1. Hydrologist, Water Assessment, Natural Resource Sciences, Dept. of Natural Resources and Water, Queensland Government. E-mail: john.vitkovsky@nrm.qld.gov.au
2. Associate Professor, School of Civil and Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia (corresponding author). E-mail: mlambert@civeng.adelaide.edu.au
3. Professor, School of Civil and Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia. E-mail: asimpson@civeng.adelaide.edu.au
4. Professor Emeritus, School of Civil and Environmental Engineering, Cornell Univ., Ithaca, N.Y. 14853-3501. E-mail: jal8@cornell.edu