1. Hydrotechnical Engineer, Civil Design, BC Hydro, 6911 Southpoint Dr., Burnaby BC, Canada V3N 4X8.
2. Professor Emeritus, Dept. of Civil Engineering, Univ. of Alberta, Edmonton AB, Canada T6G 2W2 (corresponding author).
3. Professor, Dept. of Civil Engineering, Univ. of Alberta, Edmonton AB, Canada T6G 2W2.