Firstly, while 'affleurant' works in French in relation to groundwater levels, as it does for rock formations, the same cannot be said of 'outcrop' in English.

Secondly, I don't think there is any codification of aquifer depths, in either language, i.e. no set measured depths for different qualifications. IOW, the depths given in the excerpt attached are not representative. Were an aquifer to 'affleure', you would have water at the surface, if it is 'sub-affleurant' it is close (but how close? Everything is relative) to the surface.

In English a 'nappe sub-affleurante' would be a shallow aquifer or shallow water table, the degree of shallowness being a matter of interpretation.

In the State of Minnesota 'shallow groundwater' IS defined:

"Shallow groundwater is a condition where the seasonal high groundwater table, or saturated soil, is less than 3 feet from the land surface."
https://stormwater.pca.state.mn.us/index.php/Shallow_groundw...

but the depth could well be different elsewhere.


--------------------------------------------------
Note added at 59 mins (2022-05-16 15:18:43 GMT)
--------------------------------------------------