1. Doctoral Candidate, Dept. of Civil Engineering, Univ. of British Columbia, Environmental Fluid Mechanics Group, Vancouver BC, Canada V6T 1Z4 (corresponding author). E-mail: forrest@civil.ubc.ca
2. Doctoral Candidate, Dept. of Civil Engineering, Univ. of British Columbia, Environmental Engineering Group, Vancouver BC, Canada V6T 1Z4.
3. Professor, Dept. of Civil Engineering, Univ. of British Columbia, Environmental Engineering Group, Vancouver BC, Canada V6T 1Z4.
4. Research Associate, Dept. of Civil Engineering, Univ. of British Columbia, Environmental Engineering Group, Vancouver BC, Canada V6T 1Z4.