[GRASSLIST:6209] Re: Water basin filling w Grass

[Massimiliano Cannata]

Hi, In that case you may extract isoline from dem, get area and  and 
then select the ones with a quota attribute lower than a value....
that will be the area filled by water at the select value level.....
Or r.mapcalc can do the trick.... r.mapcalc 'areafilled=if(dem<100)' a 
map of 0-1 where quota is lower or higher then 100m.

Hi,
Maxi

Māris Nartišs wrote:

>Hi,
>tnx for idea about teraflow. I will try it. I'm newbie - so its hard
>to find best tools for doing jobs :)
>
>But second idea would not fit to my needs - I don't have any border
>polylines for lakes - I need to find out possible lake locations,
>maximum possible water levels and potential spill out points. All I
>have is DTM and notes on some areas where possibly where lakes.
>
>Yeah, I know it sounds crazy, but I have only some month to write
>paper for my MSc ;)
>
>
>Maris.
>
>On Thu, 17 Mar 2005 17:19:38 +0100, Massimiliano Cannata
><massimiliano.cannata at supsi.ch> wrote:
>  
>
>> For flat areas you can give a try to r.terraflow that manage this situation
>>with a different approach.
>> For find the maximum heigth to have a spill maybe you have to find the
>>lowest point around the border of the lake,
>> just an idea (probably stupid!): you can convert the border polyline to
>>raster, with r.mapcalc get the heigth of the dem in the corrispondence cell
>>and then with r.stats see the lower heigth in the map.
>> v.to.rast ....input=lake_border_polyline output=border
>> r.mapcalc 'dem_border=if(border,dem)'
>> r.stats dem_border
>> 
>> Hello!
>> Max
>>
>> 
>> 
>> 
>> Māris Nartišs wrote: 
>> Hi all, I'm doing research - a water body simulation with Grass. I
>>successfully created DTM w Grass (Hooray!) and now need to do more specific
>>things. I need to find maximum possible water level for lake. I have place
>>where must be a lake and I need to know what water level is maximal until it
>>starts to spill out. And I need to find those spill out points and levels
>>(height). I know it is possible, because I saw a demo on web but w/o HOWTO.
>>http://skagit.meas.ncsu.edu/%7Ehelena/gmslab/viz/erosion.html Any help,
>>ideas welcome :) 
>>
>>And another question - I was following Grass tutorial (
>>http://www.ing.unitn.it/~grass/docs/tutorial/english/index_en.htm ) and
>>creating basins with r.watershed but on low land it produced thousands of
>>small and narrow, parallel basins and result was not even close looking to
>>sample shown on tutorial
>>(http://www.ing.unitn.it/~grass/docs/tutorial/english/dtm4_en.htm). I
>>understand, that different data give different results, but not so
>>different! Or its OK and I was just confused by beautiful results shown in
>>this tutorial? (See attachment.) Grass 6.0.0 b2 TNX for reading, Maris. 
>> 
>>-- 
>> _____________________________________________________ 
>> 
>> Ing. Massimiliano Cannata 
>> 
>> SUPSI - Istituto Scienze della Terra 
>> C.P. 72 - CH-6952 Canobbio (Ticino, Switzerland) 
>> Tel +41 (0)91 935 12 25 - Fax +41 (0)91 935 12 09 
>> mailto:massimiliano.cannata at supsi.ch 
>> http://www.ist.supsi.ch 
>> 
>>
>>    
>>
>
>
>  
>

-- 
_____________________________________________________

Ing. Massimiliano Cannata

SUPSI - Istituto Scienze della Terra
C.P. 72 - CH-6952 Canobbio (Ticino, Switzerland)
Tel +41 (0)91 935 12 25 - Fax +41 (0)91 935 12 09
mailto:massimiliano.cannata at supsi.ch
http://www.ist.supsi.ch

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