In this paper we present the results of the Wide Area Grid (WAG) project that was carried out within the Working Group on Information Systems and Services (WGISS) of the Committee on Earth Observation Satellites (CEOS). We describe the InterGrid infrastructure that integrates several regional and national Grid systems: Ukrainian Academician Grid (with satellite data processing Grid segment, UASpaceGrid) and Grid system at the Center on Earth Observation and Digital Earth of Chinese Academy of Sciences (CEODE-CAS). The study also focuses on workflow automation and management in Grid environment, and provides an example of workflow automation for generating flood maps from satellite imagery. Examples of utilizing the developed infrastructure for operational flood mapping are given as well.