1. Graduate Student, Dept. of Irrigation and Reclamation, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, Univ. of Tehran, Karaj, 31587-77871 Tehran, Iran.
2. Professor, Dept. of Irrigation and Reclamation, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, Univ. of Tehran, Karaj, 31587-77871 Tehran, Iran (corresponding author).
3. Assistant Professor, Dept. of Civil Engineering, Iran Univ. of Science and Technology, 31587-77871 Tehran, Iran.
4. Professor, Dept. of Geography, Univ. of California, Santa Barbara, CA 93016-4060.