Thanks, I will compare them and let you know the differences. Thanks On Domh 23 MFómh 2018 at 02:09, Vaclav Petras <wenzesl...@gmail.com> wrote:
> These are steps based on: > > > https://grasswiki.osgeo.org/wiki/From_GRASS_GIS_novice_to_power_user_(workshop_at_FOSS4G_Boston_2017)#Hydrology:_Estimating_inundation_extent_using_HAND_methodology > > You need r.stream.distance module from Addons: > > g.extension r.stream.distance > > Get drainage and streams from your DEM (your carved DEM): > > r.watershed elevation=dem accumulation=flowacc drainage=drainage > stream=streams threshold=100000 > > Compute height above nearest drainage/stream (HAND): > > r.stream.distance stream_rast=streams direction=drainage > elevation=elevation method=downstream difference=hand > > Use r.lake not on the original DEM, but on the HAND and start flooding > ("lake") from the streams: > > r.lake elevation=hand water_level=3 lake=flood_3m seed=streams > > Convert to vector if desired: > > r.to.vect -s input=flood_3m output=flood_3m type=area > > The difference to the r.grow+r.mapcalc method [1] is that this uses an > addon module (there should be no problem installing it) and that r.grow > uses euclidean distance for what is later used for height difference while > r.steam.distance follows drainage and further that r.lake floods only the > cells accessible to water unlike the r.mapcalc expression which just looks > at height. The two methodological differences can be summarized as "not > respecting the surrounding terrain enough." Anyway, the r.grow+r.mapcalc > method can get you quite far and I would be interested in the comparison > (will differ for different terrains). > > Best, > Vaclav > > [1] > https://lists.osgeo.org/pipermail/grass-user/2018-September/079134.html > > On Fri, Sep 21, 2018 at 11:39 AM Shane Carey <careys...@gmail.com> wrote: > >> Hi All, >> >> I have used r.carve to carve out the rivers of a DTM - a really super >> job. I now need to pour 3meters of water into every cell in the river and >> see how for this water extends out - onto the floodplain. >> >> I was trying to use r.lake to do this, but unsure as to how r.lake will >> work to pour 3 meters of water in every cell along the river network. >> >> Any advice on this would be great. It is for the creation of a floodplain. >> >> Thanks >> >> >> Le gach dea ghui, >> *Shane Carey* >> >> _______________________________________________ >> grass-user mailing list >> grass-user@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@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user