On Fri, Jun 14, 2013 at 11:03 AM, Johannes Radinger <[email protected]> wrote: > Hi, > > as I am not very familiar with GRASS' vector capabilities maybe someone of > you has some ideas. Is there the concept of directed vector networks e.g > describing river networks with flow direction implemented in GRASS?
r.stream.extract produces a vector network with the direction of the lines corresponding to the flow direction. > > I am looking for a way that counts all barriers when routing from a starting > point in the network And I'd like to get the number of barriers that are > downstream and those that are upstream a given point. Or is there a way to > "cut" a network into two parts where one is automatically detected as > upstream while the other one is declared as the downstream network? Maybe the linear referencing system can help to count barriers. For separate upstream/downstream analysis, you could use vector network analysis tools and make use of the line direction: if want to go only upstream, set forward costs to -1, if you want to go only downstream, set backward costs to -1. > > Furthermore I am interested in calculating stream order for such dendritic > networks. I saw the v.strahler add on, is there also an add on that > calculates other types of stream order (here I am most interested in a > vector based Shreve's stream order like as already implemented in > r.stream.order). You could use r.stream.extract to produce both a raster and a vector river network, then run r.stream.order on the river raster and update the attributes of the vector with the desired order using v.what.rast. HTH, Markus M _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
