[GRASS-user] calculate the volume of a DEM with r.volume
Moritz Lennert
mlennert at club.worldonline.be
Fri Jul 13 08:41:09 PDT 2018
On 13/07/18 09:51, marion-brunet at sfr.fr wrote:
> Hello,
>
> I am working on Windows and I tried using GRASS 7.2.2, GRASS 7.4.0 and
> GRASS 7.4.1 to see if there is any difference, but it is always the same.
>
> I have a ratser map calleddec-juin
> First I didr.clump input=dec-juin at 1217_Interpo0618 output=test
> to get the clumps
> Then I didr.volume input=dec-juin at 1217_Interpo0618
> clump=test at 1217_Interpo0618
> to have the volume.
If dec-juin at 1217_Interpo0618 contains your DEM difference, than you will
have different values for each pixel and clumping the map will results
in almost as many clumps as pixels. The clumps are meant to be used to
delineate specific areas for which you want the volume. If you want the
total volume of the entire computational region, you can just create a
map with r.mapcalc like this:
r.mapcalc "clump = 1"
and then run
r.volume input=dec-juin at 1217_Interpo0618 clump=clump
which should give you the total volume.
Ideally, the clump option of r.volume should be optional. You could file
an enhancement wish on trac for that.
Then again, as Micha has already explained, you can get the same result
simply doing
r.sum dec-juin at 1217_Interpo0618
and then multply the result by the area of your pixels (ewres*nsres).
Moritz
> The result I have is:
>
> (Fri Jul 13 14:12:45 2018)
> r.volume input=dec-juin at 1217_Interpo0618 clump=test at 1217_Interpo0618
> Volume report on data from <dec-juin at 1217_Interpo0618> using clumps on
> <test at 1217_Interpo0618> raster map
> Category Average Data # Cells Centroid Total
> Number in clump Total in clump Easting Northing Volume
> -----------------------------------------------------------------------------
> 1 -8.02 -72 9 191262.28 1222178.97
> -22.59
> 2 -9.02 -622 69 191265.64 1222177.29
> -194.78
> 3 -8.04 -394 49 191268.44 1222176.73
> -123.30
> 4 -7.08 -276 39 191271.23 1222177.85
> -86.46
> 5 -5.94 -427 72 191274.59 1222176.73
> -133.75
> 6 -4.30 -275 64 191285.22 1222178.97
> -86.09
> 7 -5.10 -2714 532 191288.58 1222174.50
> -849.47
> 8 -0.60 -7 12 191221.43 1222177.29
> -2.27
> 9 -8.95 -1030 115 191230.39 1222176.17
> -322.31
> 10 -10.06 -1217 121 191245.49 1222175.61
> -380.88
> 11 -10.93 -1956 179 191249.97 1222177.29
> -612.34
> 12 -10.24 -645 63 191259.48 1222175.61
> -201.92
> 13 -7.05 -621 88 191329.43 1222177.29
> -194.28
> 14 -7.51 -60 8 191336.14 1222177.29
> -18.81
> 15 -7.47 -30 4 191337.26 1222177.29
> -9.35
> 16 -8.04 -322 40 191340.06 1222177.29
> -100.63
> 17 -8.99 -108 12 191343.98 1222177.29
> -33.78
> 18 4.98 45 9 191182.26 1222175.05
> 14.03
> etc
> etc
> 24458 -5.50 -22 4 191397.13 1221585.50
> -6.88
> 24459 -5.51 -33 6 191378.11 1221584.39
> -10.34
> 24460 -5.52 -11 2 191380.91 1221584.39
> -3.45
> 24461 -5.27 -30348 5764 191309.84 1221601.17
> -9498.51
> 24462 -5.49 -38 7 191358.53 1221582.15
> -12.02
> 24463 -5.49 -22 4 191363.56 1221583.83
> -6.87
> 24464 -5.48 -11 2 191385.38 1221583.83
> -3.43
> 24465 -5.49 -11 2 191387.06 1221583.83
> -3.44
> 24466 -5.50 -11 2 191388.74 1221583.83
> -3.44
> 24467 -5.50 -22 4 191360.20 1221582.71
> -6.88
> 24468 -5.92 -523187 88358 191241.58 1221675.00
> -163750.63
> (Fri Jul 13 14:13:03 2018) La commande s'est terminée (18 sec)
>
> As you can see, I have nothing at the end of the command... But I know
> it is finished, because when I created the clumps it said that it
> created 24468 clumps.
> Do you need any more information?
>
>
> Thank you very much
> De : "Markus Neteler"
> A : marion-brunet at sfr.fr,"grass-user"
> Envoyé: jeudi 12 juillet 2018 16:43
> Objet : Re: [GRASS-user] calculate the volume of a DEM with r.volume
> Hello Marion,
>
> On Wed, Jul 11, 2018 at 10:32 AM, <marion-brunet at sfr.fr
> <mailto:marion-brunet at sfr.fr>> wrote:
> > Hello,
> >
> > I tried using r.volume as you suggested. According to the
> documentation it
> > is suitable for what I am trying to do.
> >
> > However, when I use it, I don't have the "Total volume" line at the
> end of
> > the report, like it is shown in the documentation. I just have the total
> > volume of each clump, but not of all the clumps... Has it ever
> happened to
> > you when using this command?
>
> That's weird! Which version/operating system do you use?
>
> > in the command line
> >
> > I simply wroter.volume input=difference clump=clump in the command line
>
>
> Here on command line:
>
> GRASS 7.4.1svn (nc_spm_08_grass7):~ > g.region raster=elevation
> GRASS 7.4.1svn (nc_spm_08_grass7):~ > r.volume input=elevation
> clump=geology_30m
> 100%
>
> Volume report on data from <elevation> using clumps on <geology_30m>
> raster map
>
> Category Average Data # Cells Centroid Total
> Number in clump Total in clump Easting Northing Volume
> -----------------------------------------------------------------------------
> 217 118.93 86288828 725562 635325.00 221535.00
> 8628882798.63
> 262 108.97 21650560 198684 638935.00 222495.00
> 2165056037.02
> 270 92.23 63578874 689373 642405.00 221485.00
> 6357887443.53
> 405 132.96 33732662 253710 631835.00 224095.00
> 3373266208.59
> 583 139.35 3011288 21609 630205.00 224665.00
> 301128821.55
> 720 124.30 599618 4824 634075.00 227995.00
> 59961816.06
> 766 132.43 936791 7074 631425.00 227845.00
> 93679120.08
> 862 118.31 7302317 61722 630505.00 218885.00
> 730231746.74
> 910 94.20 4235816 44964 639215.00 216365.00
> 423581613.11
> 921 135.22 1693985 12528 630755.00 215445.00
> 169398523.05
> 945 127.24 1145 9 630015.00 215015.00
> 114512.03
> 946 89.91 365748 4068 639085.00 215255.00
> 36574833.85
> 948 129.02 112632 873 630185.00 215115.00
> 11263181.57
> -----------------------------------------------------------------------------
> Total Volume =
> 22351026655.81
> ... which looks ok.
> Can you say a bit more about your system?
> Markus
>
>
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