I have three layers, two different point layers and a line feature. The line feature is representing a river system, and one set of points shows monitoring sites along the river (purple markers) and the other shows dams and impoundments (red circles).
I would like to calculate the downstream distance between a dam and the closest monitoring station. This is a small subset of a larger river system. Ideally I would be able automate this process for ~100 dam to monitoring station distances and get a distance for each downstream station, not only the closest one (i.e. a situation in which there are two monitoring stations that are downstream of a dam). The points do not exactly intersect the river system, and most are within ~1000 m.