1. Associate Professor, Dept. of Water Resources Engineering, Bangladesh Univ. of Engineering and Technology, Dhaka 1000, Bangladesh (corresponding author).
2. Professor, School of Geography, Earth and Environmental Sciences, Univ. of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
3. Senior Lecturer, Dept. of Engineering, Queen Mary, Univ. of London, Mile End Rd., London E1 4NS, U.K.