Re: [GRASS-user] Repeated r.watershed runs

Hello Marco, Itzï (www.itzi.org) is built upon GRASS and employs a partial inertia simplification of the Saint-Venant equations. It is certainly not as hydraulically accurate as the finite-volume approach of ANUGA, but it gives quite good results as a flood model, and is likely to be much faster.

Re: [GRASS-user] Repeated r.watershed runs

Dear List, I solved the issue (defining a fuzzy watershed boundary based on cells that contribute partial flow to the catchment outlet) by using TauDEM. That software provides an Upslope Dependency product that is the fractional contribution of each upslope cell:

Re: [GRASS-user] Repeated r.watershed runs

Reading the subject and agreeing with Thomas about the limitations of r.watershed, I wonder if there is any effort to port any of the models based on the shallow water wave equations to grass. I recently read about the anuga project https://anuga.anu.edu.au/wiki and it would be nice to use it with

Re: [GRASS-user] Repeated r.watershed runs

On 01/09/17 09:50, Ken Mankoff wrote: Dear Moritz, Yes, the three day estimate is from the first hour of this command: seq 14000 | parallel --bar r.watershed elevation=DEM.fixed flow=runoff.{#} accumulation=acc.{#} Have you checked memory usage. Setting memory= to something higher than the

Re: [GRASS-user] Repeated r.watershed runs

Dear Moritz, Yes, the three day estimate is from the first hour of this command: seq 14000 | parallel --bar r.watershed elevation=DEM.fixed flow=runoff.{#} accumulation=acc.{#} I have a 4-core laptop. -k. ___ grass-user mailing list

Re: [GRASS-user] Repeated r.watershed runs

Le 1 septembre 2017 09:33:52 GMT+02:00, Moritz Lennert a écrit : >On 01/09/17 06:41, Ken Mankoff wrote: >> Hi Micha, >> >> We are getting closer to the issue. Unfortunately I'm also becoming >more >> certain the limitation is real and in GRASS and not my mental

Re: [GRASS-user] Repeated r.watershed runs

On 01/09/17 06:41, Ken Mankoff wrote: Hi Micha, We are getting closer to the issue. Unfortunately I'm also becoming more certain the limitation is real and in GRASS and not my mental model. If this email does not clarify it, I will draw a picture which may help. On 01 Sep 2017, at 00:08,

Re: [GRASS-user] Repeated r.watershed runs

Hi Micha, We are getting closer to the issue. Unfortunately I'm also becoming more certain the limitation is real and in GRASS and not my mental model. If this email does not clarify it, I will draw a picture which may help. > On 01 Sep 2017, at 00:08, Micha Silver wrote:

Re: [GRASS-user] Repeated r.watershed runs

Hi Tom, You sound like my friend reviewer #2. :) But seriously, I thank you for thinking critically about what I'm trying to do. However, the inputs I have come from a couples land/ice/snow/atmosphere regional climate model with rain, snowfall, eval, condensations, storage in snow and land,

Re: [GRASS-user] Repeated r.watershed runs

On 08/31/2017 11:03 PM, Ken Mankoff wrote: Hi Micha, I understand what you wrote (I think). I get that the basin product from r.watershed does not change with SFD or MFD. I think this is because the flow

Re: [GRASS-user] Repeated r.watershed runs

Ken, That would be a gross misapplication of r.watershed and, I'm afraid, is just bad science; I just don't know how to be more clear on that... Tom On Thu, Aug 31, 2017 at 3:52 PM, Ken Mankoff wrote: > Hi Tom, > > What if we are assuming instantaneous flow and no storage

Re: [GRASS-user] Repeated r.watershed runs

Hi Micha, I understand what you wrote (I think). I get that the basin product from r.watershed does not change with SFD or MFD. I think this is because the flow direction raster from r.watershed only provides the primary flow direction. But the accumulation map doesn't know about boundaries or

Re: [GRASS-user] Repeated r.watershed runs

Hi Tom, What if we are assuming instantaneous flow and no storage and all of the input flow variable leaves the system. Then is r.watershed usable to calculate accumulation? -k. Please excuse brevity. Sent from pocket computer with tiny non-haptic feedback keyboard. > On 31 Aug 2017, at

Re: [GRASS-user] Repeated r.watershed runs

The r.water.outlet module takes as input a flow direction raster that needs to be created first by r.watershed. So the SFD/MFD question is irrelevant at this stage. When you first ran r.watershed you chose which method to use for determining flow direction for each

Re: [GRASS-user] Repeated r.watershed runs

Ken, You wrote: 'If I give r.watershed a precip map as input (flow parameter), doesn't it route that water down the DEM? And if I know the x,y coordinate of a point in a stream, doesn't the accumulation at that point represent all of the up-basin precip that is routed past that point?' ANSWER:

Re: [GRASS-user] Repeated r.watershed runs

Yes. This! What you wrote. But the issue is that r.water.outlet make basins based on SFD, right? What if there are 10,000 cells that feed into cell C at x,y, and then cell C feeds 49% (based on MFD) into the basin. These 10,000 cells are not included in the r.water.outlet basin, are they?

Re: [GRASS-user] Repeated r.watershed runs

Micha, I was thinking the same... but the ultimate result wanted is still unclear; hope you are well! Tom On Thu, Aug 31, 2017 at 2:51 PM Micha Silver wrote: > I'm also not clear what you are asking. But risking a guess: > You could run r.water.outlet *1 time* to get the

Re: [GRASS-user] Repeated r.watershed runs

I'm also not clear what you are asking. But risking a guess: You could run r.water.outlet *1 time* to get the basin. Then use that raster as a MASK, so that the next process will address only the pixels within the basin. Now do a loop with r.univar on all 14,000 flow

Re: [GRASS-user] Repeated r.watershed runs

Ken, You "want 14,000 values" of what?? Your original email stated you were "trying to determine flow past a drainage basin outlet" -- r.watershed does NOT do this, if indeed this is what you want. And you say you have "14,000 flow rasters to be used as input" -- what exactly are these 'flow

Re: [GRASS-user] Repeated r.watershed runs

Hi Tom, I have 1 DEM and 14,000 flow rasters to be used as input. I want 14,000 values, one at a specific coordinate from each acc output. I can do this by running r.watershed 14,000 times. That is slow, unless I'm missing something (e.g. It works with I.group variables or Time Series data

Re: [GRASS-user] Repeated r.watershed runs

Ken, I'm confused about what you are trying to do with r.watershed, because the output from the module is: accumulation=name Name for output accumulation raster map Number of cells that drain through each cell tci=name Name for output topographic index ln(a / tan(b)) map spi=name Stream power

[GRASS-user] Repeated r.watershed runs

Hi List, I'm trying to determine flow past a drainage basin outlet. The complicating factor is that I need to do this each day for 40 years. If I do "r.watershed" ~14,000 times I'll get the results, but it will take 3 days. It seems that r.watershed is likely calculating many things each time