The Committee on the Unsaturated Zone was reconstituted in fall of 1984 under the direction of the incoming president of the AGU Hydrology Section. The committee met at San Francisco during the AGU Fall Meeting in December 1984.
A special session entitled “Evapotranspiration Modeling: Its Verification and Use” was jointly chaired by J. F. Stone and R. J. Reginato during the 1984 Fall Meeting in San Francisco. There were nine invitecf presentations and four contributed presentations. The purpose was to explore the utilization of models to evapotranspiration (ET) on watershed scale and to investigate why models developed for small-scale application are not of-ten suited for large scale phenomena. Principles of ET modeling over areas of many hundreds or millions of square kilometers bear special consideration and recent advances were covered. Techniques of remote sensing of input data for models are being developed and potential operational models were discussed. A summary report of the special session, highlighting points and challenges that emerged from the presentations, is under preparation by the cochairman and will appear in WaterWatch.