1. Assoc. Prof., Hydr. Res. and Testing Fac., Dept. of Civ. Engrg., Univ. of Manitoba, Winnipeg, MB, Canada R3T 5V6. E-mail: doerin@cc. umanitoba.ca
2. Hydr. Res. and Testing Fac., Dept. of Civ. Engrg., Univ. of Manitoba, Winnepeg, MB, Canada R3T 5V6.