1. Professor, Dept. of Civil Engineering, Colorado State Univ., Fort Collins, CO 80523.
2. Assistant Professor, Dept. of Environmental and Resource Sciences, Univ. of Nevada Reno, MS 186, 1000 Valley Rd., Reno, NV 89512.
3. Associate Professor, Dept. of Civil Engineering, Colorado State Univ., Fort Collins, CO 80523.