Demographic changes associated with rainfall-induced landslides and floods in a rural area with a declining population: A case study in Asakura City, Northern Kyushu, Japan

Landslide disasters often occur in rural settings; however, their demographic impacts have not been sufficiently examined. This study demonstrated the demographic changes associated with the 2017 rainfall-induced landslides and floods in Asakura City, Japan, a rural locality that is experiencing population decline. The onset and persistence of demographic changes following disaster were identified based on deviations from pre-disaster population trends using the logarithm of population change. Among Asakura's 19 communities, three that were already experiencing population decline exhibited impacts from the disaster. In these areas, accelerated decline persisted for 1–5 years, with 1.9 to 3.4 times greater than the pre-disaster levels. Analysis using a penalized logistic model revealed that the magnitude of physical damage (fatalities, housing damage, and road damage), rather than hazard magnitude (area coverage of landslides, floods, and woody debris deposits), was related to whether demographic changes occurred. In particular, the housing damage rate emerged as the strongest explanatory factor. Furthermore, the duration of population decline was positively correlated with the extent of physical damage. This study provides additional empirical evidence for the disaster–demography literature and supports decision-making for more effective landslide mitigation and community sustainability in the face of climate change. • Demographic changes associated with rainfall-induced landslides were demonstrated in a Japanese rural area. • Three communities showed accelerated population decline after the 2017 landslide disaster. • Population declines were up to 3.4 times higher than pre-disaster trends and lasted up to 5 years. • Housing damage was the strongest factor influencing demographic changes.