1. Graduate Student, Dept. of Civil, Construction, and Environmental Engineering, North Carolina State Univ., Raleigh, NC 27695 (corresponding author).
2. Hydrologist, U.S. Geological Survey Illinois-Iowa Water Science Center, 400 S. Clinton St., Room 269, Iowa City, IA 52240.
3. Emeritus Professor, Dept. of Civil and Environmental Engineering, South Dakota School of Mines and Technology, 501 E. Saint Joseph St., Rapid City, SD 57001.