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 <[email protected]> > 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 <[email protected]>: >> >>> 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 <[email protected]> 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 <[email protected]> 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 >>>>> [email protected] >>>>> https://lists.osgeo.org/mailman/listinfo/grass-user >>>> >>>> -- >>> Le gach dea ghui, >>> *Shane Carey* >>> *GIS and Data Solutions Consultant* >>> >>> _______________________________________________ >>> grass-user mailing list >>> [email protected] >>> https://lists.osgeo.org/mailman/listinfo/grass-user >>> >> >> > > > -- > Le gach dea ghui, > *Shane Carey* > *GIS and Data Solutions Consultant* >
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