1. Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
2. Institute of Environmental and Water Resource Management (IPASA), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru, Malaysia
3. Department of Agricultural and Biosystems Engineering, North Dakota State University, Fargo, ND 58108-6050, USA