Dear Wen Liu and Fumio Yamazaki,

Thank you again for your interesting submission "Detection of inundation areas due to the 2015 Kanto and Tohoku torrential rain in Japan based on multi-temporal ALOS-2 imagery" as well as for the response to the comments of the referees.

The referees agree that the manuscript might be of interest for the readers of NHESS and the flood risk community. However, combining the reports it appears that it is needed to provide a more thorough presentation of the state of the art in SAR based flood mapping and to provide more details on how your method differs from those already published, and, in particular, how it advances your previous study (Yamazaki and lisu 2016). This justification of novelty also requires testing and comparing your method with other approaches.
Such comparison should include quantitative information about performance differences as a basis to assess the improvement and added value. In this line, also a more specific description of the motivation and scientific objective of your study is needed which should make clear the improvement in comparison to other inundation detection methods.
Finally, the transfer of your method to other areas should be discussed.

Your responses seem to take-up most of the constructive comments of the referees and will allow to present your approach and results more clear. However, it is not yet fully clear if and how you are going to compare your method to other approaches and discuss its transferability to other areas.
Therefore, I decided for major revisions.

Please follow the guidelines of NHESS to prepare and submit your revision (as .pdf) including (1) comments from referees/public, (2) author's response to each comment one by one, and (3) author's changes in maqunuscript. Regarding author's changes, a marked-up manuscript version (track changes in Word, latexdiff in LaTeX) converted into a *.pdf. Additionally, you have to upload the new version of the manuscript.

If you have any question regarding the procedure or interpretation of the comments, please do not hesitate to contact me for clarification.

Kind regards,
Kai Schröter

NHESS Editor

Dear Wen Liu and Fumio Yamazaki,
based on the reports of the reviewers for your revised version of the manuscript I am happy to accept your manuscript for publications in NHESS.
Best regards
Kai Schröter