How do I determine how many barriers are downstream of each sampling location on a river network using GRASS?
I have ~20,000 points, soon to be ~600,000 points, falling on or near a river network of Europe. The points are sampling locations and barrier locations. I also have nodes for the river network. Network and node layers (ECRIN for those familiar with European river networks) have attributes relating to
What I've tried
Thus far I've tried
v.distance in GRASS to calculate the distance going upstream for each point along a river segment which I then subtracted from the segments
distance2mouthLine to provide a
distance2mouthPoint value for each point. Using this I counted all of the points with a
distance2mouthPointless than each point with the same
basin_id. Unfortunately this included barriers on different river branches rather than those along the path from the point to the river mouth.
I have investigated Linear Referencing in ArcGIS, however the distance along the network is the same as that which I calculated in GRASS and therefore has the same limitations. Network Analyst in ArcGIS also provides a similar metric and I'm unaware of how to automate it rather than manually select each start and end point.
Any idea if this can be achieved in GRASS by identifying something like each source to mouth path and using
v.distance as above?