Survey on how residents perceive “Senjo-Kousuitai” information

Abstract

In recent years, the occurrence of band-shaped areas of heavy rainfall “Senjo-Kousuitai” is increasing. The Japan Meteorological Agency has issued "Information on Significant Heavy Rain" from June 2021 and displays the rain area of “Senjo-Kousuitai” with a red ellipse, but there is no sufficient knowledge about how to disseminate this information. In this study, we analyzed the problem of information on “Senjo-Kousuitai” and conducted an online questionnaire survey on the risk recognition of the residents when this information was issued.

As a result, it was confirmed that displaying the ellipse of “Senjo-Kousuitai” over the precipitation distribution map has the effect of increasing the risk recognition at that point. On the other hand, it was suggested that the points without the ellipse were recognized as having a lower risk than the points with the ellipse, and could be regarded as “safety information”. It was also shown that the more correctly the person understand the phenomenon of “Senjo-Kousuitai”, the more highly the person might recognize the risk of “Senjo-Kousuitai”. It was also suggested that a correct understanding of “Senjo-Kousuitai” may be more effective in raising the risk recognition of “Senjo-Kousuitai” than by presenting an ellipse.

It was shown that the risk recognition may be higher if the ellipse of “Senjo-Kousuitai” is displayed even at a point far from the heavy rain area or “Senjo-Kousuitai”. Currently, the Japan Meteorological Agency does not issue information on “Senjo-Kousuitai” unless Real-time Landslide or Inundation Risk becomes to more than Level 4 equivalent. However, the results suggest it is meaningful to inform people away from “Senjo-Kousuitai” of its occurrence including cases where it occurs at sea.