[Webstral]

The water table can be found at varying depths. In the San Pedro River Valley (where Huachuca is located), the water table is fairly close to the surface. In 1997, the water table was significantly closer to the surface than it is today. Tucson was completely reliant on ground water until the CAP was finished, with the result that the water table was much further from the surface at the start of 1998.

Rae, you are completely right that water is going to be a defining issue in SAMAD. Much of the life of people tending their intensive gardens is going to revolve around getting water to the plants. Traditional irrigation is out of the question in most locations. Drip irrigation relies on pre-Exchange hardware. For the first couple of years after the Exchange, water is transported from a water head (well, tap still connected, etc.) to the plants. In some cases, this is a long way. Some ingenious folk fashion tanker bicycles--bikes with trailers which carry 55-gallon drums. The cyclists ride at night for six months of the year, delivering water to the fields where it is needed. Gardeners then fill containers on trolleys, carts, wagons, or backpacks and distribute the water by hand. It's a hard existence.

To make matters worse, the soil is awful in a lot of locations. Though the San Pedro River Valley used to be grassland, overgrazing towards the end of the 1800's turned the area into scrubland. By 1997, the good grassland soil is long gone.

Despite all-out efforts, the first harvest of 1998 is deplorable. Fortunately, the weather supports multiple harvests per annum (provided there's enough water). A few crops make a huge difference in the quality of the soil, according to folks who have studied this approach in other semi-arid locations. Also, the people who are not tilling the soil can work to improve the water distribution system so that less labor goes into getting water from Point A to the Point B and more goes into improving the yield.

Dryland agriculture is possible, though it's a risky enterprise. Winter rainfall amounts to several inches--six to seven. The land generally slopes towards the San Pedro. Controlling the run-off so that it soaks into the ground where the crops are being grown can add a few crucial inches to the total accumulation. This calls for some earth-moving. Obviously, somebody is going to be busy figuring out how to make the most of the scarce manpower when it comes to constructing berms to direct runoff out of the arroyos before it gets to the San Pedro River. Several years ago, I posted some findings on how other folks in the Third World grow crops in semi-arid climates. I won't repeat it here, other than to say that in some cases the contour of the land is exploited to multiple the precipitation that soaks into the ground where the crops are being grown, mcuh