1. Department of Earth and Environmental Sciences; Vanderbilt University; Nashville TN 37240 USA
2. Department of Civil and Environmental Engineering; Vanderbilt University; Nashville TN 37235 USA
3. School of Geographical Sciences and Urban Planning; Arizona State University; Tempe AZ 85281 USA
4. Department of Earth and Environmental Science; University of Pennsylvania; Philadelphia PA 19104 USA
5. Division of Hydrologic Sciences; Desert Research Institute; Reno NV 89512 USA