Context: I want to cut *.xyz data for a river channel below the free surface.
I assume I want to use ArcGIS to generate a polyline based on my free surface data, and to clip out all topographic data that exceeds it. However, this isn't a method I've used before and it's been a long time since I've used ArcGIS. I've not found a method online either. Does anyone know where I could start, or what tools would be applicable?
Thanks in advance!