A heavy rain accompanied by a front hit Saga prefecture in Kyushu, Japan in August 2019, flooded the Rokkaku river and others, and brought an inundation disaster nearby. Geospatial Information Authority of Japan (GSI), which is one of the designated government oraganizations enacted by the Disaster Countermeasures Basic Act, took aerial photographs and produced inundation-depth estimation maps to support activities of relevant disaster management organizations. These products were also published on GSI's website for general use. This article shows major GSI's activities, especially for providing the geospatial products that are helpful for flood disaster management. In addition, outreach activities to government and public organizations that conduct disaster response activities are also reported.