1. Prof., Dept. of Civ. Engrg., Istanbul Tech. Univ., 80626 Istanbul, Turkey.
2. Prof., Dept. of Hydr. and Envir. Engrg., Universidad Catolica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile.
3. Prof., Hydrologic Sci. and Engrg. Program, Dept. of Civ. Engrg., Colorado State Univ., Fort Collins, CO 80523.