1. Research Assistant, Ven Te Chow Hydrosystems Laboratory, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana–Champaign, 205 North Mathews Ave., Urbana, IL 61801.
2. Associate Professor, Dept. of Civil Engineering, Univ. of Chile, Casilla 228-3, Santiago, Chile.
3. Chester and Helen Siess Professor, and Director, Ven Te Chow Hydrosystems Laboratory, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana–Champaign, 205 North Mathews Ave., Urbana, IL 61801.