Proceedings of the International Symposium on Lysimetry, held in Honolulu, Hawaii, July 23-25, 1991. This collection contains 49 papers on lysimeters--instruments used extensively to provide baseline information for development, calibration, and validation of evapotranspiration methods. Topics include: the history and background of lysimetry; the design and operation of various types of electronic, mechanical, and hydraulic weighing lysimeters; drainage lysimeters; lysimeters for environmental studies; data acquisition systems; environmental requirements necessary for accurate measurement of evapotranspiration; and the development of evapotranspiration equations and cropping factors.