1. State Key Lab. of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Beijing 100038 China
2. Center for Agricultural Water Research China Agricultural Univ. Beijing 100083 China
3. Dep. of Geology and Geophysics Texas A&M Univ. College Station TX 77843‐3115 USA
4. Dep. of Biological and Agricultural Engineering Texas A&M Univ. College Station TX 77843‐2117 USA
5. Horticultural Sciences Dep. Univ. of Florida Gainesville FL 32611 USA