Crop and hydrological models have large variation in prediction of evapotranspiration (ET), evaporation (E) and transpiration (T), both in methodology and results. A concentrated effort by various groups of scientists is underway to improve the ET modules in crop and hydrological models. This symposium would focus on papers across a wide range of ET research, spatial-temporal-multiple techniques and models, which may directly or indirectly support the improvement in crop and hydrological models. Emphasis would be given on issues such as accuracy, uncertainty, sensitivity and limitation of ET estimations in hydrologic and crop models and on papers providing theoretical discussions on the measurement and modeling of ET. At least two invited speakers will be featured; contributed presentations are highly encouraged and welcomed.