There is some natural recharge of aquifers but the point of the new tech is to pump water out of flooded rivers to places where the water can flow into the aquifer more quickly. If this was done on a widespread basis, it could allow aquifer recharge at a much larger rate than natural infiltration.

The issue with pumping water south is that it has mainly come from the Sacramento Valley and Delta regions where water is already somewhat scarce, and likely to become more so in the future. Snowmelt from the Sierras is declining rapidly and we don’t have enough space to store all the spring runoff–but see the groundwater recharge idea above. The only place water is truly abundant in the state is the north coast, but the rugged topography up there makes the construction of aqueducts probably prohibitively expensive. And at that expense I think other options are just a better bet.

The greenhouse idea is interesting but I’m surprised they don’t overheat. Do they need a lot of energy to keep them cool in summer? Maybe if we have huge amounts of cheap solar this would be OK, since cooling would mainly be needed during the day. I know there are some crops grown in greenhouses already in CA but the scale is still small.