Longitudinal River Elevation Profiles in QGIS

  Рет қаралды 18,514

Hans van der Kwast

Hans van der Kwast

Күн бұрын

Пікірлер: 43
@rakeshkumarsahoo6296
@rakeshkumarsahoo6296 3 жыл бұрын
Respected sir, Please tell me how can I plot the stream steepness Index profile using QGIS. If in QGIS this feature is not available then which software I should follow...kindly guide me. Thank you very much.
@MathieuSimard-du8mb
@MathieuSimard-du8mb 2 ай бұрын
Is there a way to make a graph with multiple rivers to compare?
@nomenetasaili7339
@nomenetasaili7339 3 жыл бұрын
Thanks for this. Must say your text book is really good. Thanks for writing it.
@Kappa_mi
@Kappa_mi 3 жыл бұрын
How can I draw the river line? I edited the channel layer and in the attribute table I removed all the channel except the river i want but in the profile the points are not in sequence and the profile has too many up and downs and it's not a descending profile.
@rojalinpriyadarshini2277
@rojalinpriyadarshini2277 4 жыл бұрын
Sir, how to get the ''River Vector'' Layer among the Channel Network of a catchment i.e. the Longest Stream.
@sureshpatil1817
@sureshpatil1817 4 жыл бұрын
Sir please suggest the name of plugin in Qgis which gives us geomorphological parameters such as length of river, number if rivers, Bifurcation ratio, stream frequency etc
@sebastiankrolik3927
@sebastiankrolik3927 Жыл бұрын
thanks to you and this video I will be able to earn my degree
@jessycacarneiro2310
@jessycacarneiro2310 3 ай бұрын
Do those plugins work for any version of QGIS?
@HansvanderKwast
@HansvanderKwast 3 ай бұрын
Plugins have a minimum and maximum QGIS version in their metadata. Based on this you can or can't see the plugin in the Plugins Manager. If you can see them they should work. If not, this should be reported to the plugin developer.
@jessycacarneiro2310
@jessycacarneiro2310 3 ай бұрын
@@HansvanderKwast Oh, I see, thank you!
@ujjwalmeshram7183
@ujjwalmeshram7183 3 жыл бұрын
Dear sir, please tell me how to create stream length gradient index curve in qgis
@atillakoyuncu660
@atillakoyuncu660 2 жыл бұрын
sir, can we calculate SL index in this way? Could you help
@edifyingyou3769
@edifyingyou3769 4 жыл бұрын
Hello, I am confused. Can you tell me how is that "River" vector layer created with those attributes?
@HansvanderKwast
@HansvanderKwast 4 жыл бұрын
For the profile you just need a line vector of the river that contains one feature. You can get that by dissolving. In the example I used a delineated river (explained in this video kzbin.info/www/bejne/aIbFYZZtiNhgipY) and used the longest distance, which I've manually selected and exported.
@tulikamondal3049
@tulikamondal3049 4 жыл бұрын
thank you for this very helpful information sir. i just had I question, in the graph prepared by the profile plugin what does the X and Y coordinate suggests? and what does the interpolation profile suggests?
@HansvanderKwast
@HansvanderKwast 4 жыл бұрын
X is distance along the profile line. Y is elevation (or value of the raster if you use another layer).
@tulikamondal3049
@tulikamondal3049 4 жыл бұрын
@@HansvanderKwast what is the unit used here? for elevation and distance? I've used SRTM DEM here
@HansvanderKwast
@HansvanderKwast 4 жыл бұрын
The y values are sampled from the raster. So if the pixels have values in meters, like the SRTM DEM used here, it will be in meters. The x axis uses distance in map units I assume. So it depends on the projection.
@tulikamondal3049
@tulikamondal3049 4 жыл бұрын
@@HansvanderKwast thank you. That was very helpful.
@simonebrotto1977
@simonebrotto1977 2 жыл бұрын
All your videos are great Hans! Question: how do you usually estimate the channel bed slope of the main stream (used in steady flow manning equation) starting from DEM? I usually use profile tool plugin, copy to clipboard, in Excel I add a chart with linear best fit line, that slope is the dimensionless value for bed slope. I think this method is quiet straight forward and correct although it involves some extra QGIS manipulation, do you agree? Is there a tool (grass or saga) able to output bed slope value? Thank you
@HansvanderKwast
@HansvanderKwast 2 жыл бұрын
I think the approach is correct. The assumption here is that bed slope is equal to slope of DEM. With the PCRaster Tools plugin you can calculate the average or median slope of a river with a few steps. If that is useful, please let me know and I'll make a video.
@HansvanderKwast
@HansvanderKwast 2 жыл бұрын
But I think for the manning equation that's not needed. You need the general slope of the hydraulic grade. So I think your fitting method works fine.
@simonebrotto1977
@simonebrotto1977 2 жыл бұрын
@@HansvanderKwast best fit linear uses linear regression so you get the same result with =reg.lin in excel. Profile tool plugin gives you the chance to save a temporary file but unfortunately it contains just Zs not Xs (as for table). Point sampling tool saves both, distance and altitude so starting from this vector i think one should be able to obtain slope through linear regressione, maybe using statistics panel or some expression in field calc
@simonebrotto1977
@simonebrotto1977 2 жыл бұрын
@@HansvanderKwast I am more familiar with Grass and Saga tools, quite inexperienced with PCRaster, anyway for sure someone will appreciate it
@geetikachauhan6908
@geetikachauhan6908 4 жыл бұрын
Dear sir, My SRTM dem shows the lowest elevation along the river as 532m, however, my river profile lies between 550m to 570m. Sir, why is there a difference? Do the DEM contains information about the Thalweg of the river?
@HansvanderKwast
@HansvanderKwast 4 жыл бұрын
That depends on the DEM and the treatment. In my example I used a filled DEM. If the streams are derived from the filled DEM the lowest point of the DEM will be also the lowest point of the river (if you take the segments all the way to the outlet). If you use an existing river layer, like from OSM, then there is not everywhere a match with the DEM, because of sinks and spikes that are artefacts. Also the spatial resolution of the DEM will affect how well you can represent your river profile. SRTM gives an average elevation for 30 m x 30 m pixels.
@geetikachauhan6908
@geetikachauhan6908 4 жыл бұрын
​@@HansvanderKwast Thank you, sir, for the detailed reply. I have learned a lot from your videos, thank you, for making them.
@aloisiojbc9496
@aloisiojbc9496 4 жыл бұрын
@@HansvanderKwast Great video. By generating the river vector using a lower Strahler order (let's say 5 instead of 7, as u explained in the video: Webinar 4: Stream & Catchment Delineation), can I avoid the river vector dropping out of the river channel? (the problem is that. At some points, the shape is out of the river channel, and the plugin (Point Sampling Tool) captures the wrong Z value. Did u manually correct the river vector? I have used the fill Sink (wang & liu), but the river vector line is still going outside the river channel, which causes higher Z values.
@HansvanderKwast
@HansvanderKwast 4 жыл бұрын
@@aloisiojbc9496 If you calculate the channels with the same filled DEM you should have the correct values. The channels algorithm uses the Strahler algorithm first, which is derived from the filled DEM. Then it will vectorise the Strahler orders above the chosen threshold. If river pixels are not at the lowest point, something else is wrong. Mismatch of projections? Other DEM used?
@TheLuxedeluxe
@TheLuxedeluxe 2 жыл бұрын
I keep getting an error message "Active layer is not profilable layer."
@vijaykumarkashyap1840
@vijaykumarkashyap1840 3 жыл бұрын
Dear sir, many many thanks for your amazing qgis video. Sir, how can we develop hecras geometry file of a river in qgis latest version to further analyse it in hecras??
@HansvanderKwast
@HansvanderKwast 3 жыл бұрын
Have a look at RiverGIS plugin: rivergis.com/
@bbase322
@bbase322 4 жыл бұрын
If your footage is off, how do you fix it?
@HansvanderKwast
@HansvanderKwast 4 жыл бұрын
Not sure what you mean.
@bbase322
@bbase322 4 жыл бұрын
@@HansvanderKwast I believe the length is in meters, how do I change it to feet?
@suryateja6497
@suryateja6497 3 жыл бұрын
very very helpful sir! Thank you
@suneelkumarahirwar5189
@suneelkumarahirwar5189 4 жыл бұрын
Sir, We are requested to please make video on how find reservoir capacity(volume) & reservoir area at required elevation in QGIS. When we find volume by raster surface volume and raster volume tool it gives much much different result i.e. 650 Mcm from actual value 130 Mcm in case of pawai Dam, so it creates confusion. If you make video over that subject it will help all irrigation engineers to design a Dam. Thank you sir...
@naveenkumarshakya4736
@naveenkumarshakya4736 3 жыл бұрын
Survey kar le bhai wrd main paisa de to rahe hai.
@sureshpatil1817
@sureshpatil1817 4 жыл бұрын
Great information sir
@daleduenas
@daleduenas 4 жыл бұрын
Hi, sorry for the inconvenience, but I can't see the answer to your question. Could you please share it. Cheers
@mteixeira87
@mteixeira87 4 жыл бұрын
Thank you so much!! :)
@MRKRIS10
@MRKRIS10 3 жыл бұрын
Thanks you very much mr
@sureshpatil1817
@sureshpatil1817 4 жыл бұрын
Sir please suggest the name of plugin in Qgis which gives us geomorphological parameters such as length of river, number if rivers, Bifurcation ratio, stream frequency etc
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