The Surface Energy Balance Algorithm for Land (SEBAL) is a continuous development from 1989 onwards. It was originally developed for the estimation of evaporation from shallow groundwater tables in the Western Desert of Egypt (Bastiaanssen and Menenti, 1989). The most essential characteristics, which makes SEBAL different from other ETa thermal-infrared algorithms, were first published in Bastiaanssen et al. (1994) based on data collected from the EFEDA project in Spain (Bolle et al., 1993). It was 4 years later that the formulation of the algorithm became more widely accessible (Bastiaanssen et al, 1998a). The description from 1998 was based on the relationship between surface temperature and surface albedo. Applications had learned, meanwhile, that the determination of the slope between surface temperature and surface albedo was associated with poor correlations between the latter two parameters. The slope between surface temperature and surface albedo had a big impact on the aerodynamic resistance, and it was decided and shown in Bastiaanssen (2000) that friction velocities and near-surface aerodynamic resistances could be better computed from field measurements of wind speed.

During the course of the nineties, SEBAL has emerged more as a tool to assess evaporative depletion in river basins with a focus on water consumption of irrigated crops. The looming water crisis has induced worldwide a new thinking on water as a source to lifelyhood, food and feed. Knowledge on the comprehensive ETa is not longer sufficient, and directions to parition ETa in beneficial and non-beneficial usage of water resources are in rapid development.