1. Assistant Professor, Dept. of Biological Systems Engineering, Univ. of Nebraska-Lincoln, 241 L.W. Chase Hall, Lincoln, NE 68583-0726 (corresponding author).
2. Assistant Professor, School of Natural Resources and Dept. of Civil Engineering, Univ. of Nebraska-Lincoln, 311 Hardin Hall, Lincoln, NE 68583-0973.
3. Supervisory Agricultural Engineer and Research Leader, USDA-ARS Conservation and Production Research Laboratory, P.O. Drawer 10, Bushland, TX 79012-0010.
4. Professor, Dept. of Biological Systems Engineering, Univ. of Nebraska-Lincoln, 243 L.W. Chase Hall, Lincoln, NE 68583-0726.
5. Senior Research Scientist, Dept. of Primary Industries and Fisheries, Irrigated Farming Systems, 203 Tor St., P.O. Box 102, Toowoomba, Qld4350, Australia.