1. Professor, Dept. of Civil Engineering, Iran Univ. of Science and Technology, Narmak, 16844 Tehran, Iran (corresponding author).
2. Graduate Student, Dept. of Water Engineering, Isfahan Univ. of Technology, 84156-83111 Isfahan, Iran.
3. Distinguished Professor, Regents Professor and Caroline & William N. Lehrer Distinguished Chair in Water Engineering, Dept. of Biological and Agricultural Engineering and Zachry Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-2117.