1. Senior Member of the Technical Staff, Geoscience Research and Applications, Sandia National Laboratories, PO Box 5800 MS 0751, Albuquerque, NM 87185 (corresponding author).
2. Senior Scientist, Discrete Math and Complex Systems, Sandia National Laboratories, PO Box 5800 MS 1318, Albuquerque, NM 87185.
3. Research Scientist, United States Environmental Protection Agency, Water Infrastructure Protection Division, Mail Stop NG-16/NB21F, 26 West Martin Luther King Dr., Cincinnati, OH 45268.