The dew ponds and air wells are fascinating subjects. I followed your idea and googled both. Interestingly, there does not seem to be agreement on what makes a dew pond work. The theory behind air wells don’t seem to have achieved high levels of theory, either. So there is plenty of room here to rediscover some of the old technology and do some theorizing as well.

The theory behind both the Air Wells, and the Dew Ponds, is condensation… In the Dew Ponds, the pond water is physically separated from the surrounding ground to maintain a temperature difference between any captured water and the ground… at night, cooler air descends on the ground and contracts the air volume, causing a bit of dew to form near the ground and in the pond… when the sun comes up and heats the ground, that water is evaporated into the surrounding air… but the insulated pond stays a bit cooler than the surround ground… so any air that blows across the surface of the pond will condense a bit, and will add a few drops of moisture to the pond… and the moisture it adds exceeds any evaporation levels… it doesn’t work fast, but it does work… all that is needed is a slight temperature difference…

The Air Well works in a similar way… the main part is a large tank built in ancient times, out of rock… stored inside the large covered tank, are loose rocks, like limestone… There are many holes around the top sides and the bottom sides of the tank with a kind of ‘C’ shaped air tunnels that link the top row of holes to the bottom row of holes… during the night, any warm air inside the tank escapes through the top holes and the tank fills up with cool nighttime air… during the day, when there is a bit of wind, the air blows against the top holes and enters into the tank… when the warm air meets the cooler rocks, it cools the volume of air, which condenses any moisture out of the air, and causes the condensed air which is now a bit heavier, to flow downwards through the air passageway, and exit through the bottom holes, leaving most of its moisture behind, in the limestone rocks… the dripping condensation drips down into a large drip pan inside the tank and is collected into a pipe…and piped to the location where it is needed… In the Byzantine Empire, in and around Constantinople… this condensed water, which sometimes had a 14,000 gallons a day volume, was used at all the city fountains so that the citizens could collect their daily water needs and take it home for personal use…

Carlsbad Caverns is a natural condensation phenomena… there is not much rain in this area, yet inside the caverns, it is very cool, and very wet… at night, the caverns fill with cool, or cold, nighttime air… and during the day, the local warm wind blows into the caverns, condensing any humidity out of the air because of the temperature difference… One of the water survival on the desert that I learned is to dig a hole, and put a cup or glass in the center of it… then cover it with a plastic sheet, with a rock weighted in the center… condensation will form in the mornings and drip down into the glass or cup… this again, is condensation… and the process can be used… for a location, all that you would need, is a bit of wind, even a small wind would do, cool nights, and hot days… and a hill of some kind… this would be the basic needs for such a system… It had always been fascinating to me, at how ingenious ancient peoples lived and survived as they adapted to their environment…

I don’t dispute your description of how the Dew Ponds work, I don’t know… Would like to add something, however. I’m sure that night-time radiation to a clear sky plays an important role here. Any surface, isolated from inward heat flow from the surrounding environment, that is exposed to the night sky [if it’s clear] will radiate heat to the much lower temps of outer space. Without heat from the environment, the temp of the radiating surface falls well below ambient, creating conditions for condensing moisture from the air. I would think the answer for collecting this moisture, is to let it drain into an underground tank where it would be isolated from daytime temps and winds to avoid evaporation. As an example of the magnitude of this effect, Back during WW2, when arc searchlights were used for AA spotting, operators had to be careful to turn the searchlights down to “look” at the ground when they were turned off. If not, the water in the cooling coils would freeze even when the ambient temp was 20-30*F above freezing!