1. Hydraulic Engineer, U.S. Bureau of Reclamation, Water Resource Research Laboratory, 6th and Kipling, Bldg. 67 (86-68460), Denver, CO 80225-0007 (corresponding author).
2. Research Assistant Professor, Utah State Univ., Dept. of Civil and Environmental Engineering, Utah Water Research Laboratory, 8200 Old Main Hill, Logan, UT 84322-8200.