GEORGE H. HARGREAVES received bachelor's degrees in soils from the University of California, Berkeley and in Civil Engineering from the University of Wyoming. He has worked in soils, irrigated agriculture, or water resource development for various universities and governmental agencies. He retired in 1986 as Director of Research for the International Irrigation Center, Utah State University.

Professor Hargreaves has continued with consulting assignments, research, and preparation of professional papers. From 1992-1996 he served a Chair of the Working Group on Crops and Water Use for the U.S. Commission for Irrigation and Drainage. He developed methods for computing evapotranspiration and crop water requirements. The methods are now used world-wide. He is also providing assistance for the publication of a World Climate Atlas for Agriculture that utilizes the Hargreaves methods for more than 56,000 weather stations. In 1997 he received the Royce J. Tipton Award, the most prestigious award in irrigation given by the American Society of Civil Engineering (ASCE).

GARY P. MERKLEY is an Assistant Professor in the Biological and Irrigation Engineering Department at Utah State University. He grew up on a large irrigated farm in California and managed all irrigation activities before returning to complete his Ph.D. at USU. He has developed several software applications and simulation models for canal hydraulics and irrigation water management, and continues to develop new applications. Dr. Merkley has worked and lived overseas through-out much of his career at USU, and currently teaches graduate classes at USU, conducts research, and works on various domestic and international irrigation projects.