If we remember Dune, large underground aquifers could be one answer. A fully underground water cycle could occur. Underground farming could happen.
A less extreme case is higher temps that leave the equator and say 20 degrees latitude barren and baked, the next 15 degrees latitude hot and marginal for crops, and then you get the next 15 that get Mexico/Southern USA. The next 15 are temperate but warm and the next 15 are temperate cool. There would be no permanent ice caps. Overall, the world might have a 3 hyrdo or less so non water areas are all drier. Smaller rivers, fewer big lakes and few small ones. Agriculture would run to more hardy plants. Pop would be lower as overall carrying capacity is low. Irrigation would matter but is limited in total water to use.
I'd say early irrigation might be TL2 and be more useful by TL5-6. TL 8-9 might see a heavy use in some places. By TL 10-11, global water management and advanced water tech could be effective (vapor farming, uncle Ben.... boring... I am off to Toshi Station to join the IN).
At TL9 (oossible) or TL10-11, comet / ice drops (a la The Expanse) could augment.
Below hydro 3, pops would need some special explanation or take aquatech to support IME.
TomB