1. UTM-Center for Industrial and Applied Mathematics (UTM-CIAM), Ibnu Sina Institute for Scientific & Industrial Research, University of Technology Malaysia, 81310 Johor Bahru, Malaysia
2. Department of Mathematical Sciences, Faculty of Science, University of Technology Malaysia, 81310 Johor Bahru, Malaysia
3. School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
4. Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA