LeahJB
commented
5 years ago See: https://forums.naturalcapitalproject.org/uploads/FileUpload/cd/3f63ddb4f9e6e4315fd3238568fba7.pdf See in particular Fig. 10.1, which shows what looks like a continued linear relationship between soil water flow and volume below field capacity, but at a much reduced rate (unless the continuing decrease in soil water volume is due to something other than flow from the soil, e.g. ET. Can't access the source to check).
Replace the minimum groundwater flow threshold parameter with a more process-based representation. E.g. factor in percolation from the soil when soil water level drops below field capacity, but at a reduced rate.