1. Center Director, U.S. Arid Land Agricultural Research Center, USDA/ARS, 21881 N. Cardon Lane, Maricopa, AZ 85138 (corresponding author).
2. Research Hydraulic Engineer, U.S. Arid Land Agricultural Research Center, USDA/ARS, 21881 N. Cardon Lane, Maricopa, AZ 85138.