ABSTRACT
Many of the chapters in this book deal with remote-sensing-based techniques for mapping irrigated area, primarily aimed at better estimating production, current water use, and future potential for development. However, such measures are all essentially indirectly calculated from estimated area and secondary data on the crop pattern, water supply, or evapotranspiration (ET) calculated by well-known techniques, such as the Penman-Monteith Procedure [1]. It is highly desirable to be able to calculate water consumption and production data directly, and to account for their temporal and spatial variability. This chapter deals with the use of both remote sensing to directly estimate water consumption by irrigated crops, and secondary agricultural statistics to consequently derive irrigation performance and water productivity (WP) indicators.
