Joso city flood GSI information

The Geospatial Institute in Tsukuba has made a huge amount of maps available regarding this flood. I highlighted a few of them in this post. Check their website for more detailed information and presentations (in Japanese). Land use maps are also available.

Most easy to understand are these before/after and during/after maps:
before/after
during/after

They also show the progression of the flood through time on aerial photos (click for larger version):

The affected houses and agricultural areas are well documented, and the elevation map shows the bowl structure the city lies in between the two rivers Kinu (West) and Kokai (East). The north point experienced over-topping, the south point experienced a levee breach.

This final map shows the changes in the estimated inundation range of Ibaraki Joso City according to the heavy rain of typhoon 18 in 2015, September 11 to 15. The total affected area was 40km2.