Map shows up to 4.8 meters of floodwater estimated to have covered part of Okayama Pref.

TOKYO -- The Geospatial Information Authority of Japan (GSI) on July 10 released a map estimating areas submerged by floodwater following record-breaking torrential rain and its depth around the Mabicho district of Kurashiki, Okayama Prefecture.

The GSI compiled the map by assuming the edges of the flooded areas from buildings in photos and videos that members of the public uploaded to Twitter as well as data on the altitudes of the area. The GSI assumes that the maximum depth of the floodwater was about 4.8 meters.

The map shows the situation in the area as of July 7 when damage from the flood triggered by the swollen Oda River was the most serious. The floodwater was particularly deep near where the Oda River meanders before joining the Takahashi River. The map also shows that the depth of the floodwater was 3 to 4 meters in extensive areas.

The Land, Infrastructure, Transport and Tourism Ministry estimates that an area approximately 1,200 hectares in size around the Mabicho district was submerged at one point.

According to the GSI, the map showing the areas and depths of the flood almost corresponds with a hazard map that had been compiled by the Kurashiki Municipal Government before the disaster.

If the bad weather continues, it is impossible to take aerial photos, making it difficult to compile a map showing a flooded area based on such images. Therefore, the GSI employed the latest method for the first time in compiling the map showing the damage caused by the flood.

(Japanese original by Tomohiro Ikeda, Science & Environment News Department)