1. Department of Civil Engineering; Indian Institute of Technology Madras; Chennai Tamil Nadu 600036 India
2. Department of Geology; Baylor University; Waco Texas 76798
3. Freese and Nichols, Inc.; Fort Worth Texas 76109
4. Grassland, Soil and Water Research Laboratory; USDA-ARS; Temple Texas 76502
5. Departments of Ecosystem Sciences and Management and Biological and Agricultural Engineering; Texas A&M University; College Station Texas 77840