I wanted to post an idea about rescuing the Aral Sea, and it occurred to me that domed farming, while alleviating part of the problems of the Aral Sea, can be applied anywhere.
There are many engineering challenges, and possible disadvantages, to doming off a farm.
I propose focusing on designing
a 200-acre dome unit, designed for temparate zones which experience hot summers and freezing winters, tall enough to accomodate farm machinery in the growing area. It would be a matrix of domes, and will probably need support pillars at regular intervals. These pillars could be arranged in hexagonal form, and have sprinklers attached for irrigation.
The most important engineering issues are carbon management, water management, and temperature management and they are closely intertwined.
If we cut off the greenhouse from outside air, there will be many effects: First, the amount of atmosphereic carbon will drop, as plants suck in the carbon. Second, humidity will rise, as plants transpire, and the humidity cannot escape. Third, the temperature will rise, because heat cannot escape via convection.
We need to turn these factors into advantages.
One of the key factors will be the political climate. We must admit the obvious:
1. No farmer in America, much less Uzbekistan, can afford to dome over his fields.
2. If the domes are to be closed off from outside air, a cheap source of atmospheric carbon must be exploited.
Modern greenhouses have found that many plants grow better in elevated atmospheric carbon levels, 1000 ppm; as opposed to current atmospheric levels, at about 370ppm. The way they do this is to burn hydrocarbons in the greenhouse. In the winter, this is great for them, it heats the greenhouse, and extends the growing season. In the summer, it heats the greenhouse even further.
I believe that in order form domed farming to be viable, dome farmers must not only not have to pay for carbon, but actually be paid for sequestering the carbon. At first, the sequestration fees would help defray the costs of installation, but eventually, the carbon money can go to the farmers.
Anyway, as long as the carbon laws are favorable, the rest clicks into place.
Excess humidity should lead to condenstation on the dome ceiling. Natural heat transfer should be enough, but during certain times of the year, extra cooling might be called for. In this case, a form fitting, transparent jacket can be place on the roof and have cold water pumped through it. Because
Which brings us to another important component: resevoirs. These resevoirs would capture any rain that hits the domes. During winter, the water's heat can be extracted, so that the resevoirs provide cooling on the hottest days. To reduce moisture loss, the farm should have only one entry point, with an airlock. Perhaps thermoelectrics can be employed to gain electricity from the difference between the water temp and air temp.
The only water loss should be the water weight of the plants grown, and what little moisture escapes as people and machinery are moved in and out, whereas as an undomed field will require extra water for the transpiration losses.
Nevertheless, It will take extra time for the resevoirs to be filled at first so that the farms can take advantage of the cold winters to moderate the dome temperature in the summer. Water savings will kick in after a few years, once the resevoirs are full. During drought, the domed off areas will be mostly immune, or can even donate water from the resevoirs to aid their undomed neighbors.
If done on a large scale in a Uzbekistan, eventually this will get enough water flowing back to the Aral, while still preserving the agriculture income these countries desperately need. This would have extra advantages in the Aral Sea area because the carcinogenic dust would be blocked off from blowing onto the crops.
Some crops might not perform well under the increased humidity of a greenhouse. But surely several crops can be found that can thrive in it.
Those are the basics of the idea. Carbon sequestration, reduced water usage, longer growing seasons. Relatively expensive setup, but if it's built to last, it'll surely pay off.
There's more details to work out, but this seems to be a good start.