The drought in California could result in a $642 million loss in revenue to farmers and a $207 million increase in food costs to consumers this year, according to a computer model devised by Richard E. Howitt, UC Davis professor of agricultural economics. According to his model of the economic impacts of the drought on California's irrigated crops, a 20 percent reduction could occur in the production of alfalfa, cotton, grain sorghum and sugar beets, and the prices of fruits and vegetables could rise from 5 percent to 12 percent. He expects rice, hay and cotton prices to increase less than 10 percent. In devising his model, Howitt considered six agricultural regions and 30 crops, and assumed that surface-water reductions will average 80 percent of normal supplies, that groundwater pumping can be increased by 70 percent and that the average water costs to farmers double due to extra pumping costs.