Evapotranspiration（ET） is not only an important part of the coupled Eco-Hydrological processes

but also primary way of eco-agricultural consumption.A better description of the temporal-spatial pattern of a watershed greatly will enhance people’s understanding of hydrological processes and the water management approach.As quantitative measurement of surface heterogeneity

remote sensing and surface observations are combined to develop operational methods and determine eco-hydrological variables.ETWatch is such an operational platform which is designed for practical needs of watershed planning and agricultural water management using remote sensing techniques that can describe the spatial distribution and time process of surface net radiation

sensible heat

and latent heat（ET）.The reviewing of algorithms and approaches show that the parametric approach is the core component to improve the accuracy of ET estimation at regional scale and apply remote sensed ET for practical goals.The other bottlenecks include scaling

multi-source data integration and validation of modeling.Potential approaches used in ETWatch to the above issues are summarized and commented.