Our landscape features a lot of areas with trees and shrubs located over turf grass. In other words, the groundcover is completely turf grass.

I know that if, for example, groundcover and trees are found together in an area, then the category "mixed" is to be used for that area.

I would also like to use the values for "mixed" category for the proposed design for the turfg grass -shrub/ tree combination areas, but my conscience tells me that in reality turf grass is much more water hungry than reflected by the "mixed" category.

What is your experience with proposed case calculations involving turf grass as groundcover?