This is one of the best tutorial videos about QGIS I have ever seen. Thank you for your effort.
@KevinSaunders-y3k
29 күн бұрын
I watched this tutorial during my final year at varsity in 2019 for a design project we had. 5 years later and I return to this tutorial for a big project in Africa. Hans, thanks for this brilliant and elaborate video, appreciate it dearly.
@kevingonzalezhuertas7749
3 күн бұрын
What a useful video with a crystal clear explanation, thank you Hans! This is a treasure!
@roandurand3590
9 ай бұрын
Super helpful video. Just starting out my GIS journey. This will save me heaps of time trying to manually delineate catchments and produce maps! Thank you!
@brunorodrigues9736
3 жыл бұрын
Hi Hans, everyone seems to have doubts and we are used to be in a kind of a rush, but I just wanted to let you know that we deeply appreciate the work that you have been doing. This video was exceptional; the language you used was concise, clear and it worked flawlessly for me. Thank you so much!
@HansvanderKwast
3 жыл бұрын
Thanks Bruno!
@user-nt8gx7ed9y
7 ай бұрын
Thank you so much for uploading so many useful videos, I've been trying to generate catchments for a long time and this is the first time I've managed to get it to work! Thanks again!
@HansvanderKwast
7 ай бұрын
Nice to read that! Thanks!
@gisleberge4363
2 жыл бұрын
You're a teacher by "blood", really excellent content...tried the tutorial on my own maps an areas, and it is amazing how easy this can be done just following your step wise tutorial. Greetings from Norway, and a thousand thanks!
@sebdiaz1852
Жыл бұрын
Amazing tutorial, I am learning a lot from your expertise. took me a few hours to do it but finally completed all. Now I will apply this to a different catchment.
@cevuardriddick3305
27 күн бұрын
Thank you Hans very helpful for my projects in Vanuatu
@beccapotts428
2 жыл бұрын
I found this video very informative, I am a new graduate and this has helped me greatly in my new job
@shannontodd4619
3 жыл бұрын
Why couldn't I have found this at the start of my project! Great presentation, I'm now going to go and watch the rest of your content.
@sripatysatyavenkatachalam141
5 жыл бұрын
Excellent lecture and well organised covering major comands of qgis 3 with detailed explanation and demonstration simultaneously.
@davidefornacca5173
4 жыл бұрын
Thank you for this excellent tutorial.
@nbrahmareddy7690
3 жыл бұрын
Literally just mind blowing
@tzevoon
3 жыл бұрын
Thanks for the in-depth and detailed walkthrough.!
@jamesmiller2811
3 жыл бұрын
Really good lesson Hans. Clear and easy to follow.
@khutjodiphofe2245
3 жыл бұрын
It took me a while to grasp because I'm a beginner, but the video was very helpful.
@bernardkasomphe8993
2 жыл бұрын
Thank you for the tutorial. I have managed to generate a catchment of my own
@carlosreys9
5 жыл бұрын
Thank you very much! Before I did it with hydrology package in Arcmap. Fantastic!
@dr.mohanvasave3050
4 жыл бұрын
Very good demonstration sir please next video uploaded the Stream order calculated and show on River map in QGIS
@samcreazzo
4 жыл бұрын
Best tutorial on this topic, thank you very much
@kyuyeonlee430
4 жыл бұрын
Thank you so much! It was the best video for qgis ever for me. =b
@makireddysarveswararao6115
3 жыл бұрын
Thankyou so much for your detailed explanation
@HermanBooysen101
4 жыл бұрын
Thanks Hans, very helpful.
@TheWawanhn
4 жыл бұрын
Thank You for your explanation, it's very useful
@surjithpm
3 жыл бұрын
Hi Hans,thankyou for this tutorial.
@prashanthpalanisamy5862
5 жыл бұрын
Thank you for this. Very informative.
@orzuodinaev3067
4 жыл бұрын
Dear sir, I did all the steps until the clipping, when I run the process, the next error comes out "The following layers were not correctly generated.C:\Users\4BEC~1\AppData\Local\Temp/processing_c01f9474fa7a46379b398a946e7c0e36/c38651f8b05448a9bb716228107b6a2e/S_OUTPUT.shpYou can check the 'Log Messages Panel' in QGIS main window to find more information about the execution of the algorithm.". Can you help me pls!
@manotoegel6710
14 күн бұрын
The saga tool fill sinks (Wang &Liu) does not work. Any idea about the reasons?
@semunigusayalew6803
2 жыл бұрын
Thank you! Nice explanation.
@banka990
3 жыл бұрын
Is it possible to delineate only right or left hand tributaries of one river separately?
@BrunoRech23
4 жыл бұрын
Excellent explanation! I've seen in QGIS 3.10 that the value of area of a given vetorial layer can vary a lot depending on both the Coordinate Reference System (CRS) of the layer and the CRS used to proceed with the calculations. Since I'm in Brazil, I usually work with SIRGAS 2000, UTM zone 22S. An example of how different the values can be: I've drawn a square with a 10 km side (using SIRGAS 2000, UTM 22S). The calculated area with WGS 84 gave me 41 km² instead of 100 km². The same great difference happened when I did draw the very same square using WGS 84. My question is: what's the rule to calculate the area in order to get a real value of the portion of land I'm working on? When I used the "None/Planimetic" option to obtain the area (layer with SIRGAS 2000), I've got the right value. But I want to consider the surface curvature.
@HansvanderKwast
4 жыл бұрын
Thanks. First, never use a GCS (Lat/Lon coordinates) for distance and area measurements. Second, choose a projection that doesn't distort surfaces. See: kzitem.info/news/bejne/y4ykl6l5rpqAkmk
@nuclearant9523
4 жыл бұрын
Thanks for sharing!
@aliahdaneclaro2180
2 жыл бұрын
I'm having problems with the fill sink part. The running of algorithm always fails. what should I do?
@ahmad-arrafi6711
2 жыл бұрын
What a coincidence! I was facing the same problem. It was happening because of saga. You have to manually install saga gis and add it to qgis toolbox.
@karakambadiswethasree7188
21 күн бұрын
Hii sir morphometric analysis step by process pls explain it in a video
@rebekah2023
4 жыл бұрын
Thank you :) Very informative
@AhmedAdelSaleh
4 жыл бұрын
Fill sinks 10:30 Creating Stream Order - (Strahler order) 15:40
@fabioneiraalzate2755
4 жыл бұрын
Amazing video, thanks for share
@benjaminvanheerden9162
3 жыл бұрын
This is awesome! Thanks!
@marademeo
3 жыл бұрын
Thank you so much!
@roddysaltos6191
4 жыл бұрын
that's a good tutorial ,thank you
@Hydroclim
3 жыл бұрын
Is it possible to delineate sub catchment? Thanks so much for your wonderful QGIS tutorials
@HansvanderKwast
3 жыл бұрын
Yes, in the same way. Or if you have multiple outlets you can do it automatically. Check the other videos on my channel.
@damarpanoto1579
4 жыл бұрын
Thank you so much. Very help me
@burcuersoy1208
4 ай бұрын
Dear Hans, thanks for the very usefull video. I have a problem with the Uplslope area function. The system creates the catchment area that I select but the max. and min. values are changing between 100 and 100. In your case it was between 0 and 100. Therefore, my vector file does not seperate the selected catchment area from the complete rest DEM file. I tried to change also the max. and min. values by setting up the min. as 0. However nothing is changing. Do you have any opinion regarding the reason of the problem? Thanks in advance.
@jamesgere19214
2 жыл бұрын
thank you! best ever
@lalitchoudhury2041
9 ай бұрын
Sir, Can i get DEM from SRTM of less then 30 m pixel resolution…. ??? Actually my river channel are very small and 30 m pixel almost covers entire width of the river…
@riyaraut8135
2 жыл бұрын
Hello Sir, at 23:24 how did you customize the bands?
@jimsanaee1516
Жыл бұрын
This video would help you kzitem.info/news/bejne/0mtq3oivj2mYdHo
@raidanmaqtan2652
4 жыл бұрын
Thanks a lot for this very informative video.
@HansvanderKwast
4 жыл бұрын
In the processing toolbox you can find a tool called Fix Layer Geometry. If you use this first, it should work. Alternatively, you can calculate a buffer of 0 of the catchment polygon, that also repairs the polygon.
@raidanmaqtan2652
4 жыл бұрын
@@HansvanderKwast thanks a lot.
@mangeshpatil5930
4 жыл бұрын
Nice one. Thanks.
@hastingsmbale
3 жыл бұрын
Best lecture so far. How do you proceed calculating the area of a catchment?
@jonathanbacor5233
2 жыл бұрын
attribute table, geometry, area
@muhammadafiqmohamadzahir5252
5 жыл бұрын
Thank you so much for this tutorial. I have one issue though . When trying to re-project the mosaic to my project CRS (GDA94 EPSG : 4283) It gives me an error. Is there a way I can get around this ? Cheers
@HansvanderKwast
4 жыл бұрын
You are using a GCS with degrees as units. You need to project the data to a metric coordinate system.
@walelign1356
5 жыл бұрын
Hello Hans, I've found this tutorial very helpful. As a beginner for QGIS, I am having difficulty to calculate the maximum flow path and average slope of the catchment I have. I was able to generate a raster "Flow path length" map using "Flow path length" tool in SAGA, but I do not know how to convert that into a vector stream line from which I can read the maximum flow path, and its average slope. If it is worth to be your next tutorial.
@ExploreRSGISTutorials
3 жыл бұрын
*Great Tutorial 👍👍👍*
@mopisboss1754
3 жыл бұрын
Thank you verymuch
@parsamohajeri4644
4 жыл бұрын
Many thanks for your awesome tutorial Hans. I'm receiving the following error when I want to build a virtual raster. What's the problem? and what should I do? Loading resulting layers The following layers were not correctly generated./Users/parsa/Desktop/QGIS/Rur/DEM_Mosaic.vrtYou can check the 'Log Messages Panel' in QGIS main window to find more information about the execution of the algorithm.
@HansvanderKwast
4 жыл бұрын
Thanks. I can see you're saving files in your desktop folder. It's recommended to save it in a dedicated folder on your hard drive so the paths don't cause problems. Not sure, but it might be the problem here. Also check this video on good practice: kzitem.info/news/bejne/zJ2d3XqQgYp0n2k
@parsamohajeri4644
4 жыл бұрын
@@HansvanderKwast Dear Hans, Many thanks for your reply. I tried that but didn't work. I tried the QGIS on my Windows (the problem was with my Mac) and all worked well.
@danilomei4822
4 жыл бұрын
EXCELLENT video, I ALSO PURCHASED THE BOOK, FANTASTIC! TO VIEW THE SUBBASIN?
@max7164
4 жыл бұрын
Hi Hans. Great video, again! I was wondering how you would go about doing this in a heavily urbanised catchment in order to generate "sewer catchments"? I have access to very detailed 1m resolution DSM. The idea is to use this to create our urban "sub-catchments" for use in a hydraulic modelling software. My first idea is to burn the drainage network into the DSM. Would I burn the pipes only or nodes as well (manholes/gullies) in order to create local sinks? Any ideas/ advice would be great. I appreciate you're likely a busy guy. Thanks!
@satarupapattanaik7001
2 жыл бұрын
Sir I have a problem while working on channel network and drainage basins part. My layers are not generating. Any idea how to overcome this.
@jimsanaee1516
Жыл бұрын
There might be many reasons. First you can try changing the directory. If it doesn't work you can generate the filled DEM again and try
@blanossakamassi4390
4 жыл бұрын
Hi Hans, thanks for the good explenation! Please how to Delineating Multiple catchment with QGIS.
@HansvanderKwast
4 жыл бұрын
You can use the Points2Cathchment plugin from my GitHub page: github.com/jvdkwast/PyQGIS_Hydro
@maotsetung243
5 жыл бұрын
thank you
@ruchirenavikar4283
4 жыл бұрын
Hi Hans! Great video. Im perhaps stuck at a very basic step. At 23:31 when you use the directional legend for your colour ramp for the flow direction raster, how did you do that? Where can I find that legend?
@HansvanderKwast
4 жыл бұрын
Hi Ruchi. Please checkt this video where that's explained clearer: kzitem.info/news/bejne/k4uYlpdtjKVeh2k
@rojalinpriyadarshini2277
4 жыл бұрын
Sir, kindly tell the steps to find out the "Longest Flow Path" in that Catchment Area.
@yosiaa_saigupi
3 жыл бұрын
I have several questions about this video: 1. I can't use Upslope Area because my project wasn't generating in a proper way. What should I do? Should I start from the beginning? 2. What version of QGIS 3 that you use? Is there any big difference between your version and the newer one (I use QGIS 3.16 Hannover version)? Thanks
@HansvanderKwast
3 жыл бұрын
1. Make sure you're using your filled DEM and you're choosing the coordinate in the delineated channel (zoom in). 2. Only little differences with newer versions (such as click right to copy coordinate). Also watch other videos on this topic. There's a playlist: kzitem.info/door/PLeuKJkIxCDj2Gk0CkcJ-QeviE41aMZd-5
@GeneralFlop
3 жыл бұрын
Hello, I'm new to GIS and this is a fantastic video, thank you! I am examining the catchment of a lake in central America and I have an issue which the method you outline doesn't handle quite so well. That is, there is an area of extremely flat topography with a major river that I suspect will change the drainage characteristics of the region, bu due to the topography the calculated Channel Network Algorithm separates to sections of the river, irrespective of Strahler Order selected. Is there a workaround for situations like this? Any help or guidance would be greatly appreciated and I can provide further detail if you require! Thanks, Matt
@GeneralFlop
3 жыл бұрын
I see that there is a video on "burning in rivers". Sorry I was unaware of this terminology. I will explore these options!
@bricejoeldjama3805
2 жыл бұрын
thank you for your tutorial that you put online it is really for us I will ask myself I am a student djama brice in Master 2 at the university Félix houphouet boigny of Cocody side of Ivory. I have a problem to make the pollution vulnerability map on the Qgis 3.16 software. can you help me by making a tutorial on calculating the vulnerability index under qgis 3.16.
@orzuodinaev3067
4 жыл бұрын
Hi Hans, when I run "strahler order", streams in my image look incomplete, there are gaps between streams, main rivers are absent. Even when I do calculations and get rid off minor streams, still few streams are left, which are not connected with others and look isolated....
@HansvanderKwast
4 жыл бұрын
There might be problems with your filled DEM. Maybe you have voids?
@filippoberdes9114
4 жыл бұрын
Instead of calculating the catchment area from the Fill dem raster layer, why don't you export the polygon from the Drainage Basins vector layer created before? Excelent video, thank you very much for the explanation
@HansvanderKwast
4 жыл бұрын
Thanks. The automatically calculated drainage is not the same as the one from a specific outlet chosen by the user. Often you want the catchment belonging to a specific outlet. In the example they're almost the same, but you could also choose the outlet more upstream to delineate a subchatchment or choose a point where you measure discharge.
@filippoberdes9114
4 жыл бұрын
@@HansvanderKwast Right! I understand. Thank you.
@rubenbloem4265
6 ай бұрын
Hi Hans, every time when I run the Warp projection and I set the output file resolution to any value, the projection does not run. It keeps on loading for hours. Could you please assist me in this.
@HansvanderKwast
6 ай бұрын
Maybe your raster is very large (large area or high resolution). As an alternative you can click right on the layer and choose Export | Save as.... Here you can reproject and clip at the same time. Change the CRS to the target that you want and change the extent to match with your area of interest. I hope that works. If your area is very large, you can choose a coarser DEM. You can download DEMs via the OpenTopography DEM Downloader plugin: kzitem.info/news/bejne/poOttohtrXNzdpwsi=7tvwOAw9B2L1Ej-Y. Try a 90 m if 30 m doesn't work.
@tiestomate
2 жыл бұрын
Is it possible to delineated a catchment from a particular point on a map? I need to assess a road culvert and wonder if I can get a catchment upstream of the culvert.
@troynguyen1346
2 жыл бұрын
the principle is the same, just follow the video and pick your point of interest at the culvert inlet
@tirtharajishore8033
Ай бұрын
Sir there is some problem regarding upslope area. What should I do?
@HansvanderKwast
28 күн бұрын
There's a problem with SAGA after QGIS 3.18 or so. My advise is not to use SAGA, but alternatives like the PCRaster Tools plugin (lots of videos on this channel), GRASS or WhiteboxTools. If you still want to use SAGA, check these 2 work around videos: kzitem.info/news/bejne/1WNoq6ylspp6mXY kzitem.info/news/bejne/o2eCs4OFiX-ImqQ
@shramanatalapatra8364
Жыл бұрын
Can the drainage channels be considered as stream network?
@sebdiaz1852
Жыл бұрын
Hi Hans. I am confused on why in newer tutorials you use PCRaster plugins and in this one you did the same analysis with out PCRaster. Is that because with PCRaster you can edit the stralher order? Regards
@HansvanderKwast
Жыл бұрын
It's because there are issues with SAGA in newer QGIS versions. Check also this webinar kzitem.info/news/bejne/rm-e04JjrKyAZ6A at 10min53s
@sebdiaz1852
Жыл бұрын
@@HansvanderKwast thanks.
@thandothamana6175
4 жыл бұрын
I experience an error when I get to strahler order,been doing it for quite some time now and I really don't know what to do anymore. error "Layers were not correctly generated". What could be the problem?
@HansvanderKwast
4 жыл бұрын
There can be several reasons: 1. Check if you used the filled DEM as input and not another layer 2. Make sure you save it to a folder and file name without spaces or other strange characters 3. Maybe your DEM is too large and your computer memory can't handle it. Then you should reduce the area or use a coarser DEM. 4. Maybe your area is too flat. 5. Use LTR versions of QGIS to have less bugs. The current LTR is 3.10.9 6. Check if your DEM doesn't have voids. This is explained here: kzitem.info/news/bejne/p62AuXaljaBirGk I hope this helps.
@florent1611
4 жыл бұрын
Thanks :) just one remark: the source of the Rur is in Belgium and not in Germany ;)
@HansvanderKwast
4 жыл бұрын
You're right. Thanks.
@drewfrench8784
4 жыл бұрын
Having terrible trouble making the Upslope algorithm work at all. I'm getting nothing - what am I doing wrong?
@HansvanderKwast
4 жыл бұрын
Can you send me an e-mail with screenshots so I can have a look?
@Poudelshikhar
4 жыл бұрын
Hi Hans, this video is really useful. Thank you for making it. How to make sub-catchment areas? You have made drainage basins for different rivers including Rur river but my question is how to create the sub-catchments inside the catchment of Rur river? I will really appreciate your help. Thank you!
@HansvanderKwast
4 жыл бұрын
Check the new tutorial on this page: ocw.un-ihe.org/course/view.php?id=11§ion=10
@Poudelshikhar
4 жыл бұрын
@@HansvanderKwast Thank you very much, Hans! I got what I was searching for.
@nuclearant9523
4 жыл бұрын
Hi Hans, I played the dem with your guidance but found that my river value is always the small ones. Why will this happen?
@HansvanderKwast
4 жыл бұрын
I can only think of 2 reasons: 1. You didn't use the filled DEM for calculation of the Strahler order. Then it never gets into the higher orders. 2. You're applying it to another study area where there are a lot of small rivers?
@Vikas20a
3 жыл бұрын
Hi, what value i should put while creating filled_DEM for 1.5M drone resolution? DEM, Not able to generate the strahaler order DEM.
@HansvanderKwast
3 жыл бұрын
Make sure you have filled the DEM before calculating Strahler orders. You can use SAGA Fill Sinks Wang & Liu from the Processing Toolbox.
@Vikas20a
3 жыл бұрын
@@HansvanderKwast what value should i put in dem_filled in place of resolution? My dem is 1.5 m resolution
@justinecarey9692
8 ай бұрын
Hi Hans, thanks so much for your videos, I have used them a lot while studying limnology at BOKU. I'm having an issue at the thinning step - too many cells are removed and the line is no longer continuous, which leads r.to.vect to create many small lines. Any suggestions?
@HansvanderKwast
8 ай бұрын
Hi! Probably something went wrong before. The question seems to be at the wrong video, because this video uses SAGA, which doesn't need r.to.vect. I assume you're using the PCRaster approach in this playlist: kzitem.info/door/PLeuKJkIxCDj05rwD3Fun7v7rpVRg7c_kE&si=kd661MjchSynsclX. Please make sure you follow all steps carefully. Check if the raster streams were still connected before thinning. Also check if your projection is correct (should not be in Geographic Coordinate System) and make sure you use the correct inputs all the time. For further questions about this approach, please post the question under the appropriate video.
@HansvanderKwast
8 ай бұрын
This means that you can't automate this approach on Mac, unless you find a way to build PCRaster from source code and use it in your regular installation. Unfortunaltely, I'm not a Mac user, so I can't help you with this.
@Gurtblut
Жыл бұрын
Thanks for the great video. Question: In attribute table, is the number '100' the catchment area (= area of the polygon?). Otherwise, how can we calculate the catchment area finally of the Rur_catchment polygon?
@HansvanderKwast
Жыл бұрын
You can calculate the area of polygons with the field calculator. Use the $area function.
@skgaming3518
11 ай бұрын
@@HansvanderKwast whats the unit of area calculated?
@branislav990
3 жыл бұрын
Often I encounter an error when I try the "fill sinks" function. I am following every step of yours and it works on some catchments but doesn't on some others. What could be the problem? Is it important the "output layer type", because it's Float32 by default in your video and different in my project, so I always change it to Float32 as well?
@HansvanderKwast
3 жыл бұрын
Fills sinks gives problems in the following cases: 1. DEM too flat 2. DEM too large for memory 3. Geographic Coordinate System used instead of projection. 4. Spaces in folder and file names
@branislav990
3 жыл бұрын
@@HansvanderKwast Thank you so much, sir! The problem was with my folder's name, which contained a special character. Now it works perfectly. Please keep posting these amazing tutorials, they mean so much to me and many others!
@harshalhandigund8185
4 жыл бұрын
Thanks for the video, as a beginner it is very helpful but i faced a problem while generating the Strahler order for the area of interest, it shows a error saying "The following layers were not correctly generated" and gives information about the location of the save file. im currently using qgis version 3.10 , please help me out with the problem
@HansvanderKwast
4 жыл бұрын
Make sure you've upgraded to 3.10.3 and you don't have spaces in file and folder names. Also check if you've used the filled dem and it doesn't have voids.
@ferdinanmanullang4488
4 жыл бұрын
Thank you, Professor, it really helpful. I have a problem regarding the extraction clip raster by mask layer. I am not able to save the clipped mask into .sdat format. I have chosen Float32 as the output data type. Fyi, I am using QGIS Madeira. Do you have any idea?
@HansvanderKwast
4 жыл бұрын
Maybe you got a "geometry error"? In that case you can use "fix geometry" from the processing toolbox.
@ferdinanmanullang4488
4 жыл бұрын
@@HansvanderKwast Thank you for your kind reply. I will do it.
@BateAshu
4 жыл бұрын
Hi Ferdinan, please I'm having a similar problem. Did you get the solution? I try the procedure that the Professor suggested but it didn't fix the problem
@djouzhdz9839
4 жыл бұрын
please, build virtual raster does not figurate?
@ankit__kapoor
3 жыл бұрын
I am trying to use the strahler order on the Jhelum River, India but its not working there! What should I do ?
@HansvanderKwast
3 жыл бұрын
Check other answers to comments here and related videos in the catchment delineation playlist on my channel.
@chris.p.bacon.411
4 жыл бұрын
This is great content and an even better explanation! I just have one question regarding the fill tool. My computer can not execute this function what can possibly be the problem? Is it the RAM or maybe something else?
@HansvanderKwast
4 жыл бұрын
RAM can be the problem indeed. Check if you can use a coarser spatial resolution for your study area. < 5 m will not improve the results and for large catchments 30 or 90 m is okay too. I recommend at least 16 GB of RAM. If the size is not the problem, check if you use spaces and strange characters in file/folder names and if there are no voids in the raster. Also if the area is too flat you'll run into challenges.
@chris.p.bacon.411
4 жыл бұрын
Thank you for the detailed answer. I appreciate it
@joyloc8808
4 жыл бұрын
Hi there. Hans. I have a shape file of river lines. But with the automatic digitization of the raster, the directions were lost. Please tell me how to automatically set the directions of the lines in the correct direction according to the DEM. (I work in QGIS 3.14). Thank you.
@HansvanderKwast
4 жыл бұрын
Hi. When you derive the channels using the method in the video, the flow direction of the lines should be correct. You can only reverse the flow direction with a tool from the Processing Toolbox --> Vector Geometry --> Reverse line direction.
@joyloc8808
4 жыл бұрын
@@HansvanderKwast I asked about a special case. My digitization was based on cadastral drawings of rivers, not on your algorithm.. Therefore, many directions of the lines are broken. I need to select and turn in another direction the lines of rivers that "flow up". Altitude is present. Thanks.
@HansvanderKwast
4 жыл бұрын
Unfortunately, I don't know another way then manually choosing the segments and use the reverse direction tool.
@OUSTAO
4 жыл бұрын
Dear Hans, it is a wonderful tutorial video to show drainage and water network. I am using the version of Maderia 3.10.14 currently. While watching the video, on the section of 11:00, I just encountered an error for fill sinks /wang lui showing that algorithm did not work in red colour and no raster as dem_fill appeared on the left box. Despite all my efforts, I could not manage to fix it up. Could you recommend me a way of solution to it?
@HansvanderKwast
4 жыл бұрын
Thanks. For my tuturials you should always use the LTR versions. Newer versions have new features, but can introduce also new bugs. So 3.4 or 3.10.4 are recommended now. It can still give an error (see also kzitem.info/news/bejne/k4uYlpdtjKVeh2k). The these are the options: (1) run it again immediately, maybe it works the second time, (2) check if file and folder names don't contain spaces or strange characters (kzitem.info/news/bejne/zJ2d3XqQgYp0n2k), (3) check if you're using a metric CRS instead of GCS, (4) maybe your area is too large for the memory. Hope this helps.
@OUSTAO
4 жыл бұрын
@@HansvanderKwast Thank you so much for responding both quickly and informative. I will follow all instructions and advises you just given, if it does not work again, I ll keep you posted about it. Best.
@OUSTAO
4 жыл бұрын
@@HansvanderKwast Dear Hans, although I followed all your advises to solve the problem yesterday, I again encountered the same problem while on processing filled terrain (The following layers were not correctly generated.C:/mos/DEM_filled.sdatYou can check the 'Log Messages Panel' in QGIS main window to find more information about the execution of the algorithm). The area that I need is Mosul and its environs. The area is not large enough to cause an overdata problem. I suppose the Mosul dam which covers a large tract of land cannot be detected probably. Could you know if the fill sinks (wang & lui) cannot map the lakes and dams ?
@HansvanderKwast
4 жыл бұрын
@@OUSTAO The dam might be the problem. The fill sinks algorithm will fill the depression in the DEM to make sure the water flows to the outlet. It results in a large gently sloping area (like the mines in my example). If the lake is covering a large part of your DEM then probably it can't solve the equations and gives an error. Normally I advise to delineate catchments with an outlet where a river enters a lake.
@OUSTAO
4 жыл бұрын
@@HansvanderKwast Thank you but again I had the same problem, even though I followed the steps you recommended, probably the terrrain is highly mountainous and it cannot detect the catchment area.
@lukescott5064
2 жыл бұрын
worked great! is there any way to make improve accuracy of rivers in lowland areas where there is little elevation difference? thanks!!
@HansvanderKwast
2 жыл бұрын
You can play with the following: 1. Use a smaller minimum slope value in the fill sinks algorithm 2. Use another algorithm than D8, try MFD or D-INF 3. Burn in the river system so the water is forced to follow more realistic water courses. Some videos on this channel about that.
@lukescott5064
2 жыл бұрын
@@HansvanderKwast okay great, thank you!
@leanzaanino3062
3 жыл бұрын
Hi. I wanna know what is an .adf extension for? And how can I have that file cause I need it for SWAT+. Thank you.
@HansvanderKwast
3 жыл бұрын
It's the ArcInfo Binary GRID format. gdal.orgdrivers/raster/arcinfo_grid_format.html. Unfortunately it is a proprietary format. It can be read by gdal, but not written. Not sure about SWAT requirements, I'm not a SWAT user. Check QSWAT for use with QGIS.
@lalitchoudhury2041
9 ай бұрын
Sir what is the importance of minimum slope dialogue in fill sink by wang &liu method??
@HansvanderKwast
9 ай бұрын
The minimum slope parameter in the Wang & Liu fill sinks algorithm is a user-defined value that determines the minimum elevation difference (and thus slope gradient) between adjacent cells in the filled digital elevation model (DEM). This parameter is important for hydrological modeling, as it affects the flow direction and watershed partition of the surface. If the minimum slope is set to zero, the algorithm will only fill the depressions until a horizontal surface is established, which may not be realistic or helpful for simulating water flow. If the minimum slope is set to a positive value, the algorithm will fill the depressions and also create a slight downward slope along the flow path, which may improve the accuracy and stability of the hydrological analysis. The optimal value of the minimum slope parameter may depend on the resolution and quality of the input DEM, as well as the specific objectives and assumptions of the modeling.
@RK-kv3yo
4 жыл бұрын
Thank you very much for this video. my network is timed out so I can not zoom into map....could you please help me with problem?
@HansvanderKwast
4 жыл бұрын
I assume you're referring to problems with access to online layers from the QuickMapServices plugin. I can't solve that if your internet connection isn't good enough. Then you have to find some offline reference maps.
@samarjyoti-ray
7 ай бұрын
Hi Hans, I am sorry if this is really basic, but if my catchment area lies into multiple projected coordinate system, which one should I select?
@HansvanderKwast
7 ай бұрын
Hi! You can choose one of the projections, preferably the one that covers most of the study area.
@samarjyoti-ray
6 ай бұрын
@@HansvanderKwast 27:48 I have a lot of values (>17,000) in the attributes table. What am I doing wrong?
@samarjyoti-ray
6 ай бұрын
@@HansvanderKwast Hey?
@HansvanderKwast
6 ай бұрын
@samarjyotiray3488 Maybe you have polygonized the wrong raster? Hard to tell what went wrong with the limited info. If in your input raster you see a large catchment with all the cells one cell value, then that should also end up in your polygon layer.
@shrawantripathi8289
4 жыл бұрын
Hi.. I see your this video.. and i see the drainage basin and catchment boundary which you derive is same , then why you create again catchment by upslope area tool, while it was also done by drainage basin? also i want to know weather drainage basin and catchment may differ or not?
@HansvanderKwast
4 жыл бұрын
They are not exactly the same. The drainage basins derived by the channel network and drainage basins tool derive all basins in the DEM based on the flow direction. The upslope area tool will delineate a specific catchment that belongs to a specific point in the river that you indicate in the tool. That can be the outlet or any point in the river. It calculates the area that contributes to water flow at that point.
@shrawantripathi8289
4 жыл бұрын
@@HansvanderKwast Thanks for giving me clarity on this.
@victoriagrima3116
2 жыл бұрын
What is the year of the SRTM DEMs, I am trying to find the year that these were generated and can't find it. thanks
@HansvanderKwast
2 жыл бұрын
Acquisition date of SRTM is 2000.
@victoriagrima3116
2 жыл бұрын
@@HansvanderKwast thanks
@varelanderson9342
3 жыл бұрын
Hello there, thanks for the explanation. I have a problem with my QGIS 3.10.9. When I made the virtual raster, it won't show when I delete the tiles from the previous step. Can I get your help?
@HansvanderKwast
3 жыл бұрын
Are you sure that your layers virtual layer was on top of the other layers? If it's below you can only see it by switching off or removing the other layers.
@varelanderson9342
3 жыл бұрын
@@HansvanderKwast When I unticked the other layers except for the virtual raster, nothing shows up.
@varelanderson9342
3 жыл бұрын
@@HansvanderKwast Never mind, just fixed it.
@franciscosaimone2730
4 жыл бұрын
Hi Hans... How do you extract the main river flow path... and its extension?
@HansvanderKwast
4 жыл бұрын
The Strahler order method was used to delineate the river and its tributaries. kzitem.info/news/bejne/tKt80mx7kHaimYo
@lalitchoudhury2041
9 ай бұрын
Sir, I had error in upslope area calculation to generate rur-catchment file ….but found some video on youtube to debug the same by providing “|4 “ in c-drive upslope test file,,,, error was removed but the generated file is in full black colour,,,, please guide me…
@HansvanderKwast
9 ай бұрын
That means that you probably didn't put the outlet coordinate in a delineated stream or the projection of the coordinate is not the same as your flow direction raster.
@lalitchoudhury2041
9 ай бұрын
@@HansvanderKwast Issue is resolved…. Thank you 🙏
@nbrahmareddy7690
3 жыл бұрын
Sir how to create basin shape file and download Landsat path/row tiles for the same sir ? Thank you sir hope here from you soon sir
@angelos.1972
6 жыл бұрын
Thanks for your videos, they are great. I have a problem with small catchments though, even if I pick a point that falls onto the stream DEM, the up-slope area algorithm gives me a completelly black DEM, how could I solve that and get the area for a whatever sub-catchment?
@HansvanderKwast
6 жыл бұрын
Hi Angelo. Thanks for using my videos. Maybe you can send me some screenshots so I can check your problem?
@angelos.1972
6 жыл бұрын
Hi Hans, I managed to solve the problem I think. The up-slope output is sometimes a black DEM but as you suggested, by adding "0" to "Additional no data value" in Properties/Transparency, the DEM shows the watershed delineation, I just do not understand why it happens only in some case. Any clues? Thanks
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