1. Research Hydraulic Engineer, U.S. Arid Land Agricultural Research Center, USDA-ARS, 21881N, Cardon Ln., Maricopa, AZ 85138 (corresponding author).
2. Professor Emeritus, Dept. of Soil, Water and Environmental Sciences, Univ. of Arizona, Tucson, AZ 85721.
3. Information Technology Specialist, U.S. Arid Land Agricultural Research Center, USDA-ARS, 21881N, Cardon Ln., Maricopa, AZ 85138.
4. Research Agricultural Engineer, U.S. Arid Land Agricultural Research Center, USDA-ARS, 21881N, Cardon Ln., Maricopa, AZ 85138.