1. Dept. of Civil and Environmental Engineering, Univ. of Houston, Houston, TX 77204-4003; presently, Water Resources Engineer, E.I.T. at Jacob Engineering Group, 5985 Rogerdale Rd., Houston, TX 77072.
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Houston, Houston, TX 77204-4003 (corresponding author).