Dear Bert; Thank you for your reply. The reservoir is not cylindrica. This is the table I have created from the data extracted. Maybe there is a way to get the relation between Elevation, Area and Volume to get the elevation at a specific Volume. Sincerely
value Area Height Vol 3 2183 89.52593 125 11190.74 5 2181 98.92991 127 12564.10 6 2180 154.64484 128 19794.54 7 2181 123.92825 127 15738.89 9 2183 82.42211 125 10302.76 10 2183 150.12180 125 18765.23 On Wed, Dec 6, 2023 at 8:39 AM Bert Gunter <bgunter.4...@gmail.com> wrote: > The volume of a polygon = 0. Polyhedra have volumes. > > This may be irrelevant, but if the lake is cylindrical == constant cross > sectional area at all depths, then height doubles when the volume does and > vice versa. Otherwise you have to know how area varies with height or use > more sensible approximations thereto. > > Cheers, > Bert > > On Tue, Dec 5, 2023, 20:13 javad bayat <j.bayat...@gmail.com> wrote: > >> Dear all; >> I am trying to calculate the volume of a polygon shapefile according to a >> DEM raster. I have provided some codes at the end of this email.I dont >> know >> if the codes are correct or not. Following this, I have another question >> too. >> I want to know if the volume of the reservoir rises or doubles, what would >> be the elevation? >> I would be more than happy if anyone could help me. >> Sincerely >> >> " >> library(raster) >> library(terra) >> library(exactextractr) >> library(dplyr) >> library(sf) >> r <- raster("Base.tif") >> p <- shapefile("p.shp") >> r <- crop(r, p) >> r <- mask(r, p) >> x <- exact_extract(r, p, coverage_area = TRUE) >> >> x1 = as.data.frame(x[1]) >> head(x1) >> x1 = na.omit(x1) >> >> x1$Height = max(x1[,1]) - x1[,1] >> >> x1$Vol = x1[,2] * x1[,3] >> >> sum(x1$Vol) >> >> " >> >> -- >> Best Regards >> Javad Bayat >> M.Sc. Environment Engineering >> Alternative Mail: bayat...@yahoo.com >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > -- Best Regards Javad Bayat M.Sc. Environment Engineering Alternative Mail: bayat...@yahoo.com [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.