1. Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand (corresponding author).
2. Senior Lecturer, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand.
3. Scientist, Landcare Research, Private Bag 92170, Auckland Mail Centre, Auckland 1142, New Zealand.
4. Undergraduate Student, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand.