Fundamentals of Evapotranspiration aims to determine simple methods to evaluate evapotranspiration and to examine the evolution of these methods over time. It compares and contrasts best practices and discusses the opportunities for harmonization among various methods. Further, the book discusses optimal calibration of these methods in a local context, depending on particular climates and scenarios. The book serves as a practical resource for students and professionals working in agriculture, irrigation and water engineering and will aid in evaluating the methods and equations for the most efficient means of evapotranspiration. The authors examine the methods for evaluating evapotranspiration considering the evaporation from water surfaces, soil and vegetation. The authors address issues according to various regions, climates and soil types, and apply the optimal solution for each situation.