One million acres of irrigated land is located in Area 2. The land is irrigated by pumping ground water. The irrigators grow a combination of alfalfa, wheat and potatoes. The sale of these crops brings gross revenues of over 500 $/yr per acre. The irrigators pay variable costs of just under 400 $/yr per acre, so the return per acre is somewhat over 100 $/year. (These results may be checked by opening the "Crop Income Report" if you are using an advanced version of the model.)

The pumping requirement depends on the efficiency of irrigation in Area 2. A typical requirement is 4 feet/year per acre, so the one million acres would require the irrigators to pump 4 MAF/year. About half of this water returns to the aquifer through percolation. These flows may be checked by opening the "Water Use in Area 2" report. The efficiency of irrigation in Area 2 may be controlled in advanced versions of the model. The advanced version also allows you to expand or contract the land in Area 2.

The model assumes that 100% of the pumping needs are satisfied. If you are using an advanced version of the model, you may limit the irrigation in Area 2 in two ways. First, you may simply reduce the fraction of needs satisfied below 1.0. A reduction in this fraction would correspond to a restriction on ground water pumping. The second way to reduce ground water pumping is through a land fallowing program. If you are using an advanced version, you may reduce the land under irrigation by setting the land fallowing price in Area 2 to exceed the return per acre shown in the "Crop Income Report."