Googling research papers on the subject of European irrigation, I'm mostly finding water usages quoted as mm/yr. Cultivated land area seems to be discussed, exp

Googling research papers on the subject of European irrigation, I'm mostly finding water usages quoted as mm/yr. Cultivated land area seems to be discussed, explicitly but often implicitly, in hectares. But I'm having trouble finding statements or graphs that show mm/yr/ha or mm/ha. Unless I'm missing something (and I very well may be), I'll take acre-feet over mm/yr. acre-feet seems a more useful standard compound unit for discussing large scale (agricultural, industrial, etc) water usage, even if the underlying units are more archaic. If you're going to drop or leave implicit one of the three dimensions, time seems like the much better choice than area. But maybe I'm biased by familiarity (and utter lack of expertise), or maybe I'm just wrong about the standard terminology. I need to get back to hacking, otherwise I'd keep digging....