I have an XPSWMM model of a neighborhood storm drainage system. Nearly all of the drainage is above ground through a network of ditches and culverts.
I still need to create catchments for the upstream points for each culvert so I can route runoff through the network. There are around 150 culverts, and the topography is quite complex, and doing this manually is quite time-consuming and complicated.
Is it possible to create somewhat of a network of subcatchments to snap to these points in QGIS?