Evapotranspiration and Irrigation Water Requirements

This manual, Evapotranspiration and Irrigation Water Requirements (Manual No. 70) , prepared by the Committee on Irrigation Water Requirements of the Irrigation and Drainage Division of the American Society of Civil Engineers, updates the former ASCE report Consumptive Use of Water and Irrigation Water Requirements published in 1974. It incorporates many years of user experience with the previous report and recent advances in the physics of evaporation from plant and soil surfaces. The manual is divided into eight chapters. The first chapter provides the background information on evapotranspiration and irrigation water requirements throughout the world. The next chapter explores various aspects of the soil-plant-atmosphere system while the third discusses energy balance. This is followed by a discussion of evapotranspiration, potential evapotranspiration and crop evapotranspiration. Chapter 5 explores the relationship between evapotranspiration and irrigation water requirements. Chapters 6 and 7 discuss the methods for determining evapotranspiration and the evaluation of these methods respectively. The final chapter states the various ways an engineer might use this data. Therefore, this manual not only provides engineers with the necessary information to modify and improve procedures for estimating evapotranspiration, but it also helps them to evaluate and use this data.