1. M.Sc. Student, Faculty of Agricultural Engineering and Technology, Dept. of Irrigation and Reclamation Engineering, College of Agriculture and Natural Resources, Univ. of Tehran, 31587-77871 Tehran, Iran.
2. Professor, Faculty of Agricultural Engineering and Technology, Dept. of Irrigation and Reclamation Engineering, College of Agriculture and Natural Resources, Univ. of Tehran, 31587-77871 Tehran, Iran (corresponding author).
3. Professor, Dept. of Geography, Univ. of California, Santa Barbara, CA 93106.