[GRASS-user] r.watershed

[Mark Seibel]

Hi.

I just used the tutorials from this page https://grasswiki.osgeo.org/
> wiki/Creating_watersheds to extract the stream network - however it could
> be more accurate so was wondering is r.terraflow a better option for me. I
> was using r.watershed originally
>

I've found r.watershed to be the most accurate, for our work. We've field
verified the streams and its really solid data. I like that r.watershed
doesnt alter the terrain since the LiDAR point data captures terrain
nuances so well.

Mark




> Do you know why sink filling is needed for r.terraflow and not for
> r.watershed?
>
> Thanks.
>
> On Wed, Dec 6, 2017 at 11:42 AM, Marco Alicera <marco.alicera at gmail.com>
> wrote:
>
>> How did you add culverts?!
>> Such a great question and I also wonder how you did. Short ago I knew
>> about Itzï and its ability to do it with SWMM
>> http://itzi.readthedocs.io/en/latest/tutorial.html#culvert-modelling.
>> Looking forward to testing it
>> --
>> Marco
>>
>> 2017-12-06 9:24 GMT+01:00 Shane Carey <careyshan at gmail.com>:
>>
>>> Hi Mark,
>>>
>>> Thanks for your reply! Sounds great.
>>> How did you add culverts or other artificial flow control features to
>>> achieve water flowing through roads?
>>>
>>> I have a rivers layer and I compared it the streams I've obtained from
>>> r.watershed and r.watershed appears to not match these streams (which were
>>> accurately digitised) and I was wondering if I had a better resolution DTM
>>> would it solve this problem?
>>>
>>> Also, why is sink filling needed for terraflow and not watershed?
>>>
>>> Thanks for your help :-)
>>>
>>> On Máirt 5 Noll 2017 at 23:43, Mark Seibel <mseibel at gmail.com> wrote:
>>>
>>>> Hi Shane.
>>>>
>>>> I'm happy to report that I've modeled overland water flow with
>>>> r.watershed for over a quarter million acres, consisting of several large
>>>> project sites, at 1 meter DEM resolution. The data source was LiDAR
>>>> points to make the DEMs.
>>>>
>>>> At this resolution, it becomes necessary to add culverts, or other
>>>> artificial flow control features, to achieve water flowing through a road.
>>>> Otherwise, water is routed along roads until a lowest point is reached for
>>>> crossing.
>>>>
>>>> I also use r.terraflow outputs as ancillary data to help drop in
>>>> culvert locations and help provide guidance in problem areas.
>>>>
>>>> My geographic area is central Florida, which is very flat and full of
>>>> topographic depressions known as wetlands. These depressions interrupt the
>>>> stream network continuity in reality, but r.watershed does a fantastic job
>>>> making a continuous drainage network model, especially in these difficult
>>>> areas.
>>>>
>>>> Happy Modeling!
>>>>
>>>> Mark
>>>>
>>>> On Tue, Dec 5, 2017, 3:49 PM Shane Carey <careyshan at gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> I am trying to extract river network from a 5m DEM with some success
>>>>> using r.watershed. Has anyone tested this algorithm on high resolution
>>>>> LiDAR data for example - 1meter DTM and what kind of results have they
>>>>> obtained?
>>>>>
>>>>> Thanks
>>>>>
>>>>> --
>>>>> Le gach dea ghui,
>>>>> *Shane Carey*
>>>>> *GIS and Data Solutions Consultant*
>>>>>
>>>> _______________________________________________
>>>>> grass-user mailing list
>>>>> grass-user at lists.osgeo.org
>>>>> https://lists.osgeo.org/mailman/listinfo/grass-user
>>>>
>>>> --
>>> Le gach dea ghui,
>>> *Shane Carey*
>>> *GIS and Data Solutions Consultant*
>>>
>>> _______________________________________________
>>> grass-user mailing list
>>> grass-user at lists.osgeo.org
>>> https://lists.osgeo.org/mailman/listinfo/grass-user
>>>
>>
>>
>
>
> --
> Le gach dea ghui,
> *Shane Carey*
> *GIS and Data Solutions Consultant*
>
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