1. Research Engineer, USDA, ARS, Grazinglands Research Laboratory, 7202 W. Cheyenne, El Reno, OK 73036.
2. Research Hydrologist, USDA, ARS, Grazinglands Research Laboratory, 7202 W. Cheyenne, El Reno, OK 73036.
3. Professor, Dept. of Biosystems and Agricultural Engineering, Oklahoma State Univ., Stillwater, OK 74078.