Re: [GRASS-user] r.flow function

Thanks Helmut! Cumprimentos, *Valter Albino -* Geógrafo Físico, M.Sc. Modelação H / Riscos ambientais / OT www.valteralbino.wixsite.com/hydrodynamics Helmut Kudrnovsky escreveu no dia segunda, 3/02/2020 à(s) 21:07: > >Don't understand the presence of 1, he is absent in the formula. >Neither >

Re: [GRASS-user] r.flow function

>Don't understand the presence of 1, he is absent in the formula. >Neither the choice of number 50. you're right, the ultimative authority is the source code :-) https://github.com/OSGeo/grass/tree/master/raster/r.flow someone more familiar with these lines of code will probably have a better

Re: [GRASS-user] r.flow function

OOps, One example was wrong (this other for example: =MÁXIMO(1,35/50,250/50)=5.00) Cumprimentos, *Valter Albino -* Geógrafo Físico, M.Sc. Modelação H / Riscos ambientais / OT www.valteralbino.wixsite.com/hydrodynamics Valter Albino escreveu no dia segunda, 3/02/2020 à(s) 19:46: > Good evening

Re: [GRASS-user] r.flow function

Good evening Helmut, Thank you for reply (nice try, expert :-) ). Don't understand the presence of 1, he is absent in the formula. Neither the choice of number 50. So, in a spreadsheet is something like the following example: =MÁXIMO(1,150/50,338/50)=6.76 If using 10:

Re: [GRASS-user] r.flow function

Valter Albino wrote > Good afternoon > > From the function "r.flow" ( > https://grass.osgeo.org/grass78/manuals/r.flow.html), can some expert > explain me what is the meaning of: "val-th" and the meaning of: "max(1, > in elevation> > /50, > > /50)." no expert here on my side, though, from

[GRASS-user] r.flow function

Good afternoon >From the function "r.flow" ( https://grass.osgeo.org/grass78/manuals/r.flow.html), can some expert explain me what is the meaning of: "val-th" and the meaning of: "max(1, /50, /50)." Thanks in advance Regards Cumprimentos, *Valter Albino -* Geógrafo Físico, M.Sc. Modelação H /

Re: [GRASS-user] r.flow

On Wed, 15 Jan 2020, Markus Metz wrote: can you provide an example with input data where it does not work? Markus M I apparently deleted the psmap-generated .pdf when I decided it did not explain the hydrology well enough for the report. Regards, Rich

Re: [GRASS-user] r.flow

On Wed, Jan 15, 2020 at 5:09 PM Rich Shepard wrote: > > On Wed, 15 Jan 2020, Rich Shepard wrote: > > > I've noticed that, too, and no longer produce flowline maps. > > And the region is set to the DEM used for all analyses on those projects. the example in the manual works and produces 217038

Re: [GRASS-user] r.flow

On Wed, 15 Jan 2020, Rich Shepard wrote: I've noticed that, too, and no longer produce flowline maps. And the region is set to the DEM used for all analyses on those projects. Rich ___ grass-user mailing list grass-user@lists.osgeo.org

Re: [GRASS-user] r.flow

On Wed, 15 Jan 2020, Valter Albino wrote: "r. flow" gives empty flowline - how to solve? I've noticed that, too, and no longer produce flowline maps. Rich ___ grass-user mailing list grass-user@lists.osgeo.org

Re: [GRASS-user] r.flow

Hi Valter, check that the computational region is set to the extent of the input elevation map or a subset of it. Use g.region -p raster=your_raster_map_here HTH, Vero El mié., 15 ene. 2020 a las 15:16, Valter Albino () escribió: > Hi > "r. flow" gives empty flowline - how to solve? >

[GRASS-user] r.flow

Hi "r. flow" gives empty flowline - how to solve? Cumprimentos, *Valter Albino -* Geógrafo Físico, M.Sc. Modelação H / Riscos ambientais / OT www.valteralbino.wixsite.com/hydrodynamics ___ grass-user mailing list grass-user@lists.osgeo.org

Re: [GRASS-user] r.flow: units for flow accumulation [RESOLVED]

On Sat, 20 Oct 2018, Micha Silver wrote: I have always found that the best way to do watershed delineation, to get streams and flow accumulation is to set the computational region a *bit larger* than the basin you are examining, and use a DEM that covers the full region. i.e. don't second guess

Re: [GRASS-user] r.flow: units for flow accumulation

On Sat, 20 Oct 2018, Rich Shepard wrote: My interest is an area 2.1% of the drainage basin. Reading the r.watershed manual page I'm not seeing how to specify the project area (a vector polygon) as the focus of the module while using the raster DEM of the entire basin to keep all results

Re: [GRASS-user] r.flow: units for flow accumulation

On Sat, 20 Oct 2018, Rich Shepard wrote: Thank you. It's been many years since I used r.watershed so this is a valuable reminder. Micha, et al.: My interest is an area 2.1% of the drainage basin. Reading the r.watershed manual page I'm not seeing how to specify the project area (a vector

Re: [GRASS-user] r.flow: units for flow accumulation

On Sat, 20 Oct 2018, Micha Silver wrote: I have always found that the best way to do watershed delineation, to get streams and flow accumulation is to set the computational region a *bit larger* than the basin you are examining, and use a DEM that covers the full region. i.e. don't second guess

Re: [GRASS-user] r.flow: units for flow accumulation

On 10/20/18 12:55 AM, Rich Shepard wrote: On Fri, 19 Oct 2018, Rich Shepard wrote: Gotcha'. I'll do this instead of using r.flow. (Running r.watershed rather than r.flow.)   Well, this is

Re: [GRASS-user] r.flow: units for flow accumulation

On Fri, 19 Oct 2018, Rich Shepard wrote: Gotcha'. I'll do this instead of using r.flow. (Running r.watershed rather than r.flow.) Well, this is not working for me (see attached .png). Most of the upper left area is quite flat, especially east of the river. The manual's explanation of

Re: [GRASS-user] r.flow: units for flow accumulation

On Fri, 19 Oct 2018, Micha Silver wrote: If my understanding is correct, the r.flow module output raster "flowaccumulation" gives (as in manual that you quoted) the *number* of flow lines flowing into each cell. This is not upstream contributing area in the usual sense. Rather it describes

Re: [GRASS-user] r.flow: units for flow accumulation

Hi Rich On 10/17/18 8:43 PM, Rich Shepard wrote:   The r.flow manual tells us that "Flowline density downhill or uphill output is given in a raster map flowaccumulation. The value in each grid cell is the number of

Re: [GRASS-user] r.flow: units for flow accumulation

On Thu, 18 Oct 2018, Markus Neteler wrote: FWIW: I just did some typo hunting in trunk, and the release branches 7.6 and 7.4, submitted to SVN. Markus, I had seen that typo before and assumed you and others had more important things to do. Were I able to edit the page I would have

Re: [GRASS-user] r.flow: units for flow accumulation

On Wed, Oct 17, 2018 at 7:43 PM Rich Shepard wrote: ... > means the number of flowlines from thec [sic] entire map which have segment FWIW: I just did some typo hunting in trunk, and the release branches 7.6 and 7.4, submitted to SVN. (Hope someone has the answer for your question as well...)

[GRASS-user] r.flow: units for flow accumulation

The r.flow manual tells us that "Flowline density downhill or uphill output is given in a raster map flowaccumulation. The value in each grid cell is the number of flowlines which pass through that grid cell, that means the number of flowlines from thec [sic] entire map which have segment

Re: [GRASS-user] r.flow-> wrong result

On 21/12/17 15:13, Eva Schindele wrote: Hello Grassdevelopers, I try to run the r.flow module to get the flow path length of my Layer out. The input Layer is a DEM with pixelsize 0.0083 and the selected CRS (EPSG:32646, WGS 84/ UTM zone 46). First of all I generated a depressionless elevation

Re: [GRASS-user] r.flow: define contributing area

On Tue, 4 Oct 2016, Rich Shepard wrote: For current need, it is the opposite of what r.flood ^ Er, make that r.lake instead. Rich ___ grass-user mailing list grass-user@lists.osgeo.org

Re: [GRASS-user] r.flow: define contributing area

On Mon, 3 Oct 2016, Thomas Adams wrote: The only way to -correctly- do this is with hydrodynamic modeling, such as with HEC-RAS. It can be very crudely approximated with r.damflood ( https://grass.osgeo.org/grass70/manuals/addons/r.damflood.html). Tom, I had tried using HEC-RAS long ago

Re: [GRASS-user] r.flow: define contributing area

On Tue, 4 Oct 2016, Johannes Radinger wrote: Maybe have a look at r.lake ... fills the area upstream a dam or a blocked stream. Johannes, This module looks like it will do the job. The example of flooding along a small street somewhere in North Carolina is analogous to flooding of

Re: [GRASS-user] r.flow: define contributing area

On Tue, 4 Oct 2016, Johannes Radinger wrote: Maybe have a look at r.lake: https://grass.osgeo.org/grass70/manuals/r.lake.html. This module fills the area upstream a dam or a blocked stream. Johannes/Thomas, I considered r.lake and r.damflood. What I will try to learn from the manual pages

Re: [GRASS-user] r.flow: define contributing area

: Rich Shepard <rshep...@appl-ecosys.com> Cc: grass-user@lists.osgeo.org Subject: Re: [GRASS-user] r.flow: define contributing area Rich, The only way to -correctly- do this is with hydrodynamic modeling, such as with HEC-RAS. It can be very crudely approximated with r.damflood (https://gra

Re: [GRASS-user] r.flow: define contributing area

Rich, The only way to -correctly- do this is with hydrodynamic modeling, such as with HEC-RAS. It can be very crudely approximated with r.damflood ( https://grass.osgeo.org/grass70/manuals/addons/r.damflood.html). Tom On Mon, Oct 3, 2016 at 7:39 PM, Rich Shepard

[GRASS-user] r.flow: define contributing area

Reading the r.flow manual page suggests that the use of the '-u' (upstream) option allows determination of flowlines and lengths that can be used to delineate the area that would drain to a specific point. Is this correct? To determine the area flooded if an outlet is plugged would require

Re: [GRASS-user] r.flow Terminates With Error

On Fri, Feb 12, 2010 at 9:22 PM, Rich Shepard rshep...@appl-ecosys.com wrote: On Fri, 12 Feb 2010, Rich Shepard wrote:  I had no problems running r.flow with in the input elevation map resolution of 5m x 5m. However, now it won't run (even with the -m switch) on a DEM with 3m x 3m

Re: [GRASS-user] r.flow Terminates With Error

On Sat, 13 Feb 2010, Markus Neteler wrote: Did you compile with LFS (large file support) enabled? Markus, Yes. This came up before and Glynn ensured that LFS was enabled in my build. In general, is there a way to predict memory and disk space requirements before initiating processing?

Re: [GRASS-user] r.flow Terminates With Error

On Fri, 12 Feb 2010, Rich Shepard wrote: I had no problems running r.flow with in the input elevation map resolution of 5m x 5m. However, now it won't run (even with the -m switch) on a DEM with 3m x 3m resolution: Must be a memory issue (with 2G installed and top reporting Mem: 2041212k

[GRASS-user] r.flow: Insufficient Memory for dsout

I was able to run r.flow and produce maps of flow lines and lengths. However, now that I try to run it again to produce dsout (flow density) it immediately fails: GRASS 6.4.0svn (Oregon):/usr4/grassbase time r.flow -3m elevin=aber3m aspin=aber3.aspect dsout=aber3.flowdensity --o ERROR: