It is currently possible to use the culvert as input for your watershed when you define a watershed_area. The algorithm combines the DIRECTION with the OBJECT_FLOW to connect the watersystem and gain an insight in the watershed connected to that point. The culvert setting however does not work when not defining the final interest area.
I frequently come across the use case where you want to understand the system and see the large watersheds of your entire system, thus the major hydrological (sub)systems. You don’t know the endpoints beforehand thus defining these is not an option. This results in the advanced option “Use culvert…propagated” to have no influence on the result.
To sum-up: Combining the “Discharge Remaining Water” result to larger Watersheds based on structure flow (mainly culverts).
Documentation: https://support.tygron.com/wiki/Culvert_(Water_Overlay)
