1. Associate Professor, Dept. of Applied Mathematics, Indian School of Mines, Dhanbad 826004, Jharkhand, India (corresponding author).
2. Project Fellow, Dept. of Applied Mathematics, Indian School of Mines, Dhanbad 826004, Jharkhand, India.
3. Caroline & William N. Lehrer Distinguished Chair in Water Engineering and Professor, Dept. of Biological and Agricultural Engineering and Dept. of Civil & Environmental Engineering, Texas A&M Univ., 321 Scoates Hall, 2117 TAMU, College Station, TX 77843-2117.