I have found instructions that outline how to determine the watershed uphill of a selected point using a DEM in QGIS (https://youtu.be/CE7zZCkFbg4).
I am starting with a polygon representing property boundaries that lie somewhere in the midst of a watershed however - and I need to determine what the area of the entire watershed that drains water into and receives water runoff from that polygon is.
Is there a function in QGIS that will do this using a DEM to calculate the entire watershed associated with a selected polygon?
If not, then is there a function that will determine the highest single point downhill of a property boundary where all of the stormwater runoff that is generated from the property will converge - a "reverse" watershed analysis?
If so, I could then use that point and the method outlined in the youtube video linked above to get the result I'm looking for.