n5r

[@ErikaGomez23]

Hi Hans, greetings from Panama. Thank you very much for your great video, I just have a problem at the dissolve step. I have a shapefile of land use with 25 different types of class name, and I just give 1 number from 1 to 25, to the type of land, and the next step when I tried to dissolve, the program send me a lot of advertising "has invalid geometry and has been skipped. Please correct these geometries or change the Process setting to the" Ignore invalid input objects "option.", ¿Can you help me with this issue?, I am desperate, I have been working on this for days and until today I found your wonderful video and I get that error, I do not know how to solve it, thanks in advance for your answer for your great work.

[@HansvanderKwast]

Try Fix Geometries from the processing toolbox. Hope it works then.

[@user-qz5vp9rf3n]

You have shared good idea but how to get the software ?

[@HansvanderKwast]

The software is QGIS. It's open source and you can download it here: qgis.org/

[@shubhamkhairnar7301]

Hi sir. Please Forestry analysis in satellite data tutorial

[@ihinsolihin]

Waw...

[@nissmafeki3615]

Thank you