1. Doctoral Student, Environmental and Earth Sciences Program, Univ. of Texas at Arlington, 500 Yates St., Arlington, TX 76019-0049.
2. Associate Professor, Environmental and Earth Sciences Program, Univ. of Texas at Arlington, 500 Yates St., Arlington, TX 76019-0049; Dept. of Civil Engineering, Univ. of Texas at Arlington, 416 Yates St., Arlington, TX 76019-0308 (corresponding author).