1. Graduate Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801. E-mail: abad@uiuc.edu
2. Professor and Head of Dept. of Geography, Univ. of Illinois at Urbana-Champaign, 220 Davenport Hall, 607 South Mathews Ave., Urbana, IL 61801. E-mail: brhoads@uiuc.edu
3. Assistant Professor, Dept. of Geography, Texas A&M Univ., College Station, TX 77843-3147. E-mail: guneralp@geog.tamu.edu
4. Chester and Helen Siess Professor, Dept. of Civil and Environmental Engineering, Univ. Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801. E-mail: mhgarcia@uiuc.edu